To evaluate the efficacy of radiation in patients treated with neoadjuvant chemotherapy and mastectomy.

We retrospectively analyzed the outcomes of 542 patients treated on six consecutive institutional prospective trials with neoadjuvant chemotherapy, mastectomy, and radiation. These data were compared to those of 134 patients who received similar treatment in these same trials but without radiation.

Irradiated patients had a lower rate of local-regional recurrence (LRR) (10-year rates: 11% v 22%, P = .0001). Radiation reduced LRR for patients with clinical T3 or T4 tumors, stage > or = IIB disease (AJCC 1988), pathological tumor size >2 cm, or four or more positive nodes (P < or = .002 for all comparisons). Patients who presented with clinically advanced stage III or IV disease but subsequently achieved a pathological complete response to neoadjuvant chemotherapy still had a high rate of LRR, which was significantly reduced with radiation (10-year rates: 33% v 3%, P = .006). Radiation improved cause-specific survival (CSS) in the following subsets: stage > or = IIIB disease, clinical T4 tumors, and four or more positive nodes (P < or = .007 for all comparisons). On multivariate analyses of LRR and CSS, the hazard ratios for lack of radiation were 4.7 (95% CI, 2.7 to 8.1; P < .0001) and 2.0 (95% CI, 1.4 to 2.9; P < .0001), respectively.

After neoadjuvant chemotherapy and mastectomy, comprehensive radiation was found to benefit both local control and survival for patients presenting with clinical T3 tumors or stage III-IV (ipsilateral supraclavicular nodal) disease and for patients with four or more positive nodes. Radiation should be considered for these patients regardless of their response to initial chemotherapy.