Prognostic factors for breast cancer patients with T1-2 tumors and 1-3 positive lymph nodes and the role of postmastectomy radiotherapy in these patients

Purpose The purpose of this study was to identify independent prognostic factors for breast cancer patients with T1-2 tumors and 1-3 positive lymph nodes, and discuss the role of postmastectomy radiotherapy(PMRT) in these patients. Methods Between January 2005 and December 2015, the data on 840 eligible patients with breast cancer were retrospectively reviewed. Of these patients, 368 women received PMRT and 472 did not. The endpoints were locoregional recurrence (LRR) and distant metastasis (DM). Results With a median follow-up of 62.0 months, multivariate analysis identified the following independent risk factors for increased LRR: tumor size >= 4 cm (HR: 2.994, 95% CI: 1.190-7.535,P = 0.020), ER- and PR-negative tumor (HR: 2.540, 95% CI: 1.165-5.537,P = 0.019), preoperative high neutrophil-to-lymphocyte ratio (NLR) (HR: 4.716, 95% CI: 1.776-12.528,P = 0.002)and low neutrophil-to-monocyte ratio (NMR) (HR: 0.231, 95% CI: 0.084-0.633,P = 0.004). And independent risk factors for increased DM: ER- and PR-negative tumor (HR: 2.540, 95% CI: 1.880-5.625,P = 0.000), high NLR (HR: 2.693, 95% CI: 1.426-5.084,P = 0.002) and low NMR (HR: 0.460, 95% CI: 0.257-0.824,P = 0.009). The high-risk patients (>= 2 risk factors) had worse LRRFS and DFS than low-risk patients (0-1 risk factor) (all,P < 0.05). In the subgroup analysis, both low- and high-risk patients received PMRT had better LRRFS and DFS than those who without PMRT (all,P < 0.05), and the high-risk patients received PMRT had similar 5-year rates of LRRFS and DFS than low-risk patients who without PMRT (94.5 vs. 94.3%,P = 0.402; 83.4 vs.87.4%,P = 0.877, respectively). Conclusions Tumor size, ER/PR status, preoperative NLR and NMR were independent predictors of risk of recurrence. PMRT could improve locoregional control even in low-risk subgroup of breast cancer patients with T1-2 tumors and 1-3 positive lymph nodes significantly.