Abstract
Purpose
The prognostic significance of multifocal and multicentric breast cancer (MMBC) with low tumor burden remains controversial, and adjuvant chemotherapy guidelines for these patients are lacking.
Materials and Methods
Female patients with cT1-T2 MMBC or unifocal breast cancer (UBC) diagnosed between 2010 and 2020 were identified from the SEER database. Propensity score matching (PSM) balanced baseline characteristics. Survival outcomes were evaluated using Kaplan-Meier and Cox proportional hazards models, with subgroup analyses stratified by tumor size in node-negative MMBC.
Results
After PSM, 9,751 matched pairs of patients with MMBC and UBC were included. Analyses showed MMBC had significantly worse overall survival (OS) and breast cancer–specific survival (BCSS) than UBC (both
P
P
= .353; 1-2 cm: HR, 0.577 [95% CI, 0.414 to 0.806],
P
= .001; ≥2 cm: HR, 0.535 [95% CI, 0.399 to 0.717],
P
Conclusion
MMBC predicts poorer survival than UBC. In node-negative MMBC, chemotherapy confers benefit only when tumor size is ≥1 cm, suggesting multifocality and multicentricity should guide chemotherapy decisions. Prospective studies are warranted to confirm findings and refine guidelines.