Randomized comparison of surveillance intervals after colonoscopic removal of newly diagnosed adenomatous polyps. The National Polyp Study Workgroup

Polypectomy may be adequate treatment for adenoma-like dysplastic lesions in chronic ulcerative colitis

BACKGROUND & AIMS

Chronic ulcerative colitis (CUC)-associated adenoma-like DALMs (dysplasia-associated lesions or masses) pose a difficult clinical problem to both gastroenterologists and pathologists because they are difficult to distinguish endoscopically and pathologically from sporadic adenomas that develop coincidentally in patients with CUC. The aim of this study was to evaluate the outcome of CUC patients with an adenoma-like DALM treated conservatively and to compare the findings with CUC patients with a coincidental sporadic adenoma.

METHODS

Clinical, endoscopic, and pathological features and outcome of 24 CUC patients with an adenoma-like DALM were compared with those of 10 CUC patients with a coincidental sporadic adenoma and 49 non-CUC (control) patients with a sporadic adenoma. Patients were followed up for a mean of 42.4 and 41.2 months for the 2 CUC groups, respectively, and 37.0 months for the non-CUC controls by endoscopic surveillance.

RESULTS

Of the 24 CUC patients with adenoma-like DALMs (male/female ratio, 14/10; mean age, 61.5 years; mean duration of colitis, 10.4 years), 14 (58%) developed further adenoma-like DALMs within the follow-up interval. Only 1 patient (4%) developed an isolated focus of low-grade dysplasia, and none developed adenocarcinoma. Five of 10 (50%) CUC patients with sporadic adenomas developed further adenomas, and none of the patients in this group developed either dysplasia or adenocarcinoma. Of the 49 non-CUC control patients, 39% developed further adenomas.

CONCLUSIONS

CUC patients who develop an adenoma-like DALM that endoscopically and histologically resembles a sporadic adenoma, regardless of its location (either within or outside areas of documented colitis), may be treated with polypectomy and endoscopic surveillance because of its relatively benign course.

Colorectal cancer screening: a community case-control study of proctosigmoidoscopy, barium enema radiography, and fecal occult blood test efficacy

OBJECTIVE

To examine the effectiveness of screening proctosigmoidoscopy, barium enema radiography, and the fecal occult blood test (FOBT) in decreasing colorectal cancer mortality in a community setting.

PATIENTS AND METHODS

In this population-based case-control study, cases comprised 218 Rochester, Minn, residents who died of colorectal cancer between 1970 and 1993. Controls were 435 age- and sex-matched residents who did not have a diagnosis of colorectal cancer. Screening proctosigmoidoscopy, barium enema radiography, and FOBT results were documented for the 10 years prior to and including the date of diagnosis of fatal colorectal cancer in cases and for the same period in matched controls. History of general medical examinations and hospitalizations was also recorded.

RESULTS

Within the 10 years prior to diagnosis, the percentages of cases vs controls with at least 1 screening proctosigmoidoscopy were 23 (10.6%) of 218 cases vs 43 (9.9%) of 435 controls; at least 1 screening barium enema radiographic study was done in 12 (5.5%) of 218 vs 25 (5.7%) of 435. Within 3 years prior to diagnosis, the percentages of cases vs controls with at least 1 screening FOBT were 27 (12.4%) of 218 vs 44 (10.1%) of 435. Adjusted odds ratios were 1.04 (95% confidence interval [CI], 0.21-5.13) for proctosigmoidoscopy (distal rectosigmoid cancers only), 0.67 (95% CI, 0.31-1.48) for barium enema radiography, and 0.83 (95% CI, 0.45-1.52) for FOBT over the above time periods.

CONCLUSION

In this case-control study within a community setting, a colorectal cancer-specific mortality benefit could not be demonstrated for screening by FOBT, proctosigmoidoscopy, or barium enema radiography. Screening frequency was low, which may have contributed to the lack of measurable effects.

Colonoscopic polypectomy in chronic colitis: conservative management after endoscopic resection of dysplastic polyps

BACKGROUND & AIMS

Adenomatous polyps are by definition dysplastic and pathologically indistinguishable from the dysplasia-associated lesion or mass (DALM) described in 1981. Yet, adenomatous polyps in noncolitic colons are usually removed definitively endoscopically, whereas DALMs are regarded as harbingers of colon cancer, mandating colectomy.

METHODS

Since 1988, all of our patients with chronic ulcerative or Crohn's colitis and dysplastic polyps and no coexistent dysplasia in flat mucosa underwent colonoscopic polypectomy. Biopsy specimens were obtained also adjacent to polypectomy sites, from strictures, and throughout the colon at 10-cm intervals. Follow-up colonoscopies and biopsies were performed within 6 months after polypectomy and yearly thereafter.

RESULTS

Colonoscopy in 48 patients with chronic colitis (mean duration, 25.4 years) resected 70 polyps (60 in colitic and 10 in noncolitic mucosa). Polyps were detected on screening colonoscopies (29%) and on surveillance (71%). Pathology was tubular adenoma in all polyps from noncolitic mucosa and low-grade dysplasia (57), high-grade dysplasia (2), or carcinoma (1) in polyps from colitic mucosa. Subsequent colonoscopies (mean follow-up, 4.1 years) revealed additional polyps in 48% but no carcinomas. Surgical resection (6 patients) for recurrent polyps confirmed colonoscopic findings. No dysplasia or cancers in flat mucosa were found at surgery or on follow-up colonoscopies.

CONCLUSIONS

In patients with chronic colitis who have no dysplasia in flat mucosa, colonoscopic resection of dysplastic polyps can be performed effectively, just as in noncolitic colons.

Dairy foods and prevention of colon cancer: human studies

Colon cancer is the commonest gastrointestinal cancer and the second leading cause of cancer deaths in the United States. Recent approaches to lowering the incidence of colon cancer have included attempts at dietary prevention and chemoprevention. International and national incidence rates for colon cancer suggest an inverse relationship with dietary calcium and/or vitamin D intake (or sun exposure). Several human intervention studies have suggested that supplemental calcium administration will change proliferative indices of risk for colon cancer from high to lower risk patterns. The principal current hypothesis for the action of calcium implies that calcium may precipitate or bring out of solution fatty acids and bile acids that are potentially toxic to the colorectal epithelium. Both calcium administration and dairy food administration are associated with lowering aqueous fecal concentrations of bile acids and fatty acids accompanied by a highly significant lowering of cytotoxicity in studies in vitro. There is biochemical and biological evidence in cell culture systems that exposure to calcium and/or vitamin D reduces the oncogenic properties of colon cancer cells. A recent blinded study of the administration of low-fat dairy foods demonstrated a significant improvement in several parameters of proliferation as well as in two differentiation markers from a high to a lower risk pattern. Furthermore, administration of calcium also has been shown to reduce the incidence of recurrent adenomatous polyps in individuals at increased risk for colon polyp formation because of the presence of prior colon adenomata. These combined data suggest that administration of supplemental calcium or low-fat dairy foods may have a significant effect upon colonic polyp and perhaps colon cancer incidence.

Nonsteroidal anti-inflammatory drugs and prevention of colorectal cancer

Increasing evidence suggests that aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs) reduce the risk of colorectal cancer. This observation is supported by results from animal studies that show fewer tumors per animal and fewer animals with tumors after administration of several different NSAIDs. Results from clinical studies with humans consistently support these findings as well. The intervention data in familial adenomatous polyposis patients establishes that the antineoplastic effect may target human adenoma formation. Supportive evidence comes with both aspirin and non-aspirin NSAIDs. Earlier detection of lesions as a result of drug-induced gastrointestinal bleeding does not seem to account for these findings. The molecular mechanism responsible for the chemopreventive action of this class of drugs is not clear. Protection may affect several pathways, with results including cell cycle arrest, induction of apoptosis, and angiogenesis. This review focuses primarily on the potential chemopreventive activity of NSAIDS in sporadic human colon cancer and adenomas and outlines current concepts for the biologic and biochemical mechanisms for this protective effect.

A practical approach to familial and hereditary colorectal cancer

Recent genetic research has isolated the primary genetic defect underlying many of the hereditary colorectal cancer syndromes. Obtaining a detailed family history is the first step in identifying individuals at increased risk of developing colorectal cancer. Once identified, individuals and their families may benefit from earlier, more intensified surveillance, prophylactic surgery, cancer risk assessment and education, and genetic testing. Clinicians, especially those with many patients with colorectal cancer in their practice, must be able to address the complex issues associated with the familial and hereditary colorectal cancer syndromes. A well-integrated partnership among colorectal surgeons, gastroenterologists, oncologists, and medical geneticists is necessary to address these complex issues and provide comprehensive medical care.

Screening for colorectal cancer and other GI cancers

Most of the major advances in the screening for gastrointestinal cancers this year were in the area of colorectal cancer screening. Currently, screening is recommended for the prevention of colorectal cancer in average and high-risk populations. For average risk populations, large randomized trials support the use of screening fecal occult blood testing, and case-control studies support the use of screening sigmoidoscopy. This year, several investigators have addressed issues related to the probability of identifying advanced lesions in the proximal colon following a positive screening flexible sigmoidoscopy. Similarly, two studies identified that villous histology in an index polyp was associated with an increased risk of recurrent colonic polyps. Additionally, two large trials provided new insight about the prevalence of mutations in the MLH1 or MSH2 mismatch-repair genes among patients with colorectal cancer. Lastly, a case-control study from Sweden provided the best evidence to date that surveillance colonoscopies for patients with long-standing ulcerative colitis may reduce cancer-related mortality. Although further work is needed, these studies have served to advance our knowledge of colorectal cancer screening substantially.

Recommended colorectal cancer surveillance guidelines by the American Society of Clinical Oncology

OBJECTIVE

To determine the most effective, evidence-based, postoperative surveillance strategy for the detection of recurrent colon and rectal cancer. Tests are to be recommended only if they have an impact on the outcomes listed below.

POTENTIAL INTERVENTION

All tests described in the literature for postoperative monitoring were considered. In addition, the data were critically evaluated to determine the optimal frequency of monitoring.

OUTCOMES

Outcomes of interest included overall and disease-free survival, quality of life, toxicity reduction, and cost-effectiveness. The American Society of Clinical Oncology (ASCO) Colorectal Cancer Surveillance Expert Panel was guided by the principle of cost minimization, ie, when two strategies were believed to be equally effective, the least expensive test was recommended.

EVIDENCE

A complete MEDLINE search was performed of the past 20 years of the medical literature. Keywords included colorectal cancer, follow-up, and carcinoembryonic antigen, as well as the names of the specific tests. The search was broadened by articles from the tumor marker ASCO panel literature search, as well as from bibliographies of selected articles.

VALUES

Levels of evidence and guideline grades were rated by a standard process. More weight was given to studies that tested a hypothesis directly relating testing to one of the primary outcomes in a randomized design. BENEFITS/HARMS/COSTS: The possible consequences of false-positive and false-negative tests were considered in evaluating a preference for one of two tests that provide similar information. Cost alone was not a determining factor.

RECOMMENDATIONS

The expert panel's recommended postoperative monitoring schema is discussed in this article.

VALIDATION

Five outside reviewers, the ASCO Health Services Research Committee, and the ASCO Board of Directors examined this document.

SPONSOR

American Society of Clinical Oncology.

The MISCAN-COLON simulation model for the evaluation of colorectal cancer screening

A general model for evaluation of colorectal cancer screening has been implemented in the microsimulation program MISCAN-COLON. A large number of fictitious individual life histories are simulated in each of which several colorectal lesions can emerge. Next, screening for colorectal cancer is simulated, which will change some of the life histories. The demographic characteristics, the epidemiology and natural history of the disease, and the characteristics of screening are defined in the input. All kinds of assumptions on the natural history of colorectal cancer and screening and surveillance strategies can easily be incorporated in the model. MISCAN-COLON gives detailed output of incidence, prevalence and mortality, and the results and effects of screening. It can be used to test hypotheses about the natural history of colorectal cancer, such as the duration of progressive adenomas, and screening characteristics, such as sensitivity of tests, against empirical data. In decision making about screening, the model can be used for evaluation of screening policies, and for choosing between competing policies by comparing their simulated incremental costs and effectiveness outcomes.

The small polyp at flexible sigmoidoscopy: an historical perspective on why practices still vary

Current practices vary regarding the approach to small polyps discovered during screening flexible sigmoidoscopy. The most common practice is to perform colonoscopy whenever any adenoma is detected, a strategy that generally uses biopsy of polyps < or = 5 mm in size. However, data suggest that tubular adenomas < 1 cm in size in the distal colon have less predictive value than other distal adenomas for advanced adenomas in the proximal colon. Thus, some centers reserve colonoscopy for distal adenomas with tubulovillous or villous histology, > 1 cm in size, or with high-grade dysplasia. At the other end of the spectrum, another school of thought advocates screening colonoscopy, recognizing that most patients with advanced proximal adenomas do not have polyps in their distal colon. Advocates of this approach use any excuse to perform colonoscopy, whether it be a positive fecal occult blood test, minor symptoms, or small polyp at flexible sigmoidoscopy, even if hyperplastic. This review describes the history of the controversy regarding management of findings at flexible sigmoidoscopy, the data pertinent to the controversy, and the basis for the three approaches described above, all of which are currently within the standard of medical care.

Cancer and adenomatous polyp distribution in the colorectum

OBJECTIVE

To examine the possible role of adenomatous polyps in colorectal cancer development, this study focused on the relationship of the distribution between adenomatous polyps and cancer in the colorectum.

METHODS

The distribution of 753 adenomatous polyps was compared with that of 35 colorectal cancer lesions in 510 male patients ranging from 45 to 55 yr of age who underwent a total colonoscopy.

RESULTS

The incidence of cancer significantly increased with a distal shift in the colorectal sites in comparison with that of adenomatous polyps (p < 0.02).

CONCLUSION

The different distribution between adenomatous polyps and cancer thus suggested that adenomatous polyps at various colorectal sites appear to have a different malignant potential for cancer development.

Pathologic features of initial adenomas as predictors for metachronous adenomas of the rectum

BACKGROUND

Colorectal cancer is the third most common cancer in the world, arising mostly from pre-existing adenomatous polyps (adenomas) of the large bowel. Patients with colorectal adenomas are at increased risk of colorectal cancer because of a high recurrence rate for adenomas. We followed a cohort of 1490 patients with rectal adenomas to determine whether recurrence might be related to pathologic characteristics of the initial adenomas.

METHODS

The patients were identified in Haining County, China, from 1977 through 1978 by means of examination with a 15-cm rigid sigmoidoscope. They were followed by endoscopic examination at years 2, 4, 6, 11, and 16 after their initial polypectomy. New adenomas in the rectum were identified in 280 patients in these follow-up examinations.

RESULTS

Statistically significant twofold to threefold elevated risks of metachronous (recurrent) adenomas were observed for patients who had more than two initial adenomas or whose most advanced initial adenoma was more than 1.0 cm in size, was of villous/tubulovillous type, or showed moderate to severe dysplasia. Much stronger associations were observed for advanced metachronous neoplasms, which are defined as cancers or adenomas with severe dysplasia, with multivariate adjusted relative risks (95% confidence interval) of 4.2 (1.8-9.9) for a large initial adenoma (>1.0 cm), 8.1 (4.2-15.6) for villous/tubulovillous architecture, and 14.4 (5.0-41.3) for severe dysplasia. In particular, patients who had a large (>1.0 cm) adenoma with severe dysplasia at baseline had a relative risk of 37 (7.8-174.7) of developing advanced metachronous neoplasms compared with patients who had small adenoma(s) with mild dysplasia.

CONCLUSIONS

The risk of metachronous adenomas is closely related to the pathology of initial adenomas, thus allowing identification of a high-risk group of adenoma patients for close surveillance after their initial polypectomy.

Current surgical practice in screening for colorectal cancer based on family history criteria

BACKGROUND

As awareness about colorectal cancer increases there has been a steady rise in the number of referrals of relatives of patients with colorectal cancer to colorectal surgeons for screening investigations based on family history criteria. Surgeons are generally not trained in either risk assessment of inherited colorectal cancer or genetic counselling. As this is a relatively new area of service, there is likely to be variation in the management of these individuals.

METHODS

This study investigated the family history criteria used and the colonic screening practices employed by a group of consultant colorectal surgeons by means of a postal questionnaire distributed and collected through their specialist association.

RESULTS

The results show not only wide variation in the practice of colorectal screening based on family history criteria, but also a considerable waste of resources in the provision of illogical and inappropriate investigations.

CONCLUSION

Given the lack of evidence on which to base this clinical practice and the current financial difficulties in the health service, the authors question whether it is appropriate for surgeons to continue to provide such a service.

Colorectal cancer screening and follow-up

Cancer of the colon and rectum is a significant health problem in the United States. Nearly 50% of the 186,000 patients diagnosed annually with colorectal cancer will eventually die of their disease. Because development of a colorectal carcinoma is most frequently preceded by the development of a well-recognized pre-malignant lesion, screening modalities can significantly impact the incidence and mortality rate of this disease. Population screening employing digital rectal examination, fecal occult blood testing and endoscopic examination of the rectum and colon has been demonstrated to reduce the risk of death from colorectal cancer. Screening regimens should be instituted at an earlier age and with increased frequency for patients in the highest risk categories. Patients who have been treated for a cancer of the colon or rectum should undergo surveillance at regular intervals in an attempt to identify recurrences of disease both in the residual colon and rectum and at distant sites. Most physicians and patients believe that intensive follow-up strategies will afford improved survival and quality of life, however few randomized studies examining the utility of intensive follow-up programs have been performed and the quality of cancer-related follow-up literature is generally poor. Good-quality clinical trials are needed to sort out which tests make a difference in the patient's long-term outcome. The algorithm for surveillance for recurrence in the future may be altered as newer testing modalities are developed.

In a resource-poor country, mutation identification has the potential to reduce the cost of family management for hereditary nonpolyposis colorectal cancer

PURPOSE

Colonoscopic surveillance of family members at risk of hereditary nonpolyposis colorectal cancer is difficult in a resource-poor country because of its expense. For family members who live in remote areas, poor communication and limited access to sophisticated medical care make surveillance even more difficult. The identification of the mutation causing the disease will simplify surveillance. Our aim was to assess the impact of mutation analysis on the management of a South African family with more than 150 members at risk for hereditary nonpolyposis colorectal cancer.

METHODS

We studied a family that met the Amsterdam criteria for hereditary nonpolyposis colorectal cancer. Colorectal cancer affected 27 members in three generations (evidence from histology in 12, barium enema in 1, and family statements in 14 family members). Leukocyte DNA from family members was tested for linkage to candidate loci for colorectal cancer, and DNA from formalin-fixed cancers from six family members was studied for microsatellite instability. DNA from all available family members was then screened for mutations in the hMLH1 gene. The number of individuals at 50 percent risk was calculated by family pedigree and compared with the number who have the mutation.

RESULTS

A disease-causing mutation in exon 13 of hMLH1 segregated with the disorder in members of this kindred. Test results of 100 chromosomes from population-matched controls were negative. Sixty family members between the ages of 16 and 50 years are at 50 percent risk for colon cancer by pedigree analysis, but of these, only 26 (43 percent) have the mutation.

CONCLUSION

A mutation in the DNA repair gene hMLH1 was found in family members with hereditary nonpolyposis colorectal cancer and in some unaffected relatives previously at 50 percent risk, but not in unrelated subjects. The blood test for the mutation will simplify management, counseling, and surveillance and help to establish prophylactic colectomy.

Outcome states of colorectal cancer: identification and description using patient focus groups

OBJECTIVE

Utilities for the outcome states of colorectal cancer must be measured to evaluate the cost-utility of screening and surveillance strategies for this disease. We sought to identify these outcome states, define their associated areas of morbidity, and construct representative descriptions of them for use in a utilities assessment instrument.

METHODS

We identified candidate colorectal cancer outcome states based on a review of the literature and interviews with health care professionals. We organized patient focus groups from each of the candidate outcome states to examine their homogeneity and define their associated areas of morbidity. After analyzing the focus group transcripts, we identified and described outcome states of colorectal cancer for future incorporation into a utilities assessment instrument.

RESULTS

Six candidate outcome states of colorectal cancer were identified based on disease stage and location at diagnosis. Thirty-eight patients then participated in six focus groups. Analysis of the focus group transcripts revealed seven areas of morbidity associated with colorectal cancer. These areas included problems with social interaction and cognition, fear of cancer recurrence, pain, fatigue, changes in bowel habits, and sexual dysfunction. Based on differences in the intensity and frequency of the symptoms reported in each of these areas, seven distinct outcome states of colorectal cancer were identified and described.

CONCLUSION

Clinically distinct outcome states of colorectal cancer are determined by the stage and location of the cancer at the time of diagnosis. Descriptions of these outcome states were created using data collected from patient focus groups. These descriptions can be incorporated into a utilities assessment instrument.

Adenoma characteristics at first colonoscopy as predictors of adenoma recurrence and characteristics at follow-up. The Polyp Prevention Study Group

BACKGROUND & AIMS

All patients with colorectal adenomas may not require identical follow-up. We aimed to determine if adenoma characteristics at initial colonoscopy could predict adenoma recurrence or characteristics at follow-up.

METHODS

The number of adenomas and the size, type, and degree of atypia in 479 patients in a polyp prevention trial were evaluated as predictors of the same characteristics at follow-up using odds ratios (ORs) with 95% confidence intervals (CIs). Multiple logistic regression analysis was performed to determine if several baseline characteristics were simultaneously associated with outcome.

RESULTS

Although several characteristics were significant predictors of recurrence univariately, by multivariate analysis, multiple adenomas at follow-up were more likely when patients had > or = 3 baseline adenomas (OR, 2.25; 95% CI, 1.20-4.21) or at least 1 tubulovillous adenoma (OR, 2.12; 95% CI, 1.12-4.02). No specific characteristic was associated with recurrence of high-risk polyps (> or = 1 cm, villous, severe atypia). Seventy percent of patients with 1 or 2 baseline adenomas had no recurrence, and only 3.3% had any adenomas of clinical concern.

CONCLUSIONS

Number and type of baseline adenomas predict recurrent adenomas, but the recurrence is rarely of clinical concern. Patients with 1 or 2 tubular adenomas constitute a low-risk group for whom follow-up might be extended beyond 3 years.

Postsurgical surveillance of colon cancer: preliminary cost analysis of physician examination, carcinoembryonic antigen testing, chest x-ray, and colonoscopy

OBJECTIVE

This study is the first to examine the relative and absolute costs of physician examination, carcinoembryonic antigen (CEA) assessment, chest x-ray, and colonoscopy in detecting recurrent disease in patients who have undergone surgical resection for primary colon carcinoma.

METHODS

Of the 1356 Eastern Cooperative Oncology Group patients in Intergroup Protocol 0089 who underwent surgical resection for Dukes' B2 and C colon carcinoma, 421 patients who developed recurrent disease were reviewed. Follow-up testing was performed according to protocol guidelines, with the cost of each test equal to 1995 Medicare reimbursement. Follow-up was defined as the time to recurrence for the 421 patients in whom disease recurred (mean 18.6 months) or up to 5 years for the additional 930 patients in whom disease did not recur (mean 38.6 months). Patients were divided into three categories: nonrecurrent, recurrent but not resectable, and recurrent but resectable with curative intent. The estimated mean cost of each test in detecting group 3 (recurrent but resectable) patients was calculated.

RESULTS

Of the 421 patients who developed recurrent disease, 96 underwent surgical resection of their disease with curative intent (group 3). For group 3 patients, the first indication of recurrent disease was CEA testing (30), chest x-ray (12), colonoscopy (14), and other (40). Of the 40 "other" patients, 24 presented with symptoms. Routine physician examination, however, failed to identify a single resectable recurrence, and the total cost for physician examination was $418,615. The detection rate for CEA testing was 2.2%, the total cost was $170,880, and the cost per recurrence was $5,696. The detection rate for chest x-ray was 0.9%, the total cost was $120,934, and the cost per recurrence was $10,078. The detection rate of colonoscopy was 1%, the total cost was $641,344, and the cost per recurrence was $45,810.

CONCLUSIONS

CEA measurement was the most cost-effective test in detecting potentially curable recurrent disease. Physician visits were useful only in the evaluation of symptoms; a routine physician examination had no added benefit.

The development of dysplasia and adenocarcinoma during endoscopic surveillance of Barrett's esophagus

OBJECTIVE

Periodic endoscopic surveillance is generally recommended for patients with Barrett's esophagus. The optimal follow-up strategy for uncomplicated Barrett's esophagus is controversial, in part because of limited data on the rate of neoplastic progression (through the sequence of metaplasia-dysplasia-carcinoma) during endoscopic surveillance. This study aims to quantify the development of dysplasia in patients with uncomplicated Barrett's esophagus and to explore clinical risk factors associated with the development of dysplastic lesions.

METHODS

We identified 102 patients with endoscopic evidence of Barrett's esophagus and the presence of specialized columnar epithelium who had received endoscopic surveillance for adenocarcinoma at our medical center between 1970 and 1994. We abstracted endoscopic and histologic data from the medical record. All specimens that showed any degree of atypia (per report) were reexamined in blinded fashion by a team of study pathologists who indicated the grade of dysplasia. Time to first diagnosis of dysplasia was plotted using Kaplan-Meier survival curves, and risk factors for development of dysplasia were assessed using Cox regression.

RESULTS

During 563 patient-yr of endoscopic follow-up, three patients developed adenocarcinoma at least 4 yr after initial diagnosis (one developed adenocarcinoma of the cardia, which was incidentally detected during surveillance for Barrett's esophagus). At some point during follow-up, 19 patients developed new onset, low grade dysplasia and four developed high grade dysplasia. None of the patients who had received antireflux surgery developed dysplasia.

CONCLUSION

If confirmed by larger follow-up studies, our results suggest that surveillance endoscopy can be safely deferred for at least 2 yr following an initial biopsy that is negative or indeterminate for dysplasia. Adoption of this approach would substantially reduce the cost of surveillance for adenocarcinoma. Future trials should explore the role of antireflux surgery in protecting against neoplastic transformation of Barrett's esophagus.

How to screen for colon cancer

The biology of colorectal cancer provides a unique opportunity for early detection and prevention. There is now evidence that screening of asymptomatic average-risk individuals over 50 years of age can reduce mortality resulting from colorectal cancer. New recommendations from the US Preventive Services Task Force endorse screening with fecal occult blood tests or sigmoidoscopy. The best method for population screening remains uncertain. The cost of screening is an important issue in the development of public policy. This review discusses the various screening options, examines the "downstream" effects of screening, and reviews the anticipated costs and effectiveness. Ultimately, the effectiveness of any screening program depends on patient compliance. Further research is needed to determine the best methods of enhancing patient adherence to a screening program.

The pathologic measurement of polyp size is preferable to the endoscopic estimate

BACKGROUND

There is no standardized technique to measure polyp size. Estimation of polyp size at endoscopy is difficult. Polyp size measurement by pathologists would seem to be an accurate alternative, but tissue fixation may alter polyp size. To evaluate methods of determining polyp size, we compared endoscopists' estimates and pathologists' measurements with measurements made by an independent examiner.

METHODS

Polyps were measured by an independent investigator before and after formalin fixation. The investigator's measurement before fixation (the "gold standard") was compared with the endoscopists' estimates and the pathologists' measurements.

RESULTS

Ten endoscopists removed 61 polyps with a snare in 33 patients: 82% were adenomatous and 72% were pedunculated. Mean size was 0.85 +/- 0.6 cm (SD) (range: 0.3 to 3.6 cm, 26% > or = 1 cm). Polyps remained in formalin for a mean of 239 minutes (46 to 1164 minutes). Polyps neither consistently shrank nor enlarged in formalin (maximum change +/- 0.2 cm, r = 0.99 [p < 0.001]). Interobserver agreement between pathologists' and the investigator's post-formalin measurements showed that 55 of 57 polyps (97%) were within +/- 0.3 cm. Endoscopists inaccurately estimated 11 of 56 polyps (20%) (> 0.3 cm difference from the independent examiner). Polyp size was underestimated in three instances (range 0.5 to 0.9 cm) and overestimated in eight (range 0.4 to 0.8 cm). In 5 of 11 instances (46%), this inaccuracy altered polyp size classification across the 1 cm threshold. Results were not dependent on endoscopist, histology, or polyp location.

CONCLUSIONS

(1) Polyp size is not significantly affected by formalin fixation; 2) Endoscopists' estimates of polyp size are often unreliable; and, when possible, (3) Pathologists' measurements of polyp size should be used in clinical trials and in clinical practice.

Is in vivo measurement of size of polyps during colonoscopy accurate?

BACKGROUND

Accurate measurement of polyp size during colonoscopy is important because of the direct correlation of size with colon cancer. Major studies of colorectal neoplasms have measured polyp size differently. It is also well documented that endoscopists underestimate polyp size frequently. The goal of this prospective study was to determine which one of the five methods of estimating polyp size during colonoscopy is most accurate.

METHODS

One hundred colon polyps were measured by means of visual estimation, open biopsy forceps methods, linear probe, a ruler immediately after excision, and after fixation in formalin. The size of the polyps measured outside the body immediately after excision was considered the "gold standard" against which all measurements were compared.

RESULTS

Forty-seven polyps were 5 mm or less in diameter, 33 polyps were 5.01 mm to 10 mm, and 20 polyps were more than 10 mm in size. For all polyps the mean difference versus the actual size of the polyps was 3.4% for linear probe, 6.4% for visual estimation, and 12.3% for the forceps.

CONCLUSION

Measurement of polyp size by linear probe agreed best with the actual polyp size, followed closely by visual estimation. The open biopsy forceps method was the least accurate.

K-RAS-2 gene mutations as predictors of metachronous colorectal adenomas

BACKGROUND

Mutations of K-RAS-2 gene and tumour suppressor genes have been found in both colorectal adenomas and carcinomas. The aim of this study was to investigate the prognostic value of K-RAS-2 gene mutations found in initial colorectal adenomas for predicting the risk of metachronous adenomas.

METHODS

Genomic DNA was extracted from formalin-fixed and paraffin-embedded adenomas larger than 5 mm in diameter removed at the initial total colonoscopy between 1980 and 1982. All patients underwent colonoscopic follow-up for at least 10 years. The sequence of exon 1 of the K-RAS-2 oncogene was amplified with the polymerase chain reaction technique and screened for mutation by single-strand conformation polymorphism analysis. All suspected mutations were confirmed by direct DNA sequencing. The predictive value of K-RAS-2 gene mutations for the risk of metachronous adenomas was assessed by chi-square testing and logistic regression analysis.

RESULTS

Of 54 patients 39 (72%) were male and 15 (28%) female. At the time the initial adenoma was removed, 31 (57%) patients were younger than 60, whereas 23 (43%) were 60 years or older. Point mutations of the K-RAS-2 oncogene were found in the index adenomas of 15 (27.7%) patients. Mutations were found more frequently in large (> or = 20 mm) adenomas and in adenomas with severe dysplasia (P = 0.0011 and P = 0.0310, respectively). There were no significant associations between K-RAS-2 mutations and anatomic location, histologic type, or number of synchronous initial lesions. Mutations were found predominantly at codon 12 with transversions from GGT to GTT (57%), from GGT to GAT (36%), and from GGT to TTT (one patient). The single mutation found at codon 13 showed a transversion from GGC to GAC. There were significant associations between size (> or = 20 mm) and K-RAS-2 mutation of the initial adenomas and the size (> 5 mm) of metachronous adenomas (P = 0.0259 and P = 0.0265, respectively). However, multivariate analysis showed that K-RAS-2 mutations did not provide a significant additional contribution to the prognostic value of the size of the initial adenoma (odds ratio, 7.62; 95% confidence interval (CI), 1.68-34.48) and the amount of villous structure (odds ratio, 0.22; 95% CI, 0.05-0.90) it contained.

CONCLUSIONS

Patients with large (> or = 20 mm) adenomas and adenomas with K-RAS-2 mutations found at the initial examination have a significantly higher risk of developing large (> 5 mm) metachronous adenomas during surveillance. Multivariate analysis of initial adenoma characteristics showed that the risk of metachronous colorectal adenomas can be adequately estimated by the size and the histologic type of the largest initial adenoma and that K-RAS-2 mutations are of secondary importance only. Further studies based on a larger series will have to identify the adenoma characteristics that will help to improve follow-up strategies.

Screening and surveillance for colorectal carcinoma

Screening and surveillance examinations are effective in lowering colorectal cancer risk. Screening tests have been demonstrated to reduce colorectal cancer mortality. Colonoscopic removal of adenomatous polyps has been determined to reduce colorectal cancer incidence. High-risk individuals and their family members should be identified and offered more aggressive recommendations for appropriate screening and surveillance guidelines. Colorectal cancer screening strategies are in an acceptable range of cost effectiveness.

Follow-up of patients with hyperplastic polyps of the large bowel

BACKGROUND

Adenomatous colonic polyps are accepted as premalignant lesions. There is controversy regarding the significance of the hyperplastic polyp. The aim of this study was to determine the incidence of further polyps in patients with only hyperplastic polyps on a first colonoscopy in comparison with patients without polyps and with adenomatous polyps.

METHODS

Ninety patients had only hyperplastic polyps (group I). These patients were paired according to age and sex with subjects having no polyps (group II) and with patients having adenomas (group III).

RESULTS

Fifty-six patients in group I had at least one follow-up examination. New polyps were found in 46.4% in group I versus 15.5% in group II (p < 0.001) and 50% in group III (NS). In group I, 30.7% of new polyps were hyperplastic and 69.3% were adenomas. In fact, 32.2% of group I patients developed further adenomas (mean 1.5 +/- 0.8 adenomas). These adenomas occurred 1 to 4 years after the first polypectomy (mean 2.4 +/- 0.8 years). Most of these adenomas were small and tubular, but 16.6% were villous or had severe dysplasia.

CONCLUSION

Patients with hyperplastic polyps were 2.4 times more likely to have further adenomas than were those without polyps.

Preoperative and postoperative imaging for colorectal cancer

Management and survival in colorectal cancer are dictated by the extent of the disease at the initial diagnosis. Technological advances over the past 25 years have improved the ability to accurately preoperatively stage these lesions and detect recurrence. This article reviews the focus on the utility of computerized tomography, magnetic resonance, endoscopic ultrasound, and newer imaging methods including PET scan and monoclonal antibodies in the management of colorectal carcinoma.

Development of oxygen insensitivity of the quantitative histochemical assay of G6PDH activity during colorectal carcinogenesis

The effects of oxygen on the quantitative histochemical assay to detect glucose-6-phosphate dehydrogenase (G6PDH) activity based on neotetrazolium reduction were studied in the different stages of carcinogenesis in the colon. Normal and hyperplastic epithelium, mucosae of patients with active Crohn's disease, and adenomas and adenocarcinomas of the colon were used. Epithelium of normal and inflamed mucosa, and hyperplastic epithelium, showed a residual G6PDH activity (RA) in oxygen that was always less than 20 per cent of the activity in the absence of oxygen. In adenomas and in dysplastic epithelia adjacent to carcinomas, the RA was significantly higher than that in normal epithelium, but significantly lower than that in adenocarcinomas. The RA of adenomas never exceeded 35 per cent. The RA of adenocarcinomas was on average 53 per cent and always higher than 20 per cent. When 35 per cent was used as a cut-off level, the sensitivity of RA to diagnose malignancy was 96.5 per cent. In a parallel study, a mouse model was used in which colon carcinomas and their precursors were induced chemically. Development of oxygen insensitivity during chemically induced carcinogenesis showed a pattern similar to that observed in the human. In conclusion, the test to determine RA is a useful tool for the detection of malignant mucosa in the colon. The test is particularly helpful in addition to histopathology for the detection of small lesions and the early stages of cancer.

What is the risk factor for metachronous colorectal carcinoma?

PURPOSE

The purpose of this study was to determine the risk factors for developing metachronous colorectal carcinoma and to determine an adequate postoperative colonoscopic surveillance.

METHODS

Two hundred eighty-four patients, examined by routine colonoscopy after resection for colorectal carcinoma, were reviewed. Clinical and pathologic factors were assessed by multiple logistic regression analysis.

RESULTS

One hundred eighty-three patients with synchronous adenoma or carcinoma at the initial operation had a significantly higher incidence of both metachronous adenoma and carcinoma than the 101 patients without a synchronous lesion. Other clinical factors including age, gender, tumor stage, tumor site, and tumor grade were not significant for an increased incidence of metachronous carcinoma. The presence of synchronous lesions proved to be the only risk factor (relative risk, 3.293; P = 0.0155) for developing metachronous carcinoma. Metachronous carcinoma was detected in 30 patients (10.6 percent) and completely removed from all patients. Mucosal carcinoma was found in 25 patients (8.8 percent) and invasive carcinoma in 5 patients (1.8 percent). All five invasive carcinomas were detected in asymptomatic patients having synchronous lesion. Four patients required a second operation for metachronous carcinoma more than 13 months following the first.

CONCLUSION

The risk factor for developing metachronous carcinoma is the presence of synchronous adenoma or carcinoma at the initial operation. To detect metachronous carcinoma at a curable stage, annual colonoscopic surveillance should be performed for high-risk patients.

Characteristics of metachronous colorectal carcinoma occurring despite colonoscopic surveillance

PURPOSE

Metachronous colorectal cancer still occurs in a small percentage of patients, despite colonoscopic surveillance. Cancers in hereditary nonpolyposis colorectal cancer for which there is a high risk of metachronous cancer show distinctive DNA changes termed replication errors (RER+). Ten to 20 percent of sporadic colorectal cancers are also RER+. The aim of this study was to identify factors predictive of metachronous colorectal cancer, despite colonoscopic surveillance. Clinicopathologic characteristics and RER status of cancers were examined.

METHODS

Colorectal cancer patients, who entered into a surveillance program of being examined with colonoscopy within six months of surgery and then at intervals of three years thereafter, were reviewed. The 433 patients compliant with the protocol who had had more than one colonoscopy had been followed up for a mean of 3.8 +/- 2.2 years. DNA was extracted from archival paraffin-embedded cancer tissue for determination of RER status.

RESULTS

Ten cases of metachronous cancer were identified, giving a rate of 0.61 percent per year. The site of the index cancer in patients who later developed metachronous cancer was predominantly proximal (P = 0.0007), and these cancers were more likely to have mucinous histology (P < 0.0005). Three of 10 (30 percent) index cancers were RER+, which was not significantly different from unselected series of control colorectal cancers in which 20 of 108 (18.5 percent) were RER+.

DISCUSSION

This study documents the rate of metachronous cancer among patients compliant with a defined colonoscopic screening program and suggests that the risk is highest in patients with a proximal mucinous cancer. RER status does not appear to be a very strong predictive factor, and this study does not support its use as a guide to the frequency of surveillance colonoscopy. More data would be required to determine if RER positivity conferred a relative risk of 3.3 or less.

Initial management and follow-up surveillance of patients with colorectal adenomas

The clinical management of patients with adenomas is interesting because of the adenomas' malignant potential, the availability of effective intervention by colonoscopy, and the increasing number of patients having adenomas detected and removed. The current literature on follow-up surveillance is reviewed, and surveillance intervals are suggested based on data from the National Polyp Study. Patients newly diagnosed with three or more adenomas, an adenoma of more than 0.5 cm, or with a family history of colorectal cancer should have surveillance colonoscopy at 3 years following the polypectomy. Surveillance of patients with single, small tubular adenomas can be extended to 5 or more years. Patients with large sessile or malignant adenomas need to have follow-up earlier. Identification and removal of adenomatous polyps have been shown to reduce colorectal cancer incidence.

Colorectal polyps and their relationship to cancer

Autosomal dominant, familial forms of colorectal adenocarcinoma are recognized, but more than 90% of cases are sporadic. Most familial and sporadic cases arise through malignant transformation of benign adenomas in a process known as the adenoma-to-carcinoma sequence. Adenomas are classified histologically as tubular, tubulovillous, or villous. As a neoplasm, adenomas all manifest mild, moderate, or severe dysplasia. The majority (> 90%) of adenomas are small (< 1 cm in diameter) and do not progress. Risk factors for carcinomatous progression include the presence of multiple adenomas, size greater than or equal to 1 cm, and villous histology or severe dysplasia in adenomas of any size. The adenoma-to-carcinoma sequence advances through the accumulation of lesions involving multiple genes. It appears that similar molecular genetic mechanisms are involved in familial and sporadic forms of colorectal neoplasia.

An update of HNPCC (Lynch syndrome)

Genetic epidemiology studies of colorectal cancer (CRC) can identify persons who are at inordinately high risk and who thereby might benefit from targeted early detection and primary prevention programs, inclusive of prophylactic surgery in selected cases. The discipline of molecular genetics has identified germline mutations that include APC in familial adenomatous polyposis (FAP) and mutator genes, namely MSH2, MLH1, PMS1, and PMS2 in hereditary nonpolyposis colorectal cancer (HNPCC). These discoveries have significantly enhanced our ability to identify individuals whose cancer destiny can literally be determined at birth. This review updates HNPCC's differential diagnosis, heterogeneity, tumor spectrum, newly found evidence of accelerated colonic adenoma to CRC, survival advantage, and currently available surveillance and management programs. Emphasis has been on how knowledge of the genetics and natural history of HNPCC can be used effectively to promote early diagnosis or prevention of cancer.

Polypectomy of adenomas in the prevention of colorectal cancer: 10 years' follow-up of the Telemark Polyp Study I. A prospective, controlled population study

BACKGROUND

The efficacy of polypectomy in preventing colorectal cancer (CRC) has never been demonstrated in a controlled, prospective study. This must be done by randomization within a population with a high prevalence of colorectal polyps, and the feasibility and safety of endoscopic screening examination is a prerequisite for this type of study.

METHODS

The present study is a randomized, controlled study of the feasibility and safety of flexible sigmoidoscopic screening of a normal population sample of 799 men and women aged 50-59 years, findings at 2 and 6 years' colonoscopic follow-up, and the appearance of clinical colorectal cancer (CRC) after 10 years.

RESULTS

The attendance rate was high, and there were no complications. After 10 years 1 of 400 in the screening group had developed CRC (in the group of 76 (19%) not attending for screening examination). Four of 399 controls developed CRC.

CONCLUSIONS

Poor yield of polyps at follow-up, slow growth of in situ polyps, and no clinical CRC among screenees after 10 years provides support to infrequent or no colonoscopic follow-up after initial polypectomy in individuals with otherwise average risk of CRC.

Hereditary nonpolyposis colorectal cancer (Lynch syndrome). An updated review

BACKGROUND

Hereditary nonpolyposis colorectal cancer (HNPCC) dates to Aldred Warthin's description of Family G a century ago. The phenotype features an excess of early onset colorectal carcinoma (CRC) with a propensity to involve the proximal colon, and a variety of extracolonic cancers, particularly carcinoma of the endometrium, ovary, stomach, small bowel, ureter, and renal pelvis. The recent discovery that HNPCC patients carry germline mutations in DNA mismatch repair genes has engendered great interest in the syndrome.

METHODS

This is a description of HNPCC based on the authors' experience with more than 170 families and a review of the world literature.

RESULTS

This review describes the genotypic and phenotypic features of HNPCC. The distinctive natural history of the syndrome is discussed in light of the recent discovery that ineffective DNA mismatch repair is the principal abnormality in affected individuals.

CONCLUSIONS

Clinical and molecular genetic knowledge about HNPCC is now available to physicians, and should enable them to provide highly targeted surveillance and management for patients with a high cancer risk. Genetic counseling can prove lifesaving. The study of HNPCC will likely contribute to knowledge about the causes and control of common forms of cancer in the general population.

Colon cancer screening and the evaluation and follow-up of colonic polyps

Approximately 150,000 new cases of colon cancer are diagnosed each year, and the mortality rate continues to be greater than 50% of those diagnosed. Screening for colon cancer should be part of the routine health maintenance program of the primary physician. Use of history, physical examination, and sigmoidoscopy is part of a complete program. Colonoscopic removal of polyps reduces cancer risk.

Growth of colorectal polyps: redetection and evaluation of unresected polyps for a period of three years

BACKGROUND, AIMS, AND PATIENTS: In a prospective follow up and intervention study of colorectal polyps, leaving all polyps less than 10 mm in situ for three years, analysis of redetection rate, growth, and new polyp formation was carried out in 116 patients undergoing annual colonoscopy. The findings in relation to growth and new polyp formation were applied to 58 subjects who received placebo.

RESULTS

Redetection rate varied from 75-90% for each year, and was highest in the rectum and sigmoid colon. There was no net change in size of all polyps in the placebo group, however, polyps less than 5 mm showed a tendency to net growth, and polyps 5-9 mm a tendency to net regression in size, both for adenomas and hyperplastic polyps. This pattern was verified by computerised image analysis. Patients between 50 and 60 years showed evidence of adenoma size increase compared with the older patients, and the same was true for those with multiple adenomas (four to five) compared with those with a single adenoma. The new adenomas were significantly smaller and 71% were located in the right side of the colon. Patients with multiple adenomas had more new polyps at all the follow up examinations than patients with a single adenoma. One patient developed an invasive colorectal carcinoma, which may be evolved from a previously overlooked polyp. Two polyps, showing intramucosal carcinoma after follow up for three years, were completely removed, as judged by endoscopy and histological examination.

CONCLUSIONS

The results show that follow up of unresected colorectal polyps up to 9 mm is safe. The consistency of growth retardation of medium sized polyps suggests extended intervals between the endoscopic follow up examinations, but the increased number of new polyps in the proximal colon indicates total colonoscopy as the examination of choice. The growth retardation of the medium sized polyps may partly explain the discrepancy between the prevalence of polyps and the incidence of colorectal cancer.

Screening for colorectal cancer, 1996

Screening average-risk people aged 55 to 70 years for colorectal cancer is now a public health priority in Australia. Pilot studies of faecal occult blood testing are required to find ways of achieving optimal compliance and cost efficiency in the Australian health care setting. Flexible sigmoidoscopy probably should be used as complementary screening but further trials are needed. High-risk groups (family history of colorectal cancer, or previous ulcerative colitis, adenomas or cancer) should already be in surveillance programs.