Molecular subtyping by immunohistochemical staining and progostic evaluation in invasive breast carcinomas

Breast cancer is a very common disease and heterogeneous tumor that exhibits very different biological behavior. Some clinical and pathological prognostic factors such as age, histological grade, tumor size and estrogen receptor (ER ) status are used for patients to determine whether the needs of adjuvant hormonal therapy, radiotherapy and chemotherapy. However, for each patient, this traditional prognostic factors can not demonstrate sufficent success; determinig the prognosis, choice of treatment, to prevent local recurrence and mortality due to individual differences, and the heterogeneity observed in breast tumors. Although, there is not adopted strict limits yet, classification of 5 subtype is used most commonly in studies. These are 'luminal A, luminal B, human epidermal growth factor receptor 2 (HER2) overexpressing, basal-like and null type.' In this study, it is aimed to evaluate the relation between prognosis and these subtypes. We analyzed retrospectively by immunohistochemical staining profiles of molecular subtyping of 79 invasive breast carcinomas in our clinic. ER, PR, HER2 and CK5/6 were stained to all of the tumors by immunohistochemically. Finally, the most common histological type was invasive ductal carcinoma. Luminal A was the most frequent subtype. While most luminal A tumors were grade II, most basal-like tumors were grade III. The majority of grade I tumors were luminal A. Nearly half of the patients had tumors between 2-5 cm in diameter at diagnosis. A statistically significant correlation with prognostic factors and molecular subtype could not be determined. However, similar to the literature, tumors rate smaller than 2 cm was also higher in luminal types. Two medullary carcinoma is consistent with the literature found in the basal-like type. In basal-like group, the tumor grade was higher than in other groups.