Carcinomas mamários de tipo basal: estudo clínicopatológico e imunofenotípico em mulheres brasileiras

Abstract

Basal-like cancers (BLC) are a newly recognized subtype of breast cancer defined by the expression of genes and proteins characteristic of the myoepithelial/basal cells of normal breast, and have been associated with poor prognosis and agressive biological behavior. Aim: The aim of our study is to investigate basal phenotype in a series of triple-negative (estrogen and progesterone receptors-negative and HER2-negative) invasive mammary carcinomas. Methods: We selected 140 previously tested triple-negative tumors. Clinical, histopathological and survival data were obtained. A tissue microarray containing 2 cylinders from each tumor was constructed and immunohistochemistry for estrogen receptor (ER), progesterone receptor (PR), HER2, cytokeratins (CK) 5 and 14, EGFR, p63, caveolin, and p53 was performed. We considered BLC to be any tumors that were ER/PR/HER2- negative and CK5-positive. Results: We found 105 cases of BLC from 140 triple-negative tumors (frequency =75.0%). The mean age at diagnosis was 54.8 years-old and 34.3% were premenopausal women. The majority of tumors were high grade (83.7%) and of ductal/no-special-type (80.8%). Triple-negative tumors showed immunoreactivity for CK5 (75.0%), CK14 (29.0%), EGFR(28.6%), p63 (28.6%), caveolin (14.3%), and p53 (67.1%). Tumor size larger than 5cm was observed in 41 cases (39.0%) and axillary metastases were detected in 61 patients (59.2%). Follow-up was recorded for 89 patients (mean=51 months): 45 patients (50.5%) with no evidence of disease; 6 patients (6.7%) were alive with disease; and 38 patients (42.6%) died of the disease. Relapse was detected in 42 women (47.1%), lungs, brain, and bones being the most commom sites of metastases. The mean overall survival was 36 months and the mean disease-free interval was 28 months. Furthermore, the overall survival associated with BLC cases was shorter than that observed in non basaltumors (RR=2.4). However, this difference was not statistically significant(p=0.06). Conclusions: Our findings confirmed that BLC have a poor prognosis and are high-frequent carcinomas among triple-negative tumors, similar to the behavior previously reported in North American and European patients.