Breast cancer survival in Canada and the USA: meta-analytic evidence of a Canadian advantage in low-income areas.

BACKGROUND: This study tested the hypothesis that relatively poor Canadian women with breast cancer have a survival advantage over their counterparts in the USA.
METHODS: Seventy-eight independent retrospective cohort (incidence between 1984 and 2000, followed until 2006) outcomes were synthesized. Fixed effects meta-regression models compared women with breast cancer in low-income areas of Canada and the USA.
RESULTS: Low-income Canadian women were advantaged on survival [rate ratio (RR) = 1.14; 95% confidence interval (CI) 1.13-1.15] and their advantage was even larger among women <65 years of age who are not yet eligible for Medicare coverage in the USA (RR = 1.21, 95% CI 1.18-1.24). Canadian advantages were also larger for node positive breast cancer, which may present with greater clinical and managerial discretion (RR = 1.40, 95% CI 1.30-1.50), and smaller when Hawaii, the state providing the most Canadian-like access, was the US comparator (RR = 1.12, 95% CI 1.01-1.20).
CONCLUSIONS: More inclusive health care insurance coverage in Canada vs the USA, particularly among each country's relatively poor people, seems the most plausible explanation for such Canadian advantages. Provision of health care for all Americans would likely prevent countless early deaths, particularly among the relatively poor.