Risk of advanced proximal neoplasms in asymptomatic adults according to the distal colorectal findings

Diagnostic yield of barium enema examination after incomplete colonoscopy

PURPOSE

To determine the diagnostic yield of barium enema examination for neoplastic lesions larger than 1 cm in diameter in the nonvisualized portion of the colon after incomplete colonoscopy.

MATERIALS AND METHODS

A review of computerized gastroenterology and radiology databases identified 355 patients who underwent incomplete colonoscopy; 158 (44.5%) underwent subsequent barium enema examination (125 double-contrast and 33 single-contrast barium enema examinations). The radiographic reports were reviewed and compared with the endoscopic reports by one author to identify neoplastic lesions larger than 1 cm in the nonvisualized colon after incomplete colonoscopy. Six such lesions were found. In all six cases, the images from the barium enema examinations were reviewed together by two authors to determine the size, location, and morphologic features (polypoid, ulcerated, or annular) of the lesions. Medical, endoscopic, and surgical records were subsequently reviewed by one author to determine whether these represented true- or false-positive radiographic findings.

RESULTS

Barium enema examination depicted six possible lesions in the nonvisualized colon after incomplete colonoscopy; five were found to be true-positive radiographic findings, and one was found to be a false-positive finding. The five true-positive findings included two annular lesions (both adenocarcinomas) and three polypoid lesions (all tubulovillous adenomas, with high-grade dysplasia in one). Thus, neoplastic lesions larger than 1 cm were found on barium enema images in the nonvisualized colon in five (3.2%) of 158 patients after incomplete colonoscopy.

CONCLUSION

Barium enema examination had a diagnostic yield of 3.2% for neoplastic lesions larger than 1 cm in the nonvisualized colon after incomplete colonoscopy.

Colonoscopy in asymptomatic individuals with a family history of colorectal cancer

BACKGROUND

This study was performed to evaluate the use of total colonoscopy as the optimal screening test in asymptomatic individuals with a family history of colorectal cancer (CRC).

METHODS

Colonoscopy was performed in 249 asymptomatic individuals who had one or two first-degree relatives (FDRs) with CRC; individuals with three or more FDRs with CRC were excluded.

RESULTS

Eighty-six colonic lesions were found in 51 individuals (51 of 249; 20.5%). Among these 51 subjects, 27 had neoplastic polyps (n = 38) and 29 had metaplastic polyps (n = 44). Although no invasive cancer was detected, in 14 individuals the lesions had a high malignancy potential because of their size and histopathology. We did not confirm a statistically significant difference in the incidence of neoplastic polyps according to the number of affected FDRs. Finally, the presence of metaplastic polyps was a very strong indication for the concomitant presence of metaplastic polyps (P <.0001).

CONCLUSIONS

Total colonoscopy is the optimal screening procedure for the examination of asymptomatic individuals with a family history of CRC.

Colorectal cancer screening: an overview of current trends

Colorectal cancer can be cured and, in some cases, even prevented if detected early through screening. Studies have demonstrated that regular screening for colorectal cancer with fecal occult blood testing, sigmoidoscopy, or colonoscopy can reduce mortality from this disease. Unfortunately, rates of participation in these screening tests are unacceptably low among the U.S. population. Nurses have a significant role to play in assisting individuals to incorporate regular colorectal cancer screening into their health maintenance routines.

On-site screening sigmoidoscopy promotes long-term utilization but fails as a venue for training primary care endoscopists

BACKGROUND & AIMS

"Academic detailing" is an effective strategy for promoting the use of screening sigmoidoscopy by primary care physicians. The primary objectives of this study were to determine whether the sustained presence of an "outside" university-based gastroenterologist performing on-site screening sigmoidoscopy promoted long-term utilization and whether the provision for on-site sigmoidoscopy was an effective venue for training primary care endoscopists.

METHODS

Nine urban community health centers, including 4 intervention and 5 control sites, participated in a nonrandomized controlled trial conducted over 3 years.

RESULTS

By the end of year 3, overall self-reported use of screening sigmoidoscopy increased by 61% for the intervention group vs. only 25% for the comparison group (P = 0.001). Ninety-seven percent of those reporting compliance referred 1 or more asymptomatic average-risk patients for screening examinations. Only 2 of 83 (2.4%) eligible providers completed on-site training and continued performing screening examinations independently. The major barriers to participation included lack of interest, lack of time to learn or perform sigmoidoscopy, concerns about technical competence, and lack of need because of on-site availability.

CONCLUSIONS

Maintenance of on-site screening sigmoidoscopy services performed by an outside gastroenterologist promotes long-term utilization but fails as venue for training primary care endoscopists. Alternative strategies for expanding capacity are needed.

Method of colonoscopy in 42 consecutive patients presenting after prior incomplete colonoscopy

OBJECTIVES

Cecal intubation is one of the goals of colonoscopy. We sought to describe the methodology used by a single experienced examiner to perform colonoscopy in a consecutive group of patients with challenging colons.

METHODS

Records of 42 consecutive patients with one or more prior unsuccessful attempts at colonoscopy by a gastroenterologist or surgeon and referred for a repeat attempt at colonoscopy were reviewed.

RESULTS

Colonoscopy was complete to the cecum in 40 of the 42 patients (95%). An array of methods was employed, including propofol sedation (n = 2), pediatric colonoscope (n = 8), an external straightener (n = 9), external straightener with pediatric colonoscope (n = 2), upper endoscope (n = 8), guidewire exchange (n = 3), and enteroscope with a colon straightener (n = 1) or an enteroscope straightener (n = 1).

CONCLUSIONS

A variety of methods and instruments were employed to achieve a high cecal intubation rate during colonoscopy in a group of patients with prior incomplete colonoscopies. Others may find one or more of these methods useful in patients with challenging colons.

Colonoscopic screening and follow-up for colorectal cancer in the elderly

AIM: To improve the prevention and treatment of senile patients with colorectal cancer by evaluating the importance of colonoscopy in clinical screening and follow-up.

METHODS: Clinical screening of colonoscopy was performed for 2196 patients aged 60-90 years old according to the protocol, and 1740 of them (79.2%) were followed-up.

RESULTS: Colorectal cancer was found in 52 patients, and the detectable rate was 2.4%. Among them, 19 were diagnosed as early colorectal cancer, accounting for 36.5% of the detected colorectal cancer. Among the followed-up patients, early colorectal cancer was found in 9, accounting for 45.0% of the detected colorectal cancer. The resectable rate and 5 years survival rate of colorectal cancer were 97.7% and 80.9% respectively. The incidence of complication was 0.05%, and the successful rate of cecum intubation was 98.9%.

CONCLUSION: Colonoscopic screening and follow-up of the elderly for colorectal cancer and pre-cancerous lesion (adenomatoid polyp) can increase the detectable rate of early colorectal cancer and improve its prevention and treatment.

Single flexible sigmoidoscopy screening to prevent colorectal cancer: baseline findings of a UK multicentre randomised trial

BACKGROUND

This randomised controlled trial is examining the hypothesis that a single flexible sigmoidoscopy screening offered at around age 60 years can lower the incidence and mortality of colorectal cancer. We report here on acceptability, safety, feasibility, and yield.

METHODS

Men and women aged 55-64 years, in 14 UK centres, who responded to a mailed questionnaire that they would attend for flexible sigmoidoscopy screening if invited, were randomly assigned screening or control (ratio one to two). The control group was not contacted. Small polyps were removed during screening, and colonoscopy was undertaken if high-risk polyps (three or more adenomas, size 1 cm or greater, villous, severely dysplastic, or malignant) were found.

FINDINGS

Of 354,262 people asked about their interest in having flexible sigmoidoscopy screening, 194,726 (55%) responded positively, and 170,432 eligible individuals were randomised. Attendance among those assigned screening was 71% (40,674 of 57,254). 2131 (5%) were classified as high-risk and referred for colonoscopy; 38,525 with no polyps or only low-risk polyps detected were discharged. Distal adenomas were detected in 4931 (12.1%) and distal cancer in 131 (0.3%). Proximal adenomas were detected in 386 (18.8% of those undergoing colonoscopy) and proximal cancer in nine cases (0.4%). 62% of cancers were Dukes' stage A or locally excised. There was one perforation after flexible sigmoidoscopy and four after colonoscopy. An average of 48 people were screened, and two or three colonoscopy referrals generated, per centre each week. Interpretation Our flexible sigmoidoscopy screening regimen is acceptable, feasible, and safe. The prevalence of neoplasia is high, and colonoscopy referral rates of 5% are acceptable.

Metadata tables to enable dynamic data modeling and web interface design: the SEER example

A wealth of information addressing health status, outcomes and resource utilization is compiled and made available by various government agencies. While exploration of the data is possible using existing tools, in general, would-be users of the resources must acquire CD-ROMs or download data from the web, and upload the data into their own database. Where web interfaces exist, they are highly structured, limiting the kinds of queries that can be executed. This work develops a web-based database interface engine whose content and structure is generated through interaction with a metadata table. The result is a dynamically generated web interface that can easily accommodate changes in the underlying data model by altering the metadata table, rather than requiring changes to the interface code. This paper discusses the background and implementation of the metadata table and web-based front end and provides examples of its use with the NCI's Surveillance, Epidemiology and End-Results (SEER) database.

Cancer in inflammatory bowel disease. An evidence-based analysis and guide for physicians and patients

The risk of cancer in IBD is real and is a cause of anxiety and concern among patients and practitioners. Current modalities for detecting dysplasia in IBD are crude and insensitive and subject to observer and sampling bias. This evidence-based review confirms a significant increased risk for colorectal cancer among patients with pancolonic UC and, to a lesser extent, in patients with left-sided disease. Risk increases with longer duration of disease; early age at diagnosis; coexisting PSC; and, perhaps, a family history of colorectal cancer. Physicians must pay greater attention to the manner in which they implement surveillance colonoscopies, including paying heed to the location and number of biopsy specimens required to maximize the benefit. With respect to CD, the evidence suggests that patients with extensive colonic involvement of long duration carry a similar risk of colorectal cancer to patients with UC and should be considered candidates for surveillance colonoscopy.

Deeper examination of negative colorectal biopsies

Initial histologic sections of specimens from colorectal biopsies of putative lesions may lack polyps. These sections may contain lymphoid aggregates that seemingly correlate with endoscopic findings; however; additional sections might contain polyps. We reviewed 83 specimens from colorectal biopsies of putative lesions for which initial sections lacked polyps. Our objectives were to determine the incidence of polyps within additional sections and to determine whether the presence of lymphoid aggregates within initial sections excludes the presence of polyps within additional sections. Eight specimens (10%) contained polyps (5 adenomatous, 3 hyperplastic), which remained histologically occult until examination to depths of approximately 120 to 380 microm. Five polyps (62%) were associated with lymphoid aggregates that were present within initial sections. We conclude that additional sections may contain surprisingly large numbers of polyps and that lymphoid aggregates present within initial sections fail to exclude the presence of polyps within additional sections.

To step or not to step: an approach to clinically diagnosed polyps with no initial pathologic finding

We determined whether there were additional diagnostic findings in additional level sections performed on polyps with no pathologic diagnosis (NPD) or those in which only lymphoid aggregates (LAs) were seen initially and determined the level at which findings were identified. All colorectal biopsy specimens submitted with a clinical diagnosis of polyp during a 6-month period were included (N = 733). Initially, 3 level sections were cut for each polyp, and if a cause for the polyp was found, no additional levels were evaluated. If LAs or no cause for the polyp was found, 5 additional levels through each block were examined. Any diagnostic findings and the level at which they were identified were recorded. A discrete cause for the polyp was identified in routine levels in 574 cases (78.3%). Deeper levels were performed in 159: 23 for clarification of a suspected diagnosis, 38 for LAs, and 98 for NPD. Findings were identified in 31 (22.8%) of 136 stepped for LA or NPD with neoplastic findings in 13 (9.6%). Most diagnoses were identified in levels 4 or 5, but tubular adenomas were found in levels 7 and 8. These results support level sectioning specimens submitted as polyps with NPD or LAs on initial sections.

Colonic cancer and polyps

Colorectal cancer (CRC) is one of the best studied cancers. It is easily accessible and develops slowly over several years from premalignant lesions (adenomatous polyps) to invasive cancers. The key molecular events in this sequence have been characterized. Different screening strategies have proven to be effective in lowering both the mortality and the incidence of CRC. Nevertheless, CRC is still the second leading cause of cancer-related deaths for both men and women in the USA and other Western countries. An estimated 130 000 new cases and more than 50 000 deaths have been diagnosed in the USA in 2000. Surgical resection remains the only curative treatment, and the likelihood of cure is greater when the disease is detected at an early stage. Hereditary non-polyposis colorectal cancer (HNPCC) and the different polyposis syndromes such as familial adenomatous polyposis (FAP) or Peutz-Jeghers disease are rare causes of CRC but have been a major focus of research in past years, helping with the understanding of the molecular events in carcinogenesis. This review summarizes our current knowledge of the pathogenesis and management of colorectal polyps and polyposis syndromes as well as sporadic CRC.

Detection of APC mutations in fecal DNA from patients with colorectal tumors

BACKGROUND

Noninvasive methods for detecting colorectal tumors have the potential to reduce morbidity and mortality from this disease. The mutations in the adenomatous polyposis coli (APC) gene that initiate colorectal tumors theoretically provide an optimal marker for detecting colorectal tumors. The purpose of our study was to determine the feasibility of detecting APC mutations in fecal DNA with the use of newly developed methods.

METHODS

We purified DNA from routinely collected stool samples and screened for APC mutations with the use of a novel approach called digital protein truncation. Many different mutations could potentially be identified in a sensitive and specific manner with this technique.

RESULTS

Stool samples from 28 patients with nonmetastatic colorectal cancers, 18 patients with adenomas that were at least 1 cm in diameter, and 28 control patients without neoplastic disease were studied. APC mutations were identified in 26 of the 46 patients with neoplasia (57 percent; 95 percent confidence interval, 41 to 71 percent) and in none of the 28 control patients (0 percent; 95 percent confidence interval, 0 to 12 percent; P<0.001). In the patients with positive tests, mutant APC genes made up 0.4 to 14.1 percent of all APC genes in the stool.

CONCLUSIONS

APC mutations can be detected in fecal DNA from patients with relatively early colorectal tumors. This feasibility study suggests a new approach for the early detection of colorectal neoplasms.

Clinical significance of small polyps found during screening with flexible sigmoidoscopy

In deciding how to interpret the significance and management of small distal adenomatous polyps found on FS, one must first decide on the goal of a screening program. If the goal is maximal reduction of CRC risk, regardless of cost, there is little argument that screening colonoscopy is the most effective approach. Unfortunately cost and cost-effectiveness are important considerations when administering a screening program with a fixed budget. Although comparing the cost-effectiveness of different strategies is beyond the scope of this article, rigorous comparisons by other authors have suggested that a sigmoidoscopy-based approach is more cost-effective than a colonoscopy-based approach. The most cost-effective approach may change, however, if the frequency of screening and surveillance can be reduced without significantly impacting effectiveness. Other authors using assumptions including low compliance rates for regular FOBT or FS have determined that colonoscopy every 10 years is the most cost-effective approach. Multiple studies support the recommendation that villous polyps regardless of size and adenomatous polyps greater than 1 cm found on FS are important markers for the presence of advanced polyps and cancer in the proximal colon. These patients should undergo colonoscopy. If one assumes that a sigmoidoscopy-based approach is reasonable, and accepts that such an approach always misses a small number of proximal lesions, how should one manage patients with a small adenomatous polyp on FS? In aggregate, the studies discussed previously suggest that patients with no distal polyps, distal hyperplastic polyps, or a single small distal tubular adenoma have a similar and low risk of advanced proximal adenomas of the colon. There are some studies, however, that do not support this. With the exception of the study by Read et al, these studies included patients at elevated risk of CRC because of a family history, or inclusion of patients with positive FOBT (or not tested). The study by Read et al also included patients with distal villous adenomas in their low-risk group. Because a sigmoidoscopy-based strategy typically excludes patients at elevated risk, these results may not be applicable to low-risk patients undergoing sigmoidoscopy. Given these caveats, what can one conclude about the predictive value of a small tubular adenoma found on FS? These studies suggest that the risk of proximal advanced polyps is similar or slightly increased in patients with a distal adenoma than those with a negative FS. The risk of finding an advanced adenoma seems to be 0% to 4% regardless of the findings of no polyps, hyperplastic polyps, or small tubular adenomatous polyps on FS in low-risk patients. A small portion of patients with hyperplastic polyps found on FS have advanced proximal adenomas. If a hyperplastic polyp on FS is not an indication for colonoscopy and the risk of proximal advanced adenomas is similar in patients with only a small distal adenoma, it is inconsistent to recommend colonoscopy for a small distal tubular adenoma and not a hyperplastic polyp. Based on the studies of asymptomatic patients with no family history and negative FOBT, the authors believe it is reasonable to defer colonoscopy if no polyp, a hyperplastic, or a small tubular adenoma is found at sigmoidoscopy in low-risk patients. If the patient or physician is unwilling to accept a small (0% to 4%) chance of missing an advanced proximal lesion, then a sigmoidoscopy-based approach (regardless of the threshold to go on to colonoscopy) is not appropriate. Screening FS remains an effective examination to screen for CRC in asymptomatic patients. There is no question that colonoscopy clearly detects more lesions than FS. It remains to be seen if the increase in costs and risks justifies the improved detection rate of colonic polyps. Given manpower issues that face us today, and examining the question from a population perspective, reserving colonoscopy for only those patients with an advanced distal polyp on FS gives the biggest yield.

Rationale for colonoscopy screening and estimated effectiveness in clinical practice

Colonoscopy screening has the highest anticipated level of effectiveness of the available colorectal cancer screening techniques. Its long-term cost-effectiveness is also comparable with or superior to other modalities. Evidence for the expected reduction in colorectal cancer incidence and mortality varies with colonoscopy screening from 50% to 90%, for reasons that are not fully understood. Maintaining a high standard of performance is critical with regard to achieving the highest level of effectiveness possible.

The advanced adenoma as the primary target of screening

The advanced adenoma bridges benign and malignant states and may be the most valid neoplastic surrogate marker for present and future colorectal cancer risk. We define the advanced adenoma as an adenoma with significant villous features (>25%), size of 1.0 cm or more, high-grade dysplasia, or early invasive cancer. Prevention studies should demonstrate a high efficacy in reducing the number of advanced adenomas. We should use the advanced adenoma in the evaluation of new screening technology, nutritional interventions, and chemoprevention agents because the advanced adenoma is a more desirable target for screening efficacy than is the more uncommon but life-threatening cancer stage or the more common but early, less significant small adenoma stage.

Barriers to screening for colorectal cancer

Rapidly growing interest in colon cancer screening is a crucial first step to identifying and reducing many of the barriers that impede population screening for this common disease. Promoting screening demands health care policy change to increase the percentage of Americans with insurance coverage that includes a colon cancer screening benefit. A systematic approach to screening with invitations that come from a clinician are likely to be the most effective way to prompt more individuals to be screened. Awareness campaigns and patient educational aids, including decision tools, implemented in multiple sites, such as worksites, community centers, health care systems, and physician offices, increase the percent of eligible Americans who understand their personal risk, the need for screening, and the options available to them.

Flexible sigmoidoscopy: an important screening option for average-risk individuals

Colorectal cancer screening techniques should be effective, acceptable to patients, affordable, widely available, and safe. For average-risk adults aged more than 50 years who do not have significant colorectal symptoms, significant family history, or significant predisposing conditions, flexible sigmoidoscopy is an important option for reducing the risk for colorectal cancer, meeting all criteria for an effective and feasible screening modality. This article discusses evidence supporting flexible sigmoidoscopy, practical issues in implementation, and current controversies.

The double contrast barium enema: a retrospective single centre audit of the detection of colorectal carcinomas

AIM

To determine retrospectively the sensitivity and specificity of the double contrast barium enema (DCBE) as performed in one institution for the detection of colorectal carcinoma.

SUBJECTS AND METHODS

Eight hundred and eighty barium enema reports were reviewed of consecutive adult patients who underwent DCBE and also had hospital case notes with a minimum follow up of two years, a later diagnostic colonoscopy, or operative and histological findings.

RESULTS

Seventy-four true positive cases of colorectal carcinoma diagnosed at DCBE were confirmed at surgery and histological examination. There were four false positive diagnoses of carcinoma at DCBE. Eight false negative cases at DCBE were demonstrated within a two-year follow-up period. The sensitivity of the DCBE for detecting colorectal carcinoma was therefore 90.2% and the specificity was 99.5%.

CONCLUSION

DCBE is a sensitive and highly specific investigation for the detection of colorectal carcinoma.

The case for population-based screening for colorectal cancer

Screening for colorectal cancer is commanding increasing attention. Other cancer screening programmes have been a part of public consciousness for some time, but, until recently, colorectal cancer screening has remained in the background. Fuelled by new research, market opportunities and increased recognition of individual risk, screening for colorectal cancer is becoming a recommended procedure, but controversy about how best to implement widespread screening remains.

Analysis of colorectal cancer screening regimens

We analyze several colorectal cancer screening methods. We begin with an existing deterministic model of the colorectal cancer growth-and-development model. Using judgments from two knowledgeable experts on colorectal cancer, we incorporate probability distributions for important parameters in the model. The analysis proceeds in three phases: First is a straightforward Monte Carlo simulation that includes uncertainty about structural parameters, the results of which identify five dominant screening strategies in terms of the expected number of cancers prevented and expected cost per life-year saved. The next part of the analysis develops a two-attribute utility function to rank order the screening regimens. The results show the same top five, with the top-ranked strategy being colonoscopy every three years. Sensitivity analysis demonstrates the robustness of the results.

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.

Efficacy and safety of sodium phosphate tablets compared with PEG solution in colon cleansing: two identically designed, randomized, controlled, parallel group, multicenter phase III trials

BACKGROUND

Liquid purgatives for cleansing before colonoscopy often are poorly tolerated. A sodium phosphate tablet has been developed to provide equivalent efficacy with better patient tolerance. These 2 studies compare the safety, efficacy, and patient acceptance of the tablet (Visicol) to a polyethylene glycol (PEG) solution in adults undergoing colonoscopy.

METHODS

Two identically designed, randomized, investigator-blinded, multicenter trials were performed. The primary efficacy variable was the overall quality of colon cleansing. Patient tolerance was assessed in terms of compliance with the dosing regimen. Safety assessments included recording of adverse events and changes in biochemical tests, electrocardiogram, and vital signs.

RESULTS

Eight hundred forty-five patients participated in the studies; 420 took sodium phosphate tablets and 425 took a PEG solution. The 2 methods of preparation were equivalent in the overall quality of colon cleansing, cleansing in the right colon, and the frequency of inadequate preparation. Overall cleansing was excellent or good in 84.3% of patients in the tablet group and in 76.7% in the PEG group. Patient compliance was greater in the tablet group. There were also significantly fewer GI side effects in this group.

CONCLUSIONS

Sodium phosphate tablets, compared with PEG solution, produce equivalent colon cleansing, are associated with fewer GI side effects, and are better tolerated by patients.

The Topography of Colorectal Cancer Varies by Race/Ethnicity and Affects the Utility of Flexible Sigmoidoscopy

Colorectal cancer screening beginning at age 50 is recommended for all Americans considered at “average” risk for the development of colorectal cancer either with flexible sigmoidoscopy and fecal occult blood testing (FOBT) or with colonoscopy. Patients who elect flexible sigmoidoscopy and FOBT undergo full colonoscopy only if left-sided neoplasia is detected or if the FOBT is positive. Unfortunately in blacks and whites most right-sided colorectal lesions are unaccompanied by left-sided sentinel lesions, which leads some to prefer colonoscopic screening in these patients. The topography of colorectal cancer in Asians and Latinos is unavailable. We used 1988–1995 California Cancer Registry data to determine the topography of 105,906 consecutive colorectal cancers among Asian, black, Latino, and white patients. We found that the proportion of colorectal cancer distal to the splenic flexure and therefore detectable by flexible sigmoidoscopy varied by ethnicity: Asian (71%) > Latino (63%) > white (57%) > black (55%); P < 0.001. These differences were significant after adjusting for age and sex. The risk of distal disease relative to whites was 1.61 in Asians, 1.15 in Latinos, and 0.82 in blacks ( P < 0.001). Flexible sigmoidoscopy detects a higher proportion of colorectal cancers in Asians and Latinos than in whites or blacks. Further study is needed to assess whether the topography of benign colorectal neoplasia parallels that of malignant disease. Colorectal screening recommendations may need to incorporate racial and ethnic differences in colorectal neoplasia topography.

Subsite-specific incidence rate and stage of disease in colorectal cancer by race, gender, and age group in the United States, 1992-1997

BACKGROUND

Subsite specific incidence rates of colorectal cancer vary considerably by age, gender, and race. This variation may be related not only to distinctions in exposure to genetic and environment factors but also to current strategies of early detection screening. Patterns of stage of disease in anatomic subsite may reflect the effect of screening. This study used the largest aggregation of cancer incidence data in the U.S. to examine subsite specific incidence rates of colorectal cancer and the relation of stage of disease to anatomic subsites by race, gender, and age group.

METHODS

Data on the incidence of invasive colorectal cancer were obtained from 28 population-based central cancer registries. Age-specific and age-adjusted rates and stage distributions were analyzed by subsite, race, and gender.

RESULTS

The impact of screening can be observed in the percentage of localized disease, which increased from 31.9% among cancers in the proximal colon to 37.0% in the descending colon to 41.5% in the distal colorectum. Within the same subsite, blacks were less likely than whites to receive a diagnosis of localized disease and more likely to receive a diagnosis of distant disease whereas stage distributions were approximately the same for males and females. Blacks were more likely than whites to receive a diagnosis of proximal colon cancer than distal colorectal cancer. The male-to-female rate ratios progressively increased from the proximal colon to the distal colorectum. The ratios of proximal-to-distal colorectal cancer gradually increased with advancing age.

CONCLUSIONS

Differentials in stage of disease by subsites indicate a need for a targeted effort at early detection of cancer in the proximal colon. Risk factors and higher risk populations for colorectal cancers in each subsite need to be studied further to guide actions for improving the efficacy of screening.

Utilization of colorectal cancer screening tests: a 1997 survey of Massachusetts internists

BACKGROUND

Physician noncompliance with screening recommendations has been a major barrier to effective colorectal cancer control. The overall objectives of this study were to assess the current attitudes and screening behavior of primary care physicians in light of new efficacy data, revised guidelines, improved technology, and more widespread insurance coverage.

METHODS

Questionnaires inquiring about knowledge, beliefs, and practice patterns related to colorectal cancer screening were mailed in mid-1997 to 700 randomly selected Massachusetts internists.

RESULTS

The overall response rate was 63%. Nearly 60% of respondents reported an increase in screening behavior during the past 5 years. Most (80%) were aware of at least one set of screening guidelines and 90% reported utilizing one or more recommended screening strategies. Fecal occult blood testing (FOBT), alone (47%) or in combination with flexible sigmoidoscopy (50%), was the preferred strategy for most respondents. Colonoscopy was rarely utilized (5%) despite high perceived effectiveness. Concern about patient compliance was a significant determinant of FOBT utilization, whereas perceived effectiveness, concerns about time or efficacy data, prior procedural training, date of licensure, and use of instructional materials were independent determinants of sigmoidoscopy utilization.

CONCLUSION

Massachusetts' internists report high rates of utilization of select colorectal cancer screening strategies. Future studies must validate self-reported compliance and explore barriers to screening colonoscopy.

Virtual colonoscopy: clinical results

CT colonography is an evolving noninvasive imaging technique that allows detection of colorectal polyps and cancers. When assessing the clinical results of this test, several points need to be emphasized. First, as computed tomography (CT) technology improves, so will clinical results. Therefore, earlier results reporting the accuracy of CT colonography may not be applicable to the current state of the art. Second, as clinical experience has grown, an understanding of the limitations and pitfalls of the technique has increased. A learning curve is involved and, with increased experience, results should improve. This article will focus on the evolving clinical results of CT colonography.

Training of nurse practitioners and physician assistants to perform screening flexible sigmoidoscopy

PURPOSE

To describe the colorectal cancer-screening program at Harvard Vanguard Medical Associates, a large multispecialty medical group, in which nurse practitioners (NPs) and physician assistants (PAs) perform screening flexible sigmoidoscopies.

DATA SOURCES

Scientific literature, consensus statements and guidelines, and the protocol utilized to train NPs and PAs to perform flexible sigmoidoscopy. Data from 9,500 screening procedures are presented.

CONCLUSIONS

In comparison with gastroenterologists, trained NP and PA endoscopists perform screening flexible sigmoidoscopy with similar accuracy and safety but at lower cost.

IMPLICATIONS FOR PRACTICE

Screening flexible sigmoidoscopy performed by NPs and PAs may increase the availability and lower the cost of flexible sigmoidoscopy for colorectal cancer screening.

Sporadic colorectal cancers with microsatellite instability and their possible origin in hyperplastic polyps and serrated adenomas

BACKGROUND

Microsatellite instability (MSI) is seen in 10%-15% of sporadic colorectal cancers mostly in the right colon, but the precursors of cancers with MSI remain unknown. We examined whether sporadic cancers with MSI arise from pre-existing benign proliferative lesions (such as hyperplastic polyps or serrated adenomas [together denoted as "serrated polyps"]).

METHODS

The frequency of benign epithelial lesions (serrated polyps and conventional adenomas) was determined by histologic review of resection specimens from individuals (n = 29) with sporadic colorectal cancer with MSI and from a matched control group (n = 29) with cancer showing microsatellite stability (MSS). MSI status, expression of mismatch repair enzyme (product of the human mut-L homologue 1 [hMLH1] gene), and hMLH1 gene promoter methylation in the benign lesions were determined. Data were analyzed by the chi-square test, by Wilcoxon's rank-sum test, and by conditional logistic regression as appropriate, and a two-sided probability less than.05 was considered to be statistically significant.

RESULTS

Individuals with cancers showing MSI were more likely to harbor at least one serrated polyp than individuals with cancers showing MSS (odds ratio = 4.0; 95% confidence interval = 1.1 to 14.2; P =.03), but the frequency of conventional adenomas was the same in both groups (P =.52, Mann-Whitney test). Loss of hMLH1 protein expression was seen in lesions from 10 of 13 patients with MSI, but no loss was seen in lesions from four patients with MSS (P =.02, Fisher's exact test). Loss of hMLH1 protein expression was associated with MSI in assessable lesions. The hMLH1 promoter was methylated in all assessable serrated polyps from patients with cancers showing MSI but in none of the lesions from patients with MSS cancers.

CONCLUSIONS

Some right-sided hyperplastic polyps may give rise to sporadic colorectal carcinomas with MSI. Methylation of the hMLH1 gene promoter within neoplastic cell subpopulations may be a critical step in the progression to carcinoma. The frequency with which benign lesions progress to cancer with MSI is unknown.

Long-lasting reduction of risk of colorectal cancer following screening endoscopy

Several studies have suggested that incidence and mortality of colorectal cancer (CRC) may be strongly reduced for up to 10 years by endoscopic screening with removal of precancerous lesions, but so far there are no data on risk reduction beyond this period. We assessed long-term reduction of CRC risk following screening endoscopy in a statewide population-based case-control study in Saarland, Germany. Lifetime history of screening endoscopy was compared between 320 cases with CRC aged 45-80 and 263 controls with other forms of cancer recruited from the same population. Potential confounding factors were controlled for by multiple logistic regression. 11% of cases compared to 27% of controls had a history of endoscopy for screening purposes (adjusted odds ratio (OR) = 0.28, 95% confidence interval (CI): 0.16-0.48). This strong risk reduction was also seen (OR = 0.41, 95% CI: 0.19-0.89) in subjects who had their last screening endoscopy more than 10 years ago (median: 18.9 years). Long term (> 10 years since last screening) risk reduction appeared to be particularly strong for advanced (Dukes C or D) CRC (OR = 0.19, 95% CI: 0.06-0.64). We conclude that risk reduction by screening endoscopy is long lasting, in particular with respect to advanced CRC.

The anatomical distribution of colorectal polyps at colonoscopy

BACKGROUND

Colorectal carcinoma is one of the most common causes of cancer-related deaths in Australia. The distribution of polyps in the colon may effect the efficacy of a screening modality. The aim of this study was to determine the age-matched anatomic location and histologic type of colorectal polyps observed at colonoscopy over a 10-year period at our endoscopy unit.

STUDY

Endoscopy reports on 2,578 patients were reviewed; polyp/lesion histology and location (left, right, or both) were determined in 2,553.

RESULTS

Of all polyps observed, 1,310 (51%) cases were left-sided, 510 (20%) were right-sided, and 733 (29%) were synchronous. Adenomas were present in 1,659 cases (65%); of these, 734 (44%) were left-sided only and 405 (24.5%) were right-sided only. Carcinoma was observed in 189 (7%) cases, of which 71 (37.5%) were left-sided only. There was an increased right-sided prevalence of adenoma or carcinoma with age (p = 0.0029).

CONCLUSION

This was not a screening study, but it has shown that a significant number of adenomas and carcinomas lie proximal to the splenic flexure. Thus, in the absence of left-sided lesions, it is expected that examination of the colon limited to the splenic flexure would miss 23% of such lesions. The increasing right-sided prevalence of these lesions with age suggests that evaluation of the proximal bowel is particularly important in older people.

One-time screening for colorectal cancer with combined fecal occult-blood testing and examination of the distal colon

BACKGROUND

Fecal occult-blood testing and sigmoidoscopy have been recommended for screening for colorectal cancer, but the sensitivity of such combined testing for detecting neoplasia is uncertain. At 13 Veterans Affairs medical centers, we performed colonoscopy to determine the prevalence of neoplasia and the sensitivity of one-time screening with a fecal occult-blood test plus sigmoidoscopy.

METHODS

Asymptomatic subjects (age range, 50 to 75 years) provided stool specimens on cards from three consecutive days for fecal occult-blood testing, which were rehydrated for interpretation. They then underwent colonoscopy. Sigmoidoscopy was defined in this study as examination of the rectum and sigmoid colon during colonoscopy, and sensitivity was estimated by determining how many patients with advanced neoplasia had an adenoma in the rectum or sigmoid colon. Advanced colonic neoplasia was defined as an adenoma 10 mm or more in diameter, a villous adenoma, an adenoma with high-grade dysplasia, or invasive cancer. Classification of subjects according to the findings was based on the most advanced lesion.

RESULTS

A total of 2885 subjects returned the three specimen cards for fecal occult-blood testing and underwent a complete colonoscopic examination. A total of 23.9 percent of subjects with advanced neoplasia had a positive test for fecal occult blood. As compared with subjects who had a negative test for fecal occult blood, the relative risk of advanced neoplasia in subjects who had a positive test was 3.47 (95 percent confidence interval, 2.76 to 4.35). Sigmoidoscopy identified 70.3 percent of all subjects with advanced neoplasia. Combined one-time screening with a fecal occult-blood test and sigmoidoscopy identified 75.8 percent of subjects with advanced neoplasia.

CONCLUSIONS

One-time screening with both a fecal occult-blood test with rehydration and sigmoidoscopy fails to detect advanced colonic neoplasia in 24 percent of subjects with the condition.