ESTIMATING RELATIVE SURVIVAL OF ITALIAN CANCER-PATIENTS FROM SPARSE CANCER REGISTRIES DATA

Purpose: A method is presented for estimating relative survival of can cer patients at the national level from survival data provided by canc er registries covering only a subset of the general population and ref erring to different, and not necessarily overlapping, incidence period s. Methods: Relative survival rates are estimated as a function of the covariates sex, age, epoch of diagnosis, and registry area by means o f a multiple regression model. National estimates are then computed by appropriate weighting of the sex-, age-, time- and registry-specific expected relative survival values. Results: The method is illustrated by a sample application to survival data of female breast cancer patie nts in Italy. The national estimates of breast cancer survival pattern show a mild decrease of survival with age and a marked increase with period of diagnosis.