Prognostic Associations Between Adjuvant Chemotherapy and Survival in T1b-T2N0M0 Medullary Breast Cancer: A Population-Based Study of 2343 Patients.

Abstract

This study aimed to explore potential prognostic associations between adjuvant chemotherapy and survival outcomes in patients with T1b-T2N0M0 medullary breast cancer (MBC) who underwent surgical resection (breast-conserving surgery or mastectomy). Using the Surveillance, Epidemiology, and End Results (SEER) database (2000-2015), we analyzed 2343 women with pathologically confirmed T1b-T2N0M0 MBC who underwent surgery. Patient characteristics, treatment (chemotherapy, radiotherapy, surgery type), and survival outcomes (overall survival [OS], breast cancer-specific survival [BCSS]) were analyzed. Propensity score matching (1:1) was employed to minimize confounding. Kaplan-Meier analysis and Cox proportional hazards models assessed survival differences and prognostic factors. Among 2343 patients (median follow-up 141 months), 1507 (64.3%) received adjuvant chemotherapy. Patients receiving chemotherapy were typically younger (<65 years), more likely to be married, had larger tumors (T1c/T2), and had estrogen receptor-negative disease than those who did not. Multivariable analysis identified adjuvant chemotherapy as an independent favorable prognostic factor for both OS (P < 0.001) and BCSS (P = 0.039). Before and after propensity score matching, chemotherapy significantly improved OS and BCSS (P < 0.05). Subgroup analysis revealed significant survival benefits for patients with T1c-T2 tumors and hormone receptor-negative/human epidermal growth factor receptor 2-negative disease. However, no significant benefit was observed for patients with T1b tumors or hormone receptor-positive/human epidermal growth factor receptor 2-negative disease (P > 0.05). Adjuvant chemotherapy may optimize survival in select patients with T1b-T2N0M0 MBC, though prospective validation is warranted.