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Giving a tumor bed boost (TBB) reduced the risk of local recurrence and overall disease recurrence, but there were no significant differences in recurrence rates between conventional WBI and hypofractionated WBI.
Boon Hui Chua, MD, of the University of New South Wales, Sydney, presented these results at the 2020 San Antonio Breast Cancer Symposium.
Dr. Chua and colleagues studied 1,608 women with DCIS resected by conservative surgery. Patients were either younger than 50 years or age 50 and older with at least one of the following risk factors: symptomatic presentation, palpable tumor, multifocal disease, tumor size 1.5 cm or larger, intermediate or high nuclear grade, central necrosis, comedo histology, and/or surgical margins less than 10 mm.
The patients were randomized to treatment in three categories. In randomization A (n = 503), patients were randomized to one of the following treatments:
- WBI at 50 Gy in 25 fractions
- WBI at 42.5 Gy in 16 fractions
- WBI at 50 Gy in 25 fractions plus TBB at 16 Gy in 8 fractions
- WBI at 42.5 Gy in 16 fractions plus TBB at 16 Gy in 8 fractions.
In randomization B (n = 581), patients received WBI at 50 Gy in 25 fractions, with or without TBB at 16 Gy in 8 fractions. In randomization C (n = 524), patients received WBI at 42.5 Gy in 16 fractions, with or without TBB at 16 Gy in 8 fractions.
All patients underwent CT-based radiation planning. WBI was delivered with tangential MV photon beams, and TBB was performed with CT contouring of protocol-defined tumor bed target volumes, with electron or photon energy. The median follow-up was 6.6 years.
Giving a boost to better outcomes
The 5-year rate of freedom from local recurrence was 97% for patients who received TBB and 93% for patients who did not (hazard ratio, 0.47; P < .001). The benefit of TBB was consistent across subgroups.
There were no significant differences in 5-year rates of freedom from local recurrence by WBI fractionation, either in randomization A (P = .837) or among all randomized patients (P = .887).
The tests for interactions between TBB and WBI fractionation on local recurrence were not significant in randomization A (P = .89) or in all randomized patients (P = .89).
The risk of overall disease recurrence was lower among patients who had received TBB, with an HR of 0.63 (P = .004). The 5-year rate of freedom from disease recurrence was 97% with TBB and 91% with no boost (P = .002).
There were no significant differences in freedom from disease recurrence rates by WBI fractionation either in randomization A (P = .443) or among all randomized patients (P = .605).
Acute radiation dermatitis occurred in significantly more patients who received TBB (P = .006), as did late breast pain (P = .003), induration or fibrosis (P < .0001), and telangiectasia (P = .02). There were no significant differences by boost status for acute or late fatigue, pneumonitis, cardiac complications, or second malignancies.
Reduce the boost dose?
A radiation oncologist who was not involved in this study said that, while the results confirm a benefit of boost dose for patients with non–low-risk DCIS, the doses used in the BIG-3-07 study may be higher than needed to achieve a protective effect.
“Here in America, we usually give 10 Gy in five fractions, and, in many countries, actually, it’s 10 Gy in five fractions, although a few European centers give 16 Gy in eight fractions,” said Alphose Taghian, MD, of Massachusetts General Hospital in Boston.
“I personally only give 10 Gy in five fractions. I am not under the impression that 16 Gy in eight fractions will give better results. The local failure rate is so low, it’s likely that 10 Gy will do the job,” Dr. Taghian said in an interview.
Dr. Taghian noted that raising the dose to 16 Gy increases the risk of fibrosis, as seen in the BIG-3-07 trial.
Nonetheless, the trial demonstrates the benefit of radiation boost dose in patients with high-risk DCIS, he said, adding that the local recurrence-free benefit curves may separate further with longer follow-up.
The study was sponsored by the Trans Tasman Radiation Oncology Group. Dr. Chua and Dr. Taghian reported no conflicts of interest.
Giving a tumor bed boost (TBB) reduced the risk of local recurrence and overall disease recurrence, but there were no significant differences in recurrence rates between conventional WBI and hypofractionated WBI.
Boon Hui Chua, MD, of the University of New South Wales, Sydney, presented these results at the 2020 San Antonio Breast Cancer Symposium.
Dr. Chua and colleagues studied 1,608 women with DCIS resected by conservative surgery. Patients were either younger than 50 years or age 50 and older with at least one of the following risk factors: symptomatic presentation, palpable tumor, multifocal disease, tumor size 1.5 cm or larger, intermediate or high nuclear grade, central necrosis, comedo histology, and/or surgical margins less than 10 mm.
The patients were randomized to treatment in three categories. In randomization A (n = 503), patients were randomized to one of the following treatments:
- WBI at 50 Gy in 25 fractions
- WBI at 42.5 Gy in 16 fractions
- WBI at 50 Gy in 25 fractions plus TBB at 16 Gy in 8 fractions
- WBI at 42.5 Gy in 16 fractions plus TBB at 16 Gy in 8 fractions.
In randomization B (n = 581), patients received WBI at 50 Gy in 25 fractions, with or without TBB at 16 Gy in 8 fractions. In randomization C (n = 524), patients received WBI at 42.5 Gy in 16 fractions, with or without TBB at 16 Gy in 8 fractions.
All patients underwent CT-based radiation planning. WBI was delivered with tangential MV photon beams, and TBB was performed with CT contouring of protocol-defined tumor bed target volumes, with electron or photon energy. The median follow-up was 6.6 years.
Giving a boost to better outcomes
The 5-year rate of freedom from local recurrence was 97% for patients who received TBB and 93% for patients who did not (hazard ratio, 0.47; P < .001). The benefit of TBB was consistent across subgroups.
There were no significant differences in 5-year rates of freedom from local recurrence by WBI fractionation, either in randomization A (P = .837) or among all randomized patients (P = .887).
The tests for interactions between TBB and WBI fractionation on local recurrence were not significant in randomization A (P = .89) or in all randomized patients (P = .89).
The risk of overall disease recurrence was lower among patients who had received TBB, with an HR of 0.63 (P = .004). The 5-year rate of freedom from disease recurrence was 97% with TBB and 91% with no boost (P = .002).
There were no significant differences in freedom from disease recurrence rates by WBI fractionation either in randomization A (P = .443) or among all randomized patients (P = .605).
Acute radiation dermatitis occurred in significantly more patients who received TBB (P = .006), as did late breast pain (P = .003), induration or fibrosis (P < .0001), and telangiectasia (P = .02). There were no significant differences by boost status for acute or late fatigue, pneumonitis, cardiac complications, or second malignancies.
Reduce the boost dose?
A radiation oncologist who was not involved in this study said that, while the results confirm a benefit of boost dose for patients with non–low-risk DCIS, the doses used in the BIG-3-07 study may be higher than needed to achieve a protective effect.
“Here in America, we usually give 10 Gy in five fractions, and, in many countries, actually, it’s 10 Gy in five fractions, although a few European centers give 16 Gy in eight fractions,” said Alphose Taghian, MD, of Massachusetts General Hospital in Boston.
“I personally only give 10 Gy in five fractions. I am not under the impression that 16 Gy in eight fractions will give better results. The local failure rate is so low, it’s likely that 10 Gy will do the job,” Dr. Taghian said in an interview.
Dr. Taghian noted that raising the dose to 16 Gy increases the risk of fibrosis, as seen in the BIG-3-07 trial.
Nonetheless, the trial demonstrates the benefit of radiation boost dose in patients with high-risk DCIS, he said, adding that the local recurrence-free benefit curves may separate further with longer follow-up.
The study was sponsored by the Trans Tasman Radiation Oncology Group. Dr. Chua and Dr. Taghian reported no conflicts of interest.
Giving a tumor bed boost (TBB) reduced the risk of local recurrence and overall disease recurrence, but there were no significant differences in recurrence rates between conventional WBI and hypofractionated WBI.
Boon Hui Chua, MD, of the University of New South Wales, Sydney, presented these results at the 2020 San Antonio Breast Cancer Symposium.
Dr. Chua and colleagues studied 1,608 women with DCIS resected by conservative surgery. Patients were either younger than 50 years or age 50 and older with at least one of the following risk factors: symptomatic presentation, palpable tumor, multifocal disease, tumor size 1.5 cm or larger, intermediate or high nuclear grade, central necrosis, comedo histology, and/or surgical margins less than 10 mm.
The patients were randomized to treatment in three categories. In randomization A (n = 503), patients were randomized to one of the following treatments:
- WBI at 50 Gy in 25 fractions
- WBI at 42.5 Gy in 16 fractions
- WBI at 50 Gy in 25 fractions plus TBB at 16 Gy in 8 fractions
- WBI at 42.5 Gy in 16 fractions plus TBB at 16 Gy in 8 fractions.
In randomization B (n = 581), patients received WBI at 50 Gy in 25 fractions, with or without TBB at 16 Gy in 8 fractions. In randomization C (n = 524), patients received WBI at 42.5 Gy in 16 fractions, with or without TBB at 16 Gy in 8 fractions.
All patients underwent CT-based radiation planning. WBI was delivered with tangential MV photon beams, and TBB was performed with CT contouring of protocol-defined tumor bed target volumes, with electron or photon energy. The median follow-up was 6.6 years.
Giving a boost to better outcomes
The 5-year rate of freedom from local recurrence was 97% for patients who received TBB and 93% for patients who did not (hazard ratio, 0.47; P < .001). The benefit of TBB was consistent across subgroups.
There were no significant differences in 5-year rates of freedom from local recurrence by WBI fractionation, either in randomization A (P = .837) or among all randomized patients (P = .887).
The tests for interactions between TBB and WBI fractionation on local recurrence were not significant in randomization A (P = .89) or in all randomized patients (P = .89).
The risk of overall disease recurrence was lower among patients who had received TBB, with an HR of 0.63 (P = .004). The 5-year rate of freedom from disease recurrence was 97% with TBB and 91% with no boost (P = .002).
There were no significant differences in freedom from disease recurrence rates by WBI fractionation either in randomization A (P = .443) or among all randomized patients (P = .605).
Acute radiation dermatitis occurred in significantly more patients who received TBB (P = .006), as did late breast pain (P = .003), induration or fibrosis (P < .0001), and telangiectasia (P = .02). There were no significant differences by boost status for acute or late fatigue, pneumonitis, cardiac complications, or second malignancies.
Reduce the boost dose?
A radiation oncologist who was not involved in this study said that, while the results confirm a benefit of boost dose for patients with non–low-risk DCIS, the doses used in the BIG-3-07 study may be higher than needed to achieve a protective effect.
“Here in America, we usually give 10 Gy in five fractions, and, in many countries, actually, it’s 10 Gy in five fractions, although a few European centers give 16 Gy in eight fractions,” said Alphose Taghian, MD, of Massachusetts General Hospital in Boston.
“I personally only give 10 Gy in five fractions. I am not under the impression that 16 Gy in eight fractions will give better results. The local failure rate is so low, it’s likely that 10 Gy will do the job,” Dr. Taghian said in an interview.
Dr. Taghian noted that raising the dose to 16 Gy increases the risk of fibrosis, as seen in the BIG-3-07 trial.
Nonetheless, the trial demonstrates the benefit of radiation boost dose in patients with high-risk DCIS, he said, adding that the local recurrence-free benefit curves may separate further with longer follow-up.
The study was sponsored by the Trans Tasman Radiation Oncology Group. Dr. Chua and Dr. Taghian reported no conflicts of interest.
FROM SABCS 2020