Regional nodal irradiation

Regional nodal irradiation is routinely given postmastectomy to patients with involved lymph nodes; however, its role in patients who have breast-conserving surgery and whole-breast radiation therapy has been less clear. A randomized trial (NCT00005957) of 1,832 women showed that administering regional nodal irradiation after breast-conserving surgery and whole-breast radiation therapy reduced the risk of recurrence (10-year disease-free survival [DFS] rate, 82.0% vs. 77.0%; HR, 0.76; 95% CI, 0.61–0.94; P = .01) but did not affect survival (10-year OS rate, 82.8% vs. 81.8%; HR, 0.91; 95% CI, 0.72–1.13; P = .38).[18][Level of evidence A1]

Similar findings were reported from the EORTC trial (NCT00002851). Women with a centrally or medially located primary tumor with or without axillary node involvement, or an externally located tumor with axillary involvement, were randomly assigned to receive whole-breast or thoracic-wall radiation therapy in addition to regional nodal irradiation or not. Breast-conserving surgery was performed for 76.1% of the study population, and the remaining participants underwent mastectomy. No improvement in OS was seen at 10 years among patients who underwent regional nodal irradiation, compared with patients who did not undergo regional nodal radiation (82.3% vs. 80.7%, P = .06). Distant DFS was improved among patients who underwent regional nodal irradiation when compared with patients who did not undergo regional nodal irradiation (78% vs. 75%, P = .02).[19][Level of evidence A1]

A meta-analysis of individual patient data from all randomized trials of regional lymph node radiation therapy versus no regional lymph node radiation therapy in women with early breast cancer included 16 clinical trials involving 14,324 participants. It found that radiation therapy significantly reduced breast cancer mortality (RR, 0.87; 95% CI, 0.80–0.94; P = .0010), with no significant effect on non–breast cancer mortality (RR, 0.97; 0.84–1.11; P = .63), leading to significantly reduced all-cause mortality (RR, 0.90; 0.84–0.96; P = .0022). Estimated absolute reductions in 15-year breast cancer mortality were 1.6% for women with zero positive axillary nodes, 2.7% for those with one to three positive axillary nodes, and 4.5% for those with four or more positive axillary nodes.[20]