Abstract

Background: Breast cancer subtypes were designed not only to guide decision regarding targeted therapy but also to evaluate the prognosis of the disease together with other pathological factors. This study aimed at determining the distribution of breast cancer molecular subtypes, and their association with clinical and pathological outcomes in Rwandan women diagnosed with breast cancer.

Methodology: This is a retrospective study designed to document clinical and pathological data from breast cancer patients in Rwanda from January 2014 to June 2021. Records of patients with confirmed breast cancer were documented from 4 cancer centers.

Results: Histological grade I, II and III were 10.2%, 37.7% and 39.1%, respectively. The invasive ductal and lobular carcinoma were 89%, and 3.1%, respectively, while the mixed ductal and lobular was 1.4%. The most represented pathology stages were pT3 (19.1%), pT4 (18.9%) and pT2 (17.3%). Besides, the Lymphovascular invasion was present at 6.7%. Many patients expressed estrogen receptor (53.6%), followed by progesterone receptor (34.8%) and HER2 (34.2%). Luminal B was the most prevalent (29.3%), followed by TNBC (28.1%), luminal A (25.7%) and HER2-enriched (16.9%). These subtypes were found significantly different with regards tumour side (p=0.019), histological grades (p=0.025) and pathological stages (p<0.001).

Conclusion: This study demonstrated the predominance of luminal B and TNBC in breast cancer patients. Significant correlations between breast cancer subtypes, histological grades, and pathological stages supported the significance of these variables as prognostic factors in women breast cancer patients. To complete these findings, it will be necessary to evaluate the survival rates for various subtypes of breast cancer in conjunction with BI-RADs classification as well as the latest scientific evidence therapies being applied to the treatment of breast cancer patients.

Keywords: Breast cancer; Hormonal receptors; Human Epidermal Growth Factor Receptor 2(HER2); Breast cancer subtypes; Clinical histopathology