Flexible Sigmoidoscopy in Asymptomatic Patients with Negative Fecal Occult Blood Tests Joy Garrison Cauffman, PhD, Jimmy H. Hara, MD, Irving M. Rasgon, MD, and Virginia A. Clark, PhD Los Angeles, California Background. Although the American Cancer Society and tients with lesions were referred for colonoscopy; addi­ others haw established guidelines for colorectal cancer tional lesions were found in 14%. A total of 62 lesions screening, questions of who and how to screen still exist. were discovered, including tubular adenomas, villous Methods. A 60-crn flexible sigmoidoscopy was per­ adenomas, tubular villous adenomas (23 of the adeno­ formed on 1000 asymptomatic patients, 45 years of mas with atypia), and one adenocarcinoma. The high­ age or older, with negative fecal occult blood tests, est percentage of lesions discovered were in the sig­ who presented for routine physical examinations. Pa­ moid colon and the second highest percentage were in tients with clinically significant lesions were referred for the ascending colon. colonoscopy. The proportion of lesions that would not Conclusions. The 60-cm flexible sigmoidoscope was have been found if the 24-cm rigid or the 30-cm flexi­ able to detect more lesions than either the 24-cm or ble sigmoidoscope had been used was identified. 30-cm sigmoidoscope when used in asymptomatic pa­ Results. Using the 60-cm flexible sigmoidoscope, le­ tients, 45 years of age and over, with negative fecal oc­ sions were found in 3.6% of the patients. Eighty per­ cult blood tests. When significant lesions are discovered cent of the significant lesions were beyond the reach of by sigmoidoscopy, colonoscopy should be performed. the 24-cm rigid sigmoidoscope and 37% were beyond Key words. Sigmoidoscopy; colonoscopy; preventive the reach of the 30-cm sigmoidoscope. Thirty-six pa­ medicine. / Fam Bract 1992; 34:281-286. Colorectal cancer is a common lethal cancer, afflicting by the American Gastroenterological Association, the both men and women. In 1991, 157,500 new cases and American Society of Gastrointestinal Endoscopy, and nearly 60,500 deaths from colorectal cancer were ex­ other groups.4-3 pected to occur in the United States.1 The United States Preventive Services Task Force In 1980, the American Cancer Society (ACS) advo­ stated that there was insufficient evidence either for or cated annual fecal occult blood testing for men and against conducting fecal occult blood tests or sigmoid­ women over the age of 50 years and a sigmoidoscopic oscopy in asymptomatic patients.6 Discontinuation or screening at age 50 years and even' 3 to 5 years after two withholding of a procedure or test from persons who initial examinations (performed 1 year apart) in which no request it, therefore, would be inappropriate. disease is found.2 In 1988, the ACS modified part of Frame7 has taken an opposing view, stating that it is their former guideline: “sigmoidoscopy every 3 to 5 years premature to recommend flexible sigmoidoscopy as a beginning at age 50.” This meant that the National routine screening examination for colorectal cancer pri­ Cancer Institute (NCI) and the ACS now had identical marily because of the lack of patient acceptability and guidelines.3 Similar recommendations have been issued cost. Yet, he states that early cancer will be detected during an initial examination in about 4% of asympto­ matic patients. Rodney8 has taken the affirmative view. Submitted, revised^ November 19, 1991. He believes that flexible sigmoidoscopy screening should From the Depanmcnt of Family Medicine (Dr Cauffman and Dr Rasqon) and the be offered by family physicians primarily because of the Depanmcnt o f Medicine (Dr Rasjjon), University o f Southern California; from the Division o f Family Medicine (D r Hara) and the Department o f Biostatistics and value of early detection of disease, the natural history' of Biomathematics (Dr Clark), University o f California; and the Southern California colorectal cancer, and the adenoma-carcinoma sequence. Kaiser Permanente Medical Group (D n Hara and Rasjjon), Los Angeles. Requests for reprints should be addressed to Joy Gairison Cauffman, PhD, 1014-8 F aiirinvA venue, Many studies have been forwarded as providing Arcadia, CA 91007-7164. evidence that fecal occult blood testing can detect both ~© 1992 Appleton & Lange ISSN 0094-3509 The Journal of Family Practice, Vol. 34, No. 3, 1992 281 Sigmoidoscopy in Asymptomatic Patients Cauffman, Hara, Rasgon, and Clark adenomas and cancers in asymptomatic patients.9"17 Sev­ community'. This prevalence studv involved both male and eral studies have shown that occult blood testing is less female subjects. Patients in the plan were encouraged to sensitive for detecting polyps than in detecting can­ come to the Family Practice Department for routine phys­ cers.1X20 I his is predictable when one considers the ical examinations even' 3 years. histopathological differences in sites of hemorrhage from The investigators were aware that in 1980 the ACS polyps and cancers. recommended that colon cancer screening using fecal It is generally accepted that adenomas are precursors occult blood tests and sigmoidoscopic examinations of colon cancer just as dysplasias are precursors to cervical should begin at 50 years of age. For this study, however, cancer.21'22 Approximately 55% of adenomas and dc the investigators modified the ACS recommendations, novo cancers develop within the typical reach of the using 45 vears of age as the point to initiate screening. 60-cm flexible sigmoidoscope.23 To reduce the cost and Since the practice served an older population, about increase patient acceptance of flexible sigmoidoscopy, a 14,000 patients would be eligible for 60-cm flexible 30-cm flexible sigmoidoscope has been developed.24 This sigmoidoscope. From 1985 through 1989, the sample sigmoidoscope is said to detect an estimated 40% of the that was selected for this study consisted of 1000 con­ neoplastic lesions as compared with the estimated 30% of secutive patients who met the study criteria, that is, adenomas and cancers within the reach of the rigid asymptomatic, presenting for routine physical examina­ sigmoidoscope.23 In spite of the obvious 15% difference tions, having negative occult blood stools, 45 years of age in the number of lesions visualized, some authors have or older, and agreeable to having a flexible sigmoido­ gone on record stating that no significant difference exists scopic examination. Thirty patients declined having a in the detection rate between the 30-cm and the 60-cm sigmoidoscopy. instruments.25 At the time of routine physical examinations, pa­ The specific aims of this study were to determine (1) tients were told that a cancer screening test of the large the prevalence of lesions in asymptomatic patients, 45 intestine should be performed. The patients were given years of age and over, with negative fecal occult blood letters that identified colorectal cancer as the second most tests, by using a 60-cm flexible sigmoidoscope, and to common cancer and stated that it had a good cure rate if study the histopathology of colorectal lesions in terms of detected earlv. They were informed about the risks and type, size, and location; (2) what proportion of the benefits of sigmoidoscopy and given preparation instruc­ lesions found were beyond the reach of a 24-cm rigid or tions. a 30-cm flexible sigmoidoscope; (3) what proportion of Family physicians filled out consultation slips for the these patients with significant lesions had additional 60-cm flexible sigmoidoscopic examinations. lesions beyond 60 cm as detected by colonoscopy; and One thousand forms were completed by family phy­ (4) what proportion of these patients with significant sicians, and pathology report forms were obtained for lesions would have been referred for colonoscopy if ei­ those patients who were referred to gastroenterologists ther the 24-cm or the 30-cm sigmoidoscope had been for colonoscopies and biopsies. used rather than the 60-cm sigmoidoscope. Throughout the data-gathering phase of this proj­ ect, the study investigators held regular conferences with other Kaiser physicians and supervised the collection of Methods data to ensure that procedures were consistent. Informa­ tion on the data collection forms was verified against This study was conducted in a family practice with ap­ original source documents to ensure accuracy and com­ proximately 36,000 patients at the Kaiser Pcrmanente pleteness. All family physicians had extensive training Medical Group, Sunset location, in Los Angeles. The and experience in performing sigmoidoscopic examina­ practice providers consisted of 12 physicians, 24 resi­ tions using the 60-cm instrument. dents, and 45 paramedieals. Chi-square and Student’s t tests were performed on Early in 1985, the principal investigators developed selected data. a personal and family health form to be completed by physicians at the time they conducted routine physical examinations. In addition to selected variables from nine health record forms already being used by Kaiser, the Results form included new variables related to the specific aims of this study. Patient characteristics are described by age, sex, and race The Kaiser health maintenance organization (HMO) in Table 1. The mean age was 61 years and the standard serves a typical cross-section of the Los Angeles urban deviation was 9 years. There were 529 women and 471 282 The Journal of Family Practice, Vol. 34, No. 3, 1992 Sigmoidoscopy in Asymptomatic Patients Cauftman, Hara, Rasgon, and Clark