[Clinical and prognostic characteristics of the molecular subtypes of breast cancer determined by immunohistochemistry. Arequipa, Peru].

The objective of this study was to determine the clinical and prognostic characteristics of breast carcinomas according to the molecular subtype using immunohistochemical markers. The study included 280 women with unilateral breast cancer enrolled from 2009 to 2012. The carcinomas were classified into four subtypes based on immunohistochemical findings: luminal A, luminal B, HER2, and triple negative. The Kaplan-Meier test was used to determine the effect of histological type and molecular subtype on overall survival. Our results indicated that the most common breast carcinoma subtype was luminal A (105 cases, 37.5%), followed by luminal B (88 cases, 31.4%), HER2 (46 cases, 16.4%), and triple negative (41 cases, 14.6%). Luminal carcinomas were well-differentiated in most cases, without involvement of the axillary lymph nodes, and showed a similar tumor size and stage. In contrast, HER2 and triple-negative tumors were poorly differentiated in most cases, with axillary node involvement, and were associated with decreased overall survival.