Differential survival and recurrence patterns of patients operated for breast cancer according to the new immunohistochemical classification: analytical survey from 1997 to 2012

Abstract

Breast cancer can no longer be considered only one condition. It should be regarded rather as a heterogeneous group of diseases with different molecular outlines. The aim of this study is to establish a correlation between immunohistochemical tumor sub-typing and surgical treatment, local recurrence rates, distant metastases, and cancer-specific mortality at 5 and 10 years. At least, four tumor sub-types have been described, which were associated with variable risk factors, different natural clinical course, and different response to both local and systemic therapies. For Luminal A: ER + and/or PR + HER2- Ki67 <15 %; Luminal B: ER + and/or PR + HER2- Ki67 ≥ 15 %; Pure HER2: ER-PR-HER2+; Triple Negative: ER-PR-HER2-. One thousand four hundred seventy-seven patients operated for 1,511 invasive breast tumors were included. Disease-free survival, overall mortality, and breast cancer-specific mortality at 5 and 10 years were calculated. Distant metastases prevalence ranged from 8 to 28 % across sub-types, increasing stepwise from Luminal A, Luminal B, and pure HER2 through triple negative. Conversely, larger tumors with significant axillary burden were more likely to belong to HER2 or triple negative groups. Luminal A sub-type patients showed significantly lower mortality rates both overall and specific at 5 and 10 years, as compared to the rest. Luminal B patients showed lower mortality rates only when compared with triple negative patients. Simple classification of breast cancer patients based on immunohistochemistry and other risk factors is quite useful to establish groups with bad or even worse prognosis. Although results from immunohistochemical classification were not taken into account for surgical procedure decision-making, we found that pure HER2 and triple negative patients received nevertheless higher rates of radical treatment.