Breast cancer receptor status assessment and clinicopathological association in Nigerian women: A retrospective analysis

Background: Breast cancer markers are becoming increasingly important in breast cancer research due to their impact on prognosis, treatment and survival. The present retrospective study was carried out to quantify the proportion of estrogen (ER), progesterone (PR), and human epithelial receptor 2 (HER2) expressions and their association with tumour grade, age, and tumour size in breast cancer patients in Nigeria. Materials and methods: The paraffin embedded tissue sections were analysed for breast cancer markers using monoclonal antibody SP1 for ER and SP2 for PR and polyclonal antibody ErbB2 for HER2. Results: A total of 286 breast cancer paraffin wax tissue sections were analysed for ER, PR and HER2 expression. Of all the tissue samples examined, 20 (7%) were ER-positive, 6 (2.1%) were PR-positive, 11 (3.8%) were HER2-positive whereas 248 (87%) were triple-negative breast carcinoma. ER- and PR-positivity was associated with early grade I and II tumours (P < 0.010-0.009) and tumour sizes of < 50mm (p < 0.001). HER2-positivity was positively (P < 0.009) associated with grade II tumours and negatively (P < 0.0001) associated with grade III tumours. Triple-negative breast cancer was associated with grade III tumours (P < 0.0001) and larger tumour sizes of > 50mm (P < 0.0001). Conclusion: A small proportion of Nigerian women with breast cancer are ER/PR-positive which are associated with less aggressive, better prognosis and benefit from endocrine therapy. An even smaller proportion of patients with aggressive tumors were HER2-posivite but responsive to Herceptin treatment. Unfortunately, a very high proportion of cases were triple-negative which is associated with very aggressive tumours and no targeted treatment, which may explain the high mortality rates from breast cancer in Nigeria