External validation of a risk model for survival prediction in older patients with cancer undergoing elective abdominal surgery: a prospective cohort study.

We previously developed a Chang Gung Memorial Hospital (CGMH) model to predict the 1-year postoperative mortality risk in patients with solid cancer undergoing cancer surgery. This study aimed to externally validate the CGMH score for survival outcome and surgical complication prediction in a prospective patient cohort. A total of 345 consecutive patients aged ≥65 years who underwent elective abdominal surgery for cancer treatment were prospectively enrolled. Patients were categorized into the low, intermediate, high, and very high-risk groups according to the CGMH score for comparison. The postoperative 1-year mortality rate was 12.5% in the entire cohort. The postoperative 1-year mortality rates were 0%, 2.2%, 14.0%, and 31.6% among patients in the low, intermediate, high, and very-high risk groups, respectively. The c-statistic of the CGMH model was 0.82 (95% confidence interval [CI], 0.76-0.88) for predicting the 1-year mortality risk. Hazard ratios for overall survival were 3.73 (95% CI, 2.11-6.57; P<0.001) and 10.1 (95% CI, 5.84-17.6; P<0.001) when comparing the high and very-high risk groups with the low/intermediate risk groups, respectively. Patients in the higher CGMH risk groups had higher risks of adverse surgical outcomes in terms of longer length of hospital stay, major surgical complications, postoperative intensive care unit stay, and in-hospital death. The CGMH model accurately predicted thesurvival probabilityand risk of adverse surgical outcomes in older patients with cancer undergoing elective abdominal surgery. Our study justifies the prospective use of the CGMH model for survival outcome and safety profile predictionfor cancer surgery in older patients.