In the stratified analysis by Smoking-related cancers, estrogen-related cancers, ethnicity, and BRCA1/BRCA2 mutation status, significant association was only observed between RAD51 135G>C and breast cancer risk for BRCA2 mutation carriers (Table 4; recessive model: OR = 4.88, 95% CI = 1.10–21.67; additive model: OR = 4.92, 95% CI = 1.11–21.83). This evidence concerns the gene RAD51 and cancer.