Cause of mortality in 5-year survivors of childhood cancer

Abstract

Survivors of childhood and adolescent cancer are at risk for long-term effects of disease and treatment. The Childhood Cancer Survivor Study assessed overall and cause-specific mortality in a retrospective cohort of 20,690 5-year survivors. Eligible subjects were individuals diagnosed with cancer (from 1970 to 1986) before the age of 21 who had survived 5 years from diagnosis. Underlying cause of death was obtained from death certificates and other sources, then and coded and categorized as recurrent disease, sequel of cancer treatment, or non-cancer-related. Age and sex standardized mortality ratios (SMRs) were calculated using United States population mortality data. The cohort demonstrated an 8.2-fold excess in overall mortality (95% confidence interval, 7.9 to 8.5). Recurrence of the original cancer was the leading cause of death among 5-year survivors, accounting for 57% of deaths. Statistically significant excess mortality rates were seen due to subsequent malignancies (SMR = 15.0), along with cardiac (SMR = 6.9), and pulmonary (SMR = 8.7). There was no increase seen for automotive accidents (SMR = 1.0), other accidents (SMR = 1.3), or suicide (SMR = 1.0). While recurrent disease remains a major contributor to late mortality in 5-year survivors of childhood cancer, significant excesses in mortality risk associated with treatment-related complications exist up to 25 years after the initial cancer diagnosis.