Chao, Chun

Abstract Background Few studies have assessed the burden of chronic medical conditions in adolescent and young adult (AYA) cancer survivors. This study estimated the risk of these conditions among AYA survivors compared to a matched cohort without cancer. Methods This retrospective cohort study included 2‐year survivors ( n = 14,917) of 11 common AYA (15–39 years) cancers diagnosed at the integrated health care organizations of Kaiser Permanente (KP) Southern and Northern California during 2006–2020. A comparison cohort ( n = 149,164) without cancer (matched 10:1 by age, sex, calendar year, and KP site) was included. Cumulative incidence (CMI) accounting for death as a competing risk was calculated. Poisson regression estimated the incidence rate ratio (IRR) of each condition in cancer survivors versus the matched cohort, adjusting for age, sex, and race/ethnicity. Results The 5‐year CMI was highest for thyroid (17.4%), respiratory (6.6%), cardiovascular (5.0%), and liver (4.8%) diseases. At 10 years, the CMI of any condition was 39% in survivors versus 26% in the matched cohort. Survivors had a 2‐fold increased risk of being diagnosed with any medical condition (IRR, 2.0; 95% confidence interval [CI], 1.9–2.0) as well as two or more conditions (IRR, 2.3; 95% CI, 2.2–2.5). Risk was highest among survivors of hematologic cancers and those diagnosed with distant stage disease. Elevated risks were observed within all sociodemographic groups of this insured population. Conclusion AYAs with cancer had a higher risk of chronic medical conditions compared to those without cancer. Long‐term surveillance, risk mitigation through lifestyle modifications and effective disease management are crucial to reduce premature mortality.