After adjusting for age and family history of BC and other cancers, MHBs of PSMC1, CARD11, and PSMB8 were found to be associated with reduced BC risk (ORadj = 0.587, 95% CI: 0.438–0.785, p < 0.001; ORadj = 0.584, 95% CI: 0.377–0.905, p = 0.016; ORadj = 0.640, 95% CI: 0.485–0.843, p = 0.002, respectively) (Table 5). Here, PSMC1 is linked to breast cancer.