GSTP1 and renal cell adenocarcinoma: Furthermore, with respect to the GSTT1(−)/GSTP1(−) genetic model, a significant association was found between the combined effects of the null polymorphisms (GSTT1 and GSTP1) and the susceptibility to RCC (P<0.01, OR = 2.79, 95% CI = 1.44–5.42).