Cancer disparities among Alaska native people, 1970-2011.

INTRODUCTION: Cancer is the leading cause of death among Alaska Native people. The objective of this study was to examine cancer incidence data for 2007-2011, age-specific rates for a 15-year period, incidence trends for 1970-2011, and mortality trends for 1990-2011. METHODS: US data were from the Surveillance, Epidemiology, and End Results (SEER) Program SEER*Stat database and from the SEER Alaska Native Tumor Registry. Age-adjusted cancer incidence rates among Alaska Native people and US whites were compared using rate ratios. Trend analyses were performed using the Joinpoint Regression Program. Mortality data were from National Center for Health Statistics. RESULTS: During 2007-2011 the cancer incidence rate among Alaska Native women was 16% higher than the rate among US white women and was similar among Alaska Native men and US white men. Incidence rates among Alaska Native people exceeded rates among US whites for nasopharyngeal, stomach, colorectal, lung, and kidney cancer. A downward trend in colorectal cancer incidence among Alaska Native people occurred from 1999 to 2011. Significant declines in rates were not observed for other frequently diagnosed cancers or for all sites combined. Cancer mortality rates among Alaska Native people during 2 periods, 1990-2000 and 2001-2011, did not decline. Cancer mortality rates among Alaska Native people exceeded rates among US whites for all cancers combined; for cancers of the lung, stomach, pancreas, kidney, and cervix; and for colorectal cancer. CONCLUSION: Increases in colorectal screening among Alaska Native people may be responsible for current declines in colorectal cancer incidence; however; improvements in treatment of colon and rectal cancers may also be contributing factors.

The Alaska Education and Research Towards Health (EARTH) Study: cancer risk factors.

The Alaska Education and Research Towards Health (EARTH) Study assessed cancer risk among 3,821 Alaska Native people (AN). We present the prevalence of selected cancer risk factors and comparison with Healthy People 2010 goals. Participants completed extensive computer-assisted self-administered questionnaires on diet, physical activity, tobacco and alcohol use, cancer screening, family history of cancer, and environmental exposures. Measurement data were collected on blood pressure, height, weight, waist/hip circumference, fasting serum lipids, and glucose. Cancer risk factors are high for the Alaska EARTH study population. For all risk factors studied except for vegetable consumption, Alaska EARTH Study participants did not meet Healthy People 2010 goals. This study is unique in providing questionnaire and measurement data of cancer risk factors on a larger study sample than any previous study among AN living in Alaska. Data show that the prevalence of most cancer risk factors exceeded national recommendations. Given the disease disparities that exist for the AN population, these data provide important baseline data that can be used to target health interventions and reduce health disparities.

Cancers of the breast, uterus, ovary and cervix among Alaska Native women, 1974-2003.

OBJECTIVES: Alaska Native (AN) women have exhibited some of the highest incidence rates of cancer overall, and different patterns of site-specific incidence compared to other U.S. populations. This study compares incidence rates between AN and U.S. white women (USW) for cancers of the breast, uterus, ovary and cervix, and examines effects of time period and birth cohort as determinants of incidence trends among AN women. STUDY DESIGN: Observational, population-based study. METHODS: Cancer incidence data from the Alaska Native Tumor Registry and SEERStat, 1974-2003. Age-adjusted World Standard Population rates were calculated for a current 5-year period and over time (30 years), and compared to other populations using rate ratios with 95% confidence intervals. Log-linear regression models used to assess impact on trend of age, time period and birth cohort. RESULTS: Compared to U.S. white women, current cancer rates among AN women are not significantly different for cancer of the breast and cervix, and significantly lower for cancers of the ovary and uterus. Trends over time over a 30-year time period also differ for these cancer sites. There were significant increases in breast and uterine cancer, and in contrast, a marked decline in cervical cancer. There was no significant change for cancer of the ovary. Changes appear to be due largely to period, not birth cohort effects. CONCLUSIONS: Increases in breast cancer may be due to a combination of modifiable behaviours; increased BMI and a shift to a non-traditional diet. Increases in uterine cancer could be associated with increased BMI and diabetes. Cervical cancer rates have declined to USW levels. The marked decline is likely due to enhanced screening and control efforts within the Alaska Native Women's cancers among Alaska Natives Tribal Health System (formerly Alaska Area USPHS, Indian Health Service utilizing resources available from the Centers for Disease Control tribal and state Breast and Cervical Cancer Early Detection Programs).

Perspectives on communication and engagement with regard to collecting biospecimens and family health histories for cancer research in a rural Alaska Native community.

Precision medicine initiatives, such as Cancer Breakthrough 2020, promise to improve cancer outcomes by tailoring treatment to an individual's genes, environment, and lifestyle. This promise will fall short unless researchers successfully engage diverse communities, including those with histories of medical and research abuse. We examined a rural Alaska Native community's viewpoints about biospecimen collection and storage; interest and recall in reporting family health history; and interest and engagement in biospecimen collection for conducting a genetic test for cancer. In 2014, four focus groups were held with 28 adult Alaska Native rural community members. Thematic analysis was performed after establishing a coding scheme by team consensus. Study participants shared interest in engaging in genetic cancer research and suggested ways to improve community engagement in research. These included transparency and continuous communication with researchers at all stages of the research, clear communication about the intent of the research, and that research and results take into consideration the community's needs. These suggestions may be beneficial for future efforts to expand precision medicine research in Alaska Native communities and similar, diverse populations.

Disparities in cancer mortality among Alaska Native people, 1994-2003.

OBJECTIVE: To provide current data on cancer mortality among Alaska Native people for the period of 1994-2003, and to identify and quantitate cancer disparities. METHODS: Cancer mortality rates for Alaska Native (AN), U.S., White (USW) and other populations were calculated using SEERStat. Ratios of age-adjusted incidence rates with 95% confidence intervals are provided. RESULTS: Data were from SEERStat. Age-adjusted cancern mortality rates for Alaska Native exceeded those of USW population by 20%. For specific cancer sites, rates were significantly higher among AN people: oral cavity and pharynx (RR=1.9), esophagus (RR=2.0), stomach (RR=3.9), colon and rectum (RR=1.8), liver (RR=1.9), gallbladder (RR=2.6), pancreas (RR=1.3), lung and bronchus (RR=1.2), and kidney and renal pelvis (RR=2.2). In contrast, mortality rates among AN people were significantly lower than USW rates for cancers of the prostate (RR=0.7), brain and nervous system (RR=0.3), lymphoma (RR=0.6), and leukemia (RR=0.4). CONCLUSION: Marked disparities in cancer mortality exist among the Alaska Native population compared to the US White population. Excess mortality is documented for all sites combined and for many cancer specific sites. Rates for all cancers combined and for select sites are among the highest of any racial/ethnic group in the United States.

Women's cancers among Alaska Natives: [corrected] 1969-2003.

INTRODUCTION: Alaska Native (AN) people include multiple, diverse ethnic groups whose ancestors occupied what is now the state of Alaska. Cancer incidence rates among Alaska Native women for breast, cervix, uterus and ovary are presented here. Current rates and trends over time are compared with U.S. White rates. OBJECTIVE: To describe cancer incidence patterns for cancer of the breast, cervix, uterus and ovary among Alaska Native women. METHODS: Cancer incidence data for Alaska Natives are from the Alaska Native Tumor Registry, in Anchorage, Alaska. Incidence rates for U.S. Whites are from the National Cancer Institute Surveillance, Epidemiology, and End Results Program. RESULTS: Breast and cervical cancer incidence rates among Alaska Natives are similar to U.S. White rates, whereas rates for cancer of the uterus and ovary are significantly less than those of U.S. Whites. Thirty-five year trends show increasing rates in breast cancer and decreasing rates of cervical cancer. CONCLUSION: The burden of cancer among Alaska Native women for cancers unique to women is significant. Increasing breast cancer rates among Alaska Natives has greatly contributed to this burden.

Women's cancers among Alaska Natives 1969-2003.

INTRODUCTION: Alaska Native people include multiple, diverse ethnic groups whose ancestors occupied what is now the state of Alaska. Cancer incidence rates among Alaska Native women for breast, cervix, uterus and ovary are presented here. Current rates and trends over time are compared with US White rates. OBJECTIVE: To describe cancer incidence patterns for cancer of the breast, cervix, uterus and ovary among Alaska Native women. METHODS: Cancer incidence data for Alaska Natives are from the Alaska Native Tumor Registry, in Anchorage, Alaska. Incidence rates for US Whites are from the National Cancer Institute Surveillance, Epidemiology, and End Results Program. RESULTS: Breast and cervical cancer incidence rates among Alaska Natives are similar to US White rates, whereas rates for cancer of the uterus and ovary are significantly less than those of US Whites. Thirty-five year trends show increasing rates in breast cancer and decreasing rates of cervical cancer. CONCLUSION: The burden of cancer among Alaska Native women for cancers unique to women is significant. Increasing breast cancer rates among Alaska Natives has greatly contributed to this burden.

Differences in cancer incidence among Indians in Alaska and New Mexico and U.S. Whites, 1993-2002.

Cancer incidence for American Indians and Alaska Natives is typically reported as a single rate for all U.S. indigenous populations combined. Previously reported combined rates suggest that American Indians and Alaska Natives have lower cancer incidence rates compared with the U.S. population. Alaska Native people comprise three major ethnic groups: Eskimo, Indian, and Aleut people. We examined cancer incidence from only Alaska Indians and compared incidence rates with an American Indian population living in New Mexico. These data indicate striking differences in cancer patterns between two American Indian populations. Cancer data for the years 1993 to 2002 for American Indians of New Mexico and U.S. Whites are from the National Cancer Institute Surveillance, Epidemiology, and End Results Program Public-use data set. Data for Alaska Indians are from the Alaska Native Tumor Registry, which is also a Surveillance Epidemiology and End Results Program participant. Overall, cancer incidence rates for all sites combined in New Mexico Indian men and women were lower than U.S. White rates, whereas Alaska Indian men and women exceeded U.S. rates. In comparing Alaska and New Mexico Indians, we observed a 2.5-fold higher incidence of cancer among Alaska Indians. The largest differences between the two Indian populations were noted primarily in cancers associated with tobacco use, including cancers of the oral cavity/pharynx, esophagus (only in men), colon and rectum, pancreas, larynx (men), lung, prostate, and urinary bladder (men). Lung cancer rates in Alaska Indian men and women were 7 and 10 times those of New Mexico Indian men and women.

Prostate cancer in Alaska Native men, 1969-2003.

OBJECTIVES: The incidence of prostate cancer differs significantly between US race groups. In prior reviews of cancer in Alaska Natives, the incidence of prostate cancer has been observed to occur at a low rate compared to US Whites and Blacks. However, a detailed report of prostate cancer in this population has not been previously published. STUDY DESIGN: Incidence of prostate cancer in Alaska Native men was determined for the time period 1969-2003 using data from the Alaska Native Tumor Registry. The registry is a population-based registry which participates in the National Cancer Institute Surveillance, Epidemiology and End Results Program, and has collected cancer information on Alaska Natives since 1969. METHODS: Incidence rates were calculated for all Alaska Natives and for each of the three major ethnic groups (Aleut, Eskimo, Indian). Comparisons of incidence rates between Alaska Natives and US Whites were performed using odds ratios. Temporal changes were identified by a Chi square analysis for trend. RESULTS: During the 35-year period of review, 332 Alaska Native men were diagnosed with prostate cancer. The age-adjusted incidence rate of 69.5 per 100 000 in Alaska Native men during 1994-2003 was significantly higher than the rate of 45.5 per 100 000 for the earlier period 1969-1983. The US White rate for 1994-2002 of 169.5 per 100 000 was significantly higher than the rate for Alaska Native men for 1994-2003. Results of comparisons between Alaska Native ethnic groups for 1969-2003 showed that prostate cancer was highest in Indians and Aleuts and lowest among Eskimos. CONCLUSIONS: Compared to the US White population, the incidence of prostate cancer in Alaska Native men is significantly lower. Prostate cancer rates among Alaska Native ethnic groups differ. The reason for these differences remains undetermined.

Occurrence of esophageal and gastric cancer in Alaska Natives, 1969-2003.

BACKGROUND: Early reports of esophageal and gastric cancer in American Indians/Alaska Natives documented high rates. METHODS: Esophageal and gastric cancers in Alaska Natives were reviewed for 1969-2003 using the Alaska Native Tumor Registry database. Alaska Native incidence rates were age-adjusted and compared to rates of several US populations. RESULTS: The incidence of esophageal and gastric cancer has remained relatively stable during the 35-year period. Gastric cancer is higher than that seen in US Whites, Blacks and American Indians of New Mexico and similar US Asian/Pacific Islanders. Esophageal cancer incidence is higher than US Whites, Asian/Pacific Islanders and American Indians of New Mexico but similar to US Blacks. CONCLUSION: The rates of esophageal and gastric cancer in the Alaska Native population have remained high over 35 years. While the rate of gastric cancer has declined among US Whites, a similar decline has not been seen in Alaska Natives.

Cancer among circumpolar populations: an emerging public health concern.

OBJECTIVES: To determine and compare the incidence of cancer among the 8 Arctic States and their northern regions, with special focus on 3 cross-national indigenous groups--Inuit, Athabaskan Indians and Sami. METHODS: Data were extracted from national and regional statistical agencies and cancer registries, with direct age-standardization of rates to the world standard population. For comparison, the "world average" rates as reported in the GLOBOCAN database were used. FINDINGS: Age-standardized incidence rates by cancer sites were computed for the 8 Arctic States and 20 of their northern regions, averaged over the decade 2000-2009. Cancer of the lung and colon/rectum in both sexes are the commonest in most populations. We combined the Inuit from Alaska, Northwest Territories, Nunavut and Greenland into a "Circumpolar Inuit" group and tracked cancer trends over four 5-year periods from 1989 to 2008. There has been marked increase in lung, colorectal and female breast cancers, while cervical cancer has declined. Compared to the GLOBOCAN world average, Inuit are at extreme high risk for lung and colorectal cancer, and also certain rare cancers such as nasopharyngeal cancer. Athabaskans (from Alaska and Northwest Territories) share some similarities with the Inuit but they are at higher risk for prostate and breast cancer relative to the world average. Among the Sami, published data from 3 cohorts in Norway, Sweden and Finland show generally lower risk of cancer than non-Sami. CONCLUSIONS: Cancer among certain indigenous people in the Arctic is an increasing public health concern, especially lung and colorectal cancer.

Helicobacter pylori infection and markers of gastric cancer risk in Alaska Native persons: a retrospective case-control study.

BACKGROUND: Alaska Native persons experience gastric cancer incidence and mortality rates that are three to four times higher than in the general United States population. OBJECTIVE: To evaluate pepsinogen I, pepsinogen I/II ratio, anti-Helicobacter pylori and cytotoxin-associated gene A (CagA) antibody levels, and blood group for their associations with gastric cancer development in Alaska Native people. METHODS: The present analysis was a retrospective case-control study that matched gastric cancers reported to the Alaska Native Tumor Registry from 1969 to 2008 to three controls on known demographic risk factors for H pylori infection, using sera from the Alaska Area Specimen Bank. Conditional logistic regression evaluated associations between serum markers and gastric cancer. RESULTS: A total of 122 gastric cancer cases were included, with sera predating cancer diagnosis (mean = 13 years) and 346 matched controls. One hundred twelve cases (91.8%) and 285 controls (82.4%) had evidence of previous or ongoing H pylori infection as measured by anti-H pylori antibody levels. Gastric cancer cases had a 2.63-fold increased odds of having positive anti-H pylori antibodies compared with their matched controls (P=0.01). In a multivariate model, noncardia gastric cancer (n=94) was associated with anti-H pylori antibodies (adjusted OR 3.92; P=0.004) and low pepsinogen I level (adjusted OR 6.04; P=0.04). No association between gastric cancer and blood group, anti-CagA antibodies or pepsinogen I/II ratio was found. CONCLUSION: Alaska Native people with gastric cancer had increased odds of previous H pylori infection. Low pepsinogen I level may function as a precancer marker for noncardia cancer.

HPV genotypes detected in cervical cancers from Alaska Native women, 1980-2007.

BACKGROUND: Human papillomavirus (HPV) vaccine prevents cervical pre-cancers and cancers caused by HPV types 16 and 18. This study provides information on the HPV types detected in cervical cancers of Alaska Native (AN) women. METHODS: Cases of invasive cervical cancer diagnosed in AN women aged 18 and above between 1980 and 2007 were identified from the Alaska Native Tumor Registry. A representative formalin-fixed, paraffin-embedded archived pathology block was retrieved and serially sectioned to allow histologic confirmation of lesion (first and last sections) and PCR testing of intervening sections. Extracted DNA was tested for HPV using Linear Array HPV Genotyping Test (Roche Diagnostics) with additional INNO-LiPA HPV Genotyping Assay (Innogenetics) testing on negative or inadequate specimens. All specimens were tested for a minimum 37 HPV types. RESULTS: Of 62 cervical cancer specimens evaluated, 57 (91.9%) contained one or more HPV types. Thirty-eight (61.2%) cancers contained HPV types 16 or 18, and 18 (29%) contained an oncogenic type other than type 16 or 18. CONCLUSIONS: Overall, almost two-thirds (61.2%) of the archived cervical cancers had detectible HPV types 16 or 18, a finding similar to studies of US women. As expected, a proportion of cancers would not be prevented by the current vaccines. HPV vaccination and cervical cancer screening are important prevention strategies for AN women.

Colorectal cancer in alaska native people, 2005-2009.

BACKGROUND: Colorectal cancer (CRC) is the most frequently diagnosed cancer among Alaska Native (AN) people, and the second leading cause of cancer death. The incidence rate for the combined years 1999 through 2003 was 30% higher than the rate among U.S. whites (USWs) for the same period. Current incidence rates may serve to monitor the impact of screening programs in reducing CRC in the AN population. METHODS: Incidence data are from the Alaska Native Tumor Registry and the National Cancer Institute Surveillance, Epidemiology, and End Results (SEER) Program. We compared AN CRC incidence, survival rates, and stage at diagnosis with rates in USWs for cases diagnosed from 2005 through 2009. Relative survival calculations were produced in SEER*Stat by the actuarial method. RESULTS: The CRC age-adjusted incidence rate among AN men and women combined was higher than those in USW men and women (84 vs. 43/100,000; P < .05; AN:USW rate ratio [RR] = 2.0). The greatest differences between rates in AN people and USWs were for tumors in the hepatic flexure (RR = 3.1) and in the transverse (RR = 2.9) and sigmoid (RR = 2.5) regions of the colon. Rectal cancer rates among AN people were significantly higher than rates in USWs (21 vs.12/100,000). Five-year relative survival proportions by stage at diagnosis indicate that the CRC 5-year relative survival was similar in AN people and USWs for the period 2004 through 2009. CONCLUSIONS: The high rate of CRC in AN people emphasizes the need for screening programs and interventions to reduce known modifiable risks. Research in methods to promote healthy behaviors among AN people is greatly needed.

Occurrence of pancreatic, biliary tract, and gallbladder cancers in Alaska Native people, 1973-2007.

OBJECTIVES: To describe the occurrence of pancreatic, biliary tract, and gallbladder cancers within the Alaska Native (AN) population. STUDY DESIGN: Population-based analysis utilizing a tumor registry and comparative population data. METHODS: Pancreaticobiliary cancers rates for AN people during 1973-2007 were determined from the Surveillance, Epidemiology, and End Results (SEER) AN Tumor Registry. Cancer incidence rates were age-adjusted to the World Standard Million and compared over 2 time periods with US white and black rates. RESULTS: During 1973-2007, 213 AN people developed pancreatic cancer, 73 gallbladder cancer and 61 biliary tract cancer. Pancreatic cancer occurs at similar rates in AN men and women, but data for 1993-2007 indicate that the rates among AN men may be increasing. The incidence rate in AN women (9.5/100,000) was statistically higher than in US white women (5.8/100,000). The incidence for biliary tract cancer in AN men and gallbladder cancer in AN men and women is statistically higher than that for US whites and blacks. CONCLUSIONS: Pancreaticobiliary cancers, particularly biliary tract and gallbladder cancers, in both AN men and women and pancreatic cancer in women occur at an increased rate in AN people. Risk factors relating to the elevated rate are discussed. Certain factors are potentially modifiable, such as the use of tobacco and obesity.

Cancers of the urinary tract among American Indians and Alaska Natives in the United States, 1999-2004.

BACKGROUND: Assessment of the kidney parenchyma ("kidney") and urinary bladder ("bladder") cancer burden among American Indians and Alaska Natives (AI/AN) has been limited. Using a database with improved classification for AI/AN, the authors described patterns of these 2 cancers among AI/AN and non-Hispanic whites (NHW) in the United States. METHODS: Cases diagnosed during 1999 to 2004 were identified through National Program of Cancer Registries and the Surveillance, Epidemiology and End Results program and linked to the Indian Health Service (IHS) registration records. Age-adjusted incidence rates, rate ratios (RR), annual percent change, and stage at diagnosis were stratified by IHS Contract Health Service Delivery Area (CHSDA) counties to adjust for misclassification. RESULTS: Kidney cancer incidence among AI/AN in CHSDA counties exceeded that among NHW (RR, 1.51; 95% confidence interval [CI], 1.42-1.61), and was highest among AI/AN in the Northern Plains, Southern Plains, Alaska, and Southwest. Average annual increases were highest among AI/AN (5.9%) and NHW (5.9%) males aged 20 to 49 years, although statistically significant only among NHW. Conversely, bladder cancer incidence was significantly lower among AI/AN than NHW (RR, 0.40; 95% CI, 0.37-0.44). For both sites, AI/AN were significantly less likely to be diagnosed at an earlier stage than NHW. CONCLUSIONS: AI/AN have about 50% greater risk of kidney cancer and half the risk of bladder cancer than NHW. Although reasons for these enigmatic patterns are not known, sustained primary prevention efforts through tobacco cessation and obesity prevention are warranted.

Incidence of cancers of the oral cavity and pharynx among American Indians and Alaska Natives, 1999-2004.

BACKGROUND: Previous studies identified disparities in incidence rates of cancers of the oral cavity and pharynx between American Indians/Alaska Natives (AI/AN) and non-Hispanic whites (NHW) and differences between various AI/AN populations. Reporting among AI/AN has been hampered by: 1) heterogeneity among various anatomic sites of oral cavity and pharyngeal cancers obscuring unique patterns of individual anatomic sites; 2) race misclassification and underreporting of AI/AN; and 3) sparseness of data needed to identify regional variations. METHODS: To improve race classification of AI/AN, data from US central cancer registries were linked with Indian Health Service (IHS) records. AI/AN incidence data from 1999 to 2004 were stratified by sex, age, stage at diagnosis, and anatomic subsite for 6 IHS geographic regions and compared with NHW populations. RESULTS: For all oral cavity and pharynx cancers combined, among residents of Contract Health Service Delivery Area counties, AI/AN overall had significantly lower incidence rates than NHW (8.5 vs 11.0). However, AI/AN rates were significantly higher in the Northern Plains (13.9 vs 10.5) and Alaska (16.3 vs 10.6), significantly lower in the Pacific Coast (7.7 vs 11.6) and Southwest (3.3 vs 10.4), and similar in the Southern Plains (11.4). Overall AI/AN males had higher incidence rates than AI/AN women. Nasopharyngeal cancer was more frequent (1.1AI/AN vs 0.4 NHW), and tongue cancer less frequent (1.6 AI/AN vs 2.9 NHW) in AI/AN than NHW populations; however, rates varied by region. Stage distribution was modestly less favorable for AI/AN compared with NHW populations. CONCLUSIONS: Variation by region, anatomic site, and sex indicates a need for research into etiologic factors and attention to regional risk factor profiles when planning cancer control programs.

Cancer among American Indians and Alaska Natives in the United States, 1999-2004.

BACKGROUND: Cancer incidence rates vary among American Indian and Alaska Native (AI/AN) populations and often differ from rates among non-Hispanic whites (NHWs). However, the misclassification of race for AI/AN cancer cases in central cancer registries may have led to underestimates of the AI/AN cancer burden in previous reports. METHODS: Cases diagnosed during 1999 through 2004 were identified from population-based cancer registries in the United States. Age-adjusted rates were calculated for the 25 most common sites for AI/ANs and NHWs. To minimize the misclassification of race, cancer registry records were linked with patient registration files from the Indian Health Service (IHS). Analyses were restricted to Contract Health Service Delivery Area (CHSDA) counties and were stratified by IHS region. RESULTS: In CHSDA counties, cancer incidence rates among AI/ANs varied widely by region, whereas rates among NHWs did not. For all cancer sites combined, AI/AN rates were higher than NHW rates among both males and females in the Northern and Southern Plains, and among Alaska Native Females; AI/AN rates were lower than NHW rates in the Southwest, the Pacific Coast, and the East. Lung cancer and colorectal cancer rates for AI/ANs exceeded rates for NHWs in Alaska and the Northern Plains. Rates for stomach, gallbladder, kidney, and liver cancer were higher among AI/ANs than among NHWs overall, in Alaska, in the Plains regions, and in the Southwest. CONCLUSIONS: Regional differences in cancer incidence rates among AI/AN populations were not obvious from nationwide data and highlighted opportunities for cancer control and prevention. It is unlikely that such differences are explained by race misclassification.

Primary liver cancer incidence among American Indians and Alaska Natives, US, 1999-2004.

BACKGROUND: American Indians and Alaska Natives (AI/AN) experience higher morbidity and mortality from primary liver cancer than other United States (US) populations, but racial misclassification in medical records results in underestimates of disease burden. METHODS: To reduce misclassification, National Program of Cancer Registries and Surveillance, Epidemiology, and End Results data were linked with Indian Health Service (IHS) enrollment records to compare primary liver cancer incidence and stage at diagnosis between AI/AN and non-Hispanic whites (NHW) living within the regionalized IHS Contract Health Service Delivery Area counties. Incidence rates are expressed per 100,000 persons and age-adjusted by 19 age groups to the 2000 US standard population. RESULTS: Overall, AI/AN have a higher proportion of hepatocellular carcinoma compared with NHW, 77.8% versus 66.7%. Liver cancer incidence rates among AI/AN males and females were higher than those among NHW males and females for all regions except for the East. Among males, rates ranged from 7.3 (95% confidence interval [CI], 3.8-12.6) in the East to 17.2 (95% CI, 10.4-26.3) in Alaska. Among females, rates ranged from 3.8 (95% CI, 1.4-8.2) in the East to 6.9 (95% CI, 3.6-11.6) in Alaska. The AI/AN rates for all regions were consistently higher than the NHW rates at every age. An increasing trend among AI/AN was suggested but did not achieve statistical significance. CONCLUSIONS: Reducing racial misclassification revealed higher disparities in primary liver cancer incidence between NHW and AI/AN populations than previously reported. Further description of the reasons for regional differences in this disparity is needed, as are programs to reduce risk factors and to diagnose primary liver cancer at earlier, more treatable stages.