Questions and Answers: Annual Report to the Nation on the Status of Cancer, 1973-1996, With a Special Section on Lung Cancer and Tobacco Smoking

National Cancer Institute, Centers for Disease Control and Prevention

1. What is the purpose of this report and who created it?

This report provides an update on the trends in cancer death rates in the United States and presents information about trends in cancer incidence rates (new cases reported) that have not been published before. It also contains a special section on lung cancer and tobacco smoking. The American Cancer Society (ACS), the National Cancer Institute (NCI), and the Centers for Disease Control and Prevention (CDC), including the National Center for Health Statistics (NCHS), collaborated to create this annual report.

2. What is the source of the data?

Data on cancer incidence come from the NCI's Surveillance, Epidemiology, and End Results Program (SEER). The SEER program collects cancer incidence data from 11 registries: five statewide registries (Connecticut, Hawaii, Iowa, New Mexico, and Utah) and six metropolitan area registries (Atlanta, Detroit, Los Angeles, San Francisco-Oakland, San Jose-Monterey, and Seattle-Puget Sound). These registries are population-based (collect information on every cancer in a geographic area) and include approximately 14 percent of the U.S. population. SEER sampling is designed to represent diverse populations. Cancer cases were diagnosed during 1973 to 1996.

Data on cancer mortality come from NCHS. Death certificates filed in every state are processed and consolidated into the NCHS database, so that 100 percent of the U.S. population is covered. Cancer deaths for this report occurred during 1950 to 1996.

Data on smoking behavior presented in the special section on lung cancer were collected by NCHS in nationwide household interviews for the National Health Interview Survey (1965 to 1996), and by CDC and state departments of health and education in two surveys, the Behavioral Risk Factor Surveillance system (1997), and the Youth Risk Behavior Surveillance system (1997).

3. What is happening with cancer rates overall?

After increasing from 1973 to 1990, incidence rates for all cancer sites combined decreased 0.9 percent per year during 1990 to 1996. The peak year was 1992; from 1992 to 1996 the rate decreased 2.2 percent per year. This confirms the continued downward trend that was reported to the nation in 1998 for the period 1990 to 1995.

Trends in incidence rates varied by gender and age at diagnosis. During 1990 to 1996, the largest annual decreases in incidence rates for all sites combined occurred in men ages 25 to 44 and men 75 years and older at diagnosis. The declines in cancer incidence rates among women were smaller. The largest trend among women was a decline in cancer incidence (all types combined) in women ages 35 to 44.

Cancer death rates also continued to decline during the 1990s. From 1990 to 1996, cancer deaths decreased on average 0.6 percent per year. The death rate decline is greater among males (on average 1.0 percent per year) than females (0.3 percent per year). Persons younger than age 65 had the greatest drops in cancer death rates. Rates among males declined in all age groups except for men ages 85 and older. Rates decreased for women younger than 65, but increased for women 75 years and older.

4. How is the cancer burden monitored among ethnic and racial groups?

In this report, cancer incidence and death rates are analyzed for whites, blacks, Asian and Pacific Islanders, American Indians/Alaska Natives, and Hispanics. Hispanic is not mutually exclusive from whites, blacks, and Asian and Pacific Islanders. Cancer incidence rates for American Indians/Alaska Natives are based on data from Alaska plus all SEER registries.

5. What is happening with cancer among ethnic and racial groups?

Continued higher incidence and death rates among some racial and ethnic groups suggest that some populations may not have benefitted equally from cancer prevention and control efforts. Such disparities may be due to multiple factors, such as late stage of disease at diagnosis, barriers to health care access, history of other diseases, biologic and genetic differences in tumors, health behaviors, and the presence of risk factors.

The four leading cancer incidence sites for the five racial and ethnic populations were: lung and bronchus, prostate, female breast, and colon/rectum. Together these four sites account for 54 percent of all new diagnoses.

When these four sites of new cancer cases were examined by race and ethnicity, it was found that except for breast cancer, blacks had higher incidence rates than the other racial and ethnic populations. Uterine cancer was common to all five groups as one of the top 10 sites. But some cancer sites tended to be unique to a specific population. For example, melanoma and leukemia were among the top 10 incidence sites only in whites; cancers of the pancreas and oral cavity and pharynx were among the top 10 only in blacks; liver cancer was among the top 10 only in Asian and Pacific Islanders and American Indians/Alaska Natives; cancer of the kidney and renal pelvis was among the top 10 only in American Indians/Alaska Natives; and bladder cancer was among the top 10 only in whites and Hispanics.

The top four causes of cancer death from 1990 to 1996 for the racial and ethnic groups, with one exception, were the same sites as incidence: lung and bronchus, prostate, female breast, and colon/rectum. Among Asian and Pacific Islanders, the excepted group, cancer of the liver, instead of female breast cancer, ranked among the four leading causes of cancer death. When these four mortality sites were examined by race and ethnicity, it was found that blacks had higher cancer death rates than whites, Asian and Pacific Islanders, American Indians/Alaska Natives, or Hispanics. Deaths due to leukemia and cancers of the stomach and ovary were among the top 10 sites in all five racial and ethnic groups.

Other top 10 leading cancer mortality sites varied by ethnic and racial group. For example, brain and nervous system cancers were among the top 10 cancer mortality sites only in whites; esophageal cancer and multiple myeloma were among the top 10 sites only in blacks; cervical cancer was among the top 10 sites only in blacks and American Indians/Alaska Natives; and kidney and renal pelvis cancer were among the top 10 sites only in American Indians/Alaska Natives.

6. Why does the report emphasize lung cancer and tobacco smoking?

Lung cancer causes more deaths than any other cancer site, and is one of the top four incidence sites for each racial and ethnic group. Lung cancer accounts for 28 percent of all cancer deaths each year and about 14 percent of new cancer cases.

Historically, lung cancer has been a key factor driving overall cancer trends, and it continues to do so. As much as 90 percent of all lung cancer is caused by tobacco smoke, which includes cigarettes, pipes, cigars, and second-hand smoke. The prevalence of cigarette smoking among adults has declined over the past 25 years, but this trend has stalled during the past four to five years. At the same time, the number of high school students smoking cigarettes has increased during the 1990s, and unless this trend can be reversed, the lung cancer rates that are currently declining may increase again.

There has been much attention given in recent years at the state and local levels to the effects of tobacco use and efforts to effectively control it, especially among children and adolescents. This report reflects the need for more research in this area and illustrates how surveillance data can be illuminated further by comparing it with risk factor data.

7. What does the data show about lung cancer rates?

During 1990 to 1996, male lung cancer incidence and death rates decreased. By contrast, lung cancer incidence and death rates increased among females, although the rate of increase has slowed in recent years. Overall lung cancer incidence rates varied widely by race and ethnicity from a high of 73.9 per 100,000 among blacks to 27.6 per 100,000 among Hispanics. The overall rate for American Indians/Alaska Natives was low at 29.7 per 100,000, but this group had wide-ranging rates across geographic areas.

Lung cancer incidence and death rates declined among males of all racial and ethnic groups except American Indians/Alaska Natives. Male lung cancer incidence rates during 1990 to 1996 decreased an average 2.6 percent per year. Male lung cancer death rates decreased on average 1.6 percent per year. These declines reflect the large decreases over the past several decades in active smoking and exposure to environmental tobacco smoke.

Among females during the 1990s, the average annual percent increase was 0.1 percent per year for incidence and 1.4 percent per year for mortality. Smoking patterns in women lag behind smoking patterns in men, although prevalence is higher in men. The impact of decreased smoking on female lung cancer rates over all ages and racial groups combined has not yet been observed. However, the age-specific patterns of declines seen for males are beginning to occur in females. Lung cancer incidence and death rates declined among women ages 40 to 49 and 50 to 59 years old; were approximately level among females 60 to 69 years old; and continued to increase among older women.

8. What is happening with breast cancer rates in women?

Female breast cancer incidence rates have been approximately level during the 1990s. Female breast cancer death rates declined on average 1.7 percent per year since 1989.

9. What is happening with prostate cancer rates?

Prostate cancer incidence rates continued to decline after peaking in 1992, and prostate cancer death rates continued to decline.

10. What is happening with colon and rectum cancer rates?

Colorectal cancer incidence and death rates declined for males and females and for all racial and ethnic groups.

11. What other key sites had significant incidence and mortality findings?

During 1990 to 1996, incidence and death rates for non-Hodgkin's lymphoma continued to increase although the rates of increase are lower than in the 1980s. The slowing of the increase in death rates occurred among males.

Melanoma incidence rates also continued to increase on average 2.7 percent per year. Melanoma death rates have been unchanged during the 1990s.

12. Are the rates of childhood cancer increasing or decreasing?

For children younger than 15 years of age, the incidence of cancer declined 0.4 percent per year between 1990 and 1996. The mortality rates declined 2.7 percent per year for the same time period.

How to Read the Report

13. How is progress against cancer being measured in this report?

This report includes two different measures, the annual percent change in cancer rates and incidence and death rates. Annual percent change has been calculated for two time periods, 1990 to 1996, and the peak year to 1996, and by age. "Statistically significant" means that the annual percent change calculated is unlikely to have occurred by chance alone.

14. What is an annual percent change or APC?

The annual percent change is the averaged rate of change in a cancer rate per year in a given time frame, i.e. how fast or slow a cancer rate has increased or decreased each year over a period of years. Annual percent change, sometimes abbreviated as APC, was calculated for both incidence and death rates. The number is given as a percent such as the 0.9 percent per year decrease in incidence of all cancers diagnosed from 1990 to 1996.

15. How are cancer incidence and death rates presented?

Cancer incidence rates and cancer death rates are measured as a number per 100,000 people and are age-adjusted to the 1970 U.S. standard million population. When a cancer affects only one gender, such as prostate cancer, the number is per 100,000 people of that gender.

16. Where is this report being published?

The report is published in the Journal of the National Cancer Institute, April 21, 1999, Volume 91, Number 8. It is titled, "The Annual Report to the Nation on the Status of Cancer, 1973-1996, With a Special Section on Lung Cancer and Tobacco Smoking." The authors are Phyllis A. Wingo, Ph.D., M.S. (ACS), Lynn A.G. Ries, M.S. (NCI), Gary A. Giovino, Ph.D. (CDC), Daniel S. Miller, M.D., M.P.H. (CDC), Harry M. Rosenberg, Ph.D. (NCHS), Donald R. Shopland (NCI), Michael J. Thun, M.D. (ACS), and Brenda K. Edwards, Ph.D. (NCI).

17. What Internet sites have more information on cancer?

NCI's SEER home page: http://www-seer.ims.nci.nih.gov/ (This Web site contains all data points for graphs in the manuscript as well as supplementary data and charts.)

National Cancer Institute: http://rex.nci.nih.gov

American Cancer Society: http://www.cancer.org

CDC's Division of Cancer Prevention and Control: http://www.cdc.gov/cancer

CDC's National Center for Health Statistics: http://www.cdc.gov/nchswww/

CDC's Youth Risk Behavior Surveillance system: http://www.cdc.gov/nccdphp/youthris.htm