[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.