Screening for Colorectal Cancer United States, 1997

SOURCE: Centers for Disease Control and Prevention Study On Colon Cancer Screening February 19, 1999 48(06);116-121

Colorectal cancer is the second leading cause of cancer-related deaths in the United States (1).During 1999, approximately 129,400 new cases of colorectal cancer will be diagnosed, and56,600 persons will die from the disease (1). In 1996, the U.S. Preventive Services Task Force(USPSTF) recommended the use of specific screening tests (i.e., annual fecal-occult blood testing{FOBT} and/or periodic flexible sigmoidoscopy for persons aged greater than or equal to 50years) to reduce c olorectal cancer-related mortality (2). In 1997, the American Cancer Societyand an interdisciplinary task force developed guidelines that recommend one test or a combinationof several tests for colorectal cancer screening (3,4). To estimate the proportion of the U.S.population that received colorectal cancer screening tests, CDC analyzed data from the 1997Behavioral Risk Factor Surveillance System (BRFSS) on the use of a home-administered bloodstool test, or FOBT, and sigmoidoscopy/proctoscopy. This report summarizes the results of thisanalysis, which documents low rates of use of colorectal cancer screening tests.

In 1997, all 50 states, the District of Columbia, and Puerto Rico participated in the BRFSS, apopulation-based, random-digit-dialed telephone survey of the noninstitutionalized, U.S.population aged greater than or equal to 18 years. A total of 52,754 persons aged greater than orequal to 50 years were asked whether they had ever had a blood stool test (FOBT) using a homekit and whether they had ever had a sigmoidoscopy or proctoscopy, and when the last test had been performed. Responses coded as "Don't know/Not sure" or "Refused" were excluded fromthe analyses (approximately 3%). Data were weighted to the age, sex, and racial/ethnicdistribution of each state's adult population using 1990 census or intercensal estimates.Proportions, standard errors, and 95% confidence intervals were calculated using SAS andSUDAAN. Data were aggregated across states. Aggregated and state-level data are presentedfor the proportion of respondents aged greater than or equal to 50 years who reported receiving FOBT or sigmoidoscopy/proctoscopy.

Overall, 39.7% of respondents reported ever having had FOBT, and 41.7% reported ever havinghad sigmoidoscopy/proctoscopy. For this report, all results refer to tests received during therecommended time period (e.g., during the preceding year for FOBT and during the preceding 5years for sigmoidoscopy/proctoscopy).

A total of 19.8% of respondents reported having had FOBT during the preceding year, and30.4% reported having had a sigmoidoscopy/proctoscopy during the preceding 5 years(Table_1). The proportion of all respondents who reported having had either test or both testswithin the recommended time interval was 40.9% and 9.5%, respectively. Men were more likelythan women to report having had a sigmoidoscopy/proctoscopy (35.1% and 26.7%,respectively), and women were more likely than men to report having had FOBT (20.9% and18.3%, respectively). The proportion of American Indians/Alaskan Natives and Asians/PacificIslanders who reported having had FOBT was less than that of whites and blacks (Table_1).Respondents identifying themselves as of Hispanic origin were less likely to report having hadeither test than respondents identifying themselves as non-Hispanic. The proportion ofrespondents who reported having had either test increased with each age group until age 70-79years, then decreased among persons aged greater than or equal to 80 years.

For both screening modalities, the proportion of respondents who reported having had a testincreased with increasing education and income level (Table_1). The proportion of respondentswho reported having had a test was greater for those with health-care coverage than for thosewithout coverage. For persons without health-care coverage, 8.2% and 16.3% of respondentsreported having had FOBT and sigmoidoscopy/proctoscopy, respectively, and 20.6% and31.4% of those with health-care coverage reported having had the tests.

By state, the proportion of respondents who reported having had FOBT during the precedingyear ranged from 9.2% (Mississippi) to 28.4% (Maine) (Table_2). The proportion ofrespondents who reported having had sigmoidoscopy/proctoscopy during the preceding 5 yearsranged from 15.5% (Oklahoma) to 41.5% (District of Columbia).

Reported by: State Behavioral Risk Factor Surveillance System coordinators. Epidemiology andHealth Svcs Research Br, Div of Cancer Prevention and Control, National Center for ChronicDisease Prevention and Health Promotion; and an EIS Officer, CDC.

Editorial Note: Although screening can reduce mortality from colorectal cancer (2-4), the findingsin this report indicate low use of sigmoidoscopy/proctoscopy and FOBT, particularly within therecommended time intervals. Persons with health-care coverage, higher incomes, and more yearsof education were more likely to report having had these tests.

The 1997 BRFSS was the first time questions about use of FOBT specified that the test wasconducted at home using a kit. Previous survey questions did not address whether samples wereobtained at home using a kit or as part of a digital rectal examination. The home kit is therecommended method of obtaining a stool sample (3,5,6). Use of the home kit allows forcollection of multiple samples and should be performed in conjunction with dietary restrictions todecrease the possibility of false-positive or false-negative results from certain foods andmedications (4,6).

Previous estimates of the prevalence of colorectal cancer screening practices using the 1993BRFSS demonstrated that the rates of use of colorectal cancer screening tests were low (7).Although direct comparison between these two analyses is not possible because the wording ofthe survey questions differed, the current analysis demonstrates continued underuse ofsigmoidoscopy/proctoscopy. Both patient and provider barriers have contributed to the low ratesof screening. Patient barriers may include lack of knowledge of screening recommendations,access to health care, anticipated discomfort, and embarrassment. Provider barriers may includelack of skills and lack of time to counsel patients (2,8).

The findings in this report are subject to at least three limitations. First, because the BRFSS isadministered as a telephone survey, only persons with telephones are represented. Second, resultsare based on self-reports and have not been validated. However, self-report of certain colorectalcancer screening tests appears to be valid (9). Third, because the BRFSS questionnaire did notdistinguish between tests conducted for diagnostic or screening purposes, the rates of use of thesetests for screening purposes were probably lower than reported.

Activities relating to colorectal cancer screening are increasing at both the state and national levels.In 1997, the American Cancer Society and CDC established the National Colorectal CancerRoundtable, a collaboration of state health departments, professional and medical societies,private industry, consumers, and cancer survivors to promote colorectal cancer screeningawareness and activities. In 1998, the Health Care Financing Administration expanded Medicarecoverage to include colorectal cancer screening. For average-risk persons aged greater than orequal to 50 years, coverage will be provided for annual FOBT and sigmoidoscopy every 4 years,and for high-risk persons, coverage will be provided for colonoscopy every 2 years.Double-contrast barium enema may be substituted for either sigmoidoscopy or colonoscopy ifrequested in writing by the provider. Some commercial health plans also cover colorectal cancerscreening.

The findings in this report underscore the need for efforts to increase screening for colorectalcancer. In response to low rates of use of screening tests, CDC is beginning a comprehensivehealth communication campaign to educate consumers and health-care providers about theimportance of colorectal cancer screening and to encourage patients to discuss screening optionswith their providers. Public health officials, health-care providers, and commercial health plansneed to intensify efforts to increase awareness of the effectiveness of screening and to promote thewidespread use of colorectal cancer screening tests.

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