Multifocal/multicentric breast cancer: Does each focus matter?

The tendency of MF/MC breast tumors to metastasize may be related to tumor load, which can be better predicted by the aggregate dimensions of all foci. The use of the current staging systems may require further evaluation and modification. Intertumoral heterogeneity indicates the necessity for pathological and immunohistochemical assessments of each lesion in patients with MF/MC breast cancers.