BRCA1 and ovarian cancer: Subgroup analyses revealed that studies with adequate adjusted variables, but not with inadequate adjusted variables had statistically significant OS benefit in ovarian cancer patients with BRCA1/2-mutation (adequate adjusted variables, HR = 0.63, 95% CI, 0.53 to 0.75, I2 = 80.7%, P < 0.001; inadequate adjusted variables, HR = 0.89, 95% CI, 0.72 to 1.10, I2 = 0, P = 0.992).