Cohort study of family history of cancer and risks of concordant and discordant cancers among women in South Korea

A nationwide cohort study in South Korea assessed concordant and discordant cancer risks across major cancer sites in women by comparing individuals with and without a family history of cancer. Researchers from Hanyang University College of Medicine (Seoul) studied a cohort of 5,015,485 cancer-free women aged ≥ 40 years who participated in the national breast cancer screening program in 2013-2014. Partipicants reported a family history of stomach, colorectal, liver, breast, cervical , or other cancers at screening. The risk of overall, site-specific, concordant (same cancer as the family history), and discordant cancers during follow-up to 2020 were evaluated. Overall, a family history of any cancer was associated with higher hazard of cancer (HR 1.11; 95% CI 1.10-1.12), with similar associations for cancers diagnosed before age 50 years an those diagnosed at aged 50 years or older. Elevated hazards associated with a family history were observed for most cancer sites, except for cervical, kidney, and brain cancer. Concordant associations were observed for gastric, colorectal, breast, and liver cancers (HRs 1.36 to 3,43) whereas cervival cancer showed no significant concordant association. The authors conclude that a family history of cancer was associated with both overall and site-specific cancer risk, with stronger associations for concordant cancers and more modest associations for discordant cancers (graphical abstract).