GSTM1 and prostate cancer: Finally, men with 3, 4, and 5 or more copies of GSTM1 and GSTT1 genes were at significantly increased risk of prostate cancer (OR: 2.18, 95% CI: 1.21–3.91, OR: 3.24, 95% CI, 1.63–6.46, and OR: 5.77, 96% CI: 1.40–23.8, respectively) and there was a significant gene dose relationship (Ptrend<0.001).