Predicting proximal advanced neoplasms at screening sigmoidoscopy

PURPOSE: This study was designed to assess the predictive value for advanced proximal neoplasms (cancer, adenoma = 10 mm, or villous component >20 percent, or severe dysplasia) of the characteristics of distal polyps.METHODS: The study was conducted among patients, aged 55 to 64 years, referred for colonoscopy in the Italian trial of sigmoidoscopy screening for colorectal cancer. Patients reporting a history of colorectal cancer, adenomas, inflammatory bowel disease, recent colorectal endoscopy, or two first-degree relatives with colorectal cancer were excluded. We compared the prevalence of advanced proximal neoplasia in patients with low-risk (1–2 tubular adenomas, <10 mm, with low-grade dysplasia, or hyperplastic polyp) and in those with high-risk (size, =10 mm, or =3 adenomas, or villous component >20 percent, or severe dysplasia) polyps in the distal colon.RESULTS: Of 426 patients with polyps > 5 mm, 29 (6.9 percent) were detected with an advanced proximal neoplasm (including 4 colorectal cancers). The prevalence of proximal advanced neoplasia was 9.4 percent among patients with high-risk distal polyps and 2.5 percent among those with low-risk lesions (adjusted odds ratio, 3.19; 95 percent confidence interval, 1.06–9.59). Approximately 40 people with low-risk distal polyps 6 to 9 mm should undergo colonoscopy to detect one proximal advanced neoplasm; the corresponding number for patients with high-risk distal polyps is 10.CONCLUSIONS: The 2.5 percent prevalence of proximal advanced neoplasms among people with low-risk 6-mm to 9-mm distal polyps is similar to the prevalence observed among people without distal polyps. Restricting colonoscopy referral to patients with high-risk distal polyps might represent a cost-effective strategy in a screening context.The SCORE trial was funded by the Italian Association for Cancer Research (AIRC: 1995-1997) and by the Italian National Research Council (CNR - grant n. 95.00539.PF39; n.96.00736.PF39). The Istituto Oncologico Romagnolo (IOR), the Fondo E Tempia, the University of Milano and the Local Heath Unit ASL1 - Torino supported the implementation of the study in Rimini, Biella, Milano and Torino respectively.SOFAR s.p.a. provided the enemas for the bowel preparation.A report on the preliminary results of this study has been presented at the Digestive Disease Week, Orlando, Florida, May 1999, ASGE poster session.     

Efficacy of screening flexible sigmoidoscopy for colorectal neoplasia in asymptomatic subjects

PURPOSE: Although flexible sigmoidoscopy is recommended in patients over age 40 to complement fecal occult blood screening for colorectal neoplasia, the yield of this procedure in asymptomatic, average-risk subjects has varied between studies. In addition, the efficacy of flexible sigmoidoscopy in detecting early curable carcinoma has been the subject of debate. We therefore undertook this study to assess the efficacy, safety, and cost of the procedure for early detection of colorectal neoplasia in asymptomatic subjects. PATIENTS AND METHODS: Flexible sigmoidoscopy with a 60-cm scope was performed in 412 asymptomatic veterans (mean age, 63.2 years). Subjects with positive fecal occult blood and those at increased risk for colorectal neoplasia were excluded. Costs were estimated on the basis of Medicare payments. RESULTS: A mean length of 56.1 cm of sigmoid and descending colon was examined. A total of 132 polyps were detected in 93 subjects (22.6%). Thirty-five percent of the polyps were located at a distance of greater than 30 cm from the anal verge. Of 122 polyps removed, 26% were 1 cm in size or larger. A total of 77 polyps (63%) were adenomas, and six polyps (5%) were carcinomas. Of the six carcinomas detected (two carcinoma in situ, one Astler Coller stage A, two stage B1, and one stage C1), five were in a localized stage and thus potentially curable. The cost of detecting each potentially curable carcinoma was $47,174. No complications from flexible sigmoidoscopy were noted. CONCLUSION: In conclusion, 60-cm flexible sigmoidoscopy is a safe, high-yield procedure for the initial screening of colorectal neoplasia in asymptomatic, average-risk subjects over the age of 50. Because the carcinomas detected were still in an early stage, such screening may improve survival.     

Small early tubular adenomas and mixed colonic polyps found on screening flexible sigmoidoscopy do not predict proximal neoplasia in males.

BACKGROUND & AIMS: Distal colonic adenomas found on flexible sigmoidoscopy are associated with proximal neoplasias, thus requiring a complete colonoscopic examination, but data regarding the association of distal mixed polyps with proximal neoplasia are lacking. We conducted this study to elucidate the significance of distal mixed colonic polyps in predicting proximal neoplasia. METHODS: We retrospectively analyzed data from patients who underwent a flexible sigmoidoscopic examination for colorectal cancer screening and a follow-up colonoscopic examination because of distal colonic polyps. Distal index polyps were classified by a pathologist as early tubular adenoma (ETA), serrated, or true mixed categories. Index polyps also were immunostained with a monoclonal antibody, Adnab-9, a marker for the colorectal adenoma carcinoma sequence. RESULTS: In 636 patients with distal index polyps, 6% were malignant, 55% were adenomas, 13% were ETAs, 6% were serrated, 4% were true mixed, and 17% were hyperplastic. Compared with distal hyperplastic index polyps, distal malignant polyps (P = 0.0006) and adenomas (P = 0.001) were associated with a significantly increased number of synchronous proximal neoplasia, but the small distal mixed, serrated, or ETA did not predict the increased incidence of proximal neoplasia. Large distal polyps of each category were significantly associated with an increased number of synchronous proximal neoplasias. In support of these findings, immunostaining of distal polyps with Adnab-9 showed predictability for proximal neoplasia only in the adenoma category (P < 0.05). CONCLUSIONS: Small ETAs, serrated, or mixed polyps found on flexible sigmoidoscopic examination do not increase the probability of synchronous proximal neoplasia.     

Patient satisfaction with screening flexible sigmoidoscopy

BACKGROUND: Screening flexible sigmoidoscopy is an underused cancer prevention procedure. Physicians often cite patient discomfort as a reason for not requesting sigmoidoscopy, but patient experiences and attitudes toward sigmoidoscopy have not been well studied. OBJECTIVE: To measure patient satisfaction and the determinants of satisfaction with screening sigmoidoscopy. METHODS: An instrument to assess satisfaction with screening sigmoidoscopy was developed. Responses were evaluated with a factor analysis, tested for reproducibility and internal consistency, and validated against an external standard. RESULTS: A total of 1221 patients (666 men and 555 women; mean age, 61.8 years) were surveyed after sigmoidoscopy. Examinations were performed by a nurse practitioner (n = 668), internist (n = 344), or gastrointestinal specialist (n= 184). More than 93% of the participants strongly agreed or agreed they would be willing to undergo another examination, and 74.9% would strongly recommend the procedure to their friends. Regarding pain and discomfort, 76.2% strongly agreed or agreed that the examination did not cause a lot of pain, 78.1% stated that it did not cause a lot of discomfort, and 68.5% thought that it was more comfortable than they expected. Fifteen percent to 25% of the patients indicated they had a lot of pain, great discomfort, or more discomfort than expected. Women were more likely to have significant pain or discomfort than men (adjusted odds ratio, 2.9; 95% confidence interval, 1.9-4.3; P<.001). CONCLUSIONS: Approximately 70% of individuals who undergo screening sigmoidoscopy are satisfied and find the procedure more comfortable than expected, whereas only 15% to 25% find the procedure unpleasant. Physicians should not project discomfort onto patients as a reason for not requesting screening sigmoidoscopy.     

Complications of screening flexible sigmoidoscopy

BACKGROUND & AIMS: Flexible sigmoidoscopy (FS) is recommended for mass screening for colorectal cancer (CRC), yet little is known about the risk of adverse events when FS is used in general clinical practice. We aimed to determine the incidence of gastrointestinal complications and acute myocardial infarction (MI) after screening FS. METHODS: Northern California Kaiser Permanente Medical Care Program members of average risk for CRC (n = 107,704) who underwent screening FS during 1994 to 1996 (109,534 FS), as part of the Colorectal Cancer Prevention (CoCaP) program. The main outcome measure was hospitalization for gastrointestinal complications or acute MI within 4 weeks of FS. RESULTS: The mean age of subjects was 61 years, and 48.8% were female. Nongastroenterologist physicians, nurses, or physician assistants performed 72% of FS. Overall, 24 persons were hospitalized for a gastrointestinal complication. Of these, 7 were serious (2 perforations, 2 episodes of diverticulitis requiring surgery, 2 cases of bleeding requiring transfusion, and 1 episode of unexplained colitis). In multivariate models, complications were significantly more common in men than in women (odds ratio, 3.34; 95% confidence interval [CI], 1.34-10.13). MI occurred in 33 persons within 4 weeks of FS, but the incidence for this period was similar to that in the subsequent 48 weeks (rate ratio, 0.8; 95% CI, 0.6-1.2). CONCLUSIONS: The risk of serious complications after screening FS in this setting appears to be modest. Although MI occurs after FS, the risk during the 4 weeks after the procedure appears to be similar to expectations for persons of screening age.     

Uptake, yield of neoplasia, and adverse effects of flexible sigmoidoscopy screening

Background—A multicentre randomised controlledtrial to evaluate screening by "once only" flexible sigmoidoscopy(FS) for prevention of bowel cancer is in progress.
Aims—To pilot the trial protocol examining ratesof attendance, yield of neoplasia, and adverse effects.
Subjects—A total of 3540 subjects aged 55-64years in Welwyn Garden City (WGC) and 19 706 in Leicester (LE).
Methods—Subjects responding positively to an"interest in screening" questionnaire were randomised to invitationfor screening or control arms. Small polyps were removed duringscreening. Colonoscopy was undertaken for high risk polyps (more thantwo adenomas, size at least 1 cm, villous histology, severe dysplasia,or malignancy). The remainder were discharged.
Results—In WGC and LE respectively, 59% and 61%indicated an interest in screening, of which 74% and 75% attended.Adenomas were detected in 10% and 9%, respectively, and cancers in 7 per 1000 (in both centres), 55% at Dukes's stage A. The colonoscopy referral rate was 6% in both centres. Mild, short lived bleeding occurred in 3%. One person died following surgery.
Conclusions—Compliance rates, yield of adenomas,and referral rate for colonoscopy were as expected, but cancerdetection rates were higher. Adverse effects following sigmoidoscopy or colonoscopy were mild and transient, but there was one postoperative death. A randomised trial is necessary to evaluate fully the risks andbenefits of this intervention.

Keywords:screening; colorectal cancer; adenomas; sigmoidoscopy; endoscopy; randomised trial

     

Inter-endoscopist variation in polyp and neoplasia pick-up rates in flexible sigmoidoscopy screening for colorectal cancer

BACKGROUND: The Norwegian Colorectal Cancer Prevention study is an ongoing flexible sigmoidoscopy (FS) screening trial for colorectal cancer. Twenty-one thousand average-risk individuals, aged 50-64 years, living in two separate areas in Norway were randomly drawn from the Population Registry and invited to once-only screening flexible sigmoidoscopy. Examinations were performed over 3 years, at 2 centres, by 8 different endoscopists, using the same type of equipment. The aim of the present study was to investigate possible differences between endoscopists in detecting individuals with polyps, adenomas and advanced lesions (adenomas with severe dysplasia and/or villous components and/or size larger than 9 mm and carcinoma) in flexible sigmoidoscopy screening. METHODS: The present trial comprises data from 8822 individuals, aged 55-64 years, who have undergone a flexible sigmoidoscopy. In the study period, all lesions detected by the different endoscopists were registered. Tissue samples were taken from all lesions detected. RESULTS: Detection rates varied significantly between endoscopists, ranging from 36.4% to 65.5% for individuals with any polyp, from 12.7% to 21.2% for any adenoma and from 2.9% to 5.0% for advanced lesions. In a multiple logistic regression model, the performing endoscopist was a strong independent predictor for detection of individuals with polyps (P < 0.001 ), adenomas (P < 0.001) and advanced lesions (P = 0.01). CONCLUSION: Detection rates for colorectal lesions vary significantly between endoscopists in colorectal cancer screening. Establishing systems for monitoring performance in screening programmes is important. Supervised training and re-certification for endoscopists with poor performance should be considered.     

Achieving quality in flexible sigmoidoscopy screening for colorectal cancer.

BACKGROUND: Sigmoidoscopy screening, which can dramatically reduce colorectal cancer mortality, is supported increasingly by physicians and payers, and is likely to be performed more frequently in the future. As more physicians and nonphysician medical personnel learn how to perform this procedure, and with attention to quality standards, the overall impact of sigmoidoscopy screening may improve. This review describes elements that characterize high-quality examinations and identifies resources for in-depth information on performing flexible sigmoidoscopy. METHODS: The domains of quality were identified from textbooks, articles, and the professional opinions of gastroenterologists and primary care physicians. Information was obtained from MEDLINE, bibliographies in recent articles, medical professional organizations, equipment manufacturers' representatives, and focus groups of primary care physicians. RESULTS: Nine domains of quality are identified and discussed: training, logistical start-up, patient interaction, bowel preparation, examination technique, lesion recognition, complications, reporting, and processing (equipment cleaning and disinfection). CONCLUSIONS: Persons learning how to perform and to implement flexible sigmoidoscopy may use this information to help ensure the quality of screening examinations.     

Variability in flexible sigmoidoscopy performance among examiners in a screening trial.

BACKGROUND & AIMS: The efficacy of flexible sigmoidoscopy (FSG) in reducing colorectal cancer mortality is being evaluated in randomized trials. In 2 European trials, wide variability across examiners in FSG performance was noted. We report on the performance of examiners in the US randomized trial: the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial. METHODS: Screening was performed at 10 geographically dispersed clinical centers. Patients with screens positive for a lesion or mass were referred to their private health care providers for endoscopic follow-up evaluation; lesions were not removed and a biopsy examination was not performed at screening. FSG performance among 64 examiners at these centers, each performing 100 or more baseline FSG examinations, with an aggregate of almost 50,000 examinations, was analyzed. RESULTS: Screen-positivity results among examiners ranged from 9%-58%, with a coefficient of variation (CV) of 36%. CVs were 29% for distal polyp detection and 21% for distal adenoma detection. Inadequate rates ranged from 1%-27% (CV, 52%). Examiners with higher screen-positivity rates had higher false-positive rates, defined as a positive screen with no distal lesion found on endoscopic follow-up evaluation. CONCLUSIONS: Considerable variability exists in the rates of positive screens and in polyp and adenoma detection rates among FSG examiners performing the procedures using a common protocol.     

Yield of advanced adenoma and cancer based on polyp size detected at screening flexible sigmoidoscopy

BACKGROUND & AIMS: Observational screening of the colon with subsequent referral for colonoscopy raises questions about the threshold of polyp size that necessitates referral. To examine the yield at colonoscopy when a given size lesion is observed, we assessed the yield of advanced adenoma and cancer at colonoscopy based on the size of the abnormality detected at flexible sigmoidoscopy (FSG). METHODS: We used data from the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial, a randomized, controlled, community-based study of FSG. RESULTS: Subsequent colonoscopy was performed on 10,850 subjects (60.4% male; mean age, 62.9 years) with a polyp visualized on screening FSG. For women with a polyp 0.5-0.9 cm on FSG (n = 1426), the yield in the distal colon on colonoscopy was 0.6% for cancer (number needed to screen [NNS] = 166) and 14.5% for advanced adenoma (NNS = 7). In men (n = 2183), the yield was 0.7% (NNS = 142) for cancer and 15.9% (NNS = 6) for advanced adenoma. Among persons with polyps 0.5-0.9 cm identified on FSG, 5.5% (198/3609) had distal advanced adenomas that measured <1.0 cm but had villous histology or high-grade dysplasia, and 9.9% (357/3609) had adenomas > or =1 cm. CONCLUSIONS: The yield for a distal advanced adenomatous lesion when a polyp 0.5-0.9 cm is observed at FSG is substantial and is due to the presence of advanced histology in polyps <1 cm and to detection of polyps that measure > or =1.0 cm on colonoscopy. Establishing thresholds for observation versus evaluation will require careful assessment of the overall yield.     

Comparison of flexible sigmoidoscopy with other diagnostic techniques in the diagnosis of rectocolon neoplasia

Flexible sigmoidoscopy was compared to rigid sigmoidoscopy in the detection of colorectal neoplasia in a select group of patients. A distance of 30 cm or greater was obtained by flexible sigmoidoscopy in 94% of patients and a distance of 50 cm or greater in 46% of patients. A significant number of cancers and adenomas detected by flexible sigmoidoscopy were not detected by rigid sigmoidoscopy. Flexible sigmoidoscopy was tolerated better than rigid sigmoidoscopy but required twice the time. Flexible sigmoidoscopy could be combined with air-contrast barium enema the same day with the one preparation and did not interfere with the x-ray examination. All cancers and a significant number of adenomas detected subsequently on colonoscopy were detected by the combination of flexible sigmoidoscopy and air-contrast barium enema. Although the combination of flexible sigmoidoscopy and air-contrast barium enema is not adequate for thorough diagnostic evaluation of patients with a positive screening test, it may be of value in other select clinical situations. Flexible sigmoidoscopy has the potential for higher yield and better patient tolerance as compared to rigid sigmoidoscopy. This warrants further evaluation.This study presented in part at the 1977 Annual Meeting of the American Society for Gastrointestinal Endoscopy, May 1977, Toronto.This work supported in part by Public Health Service Research Grant CA-15429 from the National Cancer Institute through the National Large Bowel Cancer Project.     

Screening for colorectal neoplasia in asymptomatic patients using flexible fiberoptic sigmoidoscopy

Four hundred seventeen asymptomatic patients with an average age of 52 years underwent screening flexible fiberoptic sigmoidoscopy. Seventy-three polyps were detected in 52 patients with a 17.5 per cent detection rate. Half were above 25 cm and one-third were greater than 1.0 cm in size. Biannual follow-up of these patients is planned to determine the efficacy of this screening procedure combined with removal of all polyps in preventing the development of colorectal cancer.     

Wide variation in adenoma detection rates at screening flexible sigmoidoscopy

BACKGROUND & AIMS: Wide between-center variation in adenoma detection rates (ADRs) was observed in the U.K. Flexible Sigmoidoscopy Screening Trial (overall, 12.1%; range, 8.6%-15.9%; P < 0.0001). The aim of this study was to determine whether the observed differences could be attributed to varying performance by endoscopists, to examine the effect of experience on performance, and to identify an attainable, standard ADR to which endoscopists could aspire. METHODS: Thirteen medical endoscopists, one per trial center, each performed about 3000 examinations (200 per month) using the same equipment and protocol. Overall and monthly ADRs were compared using multivariable logistic regression. RESULTS: Differences in ADRs were not explained by patient characteristics, incidence of colorectal cancer in the local population, or the endoscopists' medical specialty or previous experience. Average ADRs increased significantly with screening experience (up to 400 examinations). Endoscopists were classified as higher, intermediate, or lower adenoma detectors, and performance levels were maintained over time. Higher detectors had ADRs of 15% overall (men, 20%; women, 10%) and also detected more adenomas per case (higher/lower detectors, 21.7/10.4 adenomas per 100 examinations). CONCLUSIONS: The differences in ADRs were due to variation in performance of the endoscopists. Long-term follow-up will determine whether this variation is clinically important. We suggest that the standards in higher detecting centers should be achievable by all endoscopists screening unscreened populations aged older than 55 years. Endoscopists should aim to stay above the lower 95% confidence interval band for 200 examinations (10% overall; 5% in women, 15% in men).     

Performing screening flexible sigmoidoscopy using colonoscopes: experience in 500 subjects

There is still controversy regarding the optimal length of flexible sigmoidoscopes. We performed screening distal colon examinations using 168-cm colonoscopes in 500 asymptomatic subjects who were unsedated and had sigmoidoscopy cleansing preparation. The mean depth of penetration was 66 cm and was similar in persons in whom the examination was discontinued because of poor preparation versus those with discomfort. Polyps were detected in 87 patients, but only 5 subjects had polyps detected above 60 cm. We conclude that in a group of unsedated subjects scheduled for flexible sigmoidoscopy after a sigmoidoscopy prep, the use of instruments longer than 60 cm gives very little additional yield.     

Predictors of proximal neoplasia in patients without distal adenomatous pathology

BACKGROUND: Previous colorectal cancer screening studies have observed that some patients may have advanced proximal neoplasia without distal findings. Since these studies have included only gender, age, and family history as risk factors, they are limited in their ability to identify predictors of isolated proximal neoplasia. METHODS: Data were collected from the charts of 1,988 patients who presented for colonoscopy. Information gathered included endoscopic findings, histology, known risk factors for colorectal neoplasia, and smoking pattern. Our main outcome was the presence of proximal adenomatous neoplasia in patients who had no distal adenomas. We defined significant neoplasia as adenocarcinoma, high-grade dysplasia, villous polyps, adenomas 1 cm or greater or more than two adenomas of any size. RESULTS: Fifty-five patients had isolated significant proximal neoplasia that would have been missed on a flexible sigmoidoscopy. While patients older than 60 yr had a greater risk for this neoplasia (odds ratio = 3.01: 95% CI = 1.66-4.23; p < 0.001), those who took a daily aspirin had a reduced risk (OR = 0.60; 95% CI = 0.30-0.88; p < 0.05). A family history of colorectal cancer increased the patient's risk of having any adenomas (OR = 2.01; 95% CI = 1.33-3.40; p < 0.01) or villous tissue (OR = 2.03; 95% CI = 1.27-3.51; p < 0.05) in the proximal colon without distal findings. Smoking was associated with an increased risk of large (> 1 cm) isolated proximal tubular polyps (OR = 2.71; 95% CI = 1.64-4.46; p < 0.01) as well as isolated significant proximal neoplasia (OR = 2.30; 95% CI = 1.59-3.31; p < 0.01). CONCLUSIONS: Age greater than 60 yr, a history of at least 10 pack-years of smoking, and a family history of colorectal cancer increased the risk of finding significant proximal polyps in patients without distal pathology.