Despite being cost-effective, the 2-stage approach was associated with increased cancer incidence and mortality compared with hyst-BSO at age 40 years for individuals with MLH1 variants (incidence: 7.76% vs 3.84%; mortality: 5.74% vs 2.55%) and those with MSH6 variants (incidence: 7.24% vs 4.52%; mortality: 5.22% vs 2.97%). This evidence concerns the gene MLH1 and cancer.