Classification moléculaire des cancer mammaires/Triple négative

Abstract

Breast cancer is a real public health problem, whether in Algeria or around the world. In our country, it represents the first female cancer in frequency and cause of female mortality. The objective of our work is the study of the epidemiological, anatomo-pathological, evolutionary features of breast cancer and the phenotypic evaluation of molecular subtypes. The retrospective study was carried out on 660 files collected at the medical oncology service and the pathological anatomy laboratory of the EPH of Mostaganem and Oran , over a period of 5 years (2015-2020). The parameters studied are: age, tumor size, location, type and histological grade, lymph nodes, type of sample, hormone receptors and molecular subtypes. A total of 660 cases of breast cancer have been identified. The age group most affected by this disease is that of [40-49], with extremes of 20 and 89 years, average age of the patients: 50 years. Depending on the location, the left breast is the most affected in 356 cases (54.09%), the right breast in 300 cases (45.45%) and the bilateral breast 4 cases (0.45%). Pathologically, the dominant histological type is invasive ductal carcinoma (81%), with a high SBR II histopronostic grade: 65.15%. The pT2 tumor size is the most frequent (51%). Lymph node invasion according to TNM classification are: N0: 24.64%, N1 with 29.33%, N2: 20.85%, N3: 13.87%, lymph nodes positive pN +: 65.23%. The dominant type of sample is mastectomy (49.86%). Hormone receptors (RE +: 58%, RE-: 39%, RP +: 57.27%, RP-: 39.54% of cases). The proliferation marker KI67 positive in 58% of the cases and the HER2 overexpressed in (Score0: 43.18%, Score1: 27.78%, Score2: 9.39%, Score3: 18.63%) of the cases. The phenotypic evaluation of the molecular subtypes is carried out by specifying their relative proportion and their biological characteristics. The IHC analysis is carried out using antibodies specific to hormone receptors, the HER2 oncoprotein, the Ki67 antigen. The Luminal group includes the LA subtype found in 9.69% and LB in 7.87%. The HER2 subtype is identified in 85%. We have listed tumors that do not express the estrogen RE receptors, the progesterone receptors RP and the HER2 oncoprotein: RE- RP- HER2-. These carcinomas of the TN negative triple subtype are observed in 17.12%. The determination of molecular subtypes in IHC confirms the aggressive tumor character of poor prognosis in patients: low proportion of LA (9.69%) and LB (7.87%) of good prognosis, predominance of prognostic subtypes unfavorable HER2 (85%), TN (17.12%). The characterization of these subtypes and the establishment of their prognosis have made it possible to significantly improve the therapeutic management of patients. Among the 660 tumors studied, we have listed 113 tumors that do not express the estrogen RE receptors, the RP progesterone receptors and the HER2 oncoprotein: these are TN carcinomas. Characteristics of TN carcinomas: average age of patients: 50.53 years. Tumor size pT1: 61%, pT2: 36% and pT3: 3%. Pathologically, the dominant histological type is invasive ductal carcinoma (88%), with a high SBR II histopronostic grade: 69.91%. Presence of pN + lymph node invasion: 68%. Lymph node invasion in class N1 with 56%, N0: 40%, N2: 4%. Depending on the location, the left breast is the most affected (51%) and the right breast (49%). The dominant type of sample is mastectomy (63.73%). Analysis of the results shows that triple-negative tumors are aggressive tumors with a poor prognosis predominant in young, tall women, of high SBR grade, with significant mitotic activity and dominant lymph node invasion.