GSTP1 and Familial prostate cancer: GSTP1 methylation in the first and in the second negative biopsy was associated with prostate cancer detection [OR per 1% increase: 1.14 (95% CI 1.01–1.29) for the second biopsy and 1.21 (95% CI 1.07–1.37) for the highest methylation level (first or second biopsy)].