Predicting loco-regional recurrence risk in T1, T2 breast cancer with 1-3 positive axillary nodes postmastectomy: Development of a predictive nomogram.

BACKGROUND: Role of postmastectomy radiotherapy (PMRT) in early breast cancer with 1-3 positive axillary nodes is still controversial. Hence, there is a need to identify subgroup of patients who have sufficiently high risk of disease recurrence to benefit from PMRT. AIM: The aim is to evaluate clinical outcomes of patients postmastectomy having pathological T1-T2 tumors with 1-3 positive axillary lymph nodes (LNs) treated with adjuvant systemic therapy and develop a predictive nomogram. MATERIALS AND METHODS: Data collected retrospectively from eligible patients from 2005 to 2011. Kaplan-Meier survival analysis was used for all time-to-event analysis. Various known clinical and pathological risk factors were correlated with outcome using uni- and multi-variable analysis in SPSS version 21. All comparisons were two-tailed and P < 0.05 were considered statistically significant. The nomogram to predict the risk of loco-regional control (LRC) was developed using least absolute shrinkage and selection operator shrinkage model in hdnom.io software. RESULTS: 38/242 (15.7%) patients had recurrent disease at loco-regional (10 patients), distant sites (22 patients) and simultaneous loco-regional and distant sites (6 patients) at a median follow-up 59.5 (range 4-133) months. Five years estimate of LRC, distant disease-free survival (DFS), DFS, cause-specific survival and overall survival was 87.8%, 85.4%, 84.2%, 93.1%, and 91.5%, respectively. Pathological tumor size, margin status, LN ratio as continuous variables and grade and triple negative breast cancer status as categorical variables were the risk factors included in the model for building nomogram. CONCLUSION: The nomogram developed based on institutional data can be a valuable tool in guiding adjuvant PMRT depending on the risk of 5 years loco-regional recurrence.