Abstract
•Cohort studies of cancer mortality among American Indian (AI) adults are rare.•We explored regional differences in cancer mortality in a cohort of older AI adults.•Differences by region occurred after adjustment for potential confounders.•Leading causes of cancer mortality also differed markedly by region.•Mortality from unspecified cancer was relatively common in all regions.
Cancer mortality among American Indian (AI) people varies widely, but factors associated with cancer mortality are infrequently assessed.
Cancer deaths were identified from death certificate data for 3516 participants of the Strong Heart Study, a population-based cohort study of AI adults ages 45–74 years in Arizona, Oklahoma, and North and South Dakota. Cancer mortality was calculated by age, sex and region. Cox proportional hazards model was used to assess independent associations between baseline factors in 1989 and cancer death by 2010.
After a median follow-up of 15.3 years, the cancer death rate per 1000 person-years was 6.33 (95 % CI 5.67–7.04). Cancer mortality was highest among men in North/South Dakota (8.18; 95 % CI 6.46–10.23) and lowest among women in Arizona (4.57; 95 % CI 2.87–6.92). Factors independently associated with increased cancer mortality included age, current or former smoking, waist circumference, albuminuria, urinary cadmium, and prior cancer history. Factors associated with decreased cancer mortality included Oklahoma compared to Dakota residence, higher body mass index and total cholesterol. Sex was not associated with cancer mortality. Lung cancer was the leading cause of cancer mortality overall (1.56/1000 person-years), but no lung cancer deaths occurred among Arizona participants. Mortality from unspecified cancer was relatively high (0.48/100 person-years; 95 % CI 0.32−0.71).
Regional variation in AI cancer mortality persisted despite adjustment for individual risk factors. Mortality from unspecified cancer was high. Better understanding of regional differences in cancer mortality, and better classification of cancer deaths, will help healthcare programs address cancer in AI communities.