Validation. The CCRS model significantly stratified LFS in the Pavia cohort (P = .005). Using low-risk group as a reference group, the HR for intermediate vs low risk (HR, 1.6; 95% CI, 0.55-4.62; P = .39) and high vs low risk (HR, 3.57; 95% CI, 1.56-8.18; P = .003).