BackgroundChildhood cancer survivors (CCS) are at increased risk for keratinocyte carcinomas (KC) however, the long-term incidence of single and multiple KC is not well established. ObjectiveIdentify risk factors and quantify KC cumulative incidence and multiple-incidence burden in CCS. MethodsKC were identified among Childhood Cancer Survivor Study participants, a cohort of five-year cancer survivors diagnosed <21 years of age between 1970-1999 in North America. Cumulative incidence was estimated, and multivariable models assessed relative rates of KC associated with survivor and treatment characteristics. ResultsAmong 25,658 participants, 1,446 developed 5,363 KC (93.5% basal cell carcinoma, 6.7% squamous cell carcinoma; mean age 37.0 years (range 7.3-67.4), mean latency 25.7 years; 95.3% White and 88.4% with radiotherapy [RT]). Mean lesion count was 3.7 with 26.1% experiencing ≥4. RT imparted a 4.5-fold increase in the rate of any KC and 9.4-fold increase in the rate of ≥4 KC. Allogeneic and autologous hematopoietic cell transplant were associated with a 3.4- and 2.3-fold increased rate of KC, respectively. LimitationsParticipant self-reporting of some data including race without skin phototype and past medical history may have impacted analysis. ConclusionsThe burden of KC in CCS remains high, but predictable risk factors should guide screening
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