Aspectos clínico-epidemiológicos dos tumores mamários triplo negativos em uma população brasileira

Abstract

Current breast cancer treatment is based on the classification of tumor stage and molecular profile. Triple-negative breast cancer (TNBC) is a specific subset of tumors characterized by the absence of hormone and HER2 receptors. Despite being usually associated with a more aggressive clinical course, there is high heterogeneity within TNBC. Therefore, it has been questioned whether current classification of TNBC is adequate enough to assess its prognosis and make therapeutic decisions. This study thus aimed to investigate to which extent TNBC profile classification was able to efficiently distinguish this tumor subtype from other subtypes of breast cancer. It was performed on a cohort of women with breast cancer treated at referral centers in Juiz de Fora, Southeastern Brazil. Overall and disease-free survival and prognostic factors were assessed and compared for TNBC and non-TNBC. Survival functions were calculated using the Kaplan-Meier method, and the log-rank test was used to compare the survival curves. Prognostic factors were analyzed by the Cox proportional hazards model. TNBC presented demographic differences compared to non-TNBC as it was more prevalent among nonwhite and less educated women. TNBC also presented at diagnosis with clinical parameters of advanced disease and had overall and disease-free survival significantly lower than non-TNBC. In univariate analysis the factors: age, color of the skin, education level, size and degree of tumor, axillary status and staging, as well as high rates of P53 e Ki 67 have been shown to be associated with disease-free survival in non-TNBC. These variables remained the same in the calculation of overall survival except for age; and it was also observed a greater risk for women from the public health service as well as the appearance of metastases during the follow-up. In multivariate analysis education level and axillary lymph node involvement presented a risk for disease-free survival while the color of skin and staging, for overall survival in non-TNBC. Regarding TNBC, its evolution was related to two aspects: axillary impairment for disease-free and global survival and multicentricity for overall survival. TNBC presents distinct biological properties compared to non-TNBC, which seems to be related to its specific histological and molecular components. The molecular classification by immunohistochemistry showed to be able to identify the two tumor groups and to support the therapeutic orientation.