Germline pathogenic variants of BRCA1 and BRCA2 confer substantially elevated lifetime risks of breast, ovarian, prostate, and other cancers, although they occur at low frequencies in the population. In contrast, common single-nucleotide polymorphisms (SNPs) individually exert only small effects but are widespread in the population. When aggregated as polygenic risk scores (PRSs), these common variants play a complementary role in enhancing risk prediction, particularly when integrated with rare high-penetrance variants to enable more accurate and nuanced risk stratification. Previous large-scale analyses have demonstrated that the PRSs further stratify the risk among BRCA1 and BRCA2 carriers, and the PRSs have been incorporated into clinical risk assessment tools for female breast cancer. However, its limitations include restricted validation across non-European populations and its applicability to only a few cancer types. To address these gaps, we integrated BRCA1 and BRCA2 carrier status with PRSs in East Asian populations using BioBank Japan data. The preliminary results suggested heterogeneous contributions of PRSs by cancer type. This integrative approach holds promise for precise prevention and individualized surveillance strategies.