Risk Factors for Locoregional Recurrence After Postmastectomy Radiotherapy in Breast Cancer Patients with Four or More Positive Axillary Lymph Nodes

Backgroud: We investigated risk factors for locoregional recurrence (lrr) in breast cancer patients with 4 or more positive axillary lymph nodes receiving postmastectomy radiotherapy (pmrt). Methods: Medical records (1998–2007) were retrospectively reviewed for the population of interest. The Kaplan–Meier method was used to calculate the survival rate; Cox regression models were used for univariate and multivariate analysis of predictors of breast cancer lrr. Results: The study enrolled 439 patients. Median duration of follow-up was 54 months. The 5-year rates of locoregional recurrence-free survival (lrrfs), distant metastasis–free survival (dmfs), and breast cancer–specific survival (bcss) were 87.8%, 59.5%, and 70.7% respectively. In patients with lrr and no concomitant metastasis, and in those without lrr, the 5-year rates of dmfs were 21.1% and 65.7% respectively (p < 0.001), and the 5-year rates of bcss were 34.5% and 76.4% respectively (p < 0.001). Univariate analysis showed that menopausal status (p = 0.041), pN stage (p = 0.006), and positivity for her2 [human epidermal growth factor receptor 2 (p = 0.003)] or the triple-negative disease subtype (p < 0.001) were determinants of lrrfs. Multivariate analysis showed that pN3 stage [hazard ratio (hr): 2.241; 95% confidence interval (ci): 1.270 to 3.957; p = 0.005], her2 positivity (hr: 2.705; 95% ci: 1.371 to 5.335; p = 0.004), and triple-negative disease subtype (hr: 4.617; 95% ci: 2.192 to 9.723; p < 0.001) were independent prognostic factors of lrrfs. Conclusions: In breast cancer patients with 4 or more positive axillary lymph nodes who undergo pmrt for breast cancer, lrr significantly influences survival. Patients who developed lrr carried a high risk for distant metastasis and death. Pathologic stage (pN3), her2 positivity, and the triple-negative disease subtype are risk factors that significantly influence lrrfs.