Colorectal Cancer Screening Participation: Comparisons With. Mammography and Prostate-Specific Antigen Screening. | Stephenie Lemon, MS, Jane Zapka, ...
RESEARCH
Colorectal Cancer Screening Participation: Comparisons With Mammography and Prostate-Specific Antigen Screening | Stephenie Lemon, MS, Jane Zapka, ScD, Elaine Puleo, PhD, Roger Luckmann, MD, MPH, and Lisa Chasan-Taber, ScD
Despite the availability of several effective screening tests that could substantially reduce colorectal cancer (CRC) morbidity and mortality, participation in screening is low; many Americans are diagnosed with and die from the disease each year.1 Available screening tests include the fecal occult blood test,2,3 flexible sigmoidoscopy,4,5 colonoscopy,6 and the double-contrast barium enema.7 The 1997 Behavioral Risk Factor Surveillance System8 indicated that 20% of age-eligible participants reported a fecal occult blood test within the previous year, 30% reported a flexible sigmoidoscopy within the previous 5 years, 41% reported having had one or the other of these tests, and 10% reported having had both. Rates in Massachusetts were slightly higher, with 28% reporting a fecal occult blood test within the previous year and 31% reporting a flexible sigmoidoscopy within the previous 5 years. Prevalence rates for mammography screening are higher than those for CRC screening.9 Among men, prostate-specific antigen (PSA) screening for prostate cancer is widespread,10,11 despite equivocal recommendations as to the appropriateness of the test.12,13 Research examining the relationships of common health-related behaviors with other screens, as well as relationships between types of screening, is sparse. The purpose of this study was to investigate the prevalence of current CRC screening in a population-based sample of Massachusetts adults, and to examine the relationship of demographic variables, family history of CRC, health insurance status, health services use, lifestyle behaviors, and other screening use to current CRC screening. We compare and contrast the prevalence and predictors of CRC screening with the prevalence and predictors of mammography screening in women and of PSA screening in men.
Objectives. The relation of personal characteristics, health and lifestyle behaviors, and cancer screening practices to current colorectal cancer (CRC) screening was assessed and compared with those factors’ relation to current mammography screening in women and prostate-specific antigen (PSA) screening in men. Methods. A cross-sectional random-digit-dialed telephone survey of 954 Massachusetts residents aged 50 and older was conducted. Results. The overall prevalence of current CRC screening was 55.3%. Logistic regression results indicated that family history of CRC (odds ratio [OR] = 1.98; 95% confidence interval [CI] = 1.02, 3.86), receiving a regular medical checkup (OR = 3.07; 95% CI = 2.00, 4.71), current screening by mammography in women and PSA in men (OR=4.40; 95% CI=2.94, 6.58), and vitamin supplement use (OR=1.87; 95% CI = 1.27, 2.77) were significant predictors of CRC screening. Conclusions. Health and lifestyle behaviors were related to increased current CRC, mammography, and PSA screening. Personal factors independently related to CRC screening were not consistent with those related to mammography and PSA screening. This lack of consistency may reflect different stages of adoption of each type of screening by clinicians and the public. (Am J Public Health. 2001;91:1264–1272) METHODS Study Design This cross-sectional study used data from a standardized telephone interview conducted from June to August 1998. We used a random-digit-dialed telephone survey and the sampling method of Kish and Frankel14 to obtain a stratified sample consisting of a basic random sample, a male oversample, and a minority (Black and Hispanic) oversample. Eligible participants were Massachusetts residents 50 years and older who were cognitively able, resided in a home with a working telephone number, and had never been diagnosed with CRC. Men ever diagnosed with prostate cancer and women ever diagnosed with breast cancer were excluded from the sample because they might have been monitored under surveillance rather than screening protocols.
Data Collection and Survey Measures Interviews were conducted with a computer-assisted telephone system. Interviewers received extensive training in instru-
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ment administration as well as technical aspects of the subject matter. As described below, measures were designed or adapted from previous work to capture screening and lifestyle and other personal characteristics. Pilot tests were conducted to refine the instrument.
Cancer Screening Practice Measures The telephone interview collected information on participants’ experiences with the fecal occult blood test kit completed at home and mailed back to the physician’s office or laboratory for interpretation, with flexible sigmoidoscopy, with colonoscopy, and with the double-contrast barium enema. For the fecal occult blood test and flexible sigmoidoscopy, participants were asked if they had ever had the test, the length of time since their last test, and whether the test was for screening or diagnostic purposes. Persons who reported never receiving a fecal occult blood test were then asked if they had ever had a stool blood test in the physician’s office and the time since their last test. Participants were asked if they had ever received a
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RESEARCH
colonoscopy or double-contrast barium enema for screening or diagnostic purposes. Owing to multiple screening options, it is difficult to determine CRC screening status. Persons were considered currently screened on the basis of recent guidelines15 if they reported having had 1 or more of the following: (1) a fecal occult blood test within the previous year; (2) flexible sigmoidoscopy within the previous 5 years; (3) colonoscopy within the previous 10 years; (4) a doublecontrast barium enema within the previous 10 years. This definition included those who received a CRC test for screening as well as for diagnostic reasons. Those who reported being screened but beyond the time periods recommended by guidelines, and those who reported never being screened, were considered not current. Those who reported only receiving a fecal occult blood test performed by a physician during an office visit were considered not current, because this is not an acceptable screen according to guidelines. For mammography and PSA screening, women and men were first asked if they had ever received the test appropriate for their sex. Those who answered yes reported the length of time since their most recent test. On the basis of accepted guidelines, for both procedures, being current was defined as having been screened within the previous year.16,17
Personal Measures Demographic information collected included sex, education, race/ethnicity, income, age, and marital status. Family histories of CRC, and of breast cancer in women and prostate cancer in men, were each classified as yes or no. Insurance and entitlement coverage was hypothesized to be a potential predictor of CRC screening, as it is for mammography.18,19 Insurance status was classified as private, non–health maintenance organization (HMO) insurance with or without supplemental insurance; private, HMO insurance with or without supplemental insurance; Medicare, non-HMO; Medicare, HMO; Medicaid or other insurance; and uninsured.20
Health and Lifestyle Behavior Measures Health service use and lifestyle behaviors were hypothesized to be associated with CRC
screening. Access to a regular source of medical care enables other preventive services.21,22 Participants were asked if they received a regular medical checkup, and if so, how often. A regular checkup was defined as a checkup every year or more often. Smokers are less likely to use many preventive services.23–25 Participants were asked if they had ever smoked 100 cigarettes, and if so, if they were current or former smokers. Smoking status was classified as never, former, and current. Certain dietary supplements may have chemoprevention potential for some cancers.26 Although evidence is equivocal, the public has adopted considerable use of supplements,27 and participants were asked if they currently used any type of vitamin supplement (yes or no).
TABLE 1—Characteristics of Participants (n = 954) in Study of Cancer Screening Practices n (%) Personal Characteristics Age, y 50–64
497 (52.6)
65–74
262 (27.8)
75–84
185 (19.6)
Race/ethnicity White
863 (91.0)
Other
85 (9.0)
Educational level < High school
312 (32.7)
High school graduate, 1–3 years
481 (50.5)
of college/trade school College graduate or higher
Statistical Analysis Univariate analyses were used to describe the study sample and screening prevalence. Both in the total sample and in the analyses stratified by sex, bivariate χ2 statistics and odds ratios, with 95% confidence intervals, were used to document the crude relationship between each independent variable and CRC screening status. Analyses were repeated with mammography and PSA as the outcome variables. Logistic regression was used to model the association between each outcome measure and health and lifestyle behavior. Personal characteristics were considered potential confounders if they were marginally associated with the outcome or the exposure variables in bivariate analyses or were strongly associated in prior literature. Variables demonstrating sex differences in relation to CRC screening were tested for statistical interaction. Covariates were retained in the model if they were independent predictors of the outcome variable or if their inclusion in the model changed the odds ratio associated with an exposure variable by more than 15%. Data manipulation and frequency estimates were conducted with SAS Version 6.12.28 All other analyses were conducted with SUDAAN Version 7.52.29 To account for the stratified sampling scheme, we weighted analyses to represent the sex, race/ethnicity, and education distributions of Massachusetts.
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160 (16.8)
Family history of colorectal cancer Yes
103 (10.8)
No
851 (87.2)
Family history of breast cancer (women) Yes
87 (16.0)
No
453 (84.0)
Family history of prostate cancer (men) Yes
35 (8.3)
No
379 (91.7)
Sex Male
414 (43.4)
Female
540 (56.6)
Marital status Married/cohabitating
546 (57.4)
Divorced/separated
140 (14.7)
Widowed
219 (23.0)
Never married
47 (4.9)
Annual household income, $
