Fifty years of cancer in an American Indian population.

Background: A clear understanding of cancer patterns among American Indian tribal groups has been complicated by a variety of issues. A retrospective cohort study design was applied to a Seneca Nation of Indians (SNI) cohort for the period from 1955 through 2004.

Methods: Incident cancers were identified through a computer match with the New York State Cancer Registry. Standardized incidence ratios (SIRs) and 95% confidence intervals were calculated for the overall interval as well as for each of the 5 10-year intervals. The SNI cohort consisted of 3935 men and 4193 women with a total of 120,403 person-years.

Results: Significant deficits in cancer incidence were noted among men for all sites combined (SIR, 69), and for lung (SIR, 59), prostate (SIR, 54), urinary bladder (SIR, 8), and Hodgkin lymphoma (SIR, 0); no cancer sites were identified with significantly elevated incidence. Women demonstrated significantly reduced cancer incidence for all sites combined (SIR, 70) and for breast (SIR, 39), colorectal (SIR, 72), ovary (SIR, 37), uterus (SIR, 42), bladder (SIR, 20), pancreas (SIR, 10), and non-Hodgkin lymphoma (SIR, 39); elevated incidence was noted for cancers of the lung (SIR, 139) and liver (SIR, 405).

Conclusions: To the authors' knowledge, the current study represents the most comprehensive investigation to date of cancer patterns among an American Indian tribal group and provides insights for the development of tribal cancer control programming.