Population-based surveillance by colonoscopy: effect on the incidence of colorectal cancer. Telemark Polyp Study I

Secondary prevention of cancer

OBJECTIVES

To review criteria for mass cancer screening among asymptomatic populations and barriers to secondary prevention of breast, cervical, and colorectal cancers. To describe challenges to implementing theoretically based interventions to increase appropriate cancer screening, follow-up, and surveillance.

DATA SOURCES

Published journal articles, text books, and epidemiologic reports.

CONCLUSION

Interventions to increase breast, cervical, and colorectal cancer screening participation must be approached from a systems perspective that includes patient, health care provider, and health care system variables.

IMPLICATIONS FOR NURSING PRACTICE

Understanding the array of factors that impede progress in the secondary prevention of cancer is necessary to improve care. Nurses have an important role in decreasing morbidity and mortality from breast, cervical, and colorectal cancers.

Lifestyle characteristics among participants in a Norwegian colorectal cancer screening trial

The aim of the present study was to evaluate to what extent lifestyle-related variables predict participation for flexible sigmoidoscopy (FS) screening when the compliance is relatively high. During 2001, a randomized sample of 6961 men and women, born between 1946 and 1950, were invited to have a flexible sigmoidoscopy screening examination. Attendees (n = 4111) were asked to fill in a questionnaire focusing on physical activity, body weight, smoking habits and diet. The questionnaire was sent by mail to non-attendees (n = 2628) and a randomized corresponding control group not invited to screening (n = 7000). Sixty-one percent attended for screening. The questionnaire response rate among attendees, non-attendees and controls was 97, 11 and 61%, respectively. Attendees were more physically active (P < 0.001), and showed more adherence to general dietary recommendations, compared with controls. Opposing their healthy exercise and dietary habits, however, attendees were more likely to be moderate smokers compared with controls. The present offer of FS screening, achieving a relatively high compliance rate, may have reached attendees using screening as a supplement to an already healthy lifestyle, but also those who seek amelioration through health checks for risks behaviour that they are perfectly well aware of, such as smoking.

Emerging technologies in colorectal cancer screening

CRC is a preventable disease through early detection, yet screening rates remain low and mortality rates remain high. The discomfort associated with the preparation and performance of some of the currently available screening modalities and the lack of public awareness about CRC and screening procedures likely account for low rates of screening. CT colonography and stool DNA testing are new promising screening technologies that are less invasive, accurate, and suitable for the public more than the current screening procedures. Before both tests can be promoted for population-based screening programs, several issues that have been detailed in this article must be addressed further, including technical improvements for improving accuracy, development of virtual preparation, test availability, patient and provider acceptability and cost-effectiveness for CTC, and identifying the optimal combination of molecular targets for stool DNA testing. The year 2005 will tell us if the ideal technology from the public health point of view was achieved. A skill-independent, anesthesia-free, self-propelling, self-navigating miniaturized endoscopic device that may move along the entire length of the colon may change the natural history of CRC. We should aim to achieve a new definition of CRC--a rare disease occurring in a subset of the population who has not been screened for the disease.

Screening Practices of Patients Presenting for Resection of a Colorectal Neoplasm

Multiple studies demonstrate the efficacy of colorectal cancer (CRC) screening in patients over 50 years of age. However, there is a lack of consensus regarding which screening method to use, and compliance has been poor. The objective of this study was to identify the CRC screening practices at two institutions and determine the relationship between screening and pathologic stage for patients presenting with a colorectal neoplasm. This study, conducted at the University of Virginia (UVA) Health System and the Salem Veterans Affairs Medical Center (VAMC) between October 30, 2000, and September 1, 2004, included 198 patients ≥50 years who presented for resection of a primary colorectal neoplasm. Pathologic stage and prior screening were identified retrospectively through chart review and patient response to an anonymous survey. Prior screening was demonstrated in 71 per cent of patients. Colonoscopy was the most commonly used modality. There was a higher percentage of CRC screening at VAMC compared with UVA (80% vs 62%, P < 0.0008). Patients at UVA were more likely screened with colonoscopy, whereas fecal occult blood testing (FOBT) was most common at VAMC (P < 0.0001). Prior CRC screening and cancer stage were inversely related. Ninety-one per cent of patients with benign polyps had been screened prior to diagnosis, compared with 72 per cent of patients with stage I and II cancer and 54 per cent of patients with stage III and IV cancer (P < 0.05). Of patients presenting for surgery, 71 per cent underwent CRC screening. Variability exists in the methods employed for CRC screening. CRC screening facilitates diagnosis at an early stage.

Colorectal cancer screening behavior in women attending screening mammography: Longitudinal trends and predictors

PURPOSE

Nationally representative surveys demonstrate that the adherence to screening mammography guidelines are associated with increased prevalence of colorectal cancer (CRC) screening; however, the incidence of CRC screening in the screening mammography population is unknown. Our purpose was to describe non-fecal occult blood test (FOBT) CRC screening utilization by women prior to and subsequent to screening mammography at a large academic medical center.

MATERIALS AND METHODS

Using the institutional administrative data base, 17,790 women aged 50 and older who underwent screening mammography between 1998 and 2002 were retrospectively identified. We determined that women were current with non-FOBT CRC screening at the time of mammography if they had undergone flexible sigmoidoscopy or double-contrast barium enema in the 5 years or colonoscopy since 1995, the earliest for which data are available. We excluded FOBT as a form of CRC screening because the administrative data base did not adequately capture episodes of FOBT. Women who were not current were considered eligible for non-FOBT CRC screening. We then assessed the number of women who underwent flexible sigmoidoscopy, barium enema, or colonoscopy within 12 months following mammography. Age, insurance status, Breast Imaging Reporting and Data System classification, recommendations after screening mammography and year of mammography were examined as potential predictors of non-FOBT CRC screening completion.

RESULTS

At the time of mammography, 13.3% women were current with non-FOBT CRC screening. Of women eligible for non-FOBT CRC screening at the time of mammography, 1.1% completed non-FOBT CRC screening within 12 months after mammography. The rate of non-FOBT CRC screening completion increased over time. After multivariate analysis, being insured by a commercial managed care organization or by Medicaid remained significant predictors of non-FOBT CRC screening.

CONCLUSION

The prevalence of non-FOBT CRC screening is low in the population of women undergoing screening mammography, with an incidence of 1.0%. Future studies should examine whether delivering CRC screening interventions at a screening mammography visit increase adherence to non-FOBT CRC screening.

Incomplete screening flexible sigmoidoscopy associated with female sex, age, and increased risk of colorectal cancer

BACKGROUND

Several previous studies have found that females and older individuals are at greater risk of having incomplete flexible sigmoidoscopy. However, no prior study has reported the subsequent risk of colorectal cancer (CRC) following incomplete sigmoidoscopy.

METHODS

Using data from 55 791 individuals screened as part of the Colon Cancer Prevention (CoCaP) programme of Kaiser Permanente of Northern California, we evaluated the likelihood of having an inadequate (<40 cm) examination by age and sex, and estimated the risk of distal CRC according to depth of sigmoidoscope insertion at the baseline screening examination. Multivariate estimation of risks was performed using Poisson regression.

RESULTS

Older individuals were at a much greater risk of having an inadequate examination (relative risk (RR) for age 80+ years compared with 50-59 years 2.6 (95% confidence interval (CI) 2.3-3.0)), as were females (RR 2.3 (95% CI 2.2-2.5)); these associations were attenuated but remained strong if Poisson models were further adjusted for examination limitations (pain, stool, and angulation). There was an approximate threefold increase in the risk of distal CRC if the baseline sigmoidoscopy did not reach a depth of at least 40 cm; a smaller increase in risk was observed for examinations that reached 40-59 cm.

CONCLUSIONS

Older individuals and women are at an increased risk of having inadequate sigmoidoscopy. Because inadequate sigmoidoscopy results in an increased risk of subsequent CRC, physicians should consider steps to maximise the depth of insertion of the sigmoidoscope or, failing this, should consider an alternative screening test.

Colorectal Screening is Associated with Reduced Colorectal Cancer Risk: A Case–Control Study within the Population-Based Ontario Familial Colorectal Cancer Registry

OBJECTIVE

This is the first study to evaluate the association between colonic screening and colorectal cancer risk among Canadians.

METHODS

A case-control study was conducted. Cases were diagnosed with cancer of the colorectum, between 1997 and 2000, aged 20 to 74 years, identified through the population-based Ontario Cancer Registry and recruited by the Ontario Familial Colorectal Cancer Registry. Controls were a sex- and age-matched random sample of the population of Ontario. 971 cases and 1944 controls completed questionnaires (including colorectal screening history and many risk factors). Multivariate logistic regression analysis was used to obtain adjusted odds ratios (OR) estimates.

RESULTS

Having had a fecal occult blood screen was associated with reduced colorectal cancer risk (OR=0.76; 95% confidence interval (CI): 0.59, 0.97). Having had a screening sigmoidoscopy was associated with a halving of colorectal cancer risk (OR = 0.52; 95% CI: 0.34, 0.80). Having had a screening colonoscopy did not significantly reduce colorectal cancer risk (OR = 0.69; 95% CI: 0.44, 1.07); however, having had either screening endoscopy was associated with a significant reduction in colorectal cancer risk (OR = 0.62; 95% CI: 0.44, 0.87). Findings differed slightly by anatomic sub-site (proximal and distal colorectum).

CONCLUSIONS

We report a reduction in colorectal cancer risk among persons who underwent colorectal cancer screening; in particular, sigmoidoscopy. Findings are of great importance for the prevention of colorectal cancer.

Colon polyp retrieval after cold snaring

BACKGROUND

The removal of small colon polyps by cold snare transection without electrocautery effectively eliminates polyps, and anecdotal reports indicate a low risk of bleeding and perforation. Concerns about using cold snaring have centered on the risk of immediate bleeding and the difficulty in retrieving the polyp. The objective was to determine the retrieval rates of polyps after cold snaring after two different methods of resection and retrieval.

METHODS

Consecutive polyps were identified by a single colonoscopist who chose the technique of polypectomy (hot snare, cold snare, or cold forceps). If cold snaring was chosen, an independent observer assigned the polyp to method A (cold resection of polyp without tenting and then suction of the transected polyp into a trap) or method B (ensnare the polyp, pull it into the colonoscope channel, and then transect it while suctioning). The size and the approximate location of all polyps were recorded and all collected specimens were sent separately for histologic examination. Results Of 519 consecutively encountered polyps, 400 were removed by cold snare: 197 were assigned to method A and 203 to method B. The mean size of polyps that were cold snared was 3.5 mm. The mean time to remove and to retrieve polyps with method A was 14.5 seconds (n = 58) and with method B was 18.1 seconds (n = 60) ( p = 0.03). There were no complications from cold snaring. The rate of successful retrieval with method A was 100% (197 of 197 polyps) and with method B was 98% (199 of 203 polyps) ( p = 0.04).

CONCLUSIONS

Cold snare removal of colon polyps is associated with a high polyp retrieval rate. Each of two methods of polyp retrieval was effective. Snare transection without tenting of the polyp, followed by suctioning of the specimen off the polyp site, was more efficient, though the difference in efficiency was minimal. Difficulty or failure to retrieve polyps should not be a concern with regard to cold snare polypectomy.

Identifying target populations for screening or not screening using logic regression

Colorectal cancer remains a significant public health concern despite the fact that effective screening procedures exist and that the disease is treatable when detected at early stages. Numerous risk factors for colon cancer have been identified, but none are very predictive alone. We sought to determine whether there are certain combinations of risk factors that distinguish well between cases and controls, and that could be used to identify subjects at particularly high or low risk of the disease to target screening. Using data from the Seattle site of the Colorectal Cancer Family Registry, we fit logic regression models to combine risk factor information. Logic regression is a methodology that identifies subsets of the population, described by Boolean combinations of binary coded risk factors. This method is well suited to situations in which interactions between many variables result in differences in disease risk. We found that neither the logic regression models nor stepwise logistic regression models fit for comparison resulted in criteria that could be used to direct subjects to screening. However, we believe that our novel statistical approach could be useful in settings where risk factors do discriminate between cases and controls, and illustrate this with a simulated data set.

Screening and surveillance of colorectal cancer

Although colorectal cancer (CRC) is the second leading cause of cancer deaths in the United States, it is preventable. Screening modalities include fecal occult blood testing, flexible sigmoidoscopy, double-contrast barium enema, and colonoscopy. Colonoscopy allows effective detection and removal of precursor adenomatous polyps and is the dominant CRC screening modality. Emerging technologies include CT and MR colonography and fecal DNA tests. Effective and cost-effective surveillance after polypectomy and curative CRC resection requires balancing the protective effect of polypectomy while maximizing intervals between examinations; thus, estimation of the risk of recurrence determines the intensity of surveillance for individual patients.

Reduction of clinically manifest colorectal cancer by endoscopic screening: empirical evaluation and comparison of screening at various ages

Endoscopic screening (sigmoidoscopy, colonoscopy) with removal of precancerous lesions can prevent a large proportion of colorectal cancers (CRCs). However, there is lack of data regarding optimal age, time intervals and numbers of screening examinations. We developed and applied modified techniques of epidemiological analysis to evaluate the impact of various endoscopy-based screening strategies on prevention of clinically manifest CRCs between the ages of 50 and 79 in a population-based case-control study (294 cases, 254 controls) conducted in Saarland, Germany. We found a strong potential for reduction of CRC occurrence even with a single screening endoscopy. The optimal age for a single screening endoscopy appears to be around 55 (estimated potential for prevention of cases between the ages of 55 and 79 in case of 100% compliance: 77% (95% confidence interval (CI) 46-90%)). A single screening endoscopy at age 50 would have a lower impact due to failure to prevent CRC at higher ages. Similarly, screening at ages 60 or older would have a lower impact because it would fail to prevent CRC at lower ages. Repeated offers of screening examinations could provide substantial additional benefit with the levels of compliance to be expected in practice, but they would have to be weighed against the increased risks and costs.

Health care provider-directed intervention to increase colorectal cancer screening among veterans: results of a randomized controlled trial

PURPOSE

Colorectal cancer screening is the most underused cancer screening tool in the United States. The purpose of this study was to test whether a health care provider-directed intervention increased colorectal cancer screening rates.

PATIENTS AND METHODS

The study was a randomized controlled trial conducted at two clinic firms at a Veterans Affairs Medical Center. The records of 5,711 patients were reviewed; 1,978 patients were eligible. Eligible patients were men aged 50 years and older who had no personal or family history of colorectal cancer or polyps, had not received colorectal cancer screening, and had at least one visit to the clinic during the study period. Health care providers in the intervention firm attended a workshop on colorectal cancer screening. Every 4 to 6 months, they attended quality improvement workshops where they received group screening rates, individualized confidential feedback, and training on improving communication with patients with limited literacy skills. Medical records were reviewed for colorectal cancer screening recommendations and completion. Literacy level was assessed in a subset of patients.

RESULTS

Colorectal cancer screening was recommended for 76.0% of patients in the intervention firm and for 69.4% of controls (P = .02). Screening tests were completed by 41.3% of patients in the intervention group versus 32.4% of controls (P = .003). Among patients with health literacy skills less than ninth grade, screening was completed by 55.7% of patients in the intervention group versus 30% of controls (P < .01).

CONCLUSION

A provider-directed intervention with feedback on individual and firm-specific screening rates significantly increased both recommendations and colorectal cancer screening completion rates among veterans.

Randomized Trial of Different Screening Strategies for Colorectal Cancer: Patient Response and Detection Rates

BACKGROUND

Although there is general consensus concerning the efficacy of colorectal cancer screening, there is a lack of agreement about which routine screening strategy should be adopted. We compared the participation and detection rates achievable through different strategies of colorectal cancer screening.

METHODS

From November 1999 through June 2001 we conducted a multicenter, randomized trial in Italy among a sample of 55-64 year olds in the general population who had an average risk of colorectal cancer. People with previous colorectal cancer, adenomas, inflammatory bowel disease, a recent (< or =2 years) colorectal endoscopy or fecal occult blood test (FOBT), or two first-degree relatives with colorectal cancer were excluded. Eligible subjects were randomly assigned, within the roster of their general practitioner, to 1) biennial FOBT (delivered by mail), 2) biennial FOBT (delivered by general practitioner or a screening facility), 3) patient's choice of FOBT or "once-only" sigmoidoscopy, 4) "once-only" sigmoidoscopy, or 5) sigmoidoscopy followed by biennial FOBT. An immunologic FOBT was used. Participation and detection rates of the strategies tested were compared using multivariable logistic regression models that adjusted for age, sex, and screening center. All statistical tests were two-sided.

RESULTS

Of 28 319 people sampled, 1637 were excluded and 26 682 were randomly assigned to a screening arm. After excluding undelivered letters (n = 427), the participation rates for groups 1, 2, 3, 4, and 5 were 30.1% (682/2266), 28.1% (1654/5893), 27.1% (970/3579), 28.1% (1026/3650), and 28.1% (3049/10 867), respectively. Of the 2858 subjects screened by FOBT, 122 (4.3%) had a positive test result, 10 (3.5 per 1000) had colorectal cancer, and 39 (1.4%) had an advanced adenoma. Among the 4466 subjects screened by sigmoidoscopy, 341 (7.6%) were referred for colonoscopy, 18 (4 per 1000) had colorectal cancer, and 229 (5.1%) harbored an advanced adenoma.

CONCLUSIONS

The participation rates were similar for sigmoidoscopy and FOBT. The detection rate for advanced neoplasia was three times higher following screening by sigmoidoscopy than by FOBT.

Colorectal cancer prevention

Colorectal cancer is the second leading cause of mortality in the United States. In the United States, the cumulative lifetime risk of developing colorectal cancer for both men and women is 6%. Despite advances in the management of this disease, the 5-year survival rate in the United States in only 62%. Because only 38% of patients are diagnosed when the cancers are localized to the bowel wall, it is likely that widespread implementation of screening could significantly improve the outcome. Colorectal cancer screening is cost effective, irrespective of the methods used. In addition to currently available methods (fecal occult blood, flexible sigmoidoscopy, colonoscopy, and double contrast barium enema), computed tomographic colonography (virtual colonoscopy) and stool-based molecular screening are under development. Four classes of chemopreventive compounds have demonstrated efficacy in reducing recurrent colorectal adenomas and/or cancer in randomized, controlled trials. They are selenium, calcium carbonate, hormone replacement therapy, and nonsteroidal anti-inflammatory drugs. The mechanisms of action of nonsteroidal anti-inflammatory drugs include inhibition of the cyclooxygenase system as well as cyclooxygenase-independent effects. Considerable effort is being expended to define chemopreventive activity, optimal dose, administration schedule, and toxicity for the coxibs in adenoma recurrence prevention trials. The threshold for tolerating toxicities is very low in asymptomatic individuals at minimally increased risk for colorectal neoplasia.

Colonoscopy screening for colorectal cancer: the outcomes of two recruitment methods

OBJECTIVES

To determine the response to colorectal cancer (CRC) screening by colonoscopy, through direct invitation or through invitation by general practitioners.

DESIGN AND SETTING

Two-way comparison of randomised population sampling versus cluster sampling of a representative general practice population in the Australian Capital Territory, May 2002 to January 2004.

INTERVENTION

Invitation to screen, assessment for eligibility, interview, and colonoscopy.

SUBJECTS

881 subjects aged 55-74 years were invited to screen: 520 from the electoral roll (ER) sample and 361 from the general practice (GP) cluster sample.

MAIN OUTCOME MEASURES

Response rate, participation rate, and rate of adenomatous polyps in the screened group.

RESULTS

Participation was similar in the ER arm (35.1%; 95% CI, 30.2%-40.3%) and the GP arm (40.1%; 95% CI, 29.2%-51.0%) after correcting for ineligibility, which was higher in the ER arm. Superior eligibility in the GP arm was offset by the labour of manual record review. Response rates after two invitations were similar for the two groups (ER arm: 78.8%; 95% CI, 75.1%-82.1%; GP arm: 81.7%; 95% CI, 73.8%-89.6%). Overall, 53.4% ineligibility arose from having a colonoscopy in the past 10 years (ER arm, 98/178; GP arm, 42/84). Of 231 colonoscopies performed, 229 were complete, with 32% of subjects screened having adenomatous polyps.

CONCLUSIONS

Colonoscopy-based CRC screening yields similar response and participation rates with either random population sampling or general practice cluster sampling, with population sampling through the electoral roll providing greater ease of recruitment.

Association between subject factors and colorectal cancer screening participation in Ontario, Canada

Colorectal cancer screening reduces colorectal cancer incidence and mortality. This population-based study was conducted to evaluate (i) the association between subject factors and colorectal screening participation and (ii) the lifetime prevalence of colorectal screening among the general population of Ontario, Canada. Population-based controls were recruited by the Ontario Familial Colorectal Cancer Registry during 1998-2000. The 1944 persons completed an epidemiologic questionnaire. Descriptive statistics were computed and step-wise multivariate logistic regression was used to estimate odds ratios and 95% confidence intervals. Overall, 23% of persons greater than 50 years of age reported ever having had colorectal cancer screening; 17% reported fecal occult blood test (FOBT), 6% sigmoidoscopy, and 4% colonoscopy. Family history of colorectal cancer, increased age, higher household income, and use of hormone replacement therapy (among women) were all significantly associated with ever having had colorectal cancer screening. The low prevalence of colorectal cancer screening among the target population suggests the need for an increased awareness of the public health importance of colorectal cancer screening.

Selective modulation of the therapeutic efficacy of anticancer drugs by selenium containing compounds against human tumor xenografts

PURPOSE

Studies were carried out in athymic nude mice bearing human squamous cell carcinoma of the head and neck (FaDu and A253) and colon carcinoma (HCT-8 and HT-29) xenografts to evaluate the potential role of selenium-containing compounds as selective modulators of the toxicity and antitumor activity of selected anticancer drugs with particular emphasis on irinotecan, a topoisomerase I poison.

EXPERIMENTAL DESIGN

Antitumor activity and toxicity were evaluated using nontoxic doses (0.2 mg/mouse/day) and schedule (14-28 days) of the selenium-containing compounds, 5-methylselenocysteine and seleno-L-methionine, administered orally to nude mice daily for 7 days before i.v. administration of anticancer drugs, with continued selenium treatment for 7-21 days, depending on anticancer drugs under evaluation. Several doses of anticancer drugs were used, including the maximum tolerated dose (MTD) and toxic doses. Although many chemotherapeutic agents were evaluated for toxicity protection by selenium, data on antitumor activity were primarily obtained using the MTD, 2 x MTD, and 3 x MTD of weekly x4 schedule of irinotecan.

RESULTS

Selenium was highly protective against toxicity induced by a variety of chemotherapeutic agents. Furthermore, selenium increased significantly the cure rate of xenografts bearing human tumors that are sensitive (HCT-8 and FaDu) and resistant (HT-29 and A253) to irinotecan. The high cure rate (100%) was achieved in nude mice bearing HCT-8 and FaDu xenografts treated with the MTD of irinotecan (100 mg/kg/week x 4) when combined with selenium. Administration of higher doses of irinotecan (200 and 300 mg/kg/week x 4) was required to achieve high cure rate for HT-29 and A253 xenografts. Administration of these higher doses was possible due to selective protection of normal tissues by selenium. Thus, the use of selenium as selective modulator of the therapeutic efficacy of anticancer drugs is new and novel.

CONCLUSIONS

We demonstrated that selenium is a highly effective modulator of the therapeutic efficacy and selectivity of anticancer drugs in nude mice bearing human tumor xenografts of colon carcinoma and squamous cell carcinoma of the head and neck. The observed in vivo synergic interaction is highly dependent on the schedule of selenium.

Institutional Commitment to Rectal Cancer Screening Results in Earlier-Stage Cancers on Diagnosis

BACKGROUND

The Veterans Administration hospitals underwent an institutional directive in 1998 to meet a colorectal cancer screening (CRCS) standard. This intervention should result in an increase in the hospital's screening rate and percentage of early-stage rectal cancers diagnosed.

METHODS

A retrospective review, from 1991 to 2002, of our institution's pathology and cancer registry databases for rectal cancers. CRCS data were obtained from the Veterans Administration Prevention Disease Index. Cancer stage at diagnosis was compared before and after the directive and was compared with the National Cancer Data Base and the Surveillance, Epidemiology, and End Results data.

RESULTS

The rate of CRCS was 55% in 1998 and increased to 75% in 2003. During the 11 years studied, a total of 147 rectal cancers were diagnosed. After the Veterans Administration directive, there was a significant increase in stage 0 cancers (P < .02) and an overall migration to earlier-stage cancers. Our Veterans Administration hospital had a significantly greater percentage of stage 0 cancers both before (P < .007) and after the directive (P < .00) and had fewer stage 3 cancers after the directive (P < .03) compared with National Cancer Data Base data. Compared with Surveillance, Epidemiology, and End Results data, the Palo Alto Veterans Affairs Health Care System had more local disease (P < .03) and less regional disease (P < .006).

CONCLUSIONS

These data suggest that a monitored institutional directive may significantly increase early detection of rectal cancers. This should result in a greater survival rate and lower local recurrence rate, because survival is predicated on stage at presentation. This may serve as a model for other health-care systems.

Multiple rare variants in different genes account for multifactorial inherited susceptibility to colorectal adenomas

Clear-cut inherited Mendelian traits, such as familial adenomatous polyposis or hereditary nonpolyposis colorectal cancer, account for <4% of colorectal cancers. Another 20% of all colorectal cancers are thought to occur in individuals with a significant inherited multifactorial susceptibility to colorectal cancer that is not obviously familial. Incompletely penetrant, comparatively rare missense variants in the adenomatous polyposis coli gene, which is responsible for familial adenomatous polyposis, have been described in patients with multiple colorectal adenomas. These variants represent a category of variation that has been suggested, quite generally, to account for a substantial fraction of such multifactorial inherited susceptibility. The aim of this study was to explore this rare variant hypothesis for multifactorial inheritance by using multiple colorectal adenomas as the model. Patients with multiple adenomas were screened for germ-line variants in a panel of candidate genes. Germ-line DNA was obtained from 124 patients with between 3 and 100 histologically proven synchronous or metachronous adenomatous polyps. All patients were tested for the adenomatous polyposis coli variants I1307K and E1317Q, and variants were also sought in AXIN1 (axin), CTNNB1 (beta-catenin), and the mismatch repair genes hMLH1 and hMSH2. The control group consisted of 483 random controls. Thirty of 124 (24.9%) patients carried potentially pathogenic germ-line variants as compared with 55 ( approximately 12%) of the controls. This overall difference is highly significant, suggesting that many rare variants collectively contribute to the inherited susceptibility to colorectal adenomas.

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.

Underuse of screening sigmoidoscopy and colonoscopy in a large cohort of US adults

OBJECTIVES

We examined the prevalence of endoscopy (sigmoidoscopy or colonoscopy) by indication and by demographic and lifestyle factors.

METHODS

We analyzed cross-sectional data collected in 1997 from participants aged 50 years and older in the Cancer Prevention Study (CPS) II Nutrition Cohort.

RESULTS

Fifty-eight percent of men and 51% of women reported ever having undergone endoscopy; only 42% of men and 31% of women reported endoscopy for screening rather than for disease diagnosis or follow-up. Prevalence varied by demographic and lifestyle factors.

CONCLUSIONS

Efforts to increase colorectal cancer screening need to target women, all persons aged 50-64 years, and those with colorectal cancer risk factors. Future studies should distinguish endoscopy for screening from procedures for disease diagnosis and follow-up to avoid overestimating screening compliance.

The incidence of colorectal cancer following a negative screening sigmoidoscopy: implications for screening interval

BACKGROUND & AIMS

Current guidelines recommend a 5-year interval for colorectal cancer (CRC) screening by sigmoidoscopy. However, the optimal screening interval is uncertain. We estimated the annual incidence of distal and proximal CRC in the first 5 years following a negative sigmoidoscopy examination to gauge the potential benefit of rescreening in <5 years.

METHODS

A cohort of 72,483 participants in the Colon Cancer Prevention program of Kaiser Permanente of Northern California (KP) was defined using computerized databases. Men and women aged 50 years and older who had a negative screening flexible sigmoidoscopy examination between 1994 and 1996 and were considered not to be at high risk for developing CRC were included. Subjects were censored at the time of diagnosis (for cases), death, termination of KP membership, or subsequent colon examination.

RESULTS

Thirty cases of distal and 80 cases of proximal CRC occurred. Age-adjusted incidence rates of distal CRC ranged from a low of 2.8 per 100,000 person-years in the first year of follow-up to a high of 13.0 per 100,000 in the fourth year (rate difference, 10.2; 95% confidence interval, 1.1-19.3). However, for the entire follow-up period, incidence of distal CRC remained much lower than age-adjusted rates of 70.6 in the general population (Surveillance, Epidemiology, and End Results registry). The incidence of proximal CRC was also decreased modestly over population rates of disease.

CONCLUSIONS

Screening by sigmoidoscopy more frequently than every 5 years would likely lead, at best, to only modest improvements as compared with a 5-year screening interval.

A survey of colonoscopic polypectomy practices among clinical gastroenterologists

BACKGROUND

Polypectomy techniques vary in clinical practice. The aim of this study was to determine patterns of polypectomy practices in a random sample of gastroenterologists.

METHODS

A total of 300 gastroenterologists were selected randomly from the membership directory of a professional society. They were asked to complete a standardized survey by telephone, electronic mail, or facsimile.

RESULTS

The offices of 285 physicians were contacted successfully. A total of 189 (63%) chose to participate. 152 (80%) of these physicians were in private practice, and 37 (20%) were in academic practice. The mean number of years in practice was 15.5 (range 1-46 years). Forceps techniques (cold or hot) dominated other polypectomy methods for polyps 1 to 3 mm in size ( p < 0.0001), whereas electrosurgical snare resection was dominate for polyps 7 to 9 mm in diameter ( p < 0.0001). No method of polypectomy was significantly more likely to be used for polyps 4 to 6 mm in size. The proportion of physicians who had used dye spraying was 8.5%; detachable snares, 20.1%; clips, 20.1%; and submucosal saline solution injection, 82%. Of those who had used submucosal saline solution injection, 29.7% had no rules for its use, and, in the remainder, there was marked variation regarding the criteria. For polyp stalks greater than 1 cm in diameter, 69% used no method to prevent bleeding. Of those who did use preventive techniques, 76% used epinephrine injection. The electrosurgical current used for polypectomy was pure coagulation in 46%, blend in 46%, and pure-cut in 3%; 4% varied the current.

CONCLUSIONS

At present, polypectomy technique among clinical gastroenterologists is highly variable. Some newer ancillary techniques have had extremely limited use thus far.

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.

Mailings timed to patients' appointments: a controlled trial of fecal occult blood test cards

BACKGROUND

Fecal occult blood testing (FOBT) programs cost-effectively reduce colon cancer mortality. To improve the rate of colon cancer screening with FOBT, we tested the effect of mailing FOBT cards timed to appointments on the rates of completion of FOBT.

DESIGN

Controlled trial.

SETTING/PARTICIPANTS

A total of 119 patients with primary care appointments scheduled in May or June 2000 for an urban, public hospital clinic that serves predominantly low-income, African Americans with chronic diseases. The patients in the study were selected by linking a quality improvement registry, the appointment system database, and an FOBT database to generate a list of clinic patients who had not completed an FOBT in the preceding year.

INTERVENTION

Subjects were assigned to either a system of mailing FOBT cards and reminders 2 weeks prior to a scheduled appointment or usual care.

MAIN OUTCOME MEASURES

The primary outcomes were the rate of screening at the index appointment and during the year beginning with the date of the index appointment.

RESULTS

The rate of return of the FOBT cards during the year beginning with the index appointment was 40.7% for the intervention group compared to 5% for the usual care group (odds ratio [OR]=13.0, p <0.001). The difference was accounted for largely by increases in screening at the index appointment (35.6% compared to 3.3%, OR=16.0, p <0.001).

CONCLUSIONS

Using computer databases to generate a list of patients due for FOBT and then mailing FOBT cards timed to a scheduled appointment significantly increased the rate of colon cancer screening. This may be an efficient approach to increasing colon cancer screening with FOBT.

Adherence to colorectal cancer screening in mammography-adherent older women

Colorectal cancer (CRC) is the third leading cause of cancer mortality among women. Screening can prevent the development of CRC or diagnose early disease when it can effectively be cured, however existing screening methods are underutilized. In this study, we examined the utility of an updated Health Belief Model to explain CRC screening adherence. The present study included 280 older women seeking routine mammography at a large, urban breast diagnostic facility. Overall, 50% of women were adherent to CRC screening guidelines. Multiple regression indicated that self-efficacy, physician recommendation, perceived benefits of and perceived barriers to screening accounted for 40% of variance in CRC screening adherence. However, there was no evidence for two mediational models with perceived benefits and perceived barriers as the primary mechanisms driving adherence to CRC screening. These findings may inform both future theoretical investigations as well as clinical interventions designed to increase CRC screening behavior.

Adenoma recurrences after resection of colorectal carcinoma: results from the Southwest Oncology Group 9041 calcium chemoprevention pilot study

BACKGROUND

Colorectal adenomas are the usual precursors to carcinoma in sporadic and hereditary colorectal cancers (CRC).

METHODS

A total of 220 CRC patients (stages 0, I, and II) were randomized prospectively in a double-blind pilot study of calcium chemoprevention by using recurrent colorectal adenomas as a surrogate end point. This trial is still in progress, and we report the preliminary findings on adenoma recurrence rates.

RESULTS

Synchronous adenomas were present in 60% of patients, and cancer confined in a polyp was present in 23% of patients. The overall cumulative adenoma recurrence rate was 31% (19% in the first year, 29% for 2 years, and 35% for 3 years). The recurrence rates were greater for patients with synchronous adenomas: 38% at 3 years (P =.01). Lower stage was associated with higher adenoma recurrence rates (P =.04). Factors including age, sex, site of primary cancer, and whether the cancer was confined to a polyp were not significantly associated with differences in adenoma recurrence rates.

CONCLUSIONS

The substantial adenoma recurrence rate in patients resected of CRC justifies colonoscopic surveillance on a periodic basis. Patients with higher rates of adenoma recurrences, such as CRC with synchronous adenomas, are ideal subjects for chemoprevention trials.

Acceptance of flexible sigmoidoscopy screening for colorectal cancer

This study was conducted in the Kaiser Permanente Medical Care Program of Northern California to identify patient characteristics that explain interest in flexible sigmoidoscopy (FS) screening. A mailed screening invitation to 6837 age-eligible patients elicited responses from 49%. Efforts to reach and interview both eligible respondents and non-respondents resulted in 2728 computer-assisted telephone interviews (CATI), with 60% indicating interest in FS screening. Five components of the Integrated Behavioral Model were measured with respect to FS screening: attitude, affect, social influence, facilitators/barriers, and perceived risk of colorectal cancer. All five model components were significantly and independently associated with interest in FS, with patient attitude being the strongest predictor. Of the 32 items comprising the model components, nine items having the highest correlations with FS interest were identified as potentially important issues to address by efforts to increase interest in screening. Six of these were attitudinal beliefs. The findings from this theory-driven study provide specific targets for the design of interventions to increase FS interest and screening rates.

Cancer-attributable costs of diagnosis and care for persons with screen-detected versus symptom-detected colorectal cancer

BACKGROUND & AIMS

Colorectal cancer screening is effective and cost-effective, but little data from health plan settings are available inform decision-makers regarding direct economic implications of colorectal cancer screening programs. The purpose of this study was to compare the prediagnosis evaluation and first-year treatment costs of persons diagnosed with colorectal cancer, stratified by whether the cancer was detected by screening using fecal occult blood testing or evaluation of symptoms.

METHODS

This retrospective study analyzed persons diagnosed with colorectal cancer from 1993 to 1999 in Group Health Cooperative, a large health maintenance organization in Washington state. Total health care costs during 3 months before and 12 months following diagnosis were compared for screen-detected versus symptom-detected individuals.

RESULTS

During this time, 206 cancers were detected by screening and 717 by symptoms. In the 3 months before diagnosis, total costs were 7346 US dollars for persons with screen-detected versus 10,042 US dollars for those with symptom-detected cancer (P < 0.01). Stratified by stage, diagnosis costs were significantly lower for persons with stage B cancer (7282 US dollars vs. 11,682 US dollars ; P < 0.01) and nonsignificantly lower for other stages. A total of 53% of screen-detected cases were Dukes' stage A or in situ at diagnosis versus 30% of symptom-detected cases (P < 0.01). Overall costs were lower for the screen-detected group in the 12 months following diagnosis (22,369 US dollars vs. 29,471 US dollars; P < 0.01).

CONCLUSIONS

Colorectal cancer screening can substantially reduce prediagnosis evaluation costs. These savings are of interest to health plans and should be factored into cost-effectiveness evaluations of screening programs.

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.

Long-term efficacy of sigmoidoscopy in the reduction of colorectal cancer incidence

Screening sigmoidoscopy is associated with a reduction in both the incidence and mortality of colorectal cancer. Although current guidelines recommend sigmoidoscopy screening every 5 years, the duration of risk reduction is not known. We conducted a population-based case-control study to examine the association between sigmoidoscopy screening and colorectal cancer incidence. We collected information on screening history and risk factors from case patients with distal (n = 1026) and proximal (n = 642) colorectal cancer and from 1294 control subjects from October 1998 through February 2002. Screening sigmoidoscopy was associated with a statistically significant reduction in the incidence of distal colorectal cancer (odds ratio [OR] = 0.24, 95% confidence interval [CI] = 0.17 to 0.33). These reductions were sustained for up to 16 years with little attenuation. We also observed strong inverse associations between cancer incidence and sigmoidoscopy in analyses that included subjects with symptom-related tests. Current recommendations regarding the frequency of sigmoidoscopy screening may be unnecessarily aggressive.

Colorectal cancer screening: scientific review

CONTEXT

Screening for colorectal cancer clearly reduces colorectal cancer mortality, yet many eligible adults remain unscreened. Several screening tests are available, and various professional organizations have differing recommendations on which screening test to use. Clinicians are challenged to ensure that eligible patients undergo colorectal cancer screening and to guide patients in choosing what tests to receive.

OBJECTIVE

To critically assess the evidence for use of the available colorectal cancer screening tests, including fecal occult blood tests, sigmoidoscopy, colonoscopy, double-contrast barium enema, and newer tests, such as virtual colonoscopy and stool-based molecular screening.

DATA SOURCES

All relevant English-language articles were identified using PubMed (January 1966-August 2002), published meta-analyses, reference lists of key articles, and expert consultation.

DATA EXTRACTION

Studies that evaluated colorectal cancer screening in healthy individuals and assessed clinical outcomes were included. Evidence from randomized controlled trials was considered to be of highest quality, followed by observational evidence. Diagnostic accuracy studies were evaluated when randomized controlled trials and observational studies were not available or did not provide adequate evidence. Studies were excluded if they did not evaluate colorectal screening tests and if they did not evaluate average-risk individuals.

DATA SYNTHESIS

Randomized controlled trials have shown that fecal occult blood testing can reduce colorectal cancer incidence and mortality. Case-control studies have shown that sigmoidoscopy is associated with a reduction in mortality, and observational studies suggest colonoscopy is effective as well. Combining fecal occult blood testing and sigmoidoscopy may decrease mortality and can increase diagnostic yield.

CONCLUSION

The recommendation that all men and women aged 50 years or older undergo screening for colorectal cancer is supported by a large body of direct and indirect evidence. At present, the available evidence does not currently support choosing one test over another.

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.

Flexible sigmoidoscopy for colorectal cancer screening: valid approach or short-sighted?

Flexible sigmoidoscopy is a safe, effective test that may be delivered feasibly on a large scale for mass colorectal cancer screening. Flexible sigmoidoscopy is 67% to 80% as sensitive as colonoscopy in a screening population, but is probably 10 to 20 times safer than colonoscopy in terms of complications. Several national guidelines recommend combining flexible sigmoidoscopy with fecal occult blood tests. There is limited evidence to support this practice, and the added benefit to an existing flexible sigmoidoscopy screening program although real, may be marginal. In the future, it is likely that flexible sigmoidoscopy screening among patients aged 50 to 65 will be supplemented with total colonic screening, using molecular-based fecal tests or virtual colonoscopy, after age 65.

Compliance and findings in a Swedish population screened for colorectal cancer with sigmoidoscopy

AIM

The aim of this study was to evaluate the patterns of compliance and the frequency of adenomas and neoplasms in a Swedish population.

METHODS

In 1996, 2000 men and women born in 1935 or 1936 were selected at random from the population registers of Uppsala and Malmö/Lund. All subjects were invited by mail to participate. In a randomised study design, subjects were either called up by a nurse to schedule the appointment for sigmoidoscopy or instructed to call themselves. At sigmoidoscopy subjects with a cancer, an adenoma (neoplastic polyp) or more than three hyperplastic polyps were scheduled for a complete colonoscopy.

RESULTS

Thirty-nine percent (770/1988) of all the invited subjects had a sigmoidoscopy. The participation differed between the two centres, 47% at the Uppsala centre and 30% at the Malmö/Lund centre (P<0.01). There was no statistically significant difference between the two different invitation groups. In all, 98 subjects (13%) were planned for colonoscopy. Thirty-one (35%) of the subjects having a colonoscopy were women and 57 (65%) were men. Fifty-five true adenomas were found in 46 subjects. All together, six subjects had proximal adenomas. Five adenocarcinomas were diagnosed, all within the reach of the sigmoidoscope.

CONCLUSIONS

The compliance was lower and the adenomas were fewer than expected. To increase compliance it is necessary with rigorously controlled invitation routines.

Complications of screening flexible sigmoidoscopy

BACKGROUND & AIMS

Flexible sigmoidoscopy (FS) is recommended for mass screening for colorectal cancer (CRC), yet little is known about the risk of adverse events when FS is used in general clinical practice. We aimed to determine the incidence of gastrointestinal complications and acute myocardial infarction (MI) after screening FS.

METHODS

Northern California Kaiser Permanente Medical Care Program members of average risk for CRC (n = 107,704) who underwent screening FS during 1994 to 1996 (109,534 FS), as part of the Colorectal Cancer Prevention (CoCaP) program. The main outcome measure was hospitalization for gastrointestinal complications or acute MI within 4 weeks of FS.

RESULTS

The mean age of subjects was 61 years, and 48.8% were female. Nongastroenterologist physicians, nurses, or physician assistants performed 72% of FS. Overall, 24 persons were hospitalized for a gastrointestinal complication. Of these, 7 were serious (2 perforations, 2 episodes of diverticulitis requiring surgery, 2 cases of bleeding requiring transfusion, and 1 episode of unexplained colitis). In multivariate models, complications were significantly more common in men than in women (odds ratio, 3.34; 95% confidence interval [CI], 1.34-10.13). MI occurred in 33 persons within 4 weeks of FS, but the incidence for this period was similar to that in the subsequent 48 weeks (rate ratio, 0.8; 95% CI, 0.6-1.2).

CONCLUSIONS

The risk of serious complications after screening FS in this setting appears to be modest. Although MI occurs after FS, the risk during the 4 weeks after the procedure appears to be similar to expectations for persons of screening age.

Colorectal polyps in the elderly: what should be done?

Colorectal cancer is an important cause of morbidity and mortality among Western nations, and is more common in the elderly than in younger individuals. With the general acceptance of the adenoma-carcinoma sequence, the current consideration is that colorectal cancer is preventable if all adenomas are removed before they have the chance to progress to cancer. To that end, physicians should now advocate screening for colorectal cancer and through this effort a large number of patients with adenomatous polyps will be discovered. It is important to understand the strategy in dealing with this growing population of patients with adenomas. After an initial polypectomy, patients with adenomas should be entered into a surveillance program to detect and remove recurrent adenomas. Recommended surveillance intervals are shorter for patients with a family history of colorectal cancer, those with multiple adenomas (>2), large adenomas (> or = 1cm), or those whose adenomas have high-grade dysplasia, villous architecture, or that are cancerous. Effective chemoprevention would be a potential method of lengthening colonoscopic surveillance intervals. Unfortunately, no treatment has been found to be effective enough to alter our current surveillance practice. The only recommendation that can be made at this time for those patients with a history of colonic adenomas is to add 3 g/day of calcium carbonate to their diet, though its effect on adenoma recurrence is modest.

Colonoscopy as a screening test for colorectal cancer in average-risk individuals

Screening for colorectal cancer has become the standard of care and is currently recommended by most major health organizations, including the American Cancer Society. Randomized controlled trials using fecal occult blood testing as the screening strategy have shown a reduction in mortality due to colorectal cancer. However, colorectal cancer differs from other cancers in that a variety of screening tests have been approved and recommended by experts. The advantages and disadvantages of different screening tests have been the subject of intense debate. Colonoscopy has theoretical advantages over other screening tests, including direct visualization of the entire colon and, more importantly, removal of precancerous adenomatous lesions. This review discusses the advantages and disadvantages of colonoscopy as a screening test for colorectal cancer with regard to efficacy, cost-effectiveness, and patient compliance.

Colonoscopy and polypectomy

Colonoscopy and polypectomy, when performed by adequately trained physicians, is a safe and effective procedure that can decrease deaths resulting from colorectal cancer.