Cancer incidence and survival among American Indians registered for Indian health service care in Montana, 1982-1987.

BACKGROUND

Cancer incidence and cancer survival estimates in American Indians are quite limited.

PURPOSE

Our purpose was to estimate cancer incidence and survival in American Indians who were registered for Indian Health Service (IHS) care in Montana.

METHODS

We linked databases from the IHS and the Montana Central Tumor Registry (MCTR) to ascertain cases for the time period from January 1, 1982, through December 31, 1987. To calculate survival rates, we used a relative survival method that incorporated age-specific risks for noncancer deaths among American Indians.

RESULTS

We identified 344 cases that were compatible with the National Cancer Institute (Surveillance, Epidemiology, and End Results Program) surveillance definition of cancer. Of these cases, 249 (72%) were listed in both the MCTR and the IHS databases; 56 (16%) and 39 (11%) were listed in only the MCTR or the IHS database, respectively. Compared with the overall cancer incidence in U.S. White men, the overall cancer incidence in Montana American Indian men was markedly lower, as was the incidence for colorectal and bladder cancers and for non-Hodgkin's lymphoma. The overall cancer incidence for Montana American Indian women differed less markedly, however, from the overall incidence in U.S. White women. Compared with the cancer incidence in U.S. White women, the incidence in Montana American Indian women was significantly higher for cervical cancer but was significantly lower for colorectal, breast, and uterine cancers. Survival rates from cancer were also examined for the first time in this population. For those sites examined, the survival rates were much lower in Montana American Indians than in U.S. Whites.

CONCLUSIONS

We conclude that it is feasible to develop state-specific cancer incidence and survival estimates for American Indians in at least some states in different regions of the United States. Collaboration between the IHS and a state tumor registry is likely to improve the case ascertainment achieved by either agency alone.