Prognostic value of albumin-to-alkaline phosphatase ratio and CONUT score in rectal cancer patients undergoing XELOX-based chemotherapy: development of a nomogram-based predictive model.

Objective: To evaluate the prognostic significance of the albumin-to-alkaline phosphatase ratio (AAPR) and the Controlling Nutritional Status (CONUT) score in rectal cancer (RC) patients receiving XELOX-based chemotherapy, and to develop a nomogram for predicting recurrence risk.

Methods: This retrospective study included 389 RC patients treated at the First Affiliated Hospital of Chongqing Medical University, along with an independent validation cohort of 120 patients. Clinical variables, including AAPR and CONUT were analyzed using Cox regression and cumulative incidence function curves. A nomogram was constructed and validated using calibration plots and time-dependent receiver operating characteristic (ROC) curves.

Results: Both AAPR (HR = 0.073, P<0.001) and CONUT score (HR = 1.497, P<0.001) were identified as independent predictors of recurrence. Additional factors significantly associated with increased recurrence risk included TNM stage III, tumor size ≥5 cm, vascular invasion, and carcinoembryonic antigen (CEA) level ≥5 ng/ml. The nomogram demonstrated strong predictive performance with a C-index of 0.860 in the training cohort, and 0.835 in the validation cohort. Calibration plots showed excellent agreement between predicted and observed recurrence probabilities.

Conclusions: AAPR and CONUT score are independent prognostic indicators for recurrence in RC patients treated with XELOX-based chemotherapy. The proposed nomogram, incorporating these variables, provides a reliable tool for individualized risk prediction and may support personalized treatment decision-making.