[Long term mortality of five-year survivors of childhood cancer in Rhône-Alpes region].

BACKGROUND: The population of survivors of childhood cancer is currently growing. Studies from other countries have shown an increased risk of late mortality. In order to measure this risk within a French cohort, the mortality of children who had survived five years from a cancer diagnosis were compared to the mortality of the general population, according to follow-up interval and cancer and treatment characteristics.

METHODS: The study population consisted of 635 children diagnosed with cancer before the age of 15 who had survived at least five years, and were registered in the Rhone-Alpes region cancer registry from 1987 to 1992. Mortality was compared with general population rates of the Rhone-Alpes region to assess age and sex standardized mortality ratio (SMR) and absolute excess risk of death.

RESULTS: The median follow-up of children was 14.0 years. Among the 42 observed deaths, 71.4% were attributed to a recurrence of the original cancer, 9.5% to a second cancer. The 15-year cumulative risk of death, all causes, was 7.1%. The overall mortality of the cohort was 20.7 fold greater than the general population (95% CI: 14.9-27.9), and the absolute excess risk of 6.9 per 1000 persons-years. The long term excess-mortality was higher in case of recurrence of original cancer (SMR=99.9, 95% CI: 67.9-141.9, absolute excess risk 35.4 per 1000 persons-years); it was raised during the five to nine years follow-up interval after diagnosis (SMR=33.8, 95% CI: 23.2-47.3) mainly due to the primary malignancy, and decreased after (10-14 years follow-up interval SMR=6.5, 95% IC 2.4-14.2).

CONCLUSION: The late mortality of childhood cancer is significantly increased during the five to nine years following diagnosis and decreases after, but the cohort follow-up has to be extended in order to assess outcome beyond 15 years after diagnosis.