Observational evidence of much better cancer care among extremely poor Canadians than Americans

Cancer care has been observed to be advantaged in studies of near poor to poor Canadian versus similar United States contexts. However, none of them studied extremely impoverished, so-called “underclass” neighborhoods. This retrospective cohort study did. It examined the differential effects of extreme impoverishment on breast and colon cancer care in Canada and the US. Ontario (N = 300) and California (N = 1,500, multiple "controls") enhanced registry-based random samples diagnosed between 2000 and 2003 were followed until 2008. Extremely poor neighborhoods (40% or more poor based on federal criteria) were compared with extremely affluent neighborhoods (< 5% poor) within-country and with similarly extremely poor neighborhoods between-country. Extreme poverty was very strongly associated with non-localized disease at diagnosis, long waits for surgery and adjuvant therapy, non-receipt of breast conserving surgery, radiation therapy (RT) and chemotherapy therapy (CT), and much shorter survival rates in California, but not in Ontario. Extremely poor people with breast and colon cancer in Ontario were largely advantaged on care as compared with their California counterparts. The relative risks of not receiving indicated RT or CT and of not surviving for at least five years after being diagnosed ranged from nearly three- to more than four-fold greater among extremely poor patients in California than among their counterparts in Ontario. Such much greater risks of substandard American cancer care among the extremely poor as compared with those previously observed among the near poor to poor suggest a dose-response relationship. More inclusive health insurance coverage in Canada seems the most plausible explanation.