Evaluating the Oncological Adequacy of Mastectomy in Breast Cancer Treatment at University College Hospital, Ibadan: A 5-Year Analysis

Mastectomy remains the predominant surgical intervention for breast cancer in Nigeria, yet the oncological adequacy of resection, measured by margin status and axillary lymph node yield, has not been systematically studied at major teaching hospitals. This study evaluates the oncological adequacy of mastectomy specimens and the association between surgical quality markers and disease-free survival among breast cancer patients at University College Hospital (UCH), Ibadan, Oyo State, South West Nigeria, from 2018 to 2023. A retrospective cohort of 180 patients who underwent modified radical mastectomy was reviewed. Primary outcomes were margin positivity rates and axillary lymph node yield. Secondary outcomes included locoregional recurrence at 3 years and disease-free survival. Histopathological reports were reviewed alongside operative notes. Positive surgical margins were documented in 19.4% of cases. The mean axillary lymph node yield was 8.6 nodes per specimen, below the recommended minimum of 10. Margin positivity was significantly associated with locoregional recurrence (HR 2.9, p=0.003). Surgeon volume and experience were independent predictors of oncological adequacy. The study recommends standardized surgical oncology protocols, frozen section availability for intraoperative margin assessment, and structured breast surgery training for specialists in South West Nigeria to improve oncological outcomes. Keywords: breast cancer, mastectomy, surgical margins, axillary dissection, UCH Ibadan