A convenient calf proportion index calculator for survival prediction in overweight and obese patients with cancer.

OBJECTIVE: This study aimed to define the calf proportion index (CPI) and investigate its association with malnutrition and survival in overweight and obese patients with cancer.

METHODS: This multicenter observational cohort study included 3499 patients diagnosed with cancer, including 3145 overweight and 354 obese individuals. The CPI was defined as the ratio of the cross-sectional area of the calf circumference (CC) to the body surface area (BSA). A CPI calculator that automatically calculated the CPI and survival probability based on the patient's sex, height, weight, and CC was developed.

RESULTS: During a median follow-up of 44.1 months, 935 deaths were recorded. Receiver operating characteristic curves revealed that the CPI was better than CC and BSA as a predictor of survival, with AUCs for the 3-year mortality rate were 0.574, 0.553 and 0.529, respectively. In overweight and obese patients with cancer, the optimal CPI cut-off value was 0.65 % for men and 0.57 % for women. The Kaplan-Meier curve revealed that patients with a low CPI had lower survival. After adjusting confounding factors, a low CPI was an independent risk factor for overweight (hazard ratio [HR]: 1.29, 95 % confidence interval [CI]: 1.11-1.51, P < 0.001) and obesity (HR: 1.92, 95 % CI: 1.20-3.09, P = 0.007) in patients with cancer. The CPI exhibited significant prognostic value in patients with lung and digestive system cancers. The risk of malnutrition was significantly higher in patients with a low CPI (HR: 1.25, 95 % CI: 1.04-1.50, P = 0.019).

CONCLUSIONS: The CPI is a useful prognostic indicator in overweight and obese patients with cancer, especially in obese patients.