Postmastectomy Radiotherapy for Breast Cancer Patients with One to Three Positive Nodes?

Prior meta-analyses have shown that postmastectomy radiotherapy (PMRT) reduces the risk for breast cancer mortality and recurrence in patients with node-positive disease. But whether PMRT benefits patients with only one to three positive nodes is controversial.

To address this issue, investigators performed a meta-analysis of individual data on 8135 patients with node-positive disease who were enrolled in 22 randomized trials from 1964 to 1986. Patients received PMRT to the chest wall, supraclavicular or axillary fossa (or both), and internal mammary nodes. A total of 3786 patients with documented axillary dissection were included. About 64% of patients received cyclophosphamide, methotrexate, and fluorouracil chemotherapy; 24% received tamoxifen endocrine therapy. Median follow-up was 9.4 years.

In 700 patients with axillary dissection and no positive nodes, PMRT had no significant effect on locoregional recurrence or breast cancer mortality, but it significantly increased the risk for overall mortality (rate ratio, 1.23; 2-sided P=0.03). In 1314 patients with axillary dissection and 1 to 3 positive nodes, PMRT significantly reduced locoregional recurrence (2P<0.00001), overall recurrence (RR, 0.68; 2P=0.00006), and breast cancer mortality (RR, 0.80; 2P=0.01); similar benefits were achieved in a subset of 1133 of patients who also received systemic therapy. However, the main issue here is that the 10-year rate of locoregional recurrence with systemic therapy and no PMRT (21%) was substantially higher than would be expected in the current era in patients receiving systemic therapy with one to three positive nodes (<5% for most patients; Ann Surg Oncol 2010; 17:2899 and Int J Radiat Oncol Biol Phys 2014 Apr 7).