GSTP1 and cystic fibrosis: Importantly, the trichotomized GSTP1 methylation emerged as an independent predictor of CF when adjusted for pT, final GS, pre-operative PSA level in both the training (Table 4; HR, 3.65; 95% CI, 1.65–8.07; P-value 0.001) and validation cohorts (Table 4, HR, 4.27; 95% CI, 1.03–17.72; P-value 0.046), as well as in the joint cohort (Table 4; HR, 2.74; 95% CI, 1.42–5.27; P-value 0.003).