Mortality among 5-year survivors of cancer diagnosed during childhood or adolescence in British Columbia, Canada

BACKGROUND: Ongoing monitoring of late mortality among survivors of a childhood or adolescent cancer is essential to appropriately evaluate risk in more recent cohorts and with longer follow-up. We examined overall and cause-specific mortality in a population-based cohort of 2,354 individuals diagnosed with a cancer or tumor prior to 20 years of age between 1970 and 1995 in British Columbia (BC), Canada who survived at least 5 years. PROCEDURE: Late deaths in a survivor cohort ascertained from the BC Cancer Registry were identified using death registrations. Standardized mortality ratios, absolute excess risk of death, and cumulative risk of death were determined. Demographic, temporal, and disease-related factors in risk of late mortality were also assessed. RESULTS: After 24,491 person-years of follow-up, there were 181 deaths, 139 of which were cancer related. Excess risk of late mortality among survivors was 7 deaths per 1,000 person-years at risk (AER = 6.6). Standardized mortality ratio (SMR) was ninefold higher relative to the underlying BC population (SMR = 9.1, 95% CI, 7.8-10.5), and was greatest for those with a recurrence within 5 years of diagnosis, and for those diagnosed with acute lymphoblastic leukemia and nervous system tumors. Absolute excess risk of late death was significantly higher for males and for those diagnosed prior to 1980, but did not vary according to age at diagnosis. Relative mortality was significantly increased due to cancer-related causes of death (SMR = 81.7, 95% CI, 68.6-95.8), as well as circulatory (SMR = 9.7, 95% CI, 4.2-19.1) and respiratory (SMR = 16.8, 95% CI, 4.6-43.0) diseases. CONCLUSIONS: In this population-based cohort with long follow-up, there continues to be excess late mortality among childhood and adolescent cancer survivors due to both cancer and non-cancer causes, even among more recently diagnosed survivors.