Trends in Colorectal Cancer Incidence -- United States, 1973-1986

In 1973, the National Cancer Institute (NCI) initiated the Surveillance, Epidemiology, and End Results (SEER) Program,* a population-based tumor registry reporting system for cancer incidence and survival. SEER receives reports from five states and four metropolitan areas** representing approximately 10% of the U.S. population. This report, based on SEER data, describes trends in the incidence of cancer of the colon and rectum (colorectal cancer) during 1973-1986 using the International Classification of Diseases for Oncology (ICD-O) categories 153.0-154.1 and 159.0 (1). Rates are age-adjusted by the direct method to the 1970 U.S. population.

From 1973 through 1986 (2), the annual incidence rate per 100,000 population for colorectal cancer increased 9.4%. The increase in the estimated annual percent change (EAPC) was 0.7%. Statistically significant increases occurred for all races combined, for whites and blacks, and for males and females (Table 1). In 1986, the incidence rates for blacks and whites were similar, while the rate for males was higher than that for females (Figure 1).

To evaluate recent changes in the incidence rates and in the rate of change, the EAPC for 1982-1986 was compared with that for 1975-1979 (Table 1). During this period, only the rates for males of all races combined had a statistically significant increase.

Colorectal cancer is primarily a cancer of the older population--in 1982-1986, the median age at diagnosis was 71 years for colon and 69 years for rectal cancer (2). Risk for colorectal cancer increased with age. For example, in 1982-1986, the incidence rate for 30-34-year-olds was 2.9 per 100,000, compared with 531.6 per 100,000 for persons aged greater than or equal to 85 years.

The segment of the colon most commonly designated as the primary site of origin was the sigmoid (1986 incidence rate of 13.1 per 100,000); from 1973 to 1986, the incidence of cancer of the sigmoid increased 14%. The increased incidence of cancer of the sigmoid may be due to early detection, although specific information on diagnostic methods is not available. Reported by: LA Gloeckler Ries, MS, BK Edwards, PhD, EJ Sondik, PhD, Surveillance Program, Div of Cancer Prevention and Control, National Cancer Institute. Cancer Prevention and Control Br, Div of Chronic Disease Control and Community Intervention, Center for Chronic Disease Prevention and Health Promotion; Div of Surveillance and Epidemiologic Studies, Epidemiology Program Office, CDC.

Editorial Note

Editorial Note: Colorectal cancer mortality continues to decline in spite of increasing incidence. Detection of disease at an earlier stage might account for some of the increase in the survival rate (2). An indicator for early detection of colorectal cancer is the increased percentage of colorectal cancer diagnosed in the in situ and localized stages and the decrease in the percentage of distant disease.

The effectiveness of colorectal cancer screening by endoscopy is not well established (3-5). Sigmoidoscopy and colonoscopy are of potential use in detecting and removing precancerous colorectal polyps and in preventing severe morbidity and mortality by earlier detection of colorectal cancer. The effectiveness of stool blood screening in reducing colorectal cancer mortality has not been conclusively demonstrated (6). However, this noninvasive and relatively inexpensive technique appears to detect a higher proportion of colorectal cancersat earlier stages than are detected through symptomatic presentation (7).

In the absence of proven detection methods, recommendations vary for screening persons without symptoms or without family histories of colorectal cancer. The American Cancer Society recommends annual digital rectal examination for all adults greater than or equal to 40 years of age, annual stool blood tests, and screening sigmoidoscopy every 3-5 years for adults greater than or equal to 50 years of age (8). Other organizations have formulated similar recommendations (9). All groups concur on the greater use of sigmoidoscopic and stool blood screening among persons with symptoms or family histories of colorectal cancer. Because of the median age of patients and the influence of age at diagnosis on survival (2), screening programs might focus on the older population.

References

1. World Health Organization. International classification of diseases for oncology. 1st ed. Geneva: World Health Organization, 1976.

2. National Cancer Institute. Cancer statistics review 1973-1986, including a report on the status of cancer control. Bethesda, Maryland: US Department of Health and Human Services, Public Health Service, 1989; NIH publication no. 89-2789.3. Selby JV, Friedman GD. Sigmoidoscopy in the periodic health examination of asymptomatic adults. JAMA 1989;261:595-601.

3. Simon JB. Occult blood screening for colorectal carcinoma: a critical review. Gastroenterology 1985;88:820-7.

4. Clayman CB. Mass screening for colorectal cancer: are we ready? JAMA 1989;261:609.

5. Knight KK, Fielding JE, Battista RN. Occult blood screening for colorectal cancer. JAMA 1989;261:587-94.

6. Hardcastle JD, Thomas WM, Chamberlain J, et al. Randomised, controlled trial of faecal occult blood screening for colorectal cancer: results for first 107 349 subjects. Lancet 1989;1:1160-4.

7. American Cancer Society. Summary of current guidelines for the cancer-related checkup: recommendations. Atlanta: American Cancer Society, 1988; ACS publication no. 3347.01-PE.

8. Fleischer DE, Goldberg SB, Browning TH, et al. Detection and surveillance of colorectal cancer. JAMA 1989;261:580-5. *SEER participants were selected for their ability to maintain population-based cancer reporting systems and for the unique population subgroups in each area rather than for demographic representation of the U.S. population. **Connecticut, Hawaii, Iowa, New Mexico, and Utah; Atlanta, Detroit, San Francisco/Oakland, and Seattle/Puget Sound.

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