Women with a family history of hereditary breast cancer need precise risk estimates to guide screening decisions. We studied whether adding a polygenic risk score (PRS-BC313), capturing the combined effect of hundreds of common genetic variants, to standard risk calculations meaningfully changes individual breast cancer risk predictions. Among women without a known high-risk gene variant but with affected relatives, adding PRS shifted some women into a different screening category. Even in women carrying high-risk gene variants, individual risk estimates changed substantially. PRS integration thus enables more personalized screening recommendations beyond monogenic status. (https://jmg.bmj.com/content/early/2026/06/04/jmg-2025-111211)