Comparing survival rates between different registries can be difficult

EDITOR—The paper by Stotter et al is an important reminder of the need for caution when comparing incidence and survival rates between different populations.1 At the Thames Cancer Registry we have developed a method of estimating completeness of ascertainment as a function of time since diagnosis.2 As part of this procedure, Kaplan-Meier estimates of survival are calculated, and we have included cases registered solely on the basis of information from their death certificates, assuming that …