Background Survivors of childhood cancer develop early and severe chronic health conditions (CHCs). A quantitative landscape of morbidity among survivors, however, has not been described. Methods Among 5,522 patients treated for childhood cancer at St. Jude Children’s Research Hospital who survived ≥10 years and were ≥18 years old, 3,010 underwent prospective clinical assessment and retrospective medical validation of health records as part of the St. Jude Lifetime Cohort Study. Age- and sex-frequency-matched community-controls (n=272) were used for comparison. 168 CHCs for all participants were graded for severity using a modified Common Terminology Criteria of Adverse Events. Multiple imputation with predictive mean matching was used for missing occurrences and grades of CHCs among the 2512 survivors not clinically evaluated. Mean cumulative count and marked-point-process regression were used for descriptive and inferential cumulative burden analyses, respectively. Findings The cumulative incidence of any grade CHC at age 50 was 99·9%; 96·0% (95·3%–96·8%) for severe/disabling, life-threatening or fatal CHCs. By age 50, a survivor experienced, on average, 17·1 (16·2–18·0) CHCs including 4·7 (4·6–4·9) graded as severe/disabling, life-threatening or fatal. The cumulative burden among survivors was nearly 2-fold greater than matched community-controls (p<0·001). Second neoplasms, spinal disorders and pulmonary disease were major contributors to the excess total cumulative burden. Significant heterogeneity in CHCs among survivors with differing primary cancer diagnoses was observed. Multivariable analyses demonstrated that age at diagnosis, treatment era and higher doses of brain and chest radiation are significantly associated with a greater cumulative burden and severity of CHCs. Interpretation The burden of surviving childhood cancer is substantial and highly variable. The total cumulative burden experienced by survivors of pediatric cancer, in conjunction with detailed characterization of long-term CHCs, provide data to better inform future clinical guidelines, research investigations and health services planning for this vulnerable, medically-complex population.

The Childhood Cancer Survivor Study (CCSS) is a comprehensive multicenter study designed to quantify and better understand the effects of pediatric cancer and its treatment on later health, including behavioral and sociodemographic outcomes. The CCSS investigators have published more than 100 articles in the scientific literature related to the study. As with any large cohort study, high standards for methodologic approaches are imperative for valid and generalizable results. In this article we describe methodological issues of study design, exposure assessment, outcome validation, and statistical analysis. METHODS for handling missing data, intrafamily correlation, and competing risks analysis are addressed; each with particular relevance to pediatric cancer survivorship research. Our goal in this article is to provide a resource and reference for other researchers working in the area of long-term cancer survivorship.