Does focal heterogeneity affect survival in postoperative ipsilateral multifocal and multicentric breast cancers?

Objective: In multicentric/multifocal breast tumors, there may be immunological and histological differences between foci that may affect survival and treatment choice. We aimed to evaluate the effect of focal heterogeneity seen in multicentric/multifocal breast tumors on survival.

Methods: We retrospectively collected and analyzed the clinicopathological data of 89 female patients with multifocal/multicentric breast cancer, whose surgical and medical treatment was completed and who were followed up for 5 years.

Results: Of all patients, 29.2% (26/89) were heterogeneous. Heterogeneity of these foci was as follows: histologic heterogeneity of index foci (mix type): 15.7% (14/89), histologic heterogeneity of inter-foci: 7.9% (7/89), and immunohistochemical heterogeneity of inter-foci: 10.1% (9/89). When additional foci were evaluated, oncological therapy was changed for 3 (3.3%) of 89 patients. Heterogeneity does not have a significant (p>0.05) effect on recurrence and survival in multicentric/multifocal breast cancers. Pathological N stage is an independent risk factor for disease-free survival (hazard ratio=2.29, 95% confidence interval=1.39-3.76, p=0.001).

Conclusions: In multifocal/multicentric breast cancers, less than 4% of patients may experience heterogeneity requiring change in the therapeutic decision. However, heterogeneity does not have a significant effect on recurrence and survival in multifocal/multicentric breast cancers. The pathological N stage is an independent risk factor for disease-free survival.