Chemotherapy improves survival for patients with lymph node-negative invasive papillary breast cancer with tumors ≥2 cm: a SEER population-based study

BACKGROUND: Invasive papillary breast cancer (IPC) is a rare cancer known to have a better prognosis than other breast cancers. This study aimed to explore whether patients with early-stage IPC can benefit from chemotherapy. MATERIALS AND METHODS: IPC cases diagnosed between 2003 and 2021 were retrieved from the Surveillance, Epidemiology, and End Results (SEER) database. The Kaplan-Meier method and the Cox proportional hazard model were performed to identify significant prognostic factors. To eliminate selection bias and baseline characteristics, propensity score matching (PSM) was used. The primary endpoints were overall survival (OS) and breast cancer-specific survival (BCSS). RESULTS: A total of 1892 patients were enrolled, and 273 pairs were screened after PSM. Multivariable analysis showed that age under 50, married status, smaller tumor size, negative lymph node (LN) status, and receipt of surgery, chemotherapy or radiotherapy were independently associated with better OS. After PSM, patients receiving chemotherapy had significantly improved OS (P = .012), while BCSS showed no significant difference (P = .099). After stratified by tumor size and LN status, chemotherapy could significantly improve the OS of patients with LN-negative IPC with tumors ≥ 2.0 cm (P < .001). Among the patients with grade III or undifferentiated diseases, the OS of the chemotherapy group was significantly better than that of the non-chemotherapy group (P < .001). CONCLUSIONS: For patients with LN-negative IPC with tumor ≥ 2.0 cm and patients with grade III or undifferentiated disease, chemotherapy significantly improved OS. Future randomized controlled trials are expected to validate the results.