Regional differences in cervical cancer incidence among American Indians and Alaska Natives, 1999-2004

BACKGROUND. Reports from limited geographic regions indicate higher rates of cervical cancer incidence in American Indian and Alaska Native (AI/AN) women than in women of other races. However, accurate determinations of cervical cancer incidence in AI/AN women have been hampered by racial misclassification in central cancer registries. METHODS. The authors linked data from cancer registries participating in the National Program of Cancer Registries (NPCR) and the Surveillance, Epidemiology, and End Results (SEER) Program with Indian Health Service (IHS) enrollment records to improve identification of AI/AN race. NPCR and SEER data were combined to estimate annualized age-adjusted rates (expressed per 100,000 persons) for the diagnosis years 1999 to 2004. Analyses focused on counties known to have less racial misclassification, and results were stratified by IHS Region. Approximately 56% of AI/ANs in the US reside in these counties. The authors examined overall and age-specific incidence rates and stage at diagnosis for AI/AN women compared with non-Hispanic white (NHW) women. RESULTS. Invasive cervical cancer incidence rates among AI/AN women varied nearly 2-fold across IHS regions, with the highest rates reported in the Southern Plains (14.1) and Northern Plains (12.5); the lowest rates were in the Eastern region and the Pacific Coast. Overall, AI/AN women had higher rates of cervical cancer than NHW women and were more likely to be diagnosed with later stage disease. CONCLUSIONS. The wide regional variation of invasive cervical cancer incidence indicates an important need for health services research regarding cervical cancer screening and prevention education as well as policy development regarding human papillomavirus vaccine use, particularly in the regions with high incidence rates.