Background: Multifocality and multicentricity are increasingly recognized in breast cancer. However, little is known about the characteristics and biology of these cancers and the clinical implications are controversial.
Methods: A retrospective, institutional database was used to compare characteristics of multifocal (MF) and multicentric (MC) breast cancers with unifocal (UF) cancers to study concordance of histology and receptor status among primary and secondary foci and to evaluate predictors of lymph node positivity using multivariate logistic regression.
Results: Of 1495 invasive cancers, 1231 (82.3 %) were UF, 169 (11.3 %) were MF, and 95 (6.4 %) were MC cancers. When MF and MC cancers were compared with UF cancers, MC but not MF cancers were associated with young age at diagnosis, larger tumor size, lymphovascular invasion, and node positivity. MF but not MC tumors were more likely to be ER/PR+Her2+ tumors and less likely to be triple-negative cancers compared with UF tumors. MF tumors were more likely to be infiltrating ductal carcinomas with an extensive intraductal component, and MC tumors were more likely to be infiltrating lobular carcinomas. Concordance of histology and receptor status between primary and secondary foci was high and was similar for both MF and MC cancers. Multicentricity remained an independent predictor of lymph node positivity on multivariate analysis.
Conclusion: MF and MC tumors seem to be biologically different diseases. MC is clinicopathologically more aggressive than MF disease and is more frequently associated with younger age and larger tumor size and also is an independent predictor of node positivity.