Breast Cancer in Women: Epidemiological, Histological, Immunohistochemical and Molecular Sub-Types in the Republic of Congo

Introduction: Breast cancer is a heterogeneous disease with a variety of morphological, molecular, treatment response and clinical outcome characteristics. The objective of this work was to assess the epidemiological, histological, immunohistochemical and molecular subtypes of breast cancer in women in the Republic of Congo. Material and Methods: We carried out a cross-sectional descriptive study which took place from January 1, 2014 to December 31, 2020. The study focused on 150 cases of breast cancer in patients diagnosed at the University Hospital of Brazzaville (CHU-B). The epidemiological, clinical, histological, immunohistochemical and molecular subtypes were the variables studied. Results: The mean age was 48.09 ± 13.87 years with the extremes of 22 years and 80 years. The study of the profession; the most represented in our study was that of the cultivator 20.67%. A predominance of breast cancer localization was observed in the left breast in 47.33%. The frequency of a family history was 7.33% or 11 cases. The most frequently represented histologic type was 62% invasive non-specific type carcinoma (CITNS). The most represented histological grade was Scarff Bloom Richardson grade II (51.33%), followed by grade III 24% and grade I in 12% of cases. Regarding the results of IHC; of the 150 cases, 102 (68%) had positive hormone receptors (HR +). The ORs were positive in 102 cases (68%) while the PRs were positive in 98 cases (65.33%). The Her2 oncogene was over expressed in 38 cases (25.3%). The Ki-67 proliferation index was known for the 150 cases, including 77 (51.33%) less than 15% and 73 (48.67%) greater than or equal to 15%. The distribution of molecular subtypes was 46% luminal A, 22% triple negative, 17% luminal B and 10% Her2 +. Tumors of unknown molecular profile were 5%. The correlation was found between molecular subtype and histological type. This result was statistically significant (p 0.05). The correlation was found between molecular subtype and histological type. This result was statistically significant (p 0.05). The correlation was found between molecular subtype and histological type. This result was statistically significant (p 0.05). Conclusion: It should be noted that the association between histological and immunohistochemical diagnosis can help determine the phenotype of breast cancer, with the aim of guiding treatment and therefore improving response to treatment. Key words: Epidemiology, Histology, Immunohistochemistry, molecular subtypes, breast cancer, Republic of Congo.