BMI May Be a Prognostic Factor for Local Advanced Rectal Cancer Patients Treated with Long-Term Neoadjuvant Chemoradiotherapy.

Objective: This study aims to develop feasible nomograms to predict the overall survival (OS) and cancer-specific survival (CSS) of the local advanced rectal cancer (LARC) patients who were treated with neoadjuvant chemoradiotherapy (nCRT) and operation.

Methods: A total of 243 LARC patients undergoing nCRT followed by total mesorectal excision (TME) were enrolled. Preoperative clinical features and postoperative pathological characteristics were collected. A Cox regression analysis was performed, and Cox-based nomograms were developed to predict the OS and CSS. We assessed the predictive performance of the nomogram with concordance index and calibration plots.

Results: A total of 243 patients were included with a median follow-up period of 46 months (range from 9 to 86 months). Cox regression analysis showed that low BMI (BMI < 18.5, HR= 21.739, < 0.05), high level of preoperative CA19-9 (HR = 3.369, = 0.036), high ypStage (HR = 19.768, < 0.001), positive neural invasion (HR = 4.218, = 0.026) and no adjuvant chemotherapy (HR = 5.495, < 0.001) were independent predictors of poor OS. Age ≥70 (HR = 2.284, <0.001), low BMI (BMI < 18.5, HR = 3.906, < 0.05), positive preoperative CA19-9 (HR = 1.920, = 0.012), high ypStage (HR = 5.147, <0.001) and positive neural invasion (HR = 2.873, = 0.022) were independent predictors of poor CSS. The predictive nomograms were developed to predict the OS and CSS with a C-index of 0.837 and 0.760. Good statistical performance on internal validation was shown by calibration plots.

Conclusion: In conclusion, this study demonstrated that BMI was an independent prognostic factor for OS and CSS in LARC patients treated with nCRT followed TME. A nomogram incorporating BMI, neural invasion, pre-CA19-9, ypStage, age, and adjuvant chemotherapy could be helpful to predict the OS and CSS.