Relative survival and the estimation of net survival: elements for further discussion.

The methods of calculation of survival corrected for independent cause of death are discussed, and a maximum likelihood method is proposed and illustrated by survival of colon cancer patients in Geneva. The methods which are at present favoured for doing such calculations are subject to various biases when estimating net survival if the populations are heterogeneous for life expectancy. The proposed maximum likelihood approach would eliminate these biases by enabling relevant adjustment for covariates which influence survival. The routine use of such methods would permit better comparison of survival within and between populations.