Predicting the Efficacy of Adjuvant Chemotherapy Using Immuno‐Nutritional and Inflammatory Markers in Elderly Patients With Stage III Colorectal Cancer

Aim Use of postoperative adjuvant chemotherapy for colorectal cancer (CRC) in elderly patients raises concerns regarding efficacy and toxicity. This study aimed to determine whether immuno‐nutritional and inflammatory markers could serve as predictors of the outcomes of postoperative adjuvant chemotherapy in this population. Methods Patients aged ≥ 70 years who were diagnosed with stage III CRC and treated at the National Cancer Center Hospital in Japan between 2000 and 2017 were retrospectively analyzed. Long‐term survival outcomes were compared after propensity score matching (PSM) according to whether adjuvant chemotherapy was administered. Subgroup analyses were performed to determine the interaction of immuno‐nutritional and inflammatory markers with the outcomes of postoperative adjuvant chemotherapy. Results A total of 606 patients were included, and PSM resulted in 78 matched pairs. After PSM, there were significant improvements in recurrence‐free survival (RFS) and overall survival (OS) in the group that received adjuvant chemotherapy (RFS: Hazard ratio (HR) 0.537, 95% confidence interval (CI) 0.302–0.955, p = 0.034; OS: HR 0.495, 95% CI 0.247–0.990, p = 0.047, respectively). The postoperative lymphocyte‐to‐monocyte ratio (LMR) significantly affected RFS and OS (interaction p = 0.030 and interaction p = 0.023, respectively), and the postoperative C‐reactive protein‐to‐albumin ratio (CAR) significantly affected RFS (interaction p = 0.033). Conclusion Postoperative LMR and postoperative CAR were associated with the outcome of adjuvant chemotherapy and may help inform its administration in elderly patients with stage III CRC.