Ellis L, et al. - Given that the ratio of cancer mortality and cancer incidence rates in a population has conventionally been used as an indicator of the completeness of cancer registration, and the complement of the mortality-to-incidence ratio (1-M/I) has increasingly been presented as a surrogate for cancer survival more recently, researchers examined why this is mistaken in principle and misleading in practice. They offer an empirical evaluation of the extent to which trends in cancer survival are reflected by trends in the 1-M/I ratio. From 1981 to 2009, they compared trends in both the 1-M/I ratio and net survival at 1, 5, and 10 years for 19 cancers in men and 20 cancers in women, utilizing national cancer incidence, mortality and survival data in England. They found that the 1-M/I ratio lacked any theoretical basis as a substitute for cancer survival. Also, its validity in practice as a substitute for cancer survival was dismissed, either, whether at 5 years or at any other time interval since diagnosis. It lacked the useful properties of a population-based survival estimate. Its use as a surrogate for cancer survival was refuted.