Histo-biological comparative analysis of bilateral breast cancer.

Bilateral breast cancer occurs in approximately 7% of surviving breast cancer patients. However, a dilemma exists concerning the notion of whether this represents a de novo second primary tumor versus a breast metastasis. We analyzed 81 patients with bilateral breast cancer, 47 (58%) synchronous tumors and 34 (42%) metachronous tumors. Additionally, charts were reviewed for age, family history, full histology data and biological receptors. We found there were no significant differences in concordance between the first and second primary tumors (in both synchronous and metachronous bilateral breast cancer) with respect to histology; grade; T-category; N-category; ER, PR and HER-2 status. In addition, there was no significant difference in the strength of correlation between ER and PR in the first and secondary primary tumors. Our findings suggest that the differentiation of the origin of contralateral breast cancer based on routine histological and biological concordance is inconclusive. Furthermore, the dilemma will continue to exist until additional molecular approaches are applied routinely for research purposes to resolve the debate.