Objectives. Previous studies have reported higher rates of cervical cancer incidence and mortality in American Indian and Alaska Native (AI/AN) women compared to women of other races. However, race misclassification hampers accurate determinations of rates among AI/AN women. Observed disparities in incidence rates of cervical cancer between AI/AN and white populations increased after efforts were made to ensure that members of AI/AN populations were properly identified, which increased the number of AI/AN cases and corresponding rates. The purpose of this analysis is to describe the incidence and mortality of cervical cancer among AI/AN women from 1999-2009, using techniques to minimize the effect of race misclassification in surveillance data, and to compare rates of cervical cancer among these women to rates among white women living in the same areas.
Methods. Data on cervical cancer deaths and incidence were linked with Indian Health Service records in order to improve identification of AI/AN populations. Analyses focused on deaths of AI/AN residents in IHS Contract Health Service Delivery Area (CHSDA) counties in 35 states. Linked data were used to produce age-adjusted incidence and death rates for 1999 to 2009. Data for both white and AI/AN populations were limited to non-Hispanics only.
Results: Mortality. AI/AN women had a cervical cancer death rate of 3.3 per 100,000, which was higher than the rate of 2.2 for white women (RR 1.54). For CHSDA areas only, the death rate from cervical cancer for AI/AN women was 4.2 per 100,000, which was nearly twice the corresponding rate among white women in CHSDA areas (rate 2.0 per 100,000; RR 2.11). Cervical cancer mortality among AI/AN women in CHSDA areas was highest in the Northern Plains region and correspondingly higher than white women in Northern Plains (RR 4.15), Southern Plains (RR 1.58), and the Southwest (RR 2.05). Cervical cancer mortality in CHSDA areas declined during 1990-2009 among both AI/AN women and white women. Major declines for AI/AN women occurred primarily during 1990-1993 (APC -25.8, p<0.05); but death rates remained relatively steady from 1993-2009 (APC -1.3). Declines among white women were more level, and statistically significant (APC -2.4 for 1990-2009)
Results: Incidence. AI/AN women had an incidence rate of cervical cancer of 8.7 per 100,000, compared to a rate of 7.5 for white women. However, when limiting to CHSDA areas, the rate for AI/AN women was 11.0 per 100,000, which was higher than for white women in CHSDA areas (rate 7.1 per 100,000). Cervical cancer incidence among AI/AN women in CHSDA areas was highest in the Southern Plains region (rate 15.1 per 100,000) and was higher than incidence for White women in Northern Plains (RR 1.97), Alaska (RR 1.94), Southern Plains (RR 1.64), Southwest (RR 1.19), and Pacific Coast (RR 1.36).
Conclusions. Our results demonstrate that AI/AN women suffer disproportionately from cervical cancer incidence and mortality, compared to white women in the same areas. However, both incidence and mortality have decreased over time, documenting improvements in identifying and treating cervical cancer and precancerous lesions. Most cervical cancers can be avoided or diagnosed early through screening and treatment. We noted steep declines in cervical cancer deaths among AI/AN women in the early 1990's. We believe that these are likely due to screening and treatment programs aimed specifically at AI/AN women. However, our data also underscore the need for further efforts as noted in CHSDA areas, where identification of AI/AN women is likely to be highest, because AI/AN women still die from cervical cancer at twice the rate of white women.
Citation Format: Meg Watson, Vicki Benard, Cheryll Thomas, Annie Brayboy, Roberta Paisano, Thomas Becker. Cervical cancer incidence and mortality disparities among American Indians and Alaska Natives, 1999-2009. [abstract]. In: Proceedings of the Sixth AACR Conference: The Science of Cancer Health Disparities; Dec 6–9, 2013; Atlanta, GA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2014;23(11 Suppl):Abstract nr B55. doi:10.1158/1538-7755.DISP13-B55