摘要：Objectives. We compared breast cancer death rates and mortality trends among American Indian/Alaska Native (AI/AN) and White women using data for which racial misclassification was minimized. Methods. We used breast cancer deaths and cases linked to Indian Health Service (IHS) data to calculate age-adjusted rates and 95% confidence intervals (CIs) by IHS-designated regions from 1990 to 2009 for AI/AN and White women; Hispanics were excluded. Mortality-to-incidence ratios (MIR) were calculated for 1999 to 2009 as a proxy for prognosis after diagnosis. Results. Overall, the breast cancer death rate was lower in AI/AN women (21.6 per 100 000) than in White women (26.5). However, rates in AI/ANs were higher than rates in Whites for ages 40 to 49 years in the Alaska region, and ages 65 years and older in the Southern Plains region. White death rates significantly decreased (annual percent change [APC] = −2.1; 95% CI = −2.3, −2.0), but regional and overall AI/AN rates were unchanged (APC = 0.9; 95% CI = 0.1, 1.7). AI/AN women had higher MIRs than White women. Conclusions. There has been no improvement in death rates among AI/AN women. Targeted screening and timely, high-quality treatment are needed to reduce mortality from breast cancer in AI/AN women. Breast cancer is the most frequently diagnosed cancer and a leading cause of cancer mortality among American Indian/Alaska Native (AI/AN) women. 1,2 Despite having a lower incidence of breast cancer than White women, AI/AN women are more likely to be diagnosed at younger ages and later stages. 3,4 Furthermore, breast cancer incidence rates vary considerably across the Indian Health Service (IHS) Contract Health Service Delivery Areas (CHSDAs). Incidence rates in the Alaska region are similar to those of White women, but other regions have lower incidence rates than White women. 4 Breast cancer death rates among AI/AN women show patterns similar to incidence rates and are lower than rates in the general US population. 5,6 Furthermore, among AI/AN women, mortality trends exhibit similar patterns in regional variation. Espey et al. 5 found that 1996 to 2001 breast cancer death rates for AI/AN women were lower in the East, Pacific Coast, and Southwest, but similar for Alaska and the Southern Plains, compared with the rate for the general US population. Although all races experienced decreases in death rates from 1990 to 1995 to 1996 to 2001, the rates for AI/AN women were stable during these 2 time periods, 5 with no noted improvements. It is uncertain whether there has been any progress in reducing breast cancer mortality among AI/AN women since 2001. To date, the study by Espey et al. 5 is the only one that has examined 1990 to 2001 breast cancer mortality trends among AI/AN women compared with the general population, while also controlling for racial misclassification of AI/AN women. In addition, no studies have used mortality-to-incidence ratios (MIRs) to assess the burden of breast cancer among AI/AN women. The MIR measures prognosis after diagnosis, and therefore, can serve as an indicator of survival. 7 Furthermore, the MIR differential between AI/AN and White women serves as a proxy for excess mortality among AI/AN women, controlling for incidence. 7 To better understand the burden of breast cancer among AI/AN women, we examined breast cancer mortality trends in 1990 to 2009 data and fatality after breast cancer diagnosis in 1999 to 2009 data among AI/AN and White women. We used an incidence and mortality data set for which racial misclassification was minimized. Furthermore, we described geographic variations and trends over time of mortality caused by breast cancer among AI/AN women during this same time period. These mortality estimates provided a baseline for measuring the impact of breast cancer control programs in decreasing the burden of breast cancer among this population and identifying geographic areas where additional outreach is needed.
