An international comparison of cancer survival: Toronto, Ontario, and Detroit, Michigan, metropolitan areas

Objectives. This study examined whether socioeconomic status has a differential effect on the survival of adults diagnosed with cancer in Canada and the United States. Methods. The Ontario Cancer Registry and the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) program provided a total of 58 202 and 76 055 population-based primary malignant cancer cases for Toronto, Ontario and Detroit, Mich, respectively. Socioeconomic data for each person's residence at time of diagnosis were taken from population censuses. Results. In the US cohort, there was a significant association between socioeconomic status and survival for 12 of the 15 most common cancer sites; in the Canadian cohort, there was no such association for 12 of the 15 sites. Among residents of low income areas, persons in Toronto experienced a survival advantage for 13 of 15 cancer sites a 1- and 5-year follow-up. No such between-country differentials were observed in the middle- or high-income groups. Conclusions. The consistent pattern of a survival advantage in Canada observed across various cancer sites and follow-up periods suggests that Canada's more equitable access to preventive and therapeutic health care services is responsible for the difference.