The results showed an raised BC risk (GSTT1 null/GSTP1 Val* vs. GSTT1 present/GSTP1 IIe/IIe: OR = 1.44, 95% CI = 1.10–1.88, all risk genotypes vs. GSTT1 present/GSTP1 IIe/IIe: OR = 1.23, 95% CI = 1.03–1.48, GSTT1 null/GSTP1 Val* vs. (GSTT1 null/GSTP1 IIe/IIe + GSTT1 present/GSTP1 Val* + GSTT1 present/GSTP1 IIe/IIe): OR = 1.26, 95% CI = 1.03–1.54) in all eligible studies. This evidence concerns the gene GSTP1 and breast cancer.