GSTP1 and pachyonychia congenita: Furthermore, a smaller study [50] investigated GSTP1 methylation in malignant tissue samples from 83 diagnostic needle-biopsy specimens from PC patients treated by RP, RT and/or ADT, and showed a moderate correlation between GSTP1 hypermethylation and time to BCR in log-rank univariate analysis, but no significance in multivariate Cox regression analysis (Table 2).