Health Outcomes Beyond Age 50 Years in Survivors of Childhood Cancer: A Report From the Childhood Cancer Survivor Study

Abstract

PURPOSE There are limited data on the risk for mortality and health outcomes among the increasing population of older (age >50 years) survivors of childhood cancer during this later stage in life when there is an expected increase in aging-related morbidities. METHODS We assessed cause-specific mortality, incident new cancers, chronic health conditions (CHCs), frailty, and health status among survivors from the Childhood Cancer Survivor Study, conditional on surviving to 50 years. We calculated conditional survival rates, standardized mortality ratios (SMRs), and, for incident new cancers, cumulative burden, standardized incidence ratios (SIRs), and relative rates (RRs), compared with the general US population. RRs for CHCs and prevalence ratios for frailty and health status outcomes were calculated for survivors compared with siblings. Piecewise exponential regression identified risk factors. RESULTS Among 7,490 childhood cancer survivors alive at age 50 years, subsequent 5-, 10-, and 15-year mortality risks were 8%, 18%, and 32%, respectively; overall SMR was 3.2 (95% CI, 3.0 to 3.4). SMRs were highest for death due to new cancer (SMR = 4.7; 95% CI, 4.2 to 5.2). In subset analysis, survivors without radiation therapy (RT) exposure had similar new cancer rates as the general population. The population attributable fraction of new cancers to RT was 40%. Survivors had >2-fold risk of severe, life-threatening, or fatal CHCs (any: RR, 2.6 [95% CI, 2.2 to 3.1]; multiple: RR, 3.3 [95% CI, 2.5 to 4.4]), specifically among survivors with history of RT exposure, compared with siblings. We identified no associations between chemotherapy and late health outcomes. CONCLUSION Older survivors of childhood cancer continue to have an elevated burden of premature mortality, new cancers, and adverse health outcomes as they age. The increased risk for cancer and CHCs among these older survivors is associated with RT, but not chemotherapy, exposure.