SURVIVAL RATES FOR 4 FORMS OF CANCER IN THE UNITED-STATES AND ONTARIO

Objectives. In this study, cancer survival rates for patients diagnose d in Ontario and selected areas within the United States were compared . Methods. Relative survival rates were computed for patients aged 15 through 84 years diagnosed with any of four forms of cancer (breast, c olon, lung, and Hodgkin's disease). The cohorts represented those diag nosed over the years 1978 through 1986 in the Canadian province of Ont ario and in nine regions covered by the US National Cancer Institute's Surveillance Epidemiology and End Results program. Patients were foll owed through the end of 1990. Results. The cumulative relative surviva l rates were similar for American and Canadian patients. The largest d ifference was observed for breast cancer, were patients in the United States enjoyed a survival advantage through the follow-up period. Conc lusions. Patients in the United States and Ontario with the diseases s tudied, except for breast cancer, experience very similar survival. Th e greater use of mammographic screening in the United States could acc ount for that country's higher breast cancer survival rate by promotin g earlier and therefor more efficacious treatment, by introducing bias , or by a combination of both treatment and bias factors.