Studies using gene expression profiling have identified five major subtypes of breast cancer, apart from the traditional hormone receptor positive or negative ones: luminal A, luminal B, the HER2 group, the basaloid carcinoma group and the "normal breast -like" group. Material and methods: In this retrospective study, 281 patients admitted to the Regional Institute of On-cology Iasi and the Clinical Hospital of Obstetrics and Gynecology Cuza Voda Iasi were in-cluded, for whom the oncological records, the operative protocols of the operating room, the unique register of the service were studied; the pathological anatomy and observation sheets were considered for a period of 8 years: 2015-2022. For all 281 invasive mammary carcino-mas diagnosed on hematoxylin-eosin staining, they were classified into one of the corre-sponding histopathological types and subtypes according to WHO criteria. Results: The his-topathological study allowed: 1. invasive ductal carcinoma NOS (not otherwise specified -non-specific type of invasive ductal carcinoma)-193 cases (68.68%),2. invasive lobular car-cinoma-42 cases (14.94%). Immuno-labeling analysis Estrogen receptors (ER) were positive (Allred score >= 3) in 61% of cases (169 patients), and progesterone receptors (PR) in 64% of cases (180 patients). Ki 67 immunolabeling analysis highlighted: the presence of positivity in all cases studied, overexpression of the p53 protein in 99 cases and HER 2 immunoassays allowed the highlighting of 42 cases. Identifying cases with p53 protein mutations can select a group of patients with a higher risk of recurrence and death, and testing p53 expression in HER2 positive patients identifies the subgroup with more aggressive tumors that will benefit from a more aggressive treatment. Conclusions: The most common histological types were invasive ductal carcinoma in 90% of patients. TNM stages was as follows: stage I in 9 cases (3.2%), stage II in 88 cases (31.49%), stage III in 138 cases (48.93%), stage IV in 31 cases (11.03%) ER+/PR-phenotype were more frequent over 50years and tumors larger than 2 cm. Patients under 50 years presented twice as often HER2 positive tumors. Ki67 immunostain-ing seems to be associated with an unfavorable prognosis (2% of cases in the present study). p53 overexpression occurs most frequently in patients under 50 years, with tumors larger than 2 cm.
