Conditional survival analyses across cancer sites.

Survival estimates measured from the time cancer diagnosis become less informative after one or two years' survival. Using records from the Canadian Cancer Registry linked to the Canadian Vital Statistics Death Database, five-year conditional relative survival ratio (RSR) estimates were derived for a large number of cancers. For each cancer with an initial five-year RSR of at least 80% (except breast cancer), a conditional five-year RSR of 95% or more was achieved after five years' survival. Among cancers with initial five-year RSRs of 50% to 79%, a five-year conditional RSR of 95% or more was observed for cancers of the cervix uteri and colon after five years. There was no apparent improvement in survival prospects during the first five years after diagnosis for chronic lymphocytic leukemia (CLL). Despite initial prognoses of less than 50%, a conditional five-year RSR of at least 90% five years after diagnosis was achieved for stomach cancer and leukemia (excluding CLL).