Disease-free survival according to the use of postmastectomy radiation therapy after neoadjuvant chemotherapy

The purpose of the study was to determine predictors of recurrence for patients treated with neoadjuvant chemotherapy (NAC) and mastectomy according to the use of postmastectomy radiation therapy (PMRT).

An analysis of 161 clinically staged T1 to T3/N0 to N3 patients treated with NAC and mastectomy with and without PMRT at our institution from 2003 to 2010 was conducted. The Kaplan-Meier product limit method was used to estimate survival and time to recurrence rates and the log-rank test was used to compare groups. A Cox proportional hazard regression analysis was carried out for time to recurrence, radiation therapy, and their interaction in the model.

The median follow-up period was 48 months and 18 patients developed a recurrence. The 5-year recurrence rate and overall survival was 16.1% (95% confidence interval [CI], 9.6%-26.3%) and 93.6% (95% CI, 88.2%-97.0%), respectively. Patients who underwent PMRT had a decreased risk of recurrence compared with patients who did not (hazard ratio [HR], 0.25; 95% CI, 0.097-0.661; P < .005). The 5-year disease-free survival (DFS) rate for those who received PMRT was 91.3% (95% CI, 82.8%-95.7%) and 64.8% (95% CI, 37.8%-82.4%) for those who did not (P = .0126). Among all clinicopathologic factors examined, pathologic T stage (ypT) and pathological N stage (ypN) significantly correlated with the risk of recurrence (P < .05). Patients with any pathological nodal disease had an increased risk of recurrence compared with patients who were pathologically node-negative (HR, 7.196; 95% CI, 2.05-25.264; P < .002).

Patients treated with NAC and mastectomy, but without PMRT had a higher risk recurrence with increasing ypT and ypN stages. PMRT might increase DFS.