HER2 Overexpression in Invasive Breast Carcinoma in the Democratic Republic of Congo and its Association with Selected Clinicopathological Characteristics

Background: Breast cancer is a heterogeneous disease and HER2 overexpression identifies a subgroup of tumors associated with aggressive behavior and targeted therapy response. Although HER2 expression has been widely studied worldwide and in some African countries, data remain limited in the Democratic Republic of the Congo, where access to molecular diagnostic techniques is still restricted. Objective: This study aimed to determine the frequency of HER2 protein overexpression and its association with clinicopathological characteristics of breast carcinoma in the Democratic Republic of the Congo in order to provide local evidence to support diagnostic and therapeutic strategies. Methods: We conducted a cross-sectional analytical study from 2014 to 2016 in Kinshasa and Lubumbashi including 86 invasive breast carcinoma cases. HER2 expression was assessed by immunohistochemistry and scored according to standard guidelines. Associations were analyzed using odds ratios with 95% confidence intervals. Results: HER2 overexpression was observed in 25.6% of cases. No statistically significant association was found between HER2 status and age, tumor size, histological type, tumor grade, or estrogen receptor status. The absence of statistical significance may be related to the limited sample size. Conclusion: Approximately one quarter of breast carcinomas showed HER2 overexpression in this Congolese population. These findings support the importance of routine HER2 testing in breast cancer management in resource-limited settings. Although no statistically significant associations were found, this study provides additional data on HER2 expression in the Congolese context and highlights the need for larger studies with longer study periods to better assess clinicopathological associations.