Prevalence and Molecular Profile of Breast Carcinoma Using Immunohistochemistry Markers in Mexican Women.

Background: In Mexico, breast cancer is the leading cause of death by malignant tumors in women aged 20 and older. The World Health Organization estimates that 69% of deaths caused by breast cancer occur in developing countries. Little is known about the prevalence of breast carcinoma in Mexico and its molecular subclassification.

Methods: This retrospective cross-sectional study included patients who underwent a mastectomy (single, radical or lumpectomy) or a breast tumor biopsy (core-needle or excisional) from January 2002 to December 2018. The primary purpose of the study was to determine the prevalence and molecular profile of breast in comprehensive cancer center in Mexico and compare our results with those published in the US. This study was approved by our scientific and bioethical committee.

Results: The final analysis included 379 patients. The youngest patient was 23 years old and the oldest patient was 89; the mean age at diagnosis was 54.63 years. Patients of 40 years old or younger accounted for 48 of the cases (12.66%) and those older than 40 accounted for 331 of the cases (87.33%). The molecular subclassification showed luminal A subtype in 139 cases (36.67%), luminal B subtype in 143 cases (37.73%), human epidermal growth factor receptor 2-positive carcinomas in 32 cases (8.44%) and triple-negative carcinomas in 65 cases (17.15%). Diabetes mellitus was present in 43 patients (11.34%), hypertension in 78 patients (20.58%), obesity in 82 patients (21.63%) and 66 patients reported being treated with exogenous hormone therapy (17.41%).

Conclusions: Breast carcinoma occurs at an earlier age in Mexican women compared to women in the US. Hormone-positive tumors were found to be more prevalent in older patients, while high-grade tumors were more frequently identified in younger patients.