Main phenotypes and histological types of breast cancer in young women attended at a reference hospital in women’s health in the city of São Paulo

It is estimated that there were 198,840 new cases of breast cancer (BC) in Brazil between 2020 and 2022. Young women who are affected by invasive BC with a triple-negative phenotype generally present more aggressive tumors that are intrinsically resistant to targeted therapies. This study evaluated the phenotypic and histological profile of BC in women up to the age of 40 years. Between 2015 and 2017, we identified 255 women with positive biopsy for carcinoma and with immunohistochemical panel, 51.76% who had a profile for luminal B (n = 132); 22.74% for triple-negative (n = 58). Of the samples, 65.88% presented histology as invasive ductal carcinoma – nonspecial type (n = 168). The results are in accordance with the literature regarding the high prevalence of triple-negative BC in young women and histological type invasive ductal carcinoma – nonspecial type.