Treatment outcomes for non-metastatic colorectal cancer in Nigeria: A 10-year retrospective study.

e15655 Background: Although the role of chemotherapy in the treatment of non-metastatic colorectal cancer (CRC) has been established little is known on its role and treatment outcomes in the Nigerian cohort. Recent data shows a unique biology and a prevalence of 28% of mismatch repair deficient CRC in the Nigerian population. It is unclear if this unique biology informs similar treatment approach in established guidelines. We set out to study the treatment outcomes of surgery, and chemotherapy in stage II and III CRC in Nigeria. Methods: This is a retrospective study on 381 patients with stage 2 and 3 CRC from 2013 to 2023. Patients were staged using the 8 th edition AJCC TNM. Data on these patients were retrieved from the African Research Group for Oncology (ARGO) database. Patients in each stage were subdivided into 5 groups based on the modality of treatment received (surgery alone; neoadjuvant therapy + surgery; surgery + adjuvant therapy; neoadjuvant therapy + surgery + adjuvant therapy; and chemotherapy alone). Primary end points of the study were overall survival (OS) and disease-free survival (DFS); and secondary end point was to identify the modality of treatment most appropriate for each stage. Data was analysed using Kaplan Meier curves and log rank test for survival outcomes. Results: The study showed that 40.6% of stage 2 and 40.4% of stage 3 CRC patients had surgery alone, while 59.4% and 59.6% of stage 2 and 3 respectively had combined chemotherapy and surgery. The median disease-free survival and overall survival was similar for both stages (10 months, p = 0.508; 9 months, p = 0.722 respectively). Patients with stage 3 who had either neoadjuvant chemotherapy or adjuvant chemotherapy had better OS when compared with patients who had surgery alone (p = 0.021; p = 0.001 respectively). Conclusions: This study advocates for the use of (neo)adjuvant chemotherapy for stage 3 CRC in Nigeria. This is in line with current NCCN and ASCO guidelines for stage 3 CRC. Prospective studies would be needed to fully explore the role of combined treatment modality (surgery and chemotherapy) in the non-metastatic setting.