Keratinocyte carcinomas in survivors of childhood cancer: A report from the childhood cancer survivor study

Background: Childhood 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. Objective: Identify risk factors and quantify KC cumulative incidence and multiple-incidence burden in CCS. Methods: KC were identified among Childhood Cancer Survivor Study participants, a cohort of 5-year cancer survivors diagnosed <21 years of age between 1970 and 1999 in North America. Cumulative incidence was estimated and multivariable models assessed relative rates of KC associated with survivor and treatment characteristics. Results: Among 25,658 participants, 1446 developed 5363 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). Mean lesion count was 3.7 with 26.1% experiencing ≥4. Radiotherapy 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. Limitations: Participant self-reporting of some data including race without skin phototype and past medical history may have impacted analysis. Conclusions: The burden of KC in CCS remains high, but predictable risk factors should guide screening.