Annual Report to the Nation on the Status of Cancer 1975-2004, Featuring Cancer in American Indians and Alaska Natives: Questions and Answers
- Death rates decreased on average 2.1 percent per year from 2002 to 2004, nearly twice the annual decrease of 1.1 percent per year from 1993 through 2002.
- Declines were observed in the incidence of lung cancer in men, colorectal cancer in men and women, and in breast cancer incidence in women from 2001 through 2004.
- Overall, rates for most cancers among American Indians and Alaska Natives (AI/AN) were lower than non-Hispanic whites from 1999 through 2004, but were higher for cancers of the stomach, liver, kidney, gallbladder, and cervix.
- Regional analyses revealed high cancer rates for AI/AN in the Northern and Southern Plains and Alaska (e.g., lung cancer and colorectal cancer).
1. What is the purpose of this report and who created it?
This report provides an update of cancer incidence rates (new cases), death rates, and trends in the United States as well as an in-depth analysis of a selected topic. The Centers for Disease Control and Prevention (CDC), the North American Association of Central Cancer Registries (NAACCR), the American Cancer Society (ACS), and the National Cancer Institute (NCI), which is part of the National Institutes of Health, have collaborated annually since 1998 to create this report. For the report this year, researchers from the Indian Health Service, the Mayo Clinic College of Medicine, and the New Mexico Tumor Registry also participated as co-authors in the report.
The feature section of this report describes cancer incidence, stage at diagnosis, screening, and risk factors by Indian Health Service (IHS) region for American Indian and Alaska Natives (AI/AN) and compares them with those of non-Hispanic white (NHW) populations.
2. What are the sources of the data?
Cancer mortality information in the United States is based on causes of death reported by physicians on death certificates and filed by state vital statistics offices. The mortality information is processed and consolidated in a national database by the CDC through the National Vital Statistics System, which covers the entire United States.
Information on newly diagnosed cancer cases occurring in the United States is based on data collected by registries in the CDC's National Program of Cancer Registries (NPCR) and NCI's Surveillance, Epidemiology, and End Results (SEER) Program. NAACCR evaluates and publishes data annually from registries in both programs. Incidence rates are for invasive cancers, except for bladder cancer, which includes in situ cancer (cancer that is confined to the inner lining of the bladder).
Long-term (1975-2004) trends for all races for all sites combined and for the 15 most common cancers were based on SEER incidence data covering about 10 percent of the U.S. population. Fixed-interval trends (1995-2004) for specific time periods for five racial/ethnic populations, (white, black, Asian/Pacific Islander and AI/AN racial groups, and Hispanic/Latino and non-Hispanic ethnic groups regardless of race) by sex, for all sites combined and for the 15 most common cancers were based on about 59 percent of the U.S. population. Average annual (2000-2004), sex-specific, and age-adjusted incidence rates were based on incidence data from 39 cancer registries, covering about 82 percent of the U.S. population.
3. Which reporting periods were chosen as a main focus of the report?
The period from 2000 through 2004 was used for describing the cancer burden (1999 through 2004 was chosen for AI/AN), and the period 1995 through 2004 was used for describing trends among the five major racial and ethnic populations. The period from 1975 through 2004 was chosen to represent the best perspective on long-term trends in cancer incidence and death rates among all races combined.
Update on Incidence and Mortality Trends for All Cancer Sites Combined and the Top 15 Cancers
4. What is happening with cancer incidence trends overall?
After increasing from 1975 through 1992, incidence rates for all cancers combined for all sexes and populations combined decreased slightly from 1992 through 2004. For men, incidence rates for all cancers decreased by 4.3 percent per year from 1992 through 1995 and were stable from 1995 through 2004. For women, incidence rates for all cancers combined stabilized from 1999 through 2004 after years of increases.
While the report did find a decline in cancer incidence of 0.3 percent per year from 1992 through 2004 in men and women combined, there are several reasons why this is not emphasized. The annual percent change is small, the trends are not significant when men and women are viewed separately, and trends in incidence are much more difficult to interpret than trends in mortality.
Incidence trends are related to screening as well as risk. For instance, an increase in the utilization of the prostate specific antigen (PSA) test from 1988 to 1992 caused a rapid increase in male cancer incidence rates due to the detection of asymptomatic prostate cancer, which was then followed by a sharp decline.
In contrast with mortality, where declines are always good news, declines in incidence may reflect good news (decreases in risk factors that cause cancer or use of screening tests such as colorectal and pap tests that can actually prevent cancer) or bad news (decreased use of screening tests) or a combination of the two.
5. What is happening with incidence rates for the top 15 cancers among men and women?
Among men, incidence rates of myeloma and cancers of the liver, kidney and esophagus continued to increase through 2004. Incidence rates are still decreasing for cancers of the lung, colon and rectum, oral cavity and stomach and were stable through 2004 for the remaining top 15 cancers (non-Hodgkin lymphoma, melanoma, leukemia and cancers of the prostate, bladder, pancreas, and brain).
Among women, the rates for non-Hodgkin lymphoma, melanoma, leukemia, and cancers of the bladder and kidney have been increasing for 29 years. Thyroid cancer incidence rates have increased in women since 1980. The incidence rates decreased for cancers of the breast, colon and rectum, uterus, ovary, cervix, oral cavity and stomach. The incidence rates for cancer of the pancreas and lung were stable.
6. What is happening with cancer mortality trends overall?
The overall decline in cancer death rates for most racial and ethnic populations, first noticed in the early 1990s, has continued through 2004. Death rates decreased on average 2.1 percent per year from 2002 through 2004, nearly twice the annual decrease of 1.1 percent per year from 1993 through 2002. This decline was more pronounced among men (2.6 percent per year from 2002-2004) than women (1.8 percent per year from 2002-2004). Death rates are the best indicator of progress against cancer.
7. What is happening with death rates for the top 15 cancers among men and women?
For the most recent reporting period, which varies by cancer type, death rates decreased for 12 of the 15 most common causes of cancer death in men (i.e., cancers of the lung, prostate, colon and rectum, pancreas, bladder, kidney, stomach, brain, and oral cavity as well as leukemia, non-Hodgkin lymphoma, and myeloma). Death rates increased for esophageal and liver cancers in men, but recently stabilized for melanoma.
Death rates among women decreased for 10 of the 15 most common cancers (i.e., breast, colon and rectum, stomach, kidney, cervix, brain and bladder cancers as well as non-Hodgkin lymphoma, leukemia, and myeloma). However, death rates were stable in women for cancers of the pancreas, ovary, and uterus and continued to increase for cancers of the liver and lung.
8. What is happening with incidence rates for breast cancer?
Breast cancer incidence rates among women decreased for the period 2001 through 2004 by 3.5 percent per year, reversing a long-term increase that began in the early 1980s. The factors that influence breast cancer incidence are complex, including changes in reproductive risks, obesity, and the prevalence of mammography screening, among others. Recent reports suggest the decrease in breast cancer incidence may be related to the rapid discontinuation of hormone replacement therapy, a known risk factor for breast cancer and a decline in mammography screening prevalence.
9. What is happening with incidence rates for lung cancer?
Overall, lung cancer incidence rates increased in women from 1975 through 1998, after which the rate stabilized. In comparison, the lung cancer incidence rate in men has been decreasing since 1991. The difference reflects changes in smoking trends in men and women.
10. If cancer rates continue to fall, does that mean the number of people dying from cancer will also continue to fall?
Not necessarily. The numbers reported in the Annual Report to the Nation are rates per 100,000 persons in the U.S. and are adjusted for age so that they are comparable across various factors, such as race. The actual number of people dying from cancer (sometimes called the count) can be influenced by several factors, including the growth in the number of older people in the U.S. (cancer is primarily a disease of aging) and the increase in size of the U.S. population.
Therefore, while the cancer rate may go down in a given year, if there is an increase in the size and the overall age of the U.S. population that same year, the actual count of the number of cancer cases could go up. The National Center for Health Statistics has already released preliminary numbers for 2005 that indicate this may be the case when the next Annual Report to the Nation is issued in 2008.
Cancer Among American Indians and Alaska Natives (AI/AN)
11. What is the size of the AI/AN population in the United States and is it changing?
AI/AN populations are among the fastest growing populations in the U.S. According to the 2000 U.S. Census, 1.1 percent of the population stated they have AI/AN ancestry.
12. How do cancer incidence rates differ in the AI/AN population compared to the non-Hispanic white population?
The report finds that for 1999 through 2004, AI/AN persons in all regions combined had lower incidence rates than non-Hispanic whites (NHW) for most cancers, but were less likely than the NHW population to be diagnosed with early stage cancers of the colon and rectum, prostate, female breast, and cervix. However, AI/AN persons had higher incidence rates for cancers of the stomach, liver, kidney, gallbladder, and cervix than NHW populations.
13. What are the possible causes of higher cancer incidence rates in AI/AN populations?
Many types of cancer with higher incidence rates in AI/AN populations are associated with infections: human papilloma virus (HPV) in cervical cancer; Helicobacter pylori (H. pylori) bacteria in stomach cancer; and hepatitis B virus (HBV) and hepatitis C virus (HCV) in liver cancer. Explanations for these differences vary by cancer type and may include higher infection rates in the countries of original residence or birth (HPV); chronic infection (HBV and HCV); sanitary conditions (H. pylori); or varied availability and use of preventive measures.>
14. What factors affect cancer disparities in AI/AN populations in comparison with non-Hispanic white populations?
Some factors that may contribute to differences in AI/AN cancer rates include higher incidence of some infection-related cancers; elevated exposures to environmental risk factors in AI/AN populations' living and work places; lower education, health literacy, and income; reduced use of screening services; limited access to health care often due to lack of insurance or geographic barriers; and less information available regarding possible genetic predispositions. Also, this population experiences unique cultural and language barriers to health services in addition to the multitude of institutional, environmental, logistical, sociodemographic and personal barriers characteristic of all minority populations in the U.S.
15. How do AI/AN cancer incidence rates differ by geographic region?
For the purposes of this report, the authors identified six regions in the U.S. that best represented AI/AN populations. For all cancer types combined, the report finds that incidence rates in the AI/AN population of the Northern and Southern Plains and in Alaska are higher than in the AI/AN population in the Southwest, Pacific Coast and East. For men, AI/AN rates are higher in the Northern Plains and similar in the remaining regions (Alaska and Southern Plains) or lower (East, Southwest and Pacific Coast). For leading cancers, there was substantial regional variation in AI/AN incidence rates. Lung cancer incidence rates are higher in the Northern Plains, Alaska and the Southern Plains, lower in the Pacific Coast and the East and lowest in the Southwest. Colorectal cancer incidence is three or more times greater in Alaska and the Northern Plains than in the Southwest. Breast cancer is greatest in Alaska Natives and lowest in the Southwest with intermediate rates in the remaining regions.
16. What are the possible causes for geographic variations in cancer incidence rates?
Several other cancers are elevated in AI/AN populations in certain geographic regions only. In the case of lung cancer, the elevated rates in Alaska and the Northern Plains can be easily explained by decades of high prevalence of cigarette smoking among the AI/AN population of those regions, evidence that is further strengthened by the very low rates in the Southwest where AI/AN smoking has historically been very low. The cause of differences in AI/AN regional colorectal cancer rates is less clear and is likely due to multiple factors that may include diet, genetic makeup, tobacco use, diabetes, environmental factors and others.
17. Do AI/AN persons have equal access to quality cancer care?
This study reports less favorable socioeconomic status and health care access for AI/AN persons compared with NHW populations. Having a usual source of care is a key predictor of cancer screening and other preventive services, and consistent with this, cancer screening for AI/AN populations is lower in comparison with NHW populations; furthermore, this report and previous studies have found that AI/AN populations are diagnosed more frequently with late-stage disease and have less favorable cancer survival compared with other populations.
The IHS provides primary health care to approximately 1.8 million enrolled members of federally-recognized tribes, out of the estimated 3.3 million AI/AN persons in the U.S. The 150 IHS hospitals and clinics are primarily located on reservation lands and in a few cities with relatively large AI/AN populations. Half of these health care facilities are managed by tribal governments under negotiated agreements with the U.S. federal government, and half are operated directly by the federal government. An additional 34 urban health centers receive some federal funding to provide health care to urban AI/AN individuals. Eligible AI/AN persons can receive free health care at any IHS facility, but a complex set of rules governs and restricts delivery of contract health services for specialty medical care, such as cancer treatment, which is generally not available in IHS facilities. Geographic, financial, and bureaucratic barriers to receiving appropriate cancer treatment as well as cultural beliefs may also contribute to poor survival rates among AI/AN persons.
18. How are cancer disparity issues being addressed for AI/AN communities?
Health disparities among U.S. populations are a focus of increased research and interventions. The following organizations and initiatives are seeking to bridge cancer disparity issues in AI/AN communities:
- The CDC's National Breast and Cervical Cancer Early Detection Program (http://www.cdc.gov/cancer/NBCCEDP ) funds 14 tribal programs, in addition to all 50 states, to build and support infrastructure and provide screening services.
- The IHS and CDC provide annual training for primary care providers in IHS and tribal programs to perform colposcopy, part of standard diagnostic follow-up for abnormal Pap smear results, to make this service more accessible and to reduce the time from abnormal cervical cancer screening results to definitive diagnosis.
- The CDC's National Comprehensive Cancer Control Program (http://www.cdc.gov/cancer/ncccp/). This program has helped address cancer disparities by supporting cancer control coalitions in each state to develop and implement cancer control plans in communities, including tribal communities, across the U.S.
- Circle of Life is an ACS program designed to decrease the breast cancer incidence and death rates among American Indian women. Working with available community resources, Circle of Life develops effective, culturally sensitive strategies to increase public awareness of the disease while also promoting the use of mammography as an early detection tool.
- The ACS's Research Targeted at Poor and Underserved Populations Initiative, through a competitive peer-reviewed mechanism, funds research grants that serve to reduce the burden of cancer in underserved populations, including Native Americans. Since 2004, four research grants have been awarded totaling $3.5 million. Two seminal studies, conducted in full collaboration and partnership with the Apsaalooke tribe, using Community-Based Participatory Research methods, focus on promoting cervical cancer screening using Lay Health Advisors (members of the tribe), as well as promoting systemic change by enhancing cultural sensitivity in the IHS. A third study focuses on smoking cessation strategies specifically tailored to Native American populations, and the fourth study on ways to relieve cancer pain in Native Americans in Arizona.
- The NCI Network for Cancer Control Research Among AI/AN Populations is a forum for Native and non-Native researchers with a mission to "reduce preventable cancer morbidity and mortality to the lowest possible levels and to improve cancer survival to the highest possible level" in AI/AN populations. Realizing the importance of AI/AN community participation in research, the Network also provides curriculum development and instructors for an annual cancer control training course for Native researchers. NCI is an important partner in promoting and funding community networks programs such as the Spirit of Eagles program.
- The Spirit of Eagles program, based at the Mayo Clinic in Rochester, Minn., is a national AI/AN leadership initiative addressing comprehensive cancer control through tribal partnerships. Funded by the NCI's Center to Reduce Cancer Health Disparities, the SOW works with major cancer centers, nonprofit organizations, policy boards, professional societies, and educators through community-based cancer control grants. NCI has funded three other regional or local community networks working with AI/AN populations in the Pacific Northwest, the Southwest and Oklahoma.
- The NCI Cancer Information Service collaborates with community networks to reach medically underserved audiences and partners with researchers to develop messages, channels, and strategies for communicating risk and early detection approaches for AI/AN populations. In addition, NCI has initiated the Patient Navigator Research Program to assist patients who receive an abnormal screening result get a definitive diagnosis, and, finally, proper treatment.
How to Read This Report
19. How are cancer incidence and death rates presented?
Cancer incidence rates and death rates are measured as the number of cases or deaths per 100,000 people per year and are age-adjusted to the 2000 U.S. standard population. When a cancer affects only one sex -- for example, prostate cancer -- then the number is per 100,000 persons of that sex. The numbers are age-adjusted, which allows for comparison of rates from different populations with varying age composition over time and regions.
20. What is annual percent change or APC
The annual percent change (APC) is the average rate of change in a cancer rate per year in a given time frame (i.e., how fast or slowly a cancer rate has increased or decreased each year over a period of years). Annual percent change was calculated for both incidence and death rates. The number is given as a percent, such as an approximate one percent per year decrease.
A negative APC describes a decreasing trend, and a positive APC describes an increasing trend. In this report, trends are reported as increasing and decreasing only if they are statistically significant.
21. What are rate ratios and why were they used in a Report to the Nation
Rate ratios (RR) allow comparison of incidence rates between AI/AN and NHW populations. In describing rate comparisons for AI/AN and NHW populations, the terms, "higher" or "lower" were used when the AI/AN incidence rates were statistically significantly higher or lower than the NHW rates. Thus, when the RR was less than 1.0, the rate among AI/AN was lower than that among NHW; when the RR was greater than 1.0, the rate among AI/AN was higher than that among NHW. Otherwise, the RRs were described as comparable.
22. Why were rates adjusted for delays in reporting incidence data to SEER?
This report presents analyses of long-term trends in cancer incidence rates with and without adjustment for reporting delays and more complete information. Adjusting for these delays and accumulating more complete and accurate information provides the basis for a potentially more definitive assessment of incidence rates and trends in the most recent years for which data are available. Cancer registries routinely take two to three years to compile their current cancer statistics. An additional one to two years may be required to have more complete incidence data on certain cancers, such as melanoma and prostate and breast cancers, particularly when they are diagnosed in outpatient settings. Cancer registries continue to update incidence rates to include these cases. Consequently, the initial data reported for certain cancer incidence rates may be an underestimate. Long-term reporting patterns in SEER registries have been analyzed, and it is now possible to adjust site-specific incidence rates and incidence rates for all cancers combined to correct for expected reporting delays and more complete information.
23. What is joinpoint analysis and how does it account for the different time periods used for trends analysis in this report?
Joinpoint analysis is a statistical method that describes changing trends over successive segments of time and the amount of increase or decrease within each segment. This statistical method chooses the best-fitting point or points, which are called joinpoints; these points are where the rate of increase or decrease changes significantly.
Joinpoint regression analysis involves fitting a series of joined straight lines to the age-adjusted rates, and each line segment is described by an annual percent change that is based on the slope of the line segment. Each joinpoint denotes a statistically significant change in trend. Thus, for death rates for all cancers combined in men, the slope, or trend, changes in 2002 and is reported as a 2.6 percent per year decline from 2002 through 2004. For women, the trend also changes in 2002 and is reported as a 1.8 percent per year decline from 2002 through 2004 in this report.
Joinpoint analyses were performed for incidence and mortality trends for 1975 to 2004.
24. Where is this report published?
The report appeared online on October 15, 2007 at www.interscience.wiley.com/cancer/report2007 and will appear in the November 15, 2007 print edition of Cancer.
25. Where can I find out more about the report?
For more information, visit the following Web sites:
'Annual Report to the Nation' press release: http://cancer.gov/newscenter/pressreleases/ReportNation2007Release
For supplemental material, please go to www.interscience.wiley.com/cancer/report2007
CDC (Division of Cancer Prevention and Control): http://www.cdc.gov/cancer
CDC (National Center for Health Statistics' mortality report): http://www.cdc.gov/nchs/deaths.htm
Citation: Espey DK, Wu X, Swan J, Wiggins C, Jim M, Ward E, Wingo PA, Howe HL, Ries LAG, Miller BA, Jemal A, Ahmed F, Cobb N, Kaur JS, Edwards BK. Annual Report to the Nation on the Status of Cancer, 1975-2004, Featuring Cancer in American Indians and Alaska Natives. Cancer. November 15, 2007. Vol. 110, Issue 10.