Pathologic Complete Response Following Neoadjuvant Chemotherapy for Breast Cancer in a Nigerian Cohort

Background: Pathologic complete response (pCR) following neoadjuvant chemotherapy (NAC) is a marker for important clinical outcomes in the management of breast cancer. In Nigeria where the majority of patients are candidates for NAC, there is limited data on pCR following NAC. This study evaluated the pCR rate in a cohort of Nigerian patients. Methods: A retrospective review of patients who had NAC and mastectomy for breast cancer between 2017 and 2022. Relevant baseline clinicopathological and treatment data were obtained, pCR was defined as the absence of invasive cancer with or without in situ disease in the breast. The relationship between receptor status, type of chemotherapy and pCR was evaluated. Results: One hundred and sixty six of the 250 patients who had mastectomy during the period had NAC and were eligible for analysis. The mean age was 50.1±11.1, the majority had stage 3 disease. Overall (pCR) rate was 19.9% with the latter part of the study corresponding to the period with increased use of taxanes, having higher pCR (35.9% in 2022 vs 7.4% in 2017, p=0.024). Patients with HER 2 positive/Hormone receptor negative (HER 2+/HR-), HER 2+/HR+ and triple negative disease had significantly higher pCR than those with HR+/HER 2 negative disease (38.9%, 30.8%, 24.5% and 6.5% respectively, p=0.03). Conclusion: NAC resulted in pCR in about one-fifth of the entire cohort, particularly those with potentially aggressive HER 2+ and triple negative disease. The use of taxanes was associated with higher pCR rates.