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As compared with White individuals, minorities often face higher barriers to cancer care. Racial and ethnic disparities in patients with solid tumors, particularly those of the prostate and breast, have been well documented. Hematologic malignancies are less common, but an increasing number of studies have documented disparities within this subgroup of cancer, particularly among Black and non-White Hispanics. An increasing armamentarium of therapeutics, including novel chemotherapy agents and targeted molecular, cellular, and immunologic therapies, has highlighted the need for understanding and exploring the differences in care as well as biology, which may lead to disparate outcomes.
Overall, an estimated 186,400 people living in the United States are expected to be diagnosed with leukemia, lymphoma, or myeloma in 2021, and new cases of hematologic malignancies are expected to account for 9.8% of the estimated 1,898,160 new cancer cases diagnosed this year.1
The underlying reasons for disparities are highly complex and multifactorial, and clinicians must consider how the biologic, clinical, demographic, and socioeconomic characteristics of their patients interact. All of these factors can play a role in prognosis and/or access to care.
Disparities in leukemia
Leukemia is a heterogeneous group of diseases affecting both children and adults, but during the past few decades survival rates have steadily improved, particularly among children. Response to therapy and prognosis do vary among leukemia types, but one large analysis reported that there were overall improvements in survival seen across racial/ethnic groups, most age groups, and genders during a 40-year period.2
From 1973 through 2014, survival trends were assessed across four leukemia types: acute lymphoblastic leukemia (ALL), acute myeloid leukemia (AML), chronic myeloid leukemia (CML), and chronic lymphoid leukemia (CLL). After stratifying survival for each leukemia type by race/ethnicity, improvement rates were not uniform among all groups.
For example, there were substantial improvements of leukemia-specific survival in 2010-2014 among Black (81.0%) and Asian (80.0%) patients with CML, as well as younger patients (20-49 years) with CLL (96.0%). But in contrast, Black patients, those with AML, and individuals over the age of 75 years experienced the lowest improvement in survival.
Studies have found that Hispanics have increased rates of ALL and acute promyelocytic leukemia (APL), but lower rates of AML, as compared to Whites. They also tend to be diagnosed at a younger age and have poorer overall survival.3
Demographics may also play a role, as Hispanics born outside the United States had a higher incidence rate of APL versus U.S.-born Hispanics (incidence rate ratio, 1.79; 1.11-2.94). Thus, the higher incidence rates of increased B-cell ALL may be due to heritable genetic factors, while APL may also be attributable to environmental exposures.4
Hispanics living on the Texas-Mexico border were also found to have a higher incidence of chronic myeloid leukemia (RR, 1.28; 95% CI, 1.07-1.51; P = .02) and acute myeloid leukemia (RR, 1.17; 95% CI, 1.04-1.33; P = .0009) as compared with Hispanics living elsewhere in Texas5 AML and CML were more likely to be observed in patients who resided in this border region, and those with ALL, AML, and CML had worse outcomes compared with Hispanics living elsewhere in Texas. In addition, both Hispanic and non-Hispanic patients along the border have a worse prognosis for ALL than patients in other areas of Texas.
“We don’t yet understand if the differences are due to nonbiologic factors, or if biology plays a role because of the more aggressive disease that we’re seeing,” said study author Anna Eiring, PhD, an assistant professor at Texas Tech University, El Paso. “This is a medically underserved region, and even though we are a safety net hospital, many of the Hispanic patients don’t have health insurance.”
They also tend to have worse socioeconomic status compared with non-Hispanic populations, and there may also be lifestyle and environmental factors. “Exposure to environmental toxins may also play a role, as many work in jobs that could put them at risk,” she said. “Lifestyle factors may also play a role.”
AML is a hematopoietic disorder that is characterized by numerous cytogenetic and molecular aberrations, with poor overall survival. Researchers found that Black patients had shorter survival than White patients, based on an analysis of Surveillance Epidemiology and End Results (SEER) Program data, and performing and performed mutational profiling of 1,339 patients with AML treated on frontline Alliance for Clinical Trials in Oncology (Alliance) protocols.6 The disparity was especially pronounced in Black patients under 60 years old, after adjustment for socioeconomic (SEER) and molecular (Alliance) factors. Black race was an independent prognosticator of poor survival.
“Based on our analyses in Black and White AML patients under the age of 60 years, we believe that a differential impact of molecular aberrations, specifically AML-associated gene mutations, contribute to the observed survival disparities,” said study author Ann-Kathrin Eisfeld, MD, an assistant professor in the division of hematology at the Ohio State University, Columbus, and a member of the leukemia research program at the university’s comprehensive cancer center, the James. “For example, NPM1 mutations seem to lack the known positive prognostic impact we are used to seeing in previous studies with White AML patients.”
She noted that when looking at molecular prognosticators just within Black AML patients, researchers found that FLT3-ITD and also IDH2 mutations were associated with poor overall survival. “While FLT3-ITD is a known adverse prognosticator, the significant impact of IDH2 mutations was surprising to us and is currently being further explored,” said Dr. Eisfeld.
“In general, however, it can’t be highlighted enough that while this study suggests an impact of somatic tumor genomics that needs a lot more attention and investigation and ideally, also prospective studies, structural racism and its impact is still the problem,” she emphasized. “It’s the ‘elephant in the room’ and the major factor that needs to be addressed in order to improve and overcome these survival disparities.”
Disparities in lymphoma
Similar to leukemia, lymphomas are a heterogenous and diverse group of malignancies that range from indolent to highly aggressive. The two main types are listed below:
Non-Hodgkin lymphoma (NHL), the most common subtype, with about 80,000 new cases a year in the United States. There are more than 90 types of NHL, the most common being B-cell lymphomas, which include diffuse large B cell, primary mediastinal B cell, follicular, small lymphocytic lymphoma, and chronic lymphocytic leukemia; marginal zone, mantle zone, and Burkitt lymphomas; and Waldenström macroglobulinemia.
Hodgkin lymphoma (HL), less common than NHL, with about 9,000 people diagnosed every year. There are five types of HL, and it is primarily seen in children and young adults.
Disparities in incidence, age at diagnosis, and overall survival have been observed in lymphoma, which, aside from marginal zone and follicular lymphoma, are more common among men. The incidence of most lymphoma subtypes is generally lower in racial and ethnic minority groups, although Black and Hispanic patients tend to be diagnosed at a younger age, and in Black patients, at a more advanced stage and the lymphomas have higher risk features at initial presentation.7
One study that looked at racial disparities in Hodgkin lymphoma found that HL was significantly more common in Hispanics versus Whites under the age of 65 years. The 5-, 10-, and 15-year overall survival rates were also inferior for Blacks and Hispanics compared with Whites (P less than 0.005 and P less than 0.001, respectively).8
Diffuse large B-cell lymphoma (DLBCL) is the most common subtype of non-Hodgkin lymphoma in the United States, comprising approximately one-third of lymphomas diagnosed in adults (Lee et al. 2020). In one study that examined ancestry and tumor genomics, recurrent somatic mutations in established driver genes, such as ATM, MGA, SETD2, TET2, DNMT3A, and MLL3, were observed more frequently in patients with African ancestry versus those of European ancestry.9 Other data suggest a variety of disparities in receipt of treatment. For example, patients with localized disease who were Black, uninsured/Medicaid insured, or of lower socioeconomic status were less likely to receive any form of chemotherapy (all P less than 0.0001), and Black race was also associated with being less likely to receive chemoimmunotherapy.
Leveling the field of disparities is complex and requires a multifaceted approach. But one facility found that they could help minority patients overcome some of the hurdles related to nonbiologic factors by the support of a nurse navigator in addition to therapy.10 Their study included 204 patients with DLBCL (47 minority patients and 157 White patients) and following the initiation of the nurse navigator program, virtually all patients received frontline chemotherapy (98% versus 96%). The incidence of relapsed/refractory disease was similar (40% versus 38%) and in the relapsed/refractory population, similar proportions of patients underwent hematopoietic stem cell transplantation (32% versus 29%) or received chimeric antigen receptor T-cell therapy (16% versus 19%). The 2-year overall survival rates were 81% and 76% for minorities and Whites, respectively, and 2-year progression-free survival rates were 62% and 65%, respectively.
“We found that the minority patients often needed more help to get care, and they utilized the nurse navigator more intensively,” said study author Bei Hu, MD, who is with the department of hematologic oncology and blood disorders, Levine Cancer Institute/Atrium Health, Charlotte, N.C. “The nurse navigator was able to help them with things like finances, transportation, and insurance.”
Minorities tended to face more barriers than White patients. “Even something as simple as needing money for gas to get to the clinic can be a barrier to care,” said Dr. Hu. “And many of the patients are often uncomfortable discussing these things with their physician – plus a lot is covered in our appointments and we focus on the cancer. So, they may be more comfortable discussing these issues with the nurse.”
Disparities in multiple myeloma
Multiple myeloma is the malignant clonal proliferation of plasma B cells in the bone marrow and, despite the advent of new therapies, remains incurable and generally fatal. It progresses from the more common but often subclinical precursor states of monoclonal gammopathy of undetermined significance (MGUS) and smoldering multiple myeloma (SMM) to overt and symptomatic multiple myeloma. Racial disparities have been observed in all stages of the disease, and as compared with Whites, individuals who are Black have a higher risk of MGUS and myeloma and a higher mortality rate.11 They have not experienced the same survival gains seen in White patients.
Some research suggests that these disparities may be more related to socioeconomic status as opposed to race. One analysis of 562 patients found that those with higher socioeconomic status had a median overall survival of 62.8 months compared with 53.7 and 48.6 months for middle and low socioeconomic status (P = 0.015).12
After controlling for confounders including race, patients with low socioeconomic status had a 54% increase in mortality rate relative to those with high status. The authors then performed a similar analysis of 45,505 patients with multiple myeloma from the S
“In some homogeneous health systems, such as the VA, we are seeing that Black patients do as well or better than White patients,” said Catherine Marinac, PhD, an assistant professor of medicine, Harvard Medical School, Boston. “Survival is equal or better, as long as treatment is not delayed and they receive the standard of care.”
Black patients generally have a more indolent disease subtype and may experience less aggressive disease, but they have not experienced the same magnitude in survival as White patients following the introduction of new therapeutics. This disparity lends support to the influence of socioeconomic factors, such as unequal access to novel therapies and/or differences in treatment response, and lower rates of autologous stem cell transplantation.13
However, there are racial/ethnic differences in risk for both myeloma and its premalignant conditions, as well as incidence. Blacks have a twofold increased risk of myeloma compared with White individuals and are diagnosed at younger ages. Differences in myeloma incidence is less marked in other racial/ethnic groups, such as Hispanics, where it is only slightly higher than in Whites at 6.7 per 100,00.11 In contrast, the incidence of myeloma is markedly lower in Asians as compared with non-Hispanic Whites (incidence rate of 3.8 versus 6.2 per 100,000). Black persons also have a markedly higher prevalence of MGUS, and these differences suggest that biology, and clinical characteristics, differ by race or ancestry.
“Mortality among Black patients is also higher,” said Dr. Marinac, who is also on the faculty in the division of population sciences at the Dana Farber Cancer Institute, also in Boston. “The higher mortality rate is driven by the higher incidence.”
There are also differences in the prevalence of immunoglobulin isotypes observed across racial/ethnic groups of MGUS patients, Dr. Marinac explained, which is consistent with the hypothesis that there is a biological basis for disparities arising in precursor lesions.
“What we are looking at now is cancer prevention and early intervention,” she said. “There are well-defined precursors to myeloma, and Blacks are three times more likely to have a precursor condition.”
Early detection of precursors followed by preventing progression to full-blown multiple myeloma is one way of addressing disparities, but right now, there are no real screening guidelines. “Most patients now are diagnosed incidentally, and then the only intervention is to monitor them,” Dr. Marinac said. “At Dana Farber, we are now looking to see if we can refine screening, and then see who may need additional monitoring.”
The Promise study, being conducted at Dana Farber, is recruiting participants to examine the molecular changes that occur when precursor conditions develop into full-blown multiple myeloma and is open to individuals considered to be at high risk: Black race and/or have a first-degree relative with multiple myeloma or one of its precursor conditions.
Dr. Marinac also pointed out that there are ongoing clinical trials that are looking at low-risk early interventions in patients with precursor conditions. “We are now looking at lifestyle and metformin,” she said. “The thought is that if we treat them now, we can prevent myeloma from developing.”
Lessening barriers to care
When trying to tease out the strongest/most prominent reasons for the disparities that have been observed in the care of patients with blood cancers, Stephanie Lee, M.D., M.P.H, professor and associate director of the clinical research division at Fred Hutchinson Cancer Research Center, Seattle, thinks that the problem is truly multifactorial.
“Access has been cited many times because some studies show that if access is equitable, sometimes racial/ethnic minorities do the same as non-Hispanic Whites,” she said. “Same thing with quality of care – if all people are treated on clinical trials, sometimes the outcomes are the same.”
That said, many things have to go right to get the best outcomes, and if one factor isn’t optimal, then treatment may never achieve the success that is possible, she noted.
Considering how complex the issue of disparities is, addressing it can seem daunting. Dr. Lee points out that the place to begin is with clinical trials. “I would like to see more studies that test interventions to correct disparities,” said Dr. Lee. “But I have actually seen in my own work that racial and ethnic minorities are less likely to participate in studies, even survey and observational studies where physical risks are low or nonexistent.”
People are studying how to increase minority participation in clinical trials, but thus far, there isn’t one solution. “As with routine care, there are probably a lot of logistical barriers to trial participation that disproportionately affect minority populations,” she noted. “There is also greater distrust of studies.”
But for now, there are some steps that clinicians can take to start to improve these disparities. “I think we can start inquiring about and documenting barriers to care and clinical trial participation, just like we document other aspects of the social history,” Dr. Lee explained. “Truly understanding the problem is the first step toward trying to solve it.”
References
1. Leukemia & Lymphoma Society. 2021. www.lls.org/facts-and-statistics/facts-and-statistics-overview.
2. Utuama O et al. PLoS One. 2019 Aug 19;14(8):e0220864.
3. Pollyea DA et al. J Cancer Prev Curr Res. 2014;1(1):14-19.
4. Bencomo-Alvarez AE et al. Cancer. 2021 Apr 1;127(7):1068-79.
5. Nabhan C et al. Cancer. 2012 Oct 1;118(19):4842-50.
6. Bhatnagar B et al. Blood. 2020;136(Suppl 1):5-7.
7. Shenoy PJ et al. Cancer. 2011;117:2530-40.
8. Evens AM et al. Ann Oncol. 2012 Aug 1;23(8):2128-37.
9. Lee MJ et al. Cancer. 2020;126:3493-3503.
10. Hu B et al. Cancer. 2021 Jul 21. doi: 10.1002/cncr.33779.
11. Marinac CR et al. Blood Cancer J. 2020 Feb 17;10(2):19.
12. Fiala MA et al. Leuk Lymphoma. 2015;56(9):2643-9.
13. Costa LJ et al. Biol Blood Marrow Transplant. 2015 Apr;21(4):701-6.
As compared with White individuals, minorities often face higher barriers to cancer care. Racial and ethnic disparities in patients with solid tumors, particularly those of the prostate and breast, have been well documented. Hematologic malignancies are less common, but an increasing number of studies have documented disparities within this subgroup of cancer, particularly among Black and non-White Hispanics. An increasing armamentarium of therapeutics, including novel chemotherapy agents and targeted molecular, cellular, and immunologic therapies, has highlighted the need for understanding and exploring the differences in care as well as biology, which may lead to disparate outcomes.
Overall, an estimated 186,400 people living in the United States are expected to be diagnosed with leukemia, lymphoma, or myeloma in 2021, and new cases of hematologic malignancies are expected to account for 9.8% of the estimated 1,898,160 new cancer cases diagnosed this year.1
The underlying reasons for disparities are highly complex and multifactorial, and clinicians must consider how the biologic, clinical, demographic, and socioeconomic characteristics of their patients interact. All of these factors can play a role in prognosis and/or access to care.
Disparities in leukemia
Leukemia is a heterogeneous group of diseases affecting both children and adults, but during the past few decades survival rates have steadily improved, particularly among children. Response to therapy and prognosis do vary among leukemia types, but one large analysis reported that there were overall improvements in survival seen across racial/ethnic groups, most age groups, and genders during a 40-year period.2
From 1973 through 2014, survival trends were assessed across four leukemia types: acute lymphoblastic leukemia (ALL), acute myeloid leukemia (AML), chronic myeloid leukemia (CML), and chronic lymphoid leukemia (CLL). After stratifying survival for each leukemia type by race/ethnicity, improvement rates were not uniform among all groups.
For example, there were substantial improvements of leukemia-specific survival in 2010-2014 among Black (81.0%) and Asian (80.0%) patients with CML, as well as younger patients (20-49 years) with CLL (96.0%). But in contrast, Black patients, those with AML, and individuals over the age of 75 years experienced the lowest improvement in survival.
Studies have found that Hispanics have increased rates of ALL and acute promyelocytic leukemia (APL), but lower rates of AML, as compared to Whites. They also tend to be diagnosed at a younger age and have poorer overall survival.3
Demographics may also play a role, as Hispanics born outside the United States had a higher incidence rate of APL versus U.S.-born Hispanics (incidence rate ratio, 1.79; 1.11-2.94). Thus, the higher incidence rates of increased B-cell ALL may be due to heritable genetic factors, while APL may also be attributable to environmental exposures.4
Hispanics living on the Texas-Mexico border were also found to have a higher incidence of chronic myeloid leukemia (RR, 1.28; 95% CI, 1.07-1.51; P = .02) and acute myeloid leukemia (RR, 1.17; 95% CI, 1.04-1.33; P = .0009) as compared with Hispanics living elsewhere in Texas5 AML and CML were more likely to be observed in patients who resided in this border region, and those with ALL, AML, and CML had worse outcomes compared with Hispanics living elsewhere in Texas. In addition, both Hispanic and non-Hispanic patients along the border have a worse prognosis for ALL than patients in other areas of Texas.
“We don’t yet understand if the differences are due to nonbiologic factors, or if biology plays a role because of the more aggressive disease that we’re seeing,” said study author Anna Eiring, PhD, an assistant professor at Texas Tech University, El Paso. “This is a medically underserved region, and even though we are a safety net hospital, many of the Hispanic patients don’t have health insurance.”
They also tend to have worse socioeconomic status compared with non-Hispanic populations, and there may also be lifestyle and environmental factors. “Exposure to environmental toxins may also play a role, as many work in jobs that could put them at risk,” she said. “Lifestyle factors may also play a role.”
AML is a hematopoietic disorder that is characterized by numerous cytogenetic and molecular aberrations, with poor overall survival. Researchers found that Black patients had shorter survival than White patients, based on an analysis of Surveillance Epidemiology and End Results (SEER) Program data, and performing and performed mutational profiling of 1,339 patients with AML treated on frontline Alliance for Clinical Trials in Oncology (Alliance) protocols.6 The disparity was especially pronounced in Black patients under 60 years old, after adjustment for socioeconomic (SEER) and molecular (Alliance) factors. Black race was an independent prognosticator of poor survival.
“Based on our analyses in Black and White AML patients under the age of 60 years, we believe that a differential impact of molecular aberrations, specifically AML-associated gene mutations, contribute to the observed survival disparities,” said study author Ann-Kathrin Eisfeld, MD, an assistant professor in the division of hematology at the Ohio State University, Columbus, and a member of the leukemia research program at the university’s comprehensive cancer center, the James. “For example, NPM1 mutations seem to lack the known positive prognostic impact we are used to seeing in previous studies with White AML patients.”
She noted that when looking at molecular prognosticators just within Black AML patients, researchers found that FLT3-ITD and also IDH2 mutations were associated with poor overall survival. “While FLT3-ITD is a known adverse prognosticator, the significant impact of IDH2 mutations was surprising to us and is currently being further explored,” said Dr. Eisfeld.
“In general, however, it can’t be highlighted enough that while this study suggests an impact of somatic tumor genomics that needs a lot more attention and investigation and ideally, also prospective studies, structural racism and its impact is still the problem,” she emphasized. “It’s the ‘elephant in the room’ and the major factor that needs to be addressed in order to improve and overcome these survival disparities.”
Disparities in lymphoma
Similar to leukemia, lymphomas are a heterogenous and diverse group of malignancies that range from indolent to highly aggressive. The two main types are listed below:
Non-Hodgkin lymphoma (NHL), the most common subtype, with about 80,000 new cases a year in the United States. There are more than 90 types of NHL, the most common being B-cell lymphomas, which include diffuse large B cell, primary mediastinal B cell, follicular, small lymphocytic lymphoma, and chronic lymphocytic leukemia; marginal zone, mantle zone, and Burkitt lymphomas; and Waldenström macroglobulinemia.
Hodgkin lymphoma (HL), less common than NHL, with about 9,000 people diagnosed every year. There are five types of HL, and it is primarily seen in children and young adults.
Disparities in incidence, age at diagnosis, and overall survival have been observed in lymphoma, which, aside from marginal zone and follicular lymphoma, are more common among men. The incidence of most lymphoma subtypes is generally lower in racial and ethnic minority groups, although Black and Hispanic patients tend to be diagnosed at a younger age, and in Black patients, at a more advanced stage and the lymphomas have higher risk features at initial presentation.7
One study that looked at racial disparities in Hodgkin lymphoma found that HL was significantly more common in Hispanics versus Whites under the age of 65 years. The 5-, 10-, and 15-year overall survival rates were also inferior for Blacks and Hispanics compared with Whites (P less than 0.005 and P less than 0.001, respectively).8
Diffuse large B-cell lymphoma (DLBCL) is the most common subtype of non-Hodgkin lymphoma in the United States, comprising approximately one-third of lymphomas diagnosed in adults (Lee et al. 2020). In one study that examined ancestry and tumor genomics, recurrent somatic mutations in established driver genes, such as ATM, MGA, SETD2, TET2, DNMT3A, and MLL3, were observed more frequently in patients with African ancestry versus those of European ancestry.9 Other data suggest a variety of disparities in receipt of treatment. For example, patients with localized disease who were Black, uninsured/Medicaid insured, or of lower socioeconomic status were less likely to receive any form of chemotherapy (all P less than 0.0001), and Black race was also associated with being less likely to receive chemoimmunotherapy.
Leveling the field of disparities is complex and requires a multifaceted approach. But one facility found that they could help minority patients overcome some of the hurdles related to nonbiologic factors by the support of a nurse navigator in addition to therapy.10 Their study included 204 patients with DLBCL (47 minority patients and 157 White patients) and following the initiation of the nurse navigator program, virtually all patients received frontline chemotherapy (98% versus 96%). The incidence of relapsed/refractory disease was similar (40% versus 38%) and in the relapsed/refractory population, similar proportions of patients underwent hematopoietic stem cell transplantation (32% versus 29%) or received chimeric antigen receptor T-cell therapy (16% versus 19%). The 2-year overall survival rates were 81% and 76% for minorities and Whites, respectively, and 2-year progression-free survival rates were 62% and 65%, respectively.
“We found that the minority patients often needed more help to get care, and they utilized the nurse navigator more intensively,” said study author Bei Hu, MD, who is with the department of hematologic oncology and blood disorders, Levine Cancer Institute/Atrium Health, Charlotte, N.C. “The nurse navigator was able to help them with things like finances, transportation, and insurance.”
Minorities tended to face more barriers than White patients. “Even something as simple as needing money for gas to get to the clinic can be a barrier to care,” said Dr. Hu. “And many of the patients are often uncomfortable discussing these things with their physician – plus a lot is covered in our appointments and we focus on the cancer. So, they may be more comfortable discussing these issues with the nurse.”
Disparities in multiple myeloma
Multiple myeloma is the malignant clonal proliferation of plasma B cells in the bone marrow and, despite the advent of new therapies, remains incurable and generally fatal. It progresses from the more common but often subclinical precursor states of monoclonal gammopathy of undetermined significance (MGUS) and smoldering multiple myeloma (SMM) to overt and symptomatic multiple myeloma. Racial disparities have been observed in all stages of the disease, and as compared with Whites, individuals who are Black have a higher risk of MGUS and myeloma and a higher mortality rate.11 They have not experienced the same survival gains seen in White patients.
Some research suggests that these disparities may be more related to socioeconomic status as opposed to race. One analysis of 562 patients found that those with higher socioeconomic status had a median overall survival of 62.8 months compared with 53.7 and 48.6 months for middle and low socioeconomic status (P = 0.015).12
After controlling for confounders including race, patients with low socioeconomic status had a 54% increase in mortality rate relative to those with high status. The authors then performed a similar analysis of 45,505 patients with multiple myeloma from the S
“In some homogeneous health systems, such as the VA, we are seeing that Black patients do as well or better than White patients,” said Catherine Marinac, PhD, an assistant professor of medicine, Harvard Medical School, Boston. “Survival is equal or better, as long as treatment is not delayed and they receive the standard of care.”
Black patients generally have a more indolent disease subtype and may experience less aggressive disease, but they have not experienced the same magnitude in survival as White patients following the introduction of new therapeutics. This disparity lends support to the influence of socioeconomic factors, such as unequal access to novel therapies and/or differences in treatment response, and lower rates of autologous stem cell transplantation.13
However, there are racial/ethnic differences in risk for both myeloma and its premalignant conditions, as well as incidence. Blacks have a twofold increased risk of myeloma compared with White individuals and are diagnosed at younger ages. Differences in myeloma incidence is less marked in other racial/ethnic groups, such as Hispanics, where it is only slightly higher than in Whites at 6.7 per 100,00.11 In contrast, the incidence of myeloma is markedly lower in Asians as compared with non-Hispanic Whites (incidence rate of 3.8 versus 6.2 per 100,000). Black persons also have a markedly higher prevalence of MGUS, and these differences suggest that biology, and clinical characteristics, differ by race or ancestry.
“Mortality among Black patients is also higher,” said Dr. Marinac, who is also on the faculty in the division of population sciences at the Dana Farber Cancer Institute, also in Boston. “The higher mortality rate is driven by the higher incidence.”
There are also differences in the prevalence of immunoglobulin isotypes observed across racial/ethnic groups of MGUS patients, Dr. Marinac explained, which is consistent with the hypothesis that there is a biological basis for disparities arising in precursor lesions.
“What we are looking at now is cancer prevention and early intervention,” she said. “There are well-defined precursors to myeloma, and Blacks are three times more likely to have a precursor condition.”
Early detection of precursors followed by preventing progression to full-blown multiple myeloma is one way of addressing disparities, but right now, there are no real screening guidelines. “Most patients now are diagnosed incidentally, and then the only intervention is to monitor them,” Dr. Marinac said. “At Dana Farber, we are now looking to see if we can refine screening, and then see who may need additional monitoring.”
The Promise study, being conducted at Dana Farber, is recruiting participants to examine the molecular changes that occur when precursor conditions develop into full-blown multiple myeloma and is open to individuals considered to be at high risk: Black race and/or have a first-degree relative with multiple myeloma or one of its precursor conditions.
Dr. Marinac also pointed out that there are ongoing clinical trials that are looking at low-risk early interventions in patients with precursor conditions. “We are now looking at lifestyle and metformin,” she said. “The thought is that if we treat them now, we can prevent myeloma from developing.”
Lessening barriers to care
When trying to tease out the strongest/most prominent reasons for the disparities that have been observed in the care of patients with blood cancers, Stephanie Lee, M.D., M.P.H, professor and associate director of the clinical research division at Fred Hutchinson Cancer Research Center, Seattle, thinks that the problem is truly multifactorial.
“Access has been cited many times because some studies show that if access is equitable, sometimes racial/ethnic minorities do the same as non-Hispanic Whites,” she said. “Same thing with quality of care – if all people are treated on clinical trials, sometimes the outcomes are the same.”
That said, many things have to go right to get the best outcomes, and if one factor isn’t optimal, then treatment may never achieve the success that is possible, she noted.
Considering how complex the issue of disparities is, addressing it can seem daunting. Dr. Lee points out that the place to begin is with clinical trials. “I would like to see more studies that test interventions to correct disparities,” said Dr. Lee. “But I have actually seen in my own work that racial and ethnic minorities are less likely to participate in studies, even survey and observational studies where physical risks are low or nonexistent.”
People are studying how to increase minority participation in clinical trials, but thus far, there isn’t one solution. “As with routine care, there are probably a lot of logistical barriers to trial participation that disproportionately affect minority populations,” she noted. “There is also greater distrust of studies.”
But for now, there are some steps that clinicians can take to start to improve these disparities. “I think we can start inquiring about and documenting barriers to care and clinical trial participation, just like we document other aspects of the social history,” Dr. Lee explained. “Truly understanding the problem is the first step toward trying to solve it.”
References
1. Leukemia & Lymphoma Society. 2021. www.lls.org/facts-and-statistics/facts-and-statistics-overview.
2. Utuama O et al. PLoS One. 2019 Aug 19;14(8):e0220864.
3. Pollyea DA et al. J Cancer Prev Curr Res. 2014;1(1):14-19.
4. Bencomo-Alvarez AE et al. Cancer. 2021 Apr 1;127(7):1068-79.
5. Nabhan C et al. Cancer. 2012 Oct 1;118(19):4842-50.
6. Bhatnagar B et al. Blood. 2020;136(Suppl 1):5-7.
7. Shenoy PJ et al. Cancer. 2011;117:2530-40.
8. Evens AM et al. Ann Oncol. 2012 Aug 1;23(8):2128-37.
9. Lee MJ et al. Cancer. 2020;126:3493-3503.
10. Hu B et al. Cancer. 2021 Jul 21. doi: 10.1002/cncr.33779.
11. Marinac CR et al. Blood Cancer J. 2020 Feb 17;10(2):19.
12. Fiala MA et al. Leuk Lymphoma. 2015;56(9):2643-9.
13. Costa LJ et al. Biol Blood Marrow Transplant. 2015 Apr;21(4):701-6.
As compared with White individuals, minorities often face higher barriers to cancer care. Racial and ethnic disparities in patients with solid tumors, particularly those of the prostate and breast, have been well documented. Hematologic malignancies are less common, but an increasing number of studies have documented disparities within this subgroup of cancer, particularly among Black and non-White Hispanics. An increasing armamentarium of therapeutics, including novel chemotherapy agents and targeted molecular, cellular, and immunologic therapies, has highlighted the need for understanding and exploring the differences in care as well as biology, which may lead to disparate outcomes.
Overall, an estimated 186,400 people living in the United States are expected to be diagnosed with leukemia, lymphoma, or myeloma in 2021, and new cases of hematologic malignancies are expected to account for 9.8% of the estimated 1,898,160 new cancer cases diagnosed this year.1
The underlying reasons for disparities are highly complex and multifactorial, and clinicians must consider how the biologic, clinical, demographic, and socioeconomic characteristics of their patients interact. All of these factors can play a role in prognosis and/or access to care.
Disparities in leukemia
Leukemia is a heterogeneous group of diseases affecting both children and adults, but during the past few decades survival rates have steadily improved, particularly among children. Response to therapy and prognosis do vary among leukemia types, but one large analysis reported that there were overall improvements in survival seen across racial/ethnic groups, most age groups, and genders during a 40-year period.2
From 1973 through 2014, survival trends were assessed across four leukemia types: acute lymphoblastic leukemia (ALL), acute myeloid leukemia (AML), chronic myeloid leukemia (CML), and chronic lymphoid leukemia (CLL). After stratifying survival for each leukemia type by race/ethnicity, improvement rates were not uniform among all groups.
For example, there were substantial improvements of leukemia-specific survival in 2010-2014 among Black (81.0%) and Asian (80.0%) patients with CML, as well as younger patients (20-49 years) with CLL (96.0%). But in contrast, Black patients, those with AML, and individuals over the age of 75 years experienced the lowest improvement in survival.
Studies have found that Hispanics have increased rates of ALL and acute promyelocytic leukemia (APL), but lower rates of AML, as compared to Whites. They also tend to be diagnosed at a younger age and have poorer overall survival.3
Demographics may also play a role, as Hispanics born outside the United States had a higher incidence rate of APL versus U.S.-born Hispanics (incidence rate ratio, 1.79; 1.11-2.94). Thus, the higher incidence rates of increased B-cell ALL may be due to heritable genetic factors, while APL may also be attributable to environmental exposures.4
Hispanics living on the Texas-Mexico border were also found to have a higher incidence of chronic myeloid leukemia (RR, 1.28; 95% CI, 1.07-1.51; P = .02) and acute myeloid leukemia (RR, 1.17; 95% CI, 1.04-1.33; P = .0009) as compared with Hispanics living elsewhere in Texas5 AML and CML were more likely to be observed in patients who resided in this border region, and those with ALL, AML, and CML had worse outcomes compared with Hispanics living elsewhere in Texas. In addition, both Hispanic and non-Hispanic patients along the border have a worse prognosis for ALL than patients in other areas of Texas.
“We don’t yet understand if the differences are due to nonbiologic factors, or if biology plays a role because of the more aggressive disease that we’re seeing,” said study author Anna Eiring, PhD, an assistant professor at Texas Tech University, El Paso. “This is a medically underserved region, and even though we are a safety net hospital, many of the Hispanic patients don’t have health insurance.”
They also tend to have worse socioeconomic status compared with non-Hispanic populations, and there may also be lifestyle and environmental factors. “Exposure to environmental toxins may also play a role, as many work in jobs that could put them at risk,” she said. “Lifestyle factors may also play a role.”
AML is a hematopoietic disorder that is characterized by numerous cytogenetic and molecular aberrations, with poor overall survival. Researchers found that Black patients had shorter survival than White patients, based on an analysis of Surveillance Epidemiology and End Results (SEER) Program data, and performing and performed mutational profiling of 1,339 patients with AML treated on frontline Alliance for Clinical Trials in Oncology (Alliance) protocols.6 The disparity was especially pronounced in Black patients under 60 years old, after adjustment for socioeconomic (SEER) and molecular (Alliance) factors. Black race was an independent prognosticator of poor survival.
“Based on our analyses in Black and White AML patients under the age of 60 years, we believe that a differential impact of molecular aberrations, specifically AML-associated gene mutations, contribute to the observed survival disparities,” said study author Ann-Kathrin Eisfeld, MD, an assistant professor in the division of hematology at the Ohio State University, Columbus, and a member of the leukemia research program at the university’s comprehensive cancer center, the James. “For example, NPM1 mutations seem to lack the known positive prognostic impact we are used to seeing in previous studies with White AML patients.”
She noted that when looking at molecular prognosticators just within Black AML patients, researchers found that FLT3-ITD and also IDH2 mutations were associated with poor overall survival. “While FLT3-ITD is a known adverse prognosticator, the significant impact of IDH2 mutations was surprising to us and is currently being further explored,” said Dr. Eisfeld.
“In general, however, it can’t be highlighted enough that while this study suggests an impact of somatic tumor genomics that needs a lot more attention and investigation and ideally, also prospective studies, structural racism and its impact is still the problem,” she emphasized. “It’s the ‘elephant in the room’ and the major factor that needs to be addressed in order to improve and overcome these survival disparities.”
Disparities in lymphoma
Similar to leukemia, lymphomas are a heterogenous and diverse group of malignancies that range from indolent to highly aggressive. The two main types are listed below:
Non-Hodgkin lymphoma (NHL), the most common subtype, with about 80,000 new cases a year in the United States. There are more than 90 types of NHL, the most common being B-cell lymphomas, which include diffuse large B cell, primary mediastinal B cell, follicular, small lymphocytic lymphoma, and chronic lymphocytic leukemia; marginal zone, mantle zone, and Burkitt lymphomas; and Waldenström macroglobulinemia.
Hodgkin lymphoma (HL), less common than NHL, with about 9,000 people diagnosed every year. There are five types of HL, and it is primarily seen in children and young adults.
Disparities in incidence, age at diagnosis, and overall survival have been observed in lymphoma, which, aside from marginal zone and follicular lymphoma, are more common among men. The incidence of most lymphoma subtypes is generally lower in racial and ethnic minority groups, although Black and Hispanic patients tend to be diagnosed at a younger age, and in Black patients, at a more advanced stage and the lymphomas have higher risk features at initial presentation.7
One study that looked at racial disparities in Hodgkin lymphoma found that HL was significantly more common in Hispanics versus Whites under the age of 65 years. The 5-, 10-, and 15-year overall survival rates were also inferior for Blacks and Hispanics compared with Whites (P less than 0.005 and P less than 0.001, respectively).8
Diffuse large B-cell lymphoma (DLBCL) is the most common subtype of non-Hodgkin lymphoma in the United States, comprising approximately one-third of lymphomas diagnosed in adults (Lee et al. 2020). In one study that examined ancestry and tumor genomics, recurrent somatic mutations in established driver genes, such as ATM, MGA, SETD2, TET2, DNMT3A, and MLL3, were observed more frequently in patients with African ancestry versus those of European ancestry.9 Other data suggest a variety of disparities in receipt of treatment. For example, patients with localized disease who were Black, uninsured/Medicaid insured, or of lower socioeconomic status were less likely to receive any form of chemotherapy (all P less than 0.0001), and Black race was also associated with being less likely to receive chemoimmunotherapy.
Leveling the field of disparities is complex and requires a multifaceted approach. But one facility found that they could help minority patients overcome some of the hurdles related to nonbiologic factors by the support of a nurse navigator in addition to therapy.10 Their study included 204 patients with DLBCL (47 minority patients and 157 White patients) and following the initiation of the nurse navigator program, virtually all patients received frontline chemotherapy (98% versus 96%). The incidence of relapsed/refractory disease was similar (40% versus 38%) and in the relapsed/refractory population, similar proportions of patients underwent hematopoietic stem cell transplantation (32% versus 29%) or received chimeric antigen receptor T-cell therapy (16% versus 19%). The 2-year overall survival rates were 81% and 76% for minorities and Whites, respectively, and 2-year progression-free survival rates were 62% and 65%, respectively.
“We found that the minority patients often needed more help to get care, and they utilized the nurse navigator more intensively,” said study author Bei Hu, MD, who is with the department of hematologic oncology and blood disorders, Levine Cancer Institute/Atrium Health, Charlotte, N.C. “The nurse navigator was able to help them with things like finances, transportation, and insurance.”
Minorities tended to face more barriers than White patients. “Even something as simple as needing money for gas to get to the clinic can be a barrier to care,” said Dr. Hu. “And many of the patients are often uncomfortable discussing these things with their physician – plus a lot is covered in our appointments and we focus on the cancer. So, they may be more comfortable discussing these issues with the nurse.”
Disparities in multiple myeloma
Multiple myeloma is the malignant clonal proliferation of plasma B cells in the bone marrow and, despite the advent of new therapies, remains incurable and generally fatal. It progresses from the more common but often subclinical precursor states of monoclonal gammopathy of undetermined significance (MGUS) and smoldering multiple myeloma (SMM) to overt and symptomatic multiple myeloma. Racial disparities have been observed in all stages of the disease, and as compared with Whites, individuals who are Black have a higher risk of MGUS and myeloma and a higher mortality rate.11 They have not experienced the same survival gains seen in White patients.
Some research suggests that these disparities may be more related to socioeconomic status as opposed to race. One analysis of 562 patients found that those with higher socioeconomic status had a median overall survival of 62.8 months compared with 53.7 and 48.6 months for middle and low socioeconomic status (P = 0.015).12
After controlling for confounders including race, patients with low socioeconomic status had a 54% increase in mortality rate relative to those with high status. The authors then performed a similar analysis of 45,505 patients with multiple myeloma from the S
“In some homogeneous health systems, such as the VA, we are seeing that Black patients do as well or better than White patients,” said Catherine Marinac, PhD, an assistant professor of medicine, Harvard Medical School, Boston. “Survival is equal or better, as long as treatment is not delayed and they receive the standard of care.”
Black patients generally have a more indolent disease subtype and may experience less aggressive disease, but they have not experienced the same magnitude in survival as White patients following the introduction of new therapeutics. This disparity lends support to the influence of socioeconomic factors, such as unequal access to novel therapies and/or differences in treatment response, and lower rates of autologous stem cell transplantation.13
However, there are racial/ethnic differences in risk for both myeloma and its premalignant conditions, as well as incidence. Blacks have a twofold increased risk of myeloma compared with White individuals and are diagnosed at younger ages. Differences in myeloma incidence is less marked in other racial/ethnic groups, such as Hispanics, where it is only slightly higher than in Whites at 6.7 per 100,00.11 In contrast, the incidence of myeloma is markedly lower in Asians as compared with non-Hispanic Whites (incidence rate of 3.8 versus 6.2 per 100,000). Black persons also have a markedly higher prevalence of MGUS, and these differences suggest that biology, and clinical characteristics, differ by race or ancestry.
“Mortality among Black patients is also higher,” said Dr. Marinac, who is also on the faculty in the division of population sciences at the Dana Farber Cancer Institute, also in Boston. “The higher mortality rate is driven by the higher incidence.”
There are also differences in the prevalence of immunoglobulin isotypes observed across racial/ethnic groups of MGUS patients, Dr. Marinac explained, which is consistent with the hypothesis that there is a biological basis for disparities arising in precursor lesions.
“What we are looking at now is cancer prevention and early intervention,” she said. “There are well-defined precursors to myeloma, and Blacks are three times more likely to have a precursor condition.”
Early detection of precursors followed by preventing progression to full-blown multiple myeloma is one way of addressing disparities, but right now, there are no real screening guidelines. “Most patients now are diagnosed incidentally, and then the only intervention is to monitor them,” Dr. Marinac said. “At Dana Farber, we are now looking to see if we can refine screening, and then see who may need additional monitoring.”
The Promise study, being conducted at Dana Farber, is recruiting participants to examine the molecular changes that occur when precursor conditions develop into full-blown multiple myeloma and is open to individuals considered to be at high risk: Black race and/or have a first-degree relative with multiple myeloma or one of its precursor conditions.
Dr. Marinac also pointed out that there are ongoing clinical trials that are looking at low-risk early interventions in patients with precursor conditions. “We are now looking at lifestyle and metformin,” she said. “The thought is that if we treat them now, we can prevent myeloma from developing.”
Lessening barriers to care
When trying to tease out the strongest/most prominent reasons for the disparities that have been observed in the care of patients with blood cancers, Stephanie Lee, M.D., M.P.H, professor and associate director of the clinical research division at Fred Hutchinson Cancer Research Center, Seattle, thinks that the problem is truly multifactorial.
“Access has been cited many times because some studies show that if access is equitable, sometimes racial/ethnic minorities do the same as non-Hispanic Whites,” she said. “Same thing with quality of care – if all people are treated on clinical trials, sometimes the outcomes are the same.”
That said, many things have to go right to get the best outcomes, and if one factor isn’t optimal, then treatment may never achieve the success that is possible, she noted.
Considering how complex the issue of disparities is, addressing it can seem daunting. Dr. Lee points out that the place to begin is with clinical trials. “I would like to see more studies that test interventions to correct disparities,” said Dr. Lee. “But I have actually seen in my own work that racial and ethnic minorities are less likely to participate in studies, even survey and observational studies where physical risks are low or nonexistent.”
People are studying how to increase minority participation in clinical trials, but thus far, there isn’t one solution. “As with routine care, there are probably a lot of logistical barriers to trial participation that disproportionately affect minority populations,” she noted. “There is also greater distrust of studies.”
But for now, there are some steps that clinicians can take to start to improve these disparities. “I think we can start inquiring about and documenting barriers to care and clinical trial participation, just like we document other aspects of the social history,” Dr. Lee explained. “Truly understanding the problem is the first step toward trying to solve it.”
References
1. Leukemia & Lymphoma Society. 2021. www.lls.org/facts-and-statistics/facts-and-statistics-overview.
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11. Marinac CR et al. Blood Cancer J. 2020 Feb 17;10(2):19.
12. Fiala MA et al. Leuk Lymphoma. 2015;56(9):2643-9.
13. Costa LJ et al. Biol Blood Marrow Transplant. 2015 Apr;21(4):701-6.