Trends in Screening for Colorectal Cancer-United States, 1997 and 1999

May 1, 2001

Colorectal cancer is the second leading cause of cancer-related death in the United States. An estimated 135,400 new cases and 56,700 deaths from colorectal cancer are expected during 2001. Since the mid-1990s, national guidelines have

Colorectal cancer is the second leadingcause of cancer-related death in the United States. An estimated 135,400 newcases and 56,700 deaths from colorectal cancer are expected during 2001. Sincethe mid-1990s, national guidelines have recommended that persons aged ³ 50years who are at average risk for colorectal cancer should have screening testsregularly. To estimate rates for the use of colorectal cancer screening testsand to evaluate trends in test use, the Centers for Disease Control andPrevention (CDC) analyzed data from the 1999 Behavioral Risk Factor SurveillanceSystem (BRFSS) on the use of a home-administered fecal occult blood test andsigmoidoscopy/colonoscopy, and then compared them with similar data from 1997.

The findings in this report indicate that the proportion of theUS population that has been screened remains low. In 1999, 44% of BRFSSrespondents reported receiving a fecal occult blood test and/orsigmoidoscopy/colonoscopy within the recommended period, compared withapproximately 41% reporting a fecal occult blood test and/orsigmoidoscopy/proctoscopy within the recommended period in 1997. Efforts toaddress barriers and to promote the use of colorectal cancer screening should beintensified.

Telephone Survey

In 1999, the 50 states, District of Columbia, and Puerto Ricoparticipated in BRFSS, an ongoing, state-based, random-digit-dialed telephonesurvey of the civilian, noninstitutionalized population aged ³ 18 years. Atotal of 63,555 respondents aged ³ 50 years were asked whether they ever had afecal occult blood test using a home kit, whether they ever had sigmoidoscopy orcolonoscopy, and when the last test had been performed. Responses coded as"don’t know/not sure" or "refused" were excluded fromanalyses (< 2%). Aggregated and state-specific proportions, standard errors,95% confidence intervals, and P values were calculated using SAS and SUDAANsoftware for statistical analysis.

Data in this analysis were weighted to the age, sex, andrace/ethnicity distribution of each state’s adult population using intercensalestimates and were age-standardized to the 1999 BRFSS population. The medianstate response rate of 56.7% (range: 38.4%-83.9%) was calculated using thecooperation rate formula (ie, the number of completed interviews divided by thenumber of potential respondents [households with a resident aged ³ 18 years]).The 1999 questions about the use of sigmoidoscopy were modified from the 1997questions.

In 1997, respondents were asked whether they had receivedsigmoidoscopy or proctoscopy. Proctoscopy is performed with a shorter instrumentthan sigmoidoscopy and is not recommended as a colorectal cancer screening test.In 1999, "sigmoidoscopy/proctoscopy" was replaced with"sigmoidoscopy/colonoscopy." Colonoscopy evaluates the entire colonand in some guidelines is recommended once every 10 years. For this report,"sigmoidoscopy/proctoscopy" and "sigmoidoscopy/colonoscopy"are referred to as "sigmoidoscopy" unless otherwise specified.

Less Than Half Undergo Screening

In 1999, 40.3% (25,263 of approximately 63,000) of respondentsreported ever having a fecal occult blood test, and 43.8% (26,388) of therespondents reported ever having sigmoidoscopy. For tests received within therecommended period, 20.6% (12,518) had a fecal occult blood test within the yearpreceding the survey, 33.6% (19,535) had sigmoidoscopy within the preceding 5years (Table 1). the proposition of respondents having either a fecal occultblood test within the year preceding the survey or sigmoidoscopy within thepreceding 5 years is shown in Figure 1.

In 1997, 19.6% (9,832 of approximately 51,000) of therespondents had a fecal occult blood test within the year preceding the survey,and 30.3% (14,678) had sigmoidoscopy within the preceding 5 years (Table1).Although these rate changes in testing use were statistically significant (P< .05), actual increases were small. By state, the proportion of respondentswho had a fecal occult blood test within the preceding year ranged from 8.2%(112 of 1,366) in Puerto Rico to 36.4% (187 of 500) in the District of Columbia;the proportion that had sigmoidoscopy/colonoscopy within the preceding 5 yearsranged from 20.4% (275 of 1,357) in Puerto Rico to 46.1% (410 of 981) inDelaware (Table 2).

Editorial Note From the CDC

Since 1997, the proportion of the US population that reportedhaving had a fecal occult blood test and sigmoidoscopy has increased slightlybut remains low. Various factors may contribute to the continued underuse ofthese tests, including lack of knowledge by the public and health-care providersof the effectiveness of screening and low reimbursement rates for health-careproviders who perform screening tests.

The findings in this report are subject to at least fourlimitations. First, because of the wording change in the BRFSS questionnairefrom "sigmoidoscopy/proctoscopy" in 1997 to"sigmoidoscopy/colonoscopy" in 1999, comparing endoscopic proceduresfor these years must be interpreted with caution. Data on the use of colonoscopywere collected only in 1999; however, some tests reported assigmoidoscopies/proctoscopies in 1997 probably were colonoscopies because somerespondents may have been unable to distinguish among the three tests. It isunknown whether the reported increase from 1997 to 1999 represents a trueincrease in sigmoidoscopy use or previously unmeasured rates of colonoscopy use.

Second, because the survey was administered over the telephone,only persons who own telephones were represented in this analysis. Third, 43.3%of the eligible respondents were contacted but did not complete the telephoneinterview or could not be reached for an interview. Finally, responses wereself-reported and were not validated through medical record review.

Recommended Screeningfor Those 50 Years and Older

For persons aged ³ 50 years at average risk for colorectalcancer, recommended screening options include one or more of the followingtests: Fecal occult blood test every year plus flexible sigmoidoscopy every 5years, annual fecal occult blood test, sigmoidoscopy every 5 years, double-contrast barium enema every 5 to 10 years, orcolonoscopy every 10 years. Despite their efficacy in reducing the incidence andmortality from colorectal cancer, screening tests are underused. To drawattention to this disease, the US Congress designated March as NationalColorectal Cancer Awareness Month. During March 2001, the CDC and the HealthCare Financing Administration launched the third annual Screen for Life: ANational Colorectal Cancer Action Campaign.

Using print, television, and radio announcements, as well asbrochures and fact sheets, the campaign was designed to raise awareness ofcolorectal cancer and to encourage persons aged ³ 50 years to discuss screeningwith their health-care provider and select the appropriate test(s). The CDC alsoproduced a slide presentation forhealth-care providers. All material is available on the Web at http://www.cdc.gov/cancer/screenforlife andhttp://www.cdc.gov/cancer/colorctl/calltoaction.