“Mastectomy is standard for recurrence of breast cancer after breast conservation therapy with whole breast irradiation. The emergence of partial breast irradiation led to consideration of its application for reirradiation after a second lumpectomy for treatment of recurrence of breast cancer in the ipsilateral breast,” the researchers wrote. Outcomes from the study, the NRG Oncology/Radiation Therapy Oncology Group 1014 trial, were published in JAMA Oncology.
The study evaluated three-dimensional (3D), conformal, external beam partial breast reirradiation following a second lumpectomy for recurrent breast cancer in the ipsilateral breast after a history of whole breast irradiation. Eligible patients were those with a recurrent breast tumor <3 cm and unifocal in the ipsilateral breast more than one year following breast-conserving therapy including whole breast irradiation and who received excision with negative margins. Patients received 1.5 Gy twice a day for 15 days with a 3D conformal technique. The primary outcome was recurrent breast cancer in the ipsilateral breast, adverse events more than one year after treatment, mastectomy incidence, distant metastatis-free survival, overall survival, and circulating tumor cell incidence.
Final analysis included 58 women (mean [SD] age, 65.12 [9.95] years; 83% were white). Most cases of recurrence in the ipsilateral breast were invasive (n = 35, 60%). In most patients (n = 53, 91%), tumors were 2 cm or smaller, and all tumors were clinically node negative. About three-quarters of patients (n = 44, 76%) tested positive for estrogen receptor, more than half (n = 33, 57%) tested positive for progesterone receptor, and 10 (17%) tested positive for ERBB2 (formerly HER2 or HER2/neu) overexpression. Breast cancer recurrence occurred in four patients; the five-year cumulative incidence was 5% (95% CI, 1% to 13%). Seven ipsilateral mastectomies were performed (five-year cumulative incidence, 10%; 95% CI, 4% to 20%). Distant metastasis-free and overall survival rates were both 95% (95% CI, 85% to 98%). Late treatment adverse events were rare; four patients (7%) experienced grade 3 events, and no grade 4 or higher events presented.
The study authors concluded, “For patients experiencing recurrence of breast cancer in the ipsilateral breast after lumpectomy and whole breast irradiation, a second breast conservation was achievable in 90%, with a low risk of re-recurrence of cancer in the ipsilateral breast using adjuvant partial breast reirradiation. This finding suggests that this treatment approach is an effective alternative to mastectomy.”