Results of screening colonoscopy among persons 40 to 49 years of age

Colon cancer specific nuclear matrix protein alterations in human colonic adenomatous polyps

Most colon cancers arise within preexisting adenomatous polyps or adenomas. The slow evolution from the non-invasive premalignant lesion, the adenomatous polyp, to invasive cancer supports a strategy of early detection. Recently, we identified unique nuclear matrix proteins (NMPs) specific for colon cancer (CC2, CC3, CC4, CC5). Most of the NMPs identified are common to all cell types, but several identified NMPs are tissue and cell line specific. The objective of this study is to describe and characterize the NMP profile of premalignant adenomatous colon polyps. Specifically when in the adenoma-carcinoma sequence four specific colon cancer NMPs, previously described, appear. Using two-dimensional (2-D) gel analysis 20 colon polyps (one juvenile polyp, six tubular adenoma (TA), seven tubulovillous adenoma (TVA), six TVA with focal high-grade dysplasia (HGD), were analyzed for the presence of four (CC2, CC3, CC4, CC5) specific NMPs. CC2 was not seen in any of the premalignant polyps. CC5 was present in only two premalignant TVA with HGD and in one TA. CC3 and CC4 were present in most adenomas. None of the NMPs were seen in the juvenile polyp, which is not considered to be a precursor of colon cancer. CC2 and CC5 are NMPs expressed at the junction of an advanced adenoma and invasive colorectal cancer. CC3 and CC4 are expressed earlier in the evolution of adenomatous polyps. Development of an assay to these proteins may serve as a new method for early detection of colorectal cancer.

Evaluation of polyp detection in relation to procedure time of screening or surveillance colonoscopy

BACKGROUND AND OBJECTIVES

Multiple factors influence the yield of colonoscopy for the detection of neoplasia. Few studies have addressed the impact of colonoscopy duration on procedure yield. The aim of our study was to determine whether endoscopist-specific procedure times correlate with the number and clinical significance of polyps detected at screening or surveillance colonoscopy.

METHODS

Procedural data from screening or surveillance colonoscopies performed at Mayo Clinic, Rochester MN, between January 1, 1996 and June 30, 2000, were reviewed. Individual endoscopists were characterized by their personal endoscopist procedure mean time (EPMT) to perform a negative colonoscopy. Procedure time included patient's consent and sedation. EPMT was then correlated with individual polyp detection rates.

RESULTS

Overall, 10,159 colonoscopies were reviewed of which 4,312 (42.4%) yielded polyps. Polyp detection varied among endoscopists between 19.0% and 62.3%. There was a close correlation between EPMT and polyp yield (all sizes), r = 0.64, although correlation was weaker for polyps >10 mm (r = 0.42) and polyps >20 mm (r = 0.20). On multivariate analysis, longer mean endoscopist time was associated with colonic lesion detection, OR = 1.54 (95% CI 1.37-1.62). Longer mean procedure duration demonstrated a looser association with identification of polyps >10 mm, OR = 1.40 (1.19-1.64) and polyps >20 mm, OR = 1.03 (0.74-1.43).

CONCLUSIONS

There is a direct correlation between colonoscopy procedure time and yield, with a three-fold variation of polyp detection rates. These results should prompt future prospective studies assessing the impact of colonoscopic withdrawal time on lesion detection.

AGA future trends report: CT colonography

BACKGROUND & AIMS

Computed tomographic colonography (CTC) was first described more than a decade ago. Recent advances in imaging hardware and software and results of clinical trials based on new methods for performing and interpreting images suggest that CTC may now be assessed as a method for colorectal cancer screening.

METHODS

The Research Policy Committee of the American Gastroenterological Association assembled a task force to review the results of recent clinical trials and quantitative mathematical models pertaining to CTC. The goal of the task force was to assess the current knowledge about CTC and to evaluate the issues that will define its impact.

RESULTS

Limitations in evaluating the current state of CTC technology include a wide variation in results of clinical trials. There are as yet insufficient data on the use of CTC in routine clinical practice. Limitations in the use of quantitative mathematical models make predictions based on such models of limited value. The cancer risk and therefore clinical importance of small colorectal polyps detected by CTC and/or nonpolypoid neoplasia not detected by CTC remains largely unknown.

CONCLUSIONS

CTC is attractive as a colon imaging modality. It is therefore anticipated that CTC will have a significant impact on the practice of gastroenterology. However, the magnitude of the impact is currently unknown. Whether the ongoing implementation of CTC will increase or decrease the number of referrals for colonoscopy or shift the procedure from colorectal cancer screening to therapeutic interventions (e.g., polypectomy) is unknown at the present time. Multidisciplinary collaboration between gastroenterology and radiology to promote effective implementation and ongoing quality assurance will be important.

Rectal cancer

Rectal cancer is an important tumour from an epidemiological point of view and represents the benchmark for an optimal use of integrated treatments (surgery, radiotherapy and chemotherapy) in the oncological practice. Performing radio-chemotherapy (best if preoperatively), medical and radiation oncologists are now able to increase survival, to decrease the occurrence of pelvic recurrence and to ameliorate the quality of life of patients. Updated recommendations for the management of these patients are here reported.

Adenomatous colonic polyps are rare in ulcerative colitis

BACKGROUND

Uncertainty exists as to whether dysplastic polyps in ulcerative colitis should always be managed as dysplasia-associated lesions/masses requiring colectomy, or whether some can be managed by polypectomy. The prevalence of non-inflammatory polyps in ulcerative colitis is unknown.

AIM

To compare dysplastic polyp occurrence in patients with ulcerative colitis and in patients without inflammatory bowel disease.

METHODS

The clinical, endoscopic and histological records of 150 ulcerative colitis patients (median disease duration, 10 years; 57% with pancolitis) undergoing colonoscopy were scrutinized for any polyp history. Two hundred and five patients undergoing colonoscopy for altered bowel habit, but without features suggestive of polyp presence, were used as a control group. Immunohistochemical staining of flat and polypoid mucosa for p16, beta-catenin, p53 and cyclo-oxygenase-2 was compared in the two groups.

RESULTS

Only six (4%) ulcerative colitis patients had ever had dysplastic polyps. Two had single adenomatous polyps proximal to the colitis segment. Of the four patients with dysplastic polyps within colitic mucosa, two were treated endoscopically, but in two the lesions were considered to be dysplasia-associated lesions/masses and colectomy was advised. In contrast, 24 controls had at least one adenomatous polyp (chi(2) = 6.7, P < 0.01). Ten (6.7%) ulcerative colitis patients and 24 (12%) control patients had metaplastic polyps (N.S.). Immunohistochemical staining was not discriminatory.

CONCLUSION

Despite the increased cancer risk in long-standing ulcerative colitis, adenomatous polyps arise less frequently in ulcerative colitis patients than in patients without ulcerative colitis.

Gene mutations in advanced colonic polyps: potential marker selection for stool-based mutated human DNA assays for colon cancer screening

The detection and removal of advanced colonic polyps (ACPs) can help prevent the development of colorectal cancer. A set of DNA mutations known to be associated with colorectal carcinoma was tested against resected ACPs to determine the set s potential utility as a marker panel for ACPs. A sensitive mutation marker panel could be used by stool-based assays that look for mutated human DNA to detect the presence of ACPs. DNA from 32 ACPs = 1.0 cm in diameter was amplified and tested for 19 colorectal cancer associated DNA mutations and for deletions in BAT-26 (microsatellite instability). One or more mutations were identified by microsequencing in 28 of the 32 ACPs (88%). Mutations were identified in k-ras (59%), APC (33%), and p53 (22%). BAT-26 mutation, a marker for microsatellite instability, was not identified. Stool DNA based assays that can identify these mutations may significantly increase the identification of patients with potentially premalignant ACPs for evaluation and treatment by colonoscopy.

Predictors of proximal neoplasia in patients without distal adenomatous pathology

BACKGROUND

Previous colorectal cancer screening studies have observed that some patients may have advanced proximal neoplasia without distal findings. Since these studies have included only gender, age, and family history as risk factors, they are limited in their ability to identify predictors of isolated proximal neoplasia.

METHODS

Data were collected from the charts of 1,988 patients who presented for colonoscopy. Information gathered included endoscopic findings, histology, known risk factors for colorectal neoplasia, and smoking pattern. Our main outcome was the presence of proximal adenomatous neoplasia in patients who had no distal adenomas. We defined significant neoplasia as adenocarcinoma, high-grade dysplasia, villous polyps, adenomas 1 cm or greater or more than two adenomas of any size.

RESULTS

Fifty-five patients had isolated significant proximal neoplasia that would have been missed on a flexible sigmoidoscopy. While patients older than 60 yr had a greater risk for this neoplasia (odds ratio = 3.01: 95% CI = 1.66-4.23; p < 0.001), those who took a daily aspirin had a reduced risk (OR = 0.60; 95% CI = 0.30-0.88; p < 0.05). A family history of colorectal cancer increased the patient's risk of having any adenomas (OR = 2.01; 95% CI = 1.33-3.40; p < 0.01) or villous tissue (OR = 2.03; 95% CI = 1.27-3.51; p < 0.05) in the proximal colon without distal findings. Smoking was associated with an increased risk of large (> 1 cm) isolated proximal tubular polyps (OR = 2.71; 95% CI = 1.64-4.46; p < 0.01) as well as isolated significant proximal neoplasia (OR = 2.30; 95% CI = 1.59-3.31; p < 0.01).

CONCLUSIONS

Age greater than 60 yr, a history of at least 10 pack-years of smoking, and a family history of colorectal cancer increased the risk of finding significant proximal polyps in patients without distal pathology.

Effects of low dose aspirin (81 mg) on proliferating cell nuclear antigen and Amaranthus caudatus labeling in normal-risk and high-risk human subjects for colorectal cancer

Epidemiological, experimental, and clinical observations provide support for a colorectal cancer chemopreventive role for aspirin. We have evaluated the effects of aspirin on proliferation biomarkers in normal-risk and high-risk human subjects for colorectal cancer. Colorectal biopsies were obtained at baseline and at 24h after 28 daily doses of 81 mg of aspirin from 13 high-risk and 15 normal-risk subjects for colorectal cancer. We evaluated aspirin's effects on proliferating cell nuclear antigen (PCNA) immunohistochemistry and epithelial mucin histochemistry using the lectin, Amaranthus caudatus agglutinin (ACA) in crypt sections from rectal biopsies. The baseline whole crypt PCNA LIs differed significantly between normal-risk and high-risk subjects. PCNA LIs are not affected by 28 days of aspirin at 81 mg daily. ACA LIs are decreased by 28 days of aspirin at 81 mg daily in both normal-risk and high-risk subjects. Aspirin's effects on ACA LIs may have mechanistic and biological implications that deserve further attention. PCNA and ACA LIs are not useful as proliferation biomarkers for aspirin's chemopreventive activity in morphologically normal human colorectal mucosa.

Screening colonoscopy in the asymptomatic 50- to 59-year-old population

BACKGROUND

In an effort to decrease the death rate from colorectal cancer, a multitude of medical societies and task forces recommend routine screening for colorectal cancer beginning at age 50. Yet, there is no consensus as to the best and most cost-effective screening method. Medicare now pays for screening colonoscopies for its average risk beneficiaries [3]. Many insurance companies, however, will not cover this test in younger patients. We therefore reviewed our institution's colonoscopy experience with asymptomatic 50- to 59-year-olds, with negative fecal occult blood tests and negative family histories.

METHODS

Between January 1999 and January 2002, 4779 colonoscopies were performed at our institution. The charts for 619 persons 50-59 years of age were retrospectively reviewed, with 91 patients meeting the strict requirements of this study. We defined polyps with high-grade neoplasias as those with villous or tubulovillous components, and cancerous lesions included those with carcinoma in situ. The distal colon was defined as the rectum and sigmoid colon.

RESULTS

There was a 58% incidence of neoplastic polyps in this younger asymptomatic population. More than 4% of our subjects had high-grade neoplasias or cancerous lesions. In the absence of any distal findings, flexible sigmoidoscopy would have missed up to 38% of these polyps.

CONCLUSIONS

The findings generally support the recommendations by the American College of Gastroenterology for average-risk patients to preferentially undergo a screening colonoscopy at age 50 in lieu of other methods.

Prevalence of advanced neoplasia at screening colonoscopy in men in private practice versus academic and Veterans Affairs medical centers

OBJECTIVES

Several large population studies assessing the yield of average risk screening colonoscopy have evaluated Veterans Affairs (VA) populations. It remains uncertain how generalizable these findings are to men in the general population. The aim of this study was to define the prevalence of advanced neoplasia in male patients undergoing screening colonoscopy in diverse practice settings.

METHODS

The Clinical Outcomes Research Initiative (CORI) national endoscopic database was analyzed to compare the findings in men undergoing average risk screening colonoscopy in community, academic, and VA endoscopy settings.

RESULTS

Between January, 1998, and May, 2002, a total of 9109 men underwent screening colonoscopy in community (5625), academic (2269), and VA (1215) settings. Overall yield of colonic lesions (mass or polyp >9 mm) on average risk colonoscopy was 5.1%; 5.7% (community), 3.4% (academic), and 5.9% (VA) in each site, respectively. Among patients with lesions identified, multiple lesions >9 mm were less common in academic settings (6.4%) compared to community (12.0%) or VA (8.9%) sites. When adjusting for age and ethnicity on multivariate analysis, colonic lesion detection at VA sites was similar to community settings. However, lesion identification was more likely in both settings (VA: OR = 1.72; community: OR = 1.56) compared to academic centers.

CONCLUSIONS

Age- and race-adjusted prevalence of polyps >9 mm in men who receive screening colonoscopy was significantly lower in academic sites compared to VA and community practice sites. One must be cautious in generalizing the findings of male patient studies from academic centers to the entire population.

Hyperplastic polyps in hereditary nonpolyposis colorectal cancer

OBJECTIVES

Hereditary nonpolyposis colorectal cancer (HNPCC) is a genetic syndrome caused by germline mutations in DNA mismatch repair (MMR) genes, in particular hMLH1, hMSH2, and hMSH6. Dysfunction of MMR genes leads to loss of MMR protein expression and to microsatellite instability (MSI). MSI is also detected in 10-20% of sporadic colorectal cancers. Hyperplastic polyps (HP) may serve as precursor for these MSI+ sporadic colorectal cancers. The aim of this study was to examine whether hyperplastic polyps are also possible premalignant lesions in HNPCC.

METHODS

All HPs resected from (suspected) mismatch repair gene mutation carriers were retrieved from a screening program database. Clinical information on patient age at colonoscopy and location of the HP was collected. MLH1, MSH2, and MLH6 protein expression was evaluated using immunohistochemistry.

RESULTS

A total of 90 HPs were resected from 21 men and 19 women. The mean patient age at resection was 45.7 yr (44.7 yr in men and 46.6 yr in women). In all patients, 19 (21%) HPs were resected from the proximal colon, 23 (26%) from the distal colon, and 48 (53%) from the rectum. None of the HPs demonstrated loss of MMR protein expression.

CONCLUSIONS

Mismatch repair dysfunction in HPs of HNPCC patients is apparently very rare. It seems unlikely that HPs in HNPCC patients are precursors for (MSI+) cancers in these patients.

The cyclooxygenase-2-selective inhibitors rofecoxib and celecoxib prevent colorectal neoplasia occurrence and recurrence

BACKGROUND & AIMS

Colorectal cancer is one of the leading causes of cancer death. Most colorectal cancers are believed to develop from colorectal adenomas. We examined the effect of the selective cyclooxygenase-2 inhibitors rofecoxib and celecoxib, nonselective nonsteroidal anti-inflammatory drugs, aspirin, and acetaminophen on colorectal neoplasia (colorectal cancer, colorectal adenoma, or both).

METHODS

This was a nested case-control study, which used data from a government insurance database on patients 65 years and older who underwent a diagnostic test or procedure for colorectal neoplasia between January and June 2001. Logistic regression models were used to determine the effect of exposure to the drugs of interest for at least 3 months on the occurrence or recurrence of colorectal neoplasia.

RESULTS

The control group included 2568 patients found to be free of colorectal neoplasia; 730 patients were diagnosed with colorectal adenoma, and 179 were diagnosed with colorectal cancer. Patients more likely to have colorectal adenoma (odds ratio, 95% confidence interval) were those diagnosed with colorectal adenoma (4.12, 3.27-5.18) or colorectal cancer (3.74, 2.32-6.03) in the previous 1-3 years and those with hemorrhage of the rectum or unspecified anemia in the prior month (3.19, 2.46-4.12). Exposures to rofecoxib (0.67, 0.46-0.98) and nonselective nonsteroidal anti-inflammatory drugs (0.41, 0.21-0.83) reduced the risk of colorectal adenoma. Rofecoxib, celecoxib, and nonselective nonsteroidal anti-inflammatory drugs were all protective against both neoplasias (0.64, 0.45-0.91; 0.73, 0.54-0.99; and 0.47, 0.26-0.86, respectively).

CONCLUSIONS

Rofecoxib, celecoxib, and nonselective nonsteroidal anti-inflammatory drugs seem to protect against the development of colorectal neoplasia.

Current capacity for endoscopic colorectal cancer screening in the United States: data from the National Cancer Institute Survey of Colorectal Cancer Screening Practices

PURPOSE

There is a national goal in the United States to increase the level of colorectal cancer screening, but there is currently little information on resources for the delivery of endoscopic screening and follow-up diagnostic and surveillance procedures. The purpose of this study was to provide nationally representative data on endoscopic resources at the provider level.

METHODS

A nationally representative survey of primary care physicians, general surgeons, and gastroenterologists that was conducted during 1999 to 2000 provided data from survey responses by 1235 primary care physicians, 349 gastroenterologists, and 316 general surgeons.

RESULTS

We estimated that 65% of all sigmoidoscopy procedures were performed by primary care physicians, 25% by gastroenterologists, and 10% by general surgeons. Only 30% of all primary care physicians performed any procedures, and average volume among those who did was relatively low (seven per month). Gastroenterologists performed two thirds of all colonoscopy procedures, with most of the remainder performed by general surgeons.

CONCLUSION

There is potential to increase the capacity to perform screening sigmoidoscopy procedures through primary care delivery. However, without careful consideration of organizational factors, this could result in increased cost and quality control problems. Increasing the capacity for screening colonoscopy is feasible, but will require attention to other problems, such as avoiding overfrequent (e.g., annual or biennial) procedures in low-risk patients.

Colonoscopy screening in the elderly: when to stop?

OBJECTIVES

The age to begin colorectal cancer (CRC) screening is based on the risk of neoplasia and is published in screening guidelines. The age to stop screening is unknown but should be based, in part, on the same principle. The purpose of this study was to establish whether the prevalence of neoplasia detected by colonoscopy diminished with advancing age, to warrant ceasing colonoscopic screening.

METHODS

The endoscopic and pathology reports of all asymptomatic subjects undergoing colonoscopy for the purpose of CRC screening or an evaluation of abdominal pain or change in bowel habits between 1997 and 2000 were reviewed. A multivariate logistic regression analysis was used to assess the effect of age, gender, and indication for examination on the prevalence of neoplasia, as well as on having more than two adenomas, advanced adenomas (tubulovillous, villous, severe dysplasia, or size > or = 1 cm), and invasive cancers.

RESULTS

A total of 915 patients were included. Of these, 50% were male, with a mean age of 65 yr (range 50-100). Neoplasia peaked in the seventh decade, with a fall thereafter (p = 0.009). Numerous adenomas, advanced adenomas, and invasive cancers increased with age. The yield for overall neoplasia, advanced adenomas, and more than two adenomas was higher in the screening group than in the symptomatic group. More invasive cancers were found in the symptomatic group compared with the asymptomatic group, but this did not achieve statistical significance (4 vs 1, p = 0.44).

CONCLUSIONS

The prevalence of advanced neoplasia continues to increase with age. Subjects undergoing colonoscopy for screening had a greater risk for neoplasia than did subjects with symptoms. There is no decline in yield of advanced neoplasia to justify stopping screening colonoscopy in the elderly.

Colorectal cancer screening: clinical applications

Screening for colorectal cancer reduces mortality in individuals aged 50 years or older. A number of screening tests, including fecal occult blood tests, sigmoidoscopy, double-contrast barium enema, and colonoscopy, are recommended by professional organizations for colorectal cancer screening, yet the rates of colorectal cancer screening remain low. Questions regarding the quality of evidence for each screening test, whether screening for individuals at higher risk should be modified, the availability of the tests, and cost-effectiveness are addressed. Many potential barriers to colorectal cancer screening exist for the patient and the physician. Strategies to increase compliance for colorectal cancer screening are proposed.

Screening for colorectal cancer in Chinese: comparison of fecal occult blood test, flexible sigmoidoscopy, and colonoscopy

BACKGROUND AND AIMS

Fecal occult blood testing (FOBT), flexible sigmoidoscopy (FS), and colonoscopy are the most commonly recommended screening tests for colorectal cancer. The aim of this study was to compare the accuracy and safety of these 3 screening procedures in a general population of ethnic Chinese.

METHODS

Asymptomatic adults older than 50 years were recruited from the general public through health exhibitions. All enrolled subjects were offered FOBT and full colonoscopy under sedation. Advanced colonic lesions (defined as adenoma > or = 10 mm, villous adenoma, adenoma with moderate or severe dysplasia, or invasive cancer) were recorded. Lesions at the distal 40 cm in the left colon and rectum were taken as findings of FS.

RESULTS

A total of 505 subjects (56% women; mean age +/- SD, 56.5 +/- 5.4 years) were enrolled, and 476 (94.3%) had a complete colonoscopy. Advanced colonic neoplasms were documented in 63 subjects (12.5%), of which 45 had lesions in the distal colon and 26 in the proximal colon. Among the 385 subjects with a normal distal colon, 14 (3.6%) had advanced lesions in the proximal colon that would be missed by FS alone. The sensitivity and specificity of FOBT for advanced colonic lesions were 14.3% and 79.2% and the sensitivity and specificity of FS were 77.8% and 83.9%, respectively. Combining FOBT with FS would not significantly improve the results of FS alone. Among these 505 subjects who underwent colonoscopy and 148 who underwent polypectomy, there was no perforation and only one occurrence of postpolypectomy bleeding recorded.

CONCLUSIONS

Colonoscopy is a safe and accurate method for the screening of colorectal neoplasms in Chinese subjects.

Screening for colorectal cancer. Guidelines for choosing the appropriate test for each patient

The importance of screening for colorectal cancer has been established, but the decision about which test to use for each patient may seem less clear. In this article, Dr Wineman discusses assessment of colorectal cancer risk and the advantages and disadvantages of the fecal occult blood test, flexible sigmoidoscopy, double-contrast barium enema, and colonoscopy. Potential screening methods that could make regular colon examination more acceptable to patients also are presented.

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