Authors: Anicet Luc Magloire Boumba, Dimitry Moudiongui Mboungou Malanda, Fabien Gaël Mouamaba, Exaucé Céleste Abena Gueyan, Fidèle Détila Mabouene, Donatien Moukassa, Jean Félix Peko.
Introduction: Breast cancer is a heterogeneous disease with a variety of morphological and molecular characteristics impacting treatment response. This study aimed to evaluate by immunohistochemistry and RT-PCR the overexpression of HER2 in breast cancer in women in the Republic of Congo.
Materials and Methods: We conducted an 8-month cross-sectional descriptive study. 25 paraffin biopsies of breast cancer cases in patients diagnosed at the University Hospital of Brazzaville were collected. Epidemiological, clinical, histological, immunohistochemical and molecular aspects were studied.
Results: The mean age of the patients was 49.64 ± 13.20 years (31-80 years). 60% of the patients had a right localization of the tumor. 76% of the patients had an invasive nonspecific type carcinoma. The T4b N1a M0 stage was predominant, representing 56% of the study population. SBR histopronostic grade 1 was represented by 60% of patients. Estrogen and progesterone receptors were positive in the range of 45% and 60%, respectively. The HER2 oncoprotein was positive in 12% (3/25) of 25 cases for IHC. The luminal group was in the majority with 32%. Molecular analysis of the HER2 gene by RT-PCR revealed over expression in 60% (15/25) of cases, 3 of which were already positive for IHC. With the "AmoyDx® HER2 Mutation Detection Kit", 12 mutations were identified, 10 of which involved exon 20, ie 83.33% and 2 mutations with exon 19, ie 16.67% of cases. The correlation of the over expression of the HER2 gene showed a statistically significant difference between the two techniques, p <0.00003.
Conclusion: HER2 is known as a prognostic and predictive marker in breast cancer, making this receptor a valuable therapeutic target. However, its highlighting by IHC remains cumbersome and subject to false negatives. Hence molecular analysis could play a crucial role in decision-making when implementing targeted breast cancer therapies in Congo.
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