Risk and cause of interval colorectal cancer after colonoscopic polypectomy

Background: To investigate the cause and risk of interval colorectal cancer (ICC) in patients undergoing surveillance colonoscopy within 5 years after colonoscopic polypectomy. Patients and Methods: We retrospectively analyzed data (endoscopy, pathology, demography) of patients who received surveillance colonoscopy within 5 years after colonoscopic polypectomy. Results: Among 1,794 patients undergoing surveillance colonoscopy within 5 years after colonoscopic polypectomy, 14 suffered from ICC. The mean follow-up time was 2.67 years and the incidence density of ICC was 2.9 cases per 1,000 person-years. 50% of ICCs were found in patients in whom adenomas had been incompletely removed by endoscopic therapy, 36% were missed cancers, and 14% were new cancers. Age >60 years (OR 2.97, 95% CI 2.31-3.82) was significantly associated with interval cancer on the surveillance colonoscopy as were advanced adenoma (OR 1.28, 95% CI 1.01-1.62), the presence of villous (HR 1.38, 95% CI 1.03-1.85) and high-grade dysplasia (OR 1.61, 95% CI 1.07-2.42). Conclusions: Among patients undergoing surveillance colonoscopy within 5 years after polypectomy, the incidence density of ICC was 2.9 cases per 1,000 person-years. The majority of interval cancers originated from incomplete resection of advanced adenomas and missed cancers, which can be prevented by improving endoscopic techniques and selecting an appropriate follow-up time interval.     

ASSESSMENT OF MISS AND INCIDENCE RATES OF NEOPLASTIC POLYPS AT COLONOSCOPY

Background: The incidence rate after a colonoscopic polypectomy includes the true incidence rate of new polyp formation and miss rate of polyps at the initial colonoscopy. It is therefore important to assess accurate incidence rates of polyps as well as those of missing polyps with colocoscopy. Methods: Six hundred and eighty‐eight patients who underwent total colonoscopy twice within 30 days were investigated to determine the miss rates of neoplastic polyps under colonoscopy. The cumulative incidence rates of neoplasm were evaluated by the Kaplan‐Meier method in another series of investigations on 864 patients who underwent surveillance total colonoscopy over 31 days. Results: In 157 (22.8%) patients out of 688, 200 neoplastic lesions (all adenomas) were missed during the first examination. The miss rate was 16% for adenomas ≤ 5 mm and 2% for adenomas > 10 mm. The miss rates of patients with 0, 1, 2, or > 2 neoplastic polyps on the first examination was 5.3%, 19.6%, 23.5% and 35.5%, respectively. One year cumulative incidence rates of patients with 1, 2, or > 2 neoplastic polyps on the first examination were 18.4%, 21.1% and 34.2%, respectively. Conclusion: Detection of multiple neoplasms on index colonoscopy predicts a high miss rate and cumulative incidence rate on surveillance colonoscopy. A substantial proportion of neoplasms detected at nearly 1‐year postpolypectomy surveillance colonoscopy were missed at the initial total colonoscopy.     

Guidelines for colonoscopy surveillance after polypectomy: a consensus update by the US Multi-Society Task Force on Colorectal Cancer and the American Cancer Society

Adenomatous polyps are the most common neoplastic findings discovered in people who undergo colorectal screening or who have a diagnostic work-up for symptoms. It was common practice in the 1970s for these patients to have annual follow-up surveillance examinations to detect additional new adenomas and missed synchronous adenomas. As a result of the National Polyp Study report in 1993, which showed clearly in a randomized design that the first postpolypectomy examination could be deferred for 3 years, guidelines published by a gastrointestinal consortium in 1997 recommended that the first follow-up surveillance take place 3 years after polypectomy for most patients. In 2003 these guidelines were updated and colonoscopy was recommended as the only follow-up examination, stratification at baseline into low risk and higher risk for subsequent adenomas was suggested. The 1997 and 2003 guidelines dealt with both screening and surveillance. However, it has become increasingly clear that postpolypectomy surveillance is now a large part of endoscopic practice, draining resources from screening and diagnosis. In addition, surveys have shown that a large proportion of endoscopists are conducting surveillance examinations at shorter intervals than recommended in the guidelines. In the present report, a careful analytic approach was designed to address all evidence available in the literature to delineate predictors of advanced pathology, both cancer and advanced adenomas, so that patients can be stratified more definitely at their baseline colonoscopy into those at lower risk or increased risk for a subsequent advanced neoplasia. People at increased risk have either 3 or more adenomas, high-grade dysplasia, villous features, or an adenoma 1 cm or larger in size. It is recommended that they have a 3-year follow-up colonoscopy. People at lower risk who have 1 or 2 small (<1 cm) tubular adenomas with no high-grade dysplasia can have a follow-up evaluation in 5-10 years, whereas people with hyperplastic polyps only should have a 10-year follow-up evaluation, as for average-risk people. There have been recent studies that have reported a significant number of missed cancers by colonoscopy. However, high-quality baseline colonoscopy with excellent patient preparation and adequate withdrawal time should minimize this and reduce clinicians concerns. These guidelines were developed jointly by the US Multi-Society Task Force on Colorectal Cancer and the American Cancer Society to provide a broader consensus and thereby increase the use of the recommendations by endoscopists. The adoption of these guidelines nationally can have a dramatic impact on shifting available resources from intensive surveillance to screening. It has been shown that the first screening colonoscopy and polypectomy produces the greatest effects on reducing the incidence of colorectal cancer in patients with adenomatous polyps.     

Number of aberrant crypt foci in the rectum is a useful surrogate marker of colorectal adenoma recurrence

Aim: Endoscopic screening and removal of colorectal adenomas can reduce the incidence of colorectal cancer. However, given the possibility of adenoma recurrence, surveillance colonoscopy is currently recommended after the initial screening and removal of colorectal adenomas. Aberrant crypt foci (ACF) have been shown to serve as a reliable surrogate marker of colorectal carcinogenesis. In this study, the relationship between the number of ACF at the initial endoscopic polypectomy and the likelihood of colorectal adenoma recurrence after polypectomy were investigated. Methods: High‐magnification chromoscopic colonoscopy was performed in 82 subjects who underwent endoscopic polypectomy to identify ACF in the lower rectum. Surveillance colonoscopy was then performed 3 years after the baseline polypectomy at Yokohama City University Hospital. Results: The number of ACF was greater in patients who showed adenoma recurrence (7.88 ± 6.35) than in those who did not (2.19 ± 2.95) (P < 0.001). Receiver–operating curve analysis showed that the number of ACF was a highly specific predictor of the risk of adenoma recurrence. Conclusions: This is the first study conducted to investigate the relationship between the number of ACF after endoscopic polypectomy and the likelihood of recurrence of colorectal adenomas. These results suggest that the number of ACF is a useful predictor of the likelihood of colorectal adenoma recurrence.     

The effect of attending a flexible sigmoidoscopic screening program on the prevalence of colorectal adenomas at 13-year follow-up

OBJECTIVES: Understanding the epidemiology of colorectal adenomas is a prerequisite for designing follow-up programs after polypectomy. The aim of the study was to investigate the effect of polypectomy on the long-term prevalence of adenomas. METHODS: In 1983, a total of 799 men and women aged 50-59 yr were drawn from the general population register. Of these, 400 comprised a screening group and 399 a matched control group. The screenees were invited to undergo a once-only flexible sigmoidoscopy. Persons with polyps had a baseline colonoscopy with follow-ups in 1985 and 1989. In 1996, both the screenees and the controls were invited to a colonoscopic examination. RESULTS: In 1996, a total of 451 (71%) individuals attended. Adenomas were found in 78 (37%) individuals in the screening group and 103 (43%) in the control group, relative risk (95% confidence interval): 0.9 (0.7-1.1), p = 0.3, and high-risk adenomas (severe dysplasia, adenomas > or = 10 mm, villous components) were found in 16 (8%) and 32 (13%), respectively; relative risk (95% confidence interval): 0.6 (0.3-1.0), p = 0.07. CONCLUSIONS: There was no significant difference in adenoma prevalence between the group after the screening program and the controls after the usual care. There was a trend toward more high-risk adenomas in the control group. This suggests a very limited effect of one-time screening sigmoidoscopy with surveillance colonoscopy on the prevalence of adenomas, but a preventive effect on the development of high-risk adenomas consistent with the reported effect on cancer prevention.     

Recurrence and surveillance of colorectal adenoma after polypectomy in a southern Chinese population

Background and aim  

Repeat colonoscopy is often performed within a short time after polypectomy due to the fear that colorectal adenomas were missed during the initial colonoscopy or that new adenomas have developed. The aim of this study was to estimate the actual recurrence rate of adenoma and its association with the length of the surveillance interval after polypectomy in a southern Chinese population.     

Case-control study supports extension of surveillance interval after colonoscopic polypectomy to at least 5 yr

OBJECTIVE: Colonoscopy with removal of polyps may strongly reduce colorectal cancer (CRC) incidence and mortality. Recommended time intervals to surveillance colonoscopy differ between countries and have recently been extended to 5 yr or longer for the majority of cases in the United States. Whereas previous evidence is mainly based on observations of adenoma recurrence, we aimed to assess risk of CRC occurrence according to time since polypectomy. METHODS: In a population-based case-control study conducted in Germany, detailed history and results of previous large bowel endoscopies were obtained by interview and from medical records. Risk of CRC among subjects with history of endoscopic polypectomy compared to subjects without previous large bowel endoscopy was assessed according to time since polypectomy among 454 cases with CRC and 391 matched controls. RESULTS: Odds ratios (95% confidence intervals) of CRC up to 2 yr, 3-5 yr, and 6-10 yr after polypectomy (using subjects without previous endoscopy as reference group) were 0.16 (0.09-0.69), 0.27 (0.08-0.87), and 1.90 (0.67-5.43), respectively. Risk was significantly reduced (odds ratio 0.27, 95% confidence interval 0.10-0.77) within 5 yr even after detection and removal of high-risk polyps (3+ polyps, at least 1 polyp > or =1 cm, at least 1 polyp with villous components). Odds ratios (95% confidence intervals) for the entire 10-yr time interval following polypectomy were 0.50 (0.23-1.12) and 0.36 (0.18-0.76) for patients with recorded high-risk adenomas and other patients, respectively. CONCLUSIONS: Our study provides empirical support for extension of the surveillance interval after colonoscopic polypectomy to at least 5 yr.     

The Miss Rate for Colorectal Adenoma Determined by Quality-Adjusted, Back-to-Back Colonoscopies

Background/Aims

Colonoscopy is considered to be the gold standard for detecting adenomatous polyps. Polyps are missed during colonoscopic examination at a rate that varies from 6% to 27%. The adenoma miss rate affects colonoscopic surveillance intervals and procedural quality. We aimed to assess the adenoma miss rate and the variables affecting the rate using same-day, quality-adjusted, back-to-back colonoscopies.

Methods

This prospective study was performed at a single institution and included 149 patients. Two consecutive same-day colonoscopies were performed by two experienced endoscopists. The adenoma miss rates and variables affecting the missed adenomas, including polyp characteristics and procedure times, were evaluated.

Results

The miss rates of polyps, adenomas, and advanced adenomas were 16.8%, 17%, and 5.4%, respectively. The smaller polyps and increased number of polyps detected during the first colonoscopy were more likely to be missed. A longer insertion time during the colonoscopy was correlated with an increased adenoma detection rate.

Conclusions

There was a significant miss rate in the detection of colonic adenomas even in quality-adjusted, back-to-back colonoscopies. The adenoma miss rate can be reduced with a sufficient observation time during colonoscopic insertion. The development of specific technological methods to reduce the adenoma miss rate is necessary.     

Korean guidelines for post-polypectomy colonoscopic surveillance

Post-polypectomy surveillance has become a major indication for colonoscopy as a result of increased use of screening colonoscopy in Korea. However, because the medical resource is limited, and the first screening colonoscopy produces the greatest effect on reducing the incidence and mortality of colorectal cancer, there is a need to increase the efficiency of postpolypectomy surveillance. In the present report, a careful analytic approach was used to address all available evidences to delineate the predictors for advanced neoplasia at surveillance colonoscopy. Based on the results of review of the evidences, we elucidated the high risk findings of the index colonoscopy as follows: 1) 3 or more adenomas, 2) any adenoma larger than 10 mm, 3) any tubulovillous or villous adenoma, 4) any adenoma with high-grade dysplasia, and 5) any serrated polyps larger than 10 mm. In patients without any high-risk findings at the index colonoscopy, surveillance colonoscopy should be performed five years after index colonoscopy. In patients with one or more high risk findings, surveillance colonoscopy should be performed three years after polypectomy. However, the surveillance interval can be shortened considering the quality of the index colonoscopy, the completeness of polyp removal, the patient's general condition, and family and medical history. This practical guideline cannot totally take the place of clinical judgments made by practitioners and should be revised and supplemented in the future as new evidence becomes available.     

Improving quality measures in colonoscopy and its therapeutic intervention

Colonoscopy with polypectomy has been shown to re-duce the risk of colon cancer. The critical element in the quality of colonoscopy in terms of polyp detection and removal continues to be the performance of the endoscopist, independent of patient-related factors. Im-proved results in terms of polyp detection and complete removal have implications regarding the development of screening and surveillance intervals and the reduction of interval cancers after negative colonoscopy. Advances in colonoscopy techniques such as high-definition colonos-copy, hood-assisted colonoscopy and dye-based chro-moendoscopy have improved the detection of small and flat-type colorectal polyps. Virtual chromoendoscopy has not proven to improve polyp detection but may be use-ful to predict polyp pathology. The majority of polyps can be removed endoscopically. Available polypectomy techniques include cold forceps polypectomy, cold snare polypectomy, conventional polypectomy, endoscopic mu-cosal resection and endoscopic submucosal dissection. The preferred choice depends on the polyp size and characteristics. Other useful techniques include colono-scopic hemostasis for acute colonic diverticular bleeding, endoscopic decompression using colonoscopic stenting, and transanal tube placement for colorectal obstruction. Here we review the current knowledge concerning the improvement of quality measures in colonoscopy and colonoscopy-related therapeutic interventions.     

The role of colonoscopy in screening persons with family history of colorectal cancer

Abstract First-degree relatives of colorectal cancer patients are at increased risk for developing colorectal neoplasms. In order to assess the potentiality of colonoscopy screening in this high-risk population, 213 asymptomatic family members (age range 30-69 years, mean 42.8 years) of those patients with colorectal cancer received colonoscopic examination at Chang-Gung Memorial Hospital from April 1992 to May 1994. Twenty-eight persons with 42 lesions (polyps or cancer) were identified, including 28 adenomas, nine hyperplastic polyps and five adenocarcinomas. The positive detection rate was 9.9% for adenoma and 2.3% for cancer. Colorectal neoplasms afflicted males more frequently than females (16.7 vs 5.7%, P < 0.05) and occurred less frequently in those < 40 years of age (5.5 vs 17.2%, P < 0.05). Forty-two per cent of the detected neoplastic lesions were beyond the reach of 60 cm flexible sigmoidoscopy and 36% of adenomas were < 0.5 cm in size and would be missed if patients were screened by air contrast barium enema. Cost analysis revealed that the charges of both screening colonoscopy and screening flexible sigmoidoscopy/air contrast barium enema were approximate. Colonoscopy also has a high acceptability and safety. It appears appropriate to use colonoscopy, rather than flexible sigmoidoscopy or air contrast barium enema, as an initial screening procedure for persons with a family history of colorectal cancer, especially those > 40 years of age.     

Validity of early colonoscopy for the treatment of adenomas missed by initial endoscopic examination.

OBJECTIVE: To determine whether the features of adenomas identified in a first endoscopic examination may predict the presence of polyps with advanced pathological features that may have gone unnoticed and whether early colonoscopy may benefit these patients. MATERIAL AND METHODS: We examined 133 patients with diagnosis of colonic adenomas who had undergone complete colonoscopy and endoscopic polypectomy. All of them underwent colonoscopic follow-up at 3 years. Seventy nine patients underwent colonoscopic follow-up both at 6 months and at 3 years, while 54 patients underwent just colonoscopic follow-up at 3 years and 47 just at 6 months. RESULTS: Fifteen per cent of the patients analyzed developed polyps with pathological features after 6 months. The size and histological analysis of the polyps detected in the initial colonoscopic examination did not affect these results (p < 0.05). The number of polyps was statistically significant: patients with 3 or more polyps in the initial colonoscopic examination presented more polyps with pathological features after six months (25.8 versus 5.8%, p = 0002). This follow-up examination at 3 years did not reveal a higher occurrence of polyps with pathological features in any of the two groups of patients, namely, those who had undergone early colonoscopy and those who had not. CONCLUSIONS: Patients with multiple polyps have greater probability of developing synchronous polyps with some pathological features which may have gone unnoticed. Since early examination has not shown to provide a benefit for these patients, the first follow-up colonoscopy should be performed at 3 years, particularly if the initial colonoscopy is negative.     

Surveillance after positive and negative colonoscopy examinations: issues,yields, and use

As colorectal cancer screening gains acceptance by the public, the use of colonoscopy will increase. The frequency of surveillance examinations after detection of an adenoma is one of the largest contributors to the cost of colorectal cancer screening. Ten years after the publication of the landmark National Polyp Study, the issue of when to perform surveillance examinations and how often to expect advanced findings remains acute. Current guidelines for surveillance vary across specialty organizations. Individuals with advanced adenomas are at increased risk for recurrent advanced adenomas. The impact of multiple nonadvanced adenomas or a single nonadvanced adenoma on subsequent risk of an advanced adenoma or cancer is less clear. Still less is known about findings on repeat examinations after an initial negative examination, whether after colonoscopy or sigmoidoscopy. The yield after a negative examination is an important consideration in determining the recommended interval for screening colonoscopy. For example, the data supporting a 10-yr interval for screening colonoscopy is only indirect. What little we do know about the yield after negative examinations comes from selected, nonrepresentative populations. Of concern, evidence from several polyp prevention trials demonstrates higher yields for subsequent cancer than would be expected, despite a relatively high use of surveillance procedures in follow-up. Further population-based research on the frequency of use and yield of surveillance examinations is needed. Studies that examine the need and the needed timing of subsequent surveillance are essential to containing costs for screening as well as to informing the public better about what endoscopic screening can and cannot accomplish.     

First-degree relatives of patients with advanced colorectal adenomas have an increased prevalence of colorectal cancer.

BACKGROUND & AIMS: The risk of colorectal cancer in relatives of patients with adenomatous colonic polyps is not well defined. This study assessed whether finding colonic neoplasia during screening colonoscopy was related to the family history of colorectal cancer among the participants' parents and siblings. METHODS: Self-reported family history of colorectal cancer was recorded for all participants in a screening colonoscopy study. The size and location of all polyps were recorded before their removal and histologic examination. Participants were grouped according to the most advanced lesion detected. RESULTS: Three thousand one hundred twenty-one patients underwent complete colonoscopic examination. Subjects with adenomas were more likely to have a family history of colorectal cancer than were subjects without polyps (odds ratio [OR], 1.36; 95% confidence interval [CI], 1.09-1.70). The finding of a small (<1 cm) tubular adenoma as the most advanced lesion was associated with only a modest increase in the OR of colorectal cancer in family members (OR, 1.26; 95% CI, 0.99-1.61), but the presence of an advanced adenoma was associated with a higher OR (OR, 1.62;5% CI, 1.16-2.26). Younger age of adenoma diagnosis was not related to a higher prevalence of a family history of colorectal cancer. CONCLUSIONS: Relatives patients with advanced colorectal adenomas have an increased risk of colorectal cancer. Individuals with advanced colorectal adenomas should be counseled about the increased risk of colorectal cancer among their relatives.     

Retrospective analysis of missed advanced adenomas on surveillance colonoscopy

OBJECTIVE: Miss rates of large polyp/cancer during colonoscopy are reported from tertiary centers where experts do the colonoscopies. This information is important for determining surveillance intervals for repeat colonoscopy, patient safety, and malpractice issues. We evaluated retrospectively the miss rates of advanced adenomas in the setting of a GI fellowship training where most colonoscopies are done by closely supervised fellows. METHODS: We reviewed the 235 patients who had at least one repeat colonoscopy after initial polypectomy, between 1992 and 1999, at the Dayton Veterans Affairs Medical Center. Advanced adenomas were defined as polyps 10 mm or greater in size with or without a villous component or high-grade dysplasia. Data of missed advanced adenomas on 122 patients who had complete colonoscopy with satisfactory preparation and the excluded patients are reported. RESULTS: Four advanced adenomas (one had intramucosal cancer) on second colonoscopy and two advanced adenomas on third colonoscopy were missed. The miss rate of advanced adenoma for 232 patients was 1.7%, and the miss rate for the 122 patients with complete colonoscopy and satisfactory colon preparation was 2.5% and 3.3% on second and third repeat colonoscopy, respectively. No cancer was missed. CONCLUSIONS: The present study shows an advanced polyp miss rate that is comparable with other studies even in a fellowship training setting. Prospective studies with tandem surveillance colonoscopy are needed to confirm our findings.     

Colorectal cancer in patients under close colonoscopic surveillance

BACKGROUND & AIMS: Colonoscopic polypectomy is considered effective for preventing colorectal cancer (CRC), but the incidence of cancer in patients under colonoscopic surveillance has rarely been investigated. We determined the incidence of CRC in patients under colonoscopic surveillance and examined the circumstances and risk factors for CRC and adenoma with high-grade dysplasia. METHODS: Patients were drawn from 3 adenoma chemoprevention trials. All underwent baseline colonoscopy with removal of at least one adenoma and were deemed free of remaining lesions. We identified patients subsequently diagnosed with invasive cancer or adenoma with high-grade dysplasia. The timing, location, and outcome of all cases of cancer and high-grade dysplasia identified are described and risks associated with their development explored. RESULTS: CRC was diagnosed in 19 of the 2915 patients over a mean follow-up of 3.7 years (incidence, 1.74 cancers/1000 person-years). The cancers were located in all regions of the colon; 10 were at or proximal to the hepatic flexure. Although most of the cancers (84%) were of early stage, 2 participants died of CRC. Seven patients were diagnosed with adenoma with high-grade dysplasia during follow-up. Older patients and those with a history of more adenomas were at higher risk of being diagnosed with invasive cancer or adenoma with high-grade dysplasia. CONCLUSIONS: CRC is diagnosed in a clinically important proportion of patients following complete colonoscopy and polypectomy. More precise and representative estimates of CRC incidence and death among patients undergoing surveillance examinations are needed.     

New occurrence and recurrence of neoplasms within 5 years of a screening colonoscopy

OBJECTIVE: The fear that colorectal adenomas were missed on initial colonoscopy or that new adenomas have developed is often a rationale for repeating a colonoscopic examination. The aim of this study was to delineate risk factors associated with recurrence of colorectal adenomas after an initial baseline screening colonoscopy. METHODS: The study population comprised 875 subjects who underwent a baseline screening colonoscopy followed by a second examination 1-5 yr later. Multiple logistic regression was used to assess the influence of potential risk factors on the occurrence or recurrence of colorectal adenomas, the strength of the influence being expressed as an OR with a 95% CI. RESULTS: Colorectal adenomas were detected in 484 of all patients (55%) at baseline colonoscopy. Within a 1- to 5-yr time interval, 181 patients (37%) had recurrent adenomas (adenomas were removed during the first colonoscopy) and 73 patients (19%) had newly developed adenomas (adenomas were absent on the first colonoscopy). The occurrence of adenomas at baseline screening colonoscopy was the only factor associated with an increased risk for the recurrence of adenomas at follow-up (OR = 2.51, 95% CI = 1.77-3.55). Recurrence was associated with multiple baseline adenomas (4.45, 2.98-6.64) and baseline adenomas larger than 1 cm (2.62, 1.99-3.11). Recurrence was not associated with histology type or family history of colorectal cancer. There was a significant trend for adenomas to recur in the same proximal or distal segment as the baseline adenomas (p = 0.02). CONCLUSIONS: Colon adenomas tend to recur with greater frequency if the adenomas removed at baseline were either large or multiple. Although patients with large adenomas or multiple adenomas at baseline screening colonoscopy are at a 2.6- to 4.5-fold risk for recurrence of adenomas, the rate of de novo adenoma formation in patients without baseline adenomas may be large enough to warrant repeat colonoscopy at some time in the future. The exact timing of the follow-up colonoscopy needs to be determined.     

Insulin-like growth factor I and the development of colorectal neoplasia in acromegaly

Patients with acromegaly are at increased risk of colorectal neoplasia and, by analogy with high-risk nonacromegalic patients, may require regular colonoscopic screening. However, it is unknown whether the risk is equal in all patients or whether some should be regarded as carrying a particularly high risk. The aims of this study were: 1) to establish the natural history of colorectal neoplasia in acromegaly; 2) to establish which patients are at increased risk of developing neoplasia; and 3) to elucidate the influence of insulin-like growth factor I (IGF-I) in adenoma formation. A prospective colonoscopic evaluation of the development of new premalignant adenomas in the colon was performed in 66 patients with biochemically proven acromegaly who had previously undergone colonoscopic screening and removal of all visible polyps. Twenty-five patients (38%) had a total of 37 polyps detected at the second colonoscopy: nine (14%) had at least one adenoma, and 18 (27%) had one or more hyperplastic polyps (2 patients had both). The development of new adenomas, but not hyperplastic polyps, was associated both with elevated serum IGF-I (P < 0.005) and, to a lesser extent, with a previous adenoma at the original colonoscopy (P < 0.07). In summary, patients with acromegaly and in whom serum IGF-I remains elevated and/or who have had a previous adenoma should be regarded as having an especially high risk for the development of subsequent colorectal neoplasia. Serum IGF-I seems to be implicated in the development of colorectal neoplasia in acromegaly, although the exact mechanisms remain uncertain.     

Surveillance strategies in patients after polypectomy

Colorectal cancer (CRC) is a major cause of cancer death in the Western world. It develops slowly over several years from premalignant lesions (most prominently adenomatous polyps) to invasive cancer. The molecular basis of CRC pathogenesis has been well characterized. The most effective method to prevent CRC is endoscopic polypectomy. However, adenomatous polyps are known to recur at significant rates. The aim of surveillance programs after polypectomy is to further reduce the incidence of CRC in individuals where precancerous lesions have been identified and treated. However, the medical risks and the costs of repeated examinations must be kept as low as possible. Therefore, the identification of patient subgroups with a particular low cancer risk who may be followed-up less frequently seems important. There is recent evidence that other colorectal lesions, namely flat and depressed type adenomas (F&D adenoma) and possibly some hyperplastic polyps and serrated adenomas may also carry a malignant potential which could influence our screening, treatment and surveillance strategies for the colorectum in the future. General surveillance guidelines regarding these entities have not been issued to date. This article will first discuss the biology, natural history, present surveillance recommendations and future issues for sporadic adenomatous polyps. Then, recent literature on F&D type adenomas, hyperplastic polyps and serrated adenomas will be reviewed with respect to their malignant potential and the potential necessity for treatment and surveillance of these lesions.     

The usefulness of colonoscopy as a screening test for detecting colorectal polyps

BACKGROUND/AIMS: Colonic polyps are the most common lesions encountered during screening colonoscopy. The purpose of this study is to evaluate the usefulness of colonoscopy to detect colonic polyps in adults. METHODOLOGY: From January 2003 to September 2005, a total of 4,629 adults underwent colonoscopic screening as a part of a health evaluation program. We analyzed the completed questionnaires, and the colonoscopic and pathologic findings. RESULTS: Complete colonic evaluation was possible in 4,491 (97.0%) subjects, and 804 (17.9%) had adenomatous polyps, including 153 subjects (3.4%) with advanced adenomas. There were no significant complications such as bowel perforation or massive bleeding requiring transfusion in relation to the procedure. There was a trend toward an increased prevalence of adenomatous polyps with age. Among the subjects with polyps, 72.1% of the subjects had distal polyps and the relative risk for proximal polyp, according to the distal findings, was 5.4 (95% CI: 4.5-6.3) for adenomatous polyp, 5.1 (95% CI 3.6-7.0) for advanced adenoma as compared to the finding of no adenomatous polyp. CONCLUSIONS: Colonoscopy performed by experienced colonoscopists as a screening test is feasible for detecting subjects with colorectal polyps.