Disparities of cancer incidence in Michigan's American Indians: Spotlight on breast cancer

Abstract

Introduction In American Indians (AI), cancer is a leading cause of mortality, yet their disease burden is not fully understood due to unaddressed racial misclassification in cancer registries. This study describes cancer trends among AIs in Michigan, focusing on breast cancer, in a linked data set of Indian Health Service (IHS), tribal and state cancer registry data adjusted for misclassification. Methods AI status was based upon reported race and linkage to IHS data and tribal registries. Data with complete linkage on all incident cancer cases in Michigan from 1995-2004 was used to calculate age-standardized incidence estimates for invasive all-site and female breast cancers stratified by racial group. For female breast cancers, stage and age-specific incidence and percent distributions of early versus late-stage cancers and age of diagnosis were calculated. Results Over 50% of all AI cases were identified through IHS and/or tribal linkage. In the linked data, AIs had the lowest rates of all-sites and breast cancer. For breast cancers, AI women had a greater late-stage cancer burden and a younger mean age of diagnosis as compared to whites. Although the age-specific rate for whites was greater than for AI women in nearly all age groups, the difference in hazard ratio increased with increasing age. Conclusions Our state-specific information will help formulate effective, tailored cancer prevention strategies to this population in Michigan. The data linkages used in our study are crucial for generating accurate rates and can be effective in addressing misclassification of the AI population and formulating cancer prevention strategies for AI nationwide.

Racial Disparities in Breast Cancer Diagnosis and Treatment by Hormone Receptor and HER2 Status

“…Consistent with the literature, our study found that African American (1–3,39), Hispanic white (1–3,40), Asian/Pacific Islander (1,3) and American Indian/Alaska Native (1,3,41,42) women had elevated risks of being diagnosed with more advanced stages of breast cancer compared to non-Hispanic white women. As reported by previous studies, African American (1,3,43–45) and Hispanic white(1,3,45) patients with early stage breast cancer were also more likely to receive inappropriate primary treatment following breast cancer diagnoses.…”

“…Beyond confirming that American Indian/Alaska Native are more likely to be diagnosed with more advanced stage breast cancer overall (1,3,41,42), we found this risk was confined primarily to triple-negative disease. According to a 2010 national survey, American Indian/Alaska Native reported the lowest breast cancer screening rate of all women aged 40 years or older, 63.9% compared to 75.4% among non-Hispanic whites (54).…”

“…According to a 2010 national survey, American Indian/Alaska Native reported the lowest breast cancer screening rate of all women aged 40 years or older, 63.9% compared to 75.4% among non-Hispanic whites (54). Another study involving American Indian/Alaska Native women in the Northern Plains found that the screening rate was lowest among 41–49 age group, with a rate as low as 33% (55). This missed opportunity in breast cancer screening among American Indian/Alaska Native may have contributed to the risk of late diagnosis of breast cancer overall, but it is not clear why the elevated risk was only seen for the triple negative subtype.…”

A Systematic Review of Barriers and Facilitators to Mammography in American Indian/Alaska Native Women

“…The likelihood of this population to reside on rural reservations and reliance on IHS eligibility for access to care can diminish researchers’ ability to gather accurate data on the AI/AN population, especially given the relatively lower incidence of breast cancer in this group. Analyzing data for AI/AN women can be problematic in that racial and ethnic minority individuals tend to be underrepresented in cancer registries; this is often related to racial misclassification, which for the AI/AN population may be very high (Roen, Copeland, Pinagtore, Meza, & Soliman, 2014). Additionally, incidence rates for AI/AN women may be less stable than for other racial/ethnic groups, due to the limited geographic areas in which their populations occur in high enough rates to aggregate data (Wingo et al, 2008).…”

Using Tribal Data Linkages to Improve the Quality of American Indian Cancer Data in Michigan

“…American Indians/Alaska Natives are more likely than members of other racial groups to be misclassified for race in cancer registries. 12-18 Restricting AI/AN data to IHS Contract Health Service Delivery Area (CHSDA) counties has been identified as one way to address racial misclassification; 19 however, nearly half of Michigan counties are non-CHSDA. 20…”