SUMMARY: Breast cancer is the most common cancer among women in the US and about 1 in 8 women (12%) will develop invasive breast cancer during their lifetime. Approximately, 231,840 new cases of invasive breast cancer will be diagnosed in 2015 and over 40,000 women will die of the disease. The National Surgical Adjuvant Breast and Bowel Project (NASBP) protocols B-04 and B-06 have clearly established, after more than a 2 decades of evaluation and follow up that, in Stage I and II breast cancer, there is no significant difference in either distant Disease Free or Overall Survival between the breast conserving surgery and breast removal surgery (Mastectomy). This data established breast-sparing surgery as the preferred local-regional procedure. Radiotherapy after breast-conserving surgery significantly decreases the risk of local recurrence and improves breast cancer–specific survival in certain subgroups of patients. Under ideal circumstances, approximately 70% of the patients can be treated with breast conserving surgery and the risk factors for local recurrences include younger age, high tumor grade, negative hormone receptor status, lymphovascular invasion, extensive intraductal component and positive surgical margins. According to the American Cancer Society, 42% of all invasive breast cancers in the US occur in women 65 years of age or older. These patients may have associated comorbidities and may therefore be appropriate candidates for breast-sparing surgery (rather than mastectomy), as post-op recovery time is shorter. Elderly patients often present with breast tumors that are hormone receptor positive and indolent. Whether women 70 years of age or older with early stage breast cancer need radiotherapy after breast conserving surgery, was addressed by the CALGB cooperative group ( CALGB 9343) and it was noted that the addition of radiation did not improve Overall Survival or distant Disease Free Survival, although there was some improvement in locoregional recurrence rate.
The authors in PRIME II study evaluated local control outcomes in elderly women with early stage breast cancer, at low risk of local recurrence at 5 years, by avoiding whole-breast radiotherapy, following breast conserving surgery. In this Phase III randomized trial, 1326 patients 65 years or older, with low risk early breast cancer, who had undergone breast conserving surgery and were receiving adjuvant hormonal treatment, were randomly assigned to receive whole-breast irradiation (N=658) or no further therapy (N=668). Low risk was defined as tumors T1–T2 up to 3 cm in greatest dimension, clear surgical margins, negative axillary nodes and positive hormone receptors. Either lymphovascular invasion or grade 3 tumor histology was permitted, but not both. The primary endpoint was ipsilateral breast tumor recurrence. After median follow up of 5 years, ipsilateral breast tumor recurrence was 1.3% in women assigned to whole-breast radiotherapy and 4.1% in those assigned no radiotherapy (P=0•0002). There was however no differences in regional recurrence, contralateral breast cancers, distant metastases or new breast cancers, noted between the two groups. The 5-year Overall Survival was similar in both groups 93•9% (P=0•34). The authors concluded that the 5-year ipsilateral breast tumor recurrence is probably low enough that radiotherapy could be avoided in a subset of elderly patients with low risk breast cancer following breast conserving surgery. Kunkler IH, Williams LJ, Jack WJ, et al: Breast-conserving surgery with or without irradiation in women aged 65 years or older with early breast cancer (PRIME II): A randomised controlled trial. Lancet -Oncol. 2015;16:266-273