Life expectancy as an indicator of outcome in follow-up of population-based cancer registries: the example of childhood leukemia.

BACKGROUND Survival analysis is a standard methodology to assess progress in oncology disease treatment. However, survival analysis commonly only measures survival during the treatment period (and the period immediately afterwards), and does not provide an estimate of life expectancy, which is often of more interest to patients and to health policy makers. In this paper we propose a method to estimate childhood acute lymphoblastic leukemia (ALL) life expectancy through the integration of traditional survival analysis and life expectancy tables. PATIENTS AND METHODS The study included 305 incident cases registered by the Childhood Cancer Registry of Piedmont in 1979-1991. Vital status on 30 June 2004 was known for 304 cases. Survival analyses were carried out using the Kaplan-Meier method and the Gompertz model, according to the time period of diagnosis and gender. RESULTS Cumulative survival at 5 years increased from 58.6% (95% CI 48.9-68.3) for cases diagnosed in March 1979-July 1982 to 79.1% (95% CI 70.8-87.5) in March 1987-February 1991 (P = 0.002). Average life expectancy increased from 46.1 years for boys and 42.6 years for girls diagnosed in March 1979-July 1982 to 58.3 and 69.1, respectively, in March 1987-February 1991. CONCLUSIONS These analyses show an improvement over the time period of diagnosis of life expectancy for children with ALL.