Postmastectomy radiotherapy in women with breast cancer metastatic to one to three axillary lymph nodes

Abstract

The influence of postmastectomy radiotherapy on survival has long been debated. Early randomized trials established a clear role for adjuvant postmastectomy chest wall radiotherapy (PMCWRT) in reducing locoregional recurrence (LRR), and PMCWRT became standard therapy for patients at high risk of LRR: those with T3 or T4 tumors and four or more involved lymph nodes. However, without effective systemic therapy, distant metastases limited any effect of improved local control on overall outcome, and radiotherapy showed no benefit in survival. In fact, early meta-analyses showed a negative impact of radiotherapy on survival. As data and techniques matured, a favorable influence of PMCWRT on breast cancer-specific mortality emerged but was offset by a radiotherapy-related increase in vascular mortality. Improvements in radiotherapy delivery to increase efficacy and reduce toxicity, restriction of PMCWRT to patients at intermediate or high risk of LRR after mastectomy, and improved distant control of disease with systemic therapy are expected to bring the greatest likelihood of a survival advantage from locoregional control. Three randomized trials with sufficient follow-up meet these criteria. All demonstrate significant improvement in overall survival with PMCWRT. However, the trials were not designed to specifically address the benefit of PMCWRT in patients at intermediate risk of LRR (those with T1 or T2 tumors and one to three involved lymph nodes). These findings have been discussed in a host of publications and conferences in light of historical negative results. This review focuses on the recent data on PMCWRT in patients with one to three involved nodes.