Screening and surveillance for the early detection of colorectal cancer and adenomatous polyps, 2008: a joint guideline from the American Cancer Society, the US Multi-Society Task Force on Colorectal Cancer, and the American College of Radiology

Understanding differences in the guidelines for colorectal cancer screening

In this issue of Gastroenterology, the editors present 2 expert perspectives on the colorectal screening guidelines published in the May 2008 issue of the journal.

Prevalence and correlates of skin cancer screening among middle-aged and older white adults in the United States

BACKGROUND

Total skin examinations performed by a physician have the potential to identify skin cancers at an early stage, when they are most amenable to successful treatment. This study examined the prevalence rates of, and factors associated with, receipt of a total skin examination by a dermatologist or other doctor during the past year.

METHODS

The participants were 10,486 white men and women aged 50 years and older drawn from a random sample of 31,428 adults aged 18 years and older who took part in the 2005 National Health Interview Survey. The data were collected via in-person interviews, and participants answered questions about their receipt of total skin examinations, their demographic characteristics, health and health care access, receipt of other cancer screenings, and personal and family history of skin cancer.

RESULTS

Sixteen percent of men and 13% of women reported having a skin examination in the past year. The factors associated with lowest skin examination rates in multivariable analyses included younger age (50-64 years), lower education level, lack of screening for colorectal, breast (women only), and prostate cancers (men only), and lack of a personal history of skin cancer.

CONCLUSIONS

Rates of having a skin examination in the past year were low among men and women and among all sub-groups. Systematic efforts are needed to increase screening rates among higher risk individuals. Physicians should be particularly aware of the need to consider skin cancer screening examinations for their male, elderly patients, as well as individuals with less education.

CT colonography after metallic stent placement for acute malignant colonic obstruction

PURPOSE

To evaluate the feasibility of using computed tomographic (CT) colonography for preoperative examination of the proximal colon after metallic stent placement in patients with acute colon obstruction caused by colorectal cancer.

MATERIALS AND METHODS

Institutional review board approval was obtained, and patient informed consent was waived. Fifty patients (mean age +/- standard deviation, 58.5 years +/- 11.7), who demonstrated no postprocedural complication after successful placement of self-expandable metallic stents to treat acute colon obstruction caused by cancer, underwent CT colonography 1-43 days (median, 5 days) after stent placement. CT colonography was performed after cathartic preparation by using magnesium citrate (n = 20) or sodium phosphate (n = 3), combined with oral bisacodyl, or by using polyethylene glycol (n = 27). Fecal/fluid tagging was achieved by using 100 mL of meglumine diatrizoate. The colon was distended by means of pressure-monitored CO(2) insufflation. The sensitivity and specificity of CT colonography in evaluating the colon proximal to the stent and CT colonography-related complications were assessed. The 95% confidence intervals (CIs) were calculated for proportional data.

RESULTS

Per-lesion and per-patient sensitivities of CT colonography for lesions 6 mm or larger in diameter in the colon proximal to the stent were 85.7% (12 of 14 lesions; 95% CI: 58.8%, 97.2%) and 90% (nine of 10 patients; 95% CI: 57.4%, 99.9%), respectively. CT colonography depicted all synchronous cancers (two lesions) and advanced adenomas (five lesions). Per-patient specificity for lesions 6 mm and larger in the proximal colon was 85.7% (18 of 21 patients; 95% CI: 64.5%, 95.9%). CT colonography did not generate any false diagnosis of synchronous cancer. False-positive findings at CT colonography did not result in a change in surgical plan for any patients. No CT colonography-associated stent dislodgment/migration or colonic perforation occurred in any patient (95% CI: 0%, 6.2%).

CONCLUSION

CT colonography is a safe and useful method for preoperative examination of the proximal colon after metallic stent placement in patients with acute colon obstruction caused by cancer. (c) RSNA, 2010.

CT colonography: advanced computer-aided detection scheme utilizing MTANNs for detection of "missed" polyps in a multicenter clinical trial

PURPOSE

The purpose of this study was to develop an advanced computer-aided detection (CAD) scheme utilizing massive-training artificial neural networks (MTANNs) to allow detection of "difficult" polyps in CT colonography (CTC) and to evaluate its performance on false-negative (FN) CTC cases that radiologists "missed" in a multicenter clinical trial.

METHODS

The authors developed an advanced CAD scheme consisting of an initial polyp-detection scheme for identification of polyp candidates and a mixture of expert MTANNs for substantial reduction in false positives (FPs) while maintaining sensitivity. The initial polyp-detection scheme consisted of (1) colon segmentation based on anatomy-based extraction and colon-based analysis and (2) detection of polyp candidates based on a morphologic analysis on the segmented colon. The mixture of expert MTANNs consisted of (1) supervised enhancement of polyps and suppression of various types of nonpolyps, (2) a scoring scheme for converting output voxels into a score for each polyp candidate, and (3) combining scores from multiple MTANNs by the use of a mixing artificial neural network. For testing the advanced CAD scheme, they created a database containing 24 FN cases with 23 polyps (range of 6-15 mm; average of 8 mm) and a mass (35 mm), which were "missed" by radiologists in CTC in the original trial in which 15 institutions participated.

RESULTS

The initial polyp-detection scheme detected 63% (15/24) of the missed polyps with 21.0 (505/24) FPs per patient. The MTANNs removed 76% of the FPs with loss of one true positive; thus, the performance of the advanced CAD scheme was improved to a sensitivity of 58% (14/24) with 8.6 (207/24) FPs per patient, whereas a conventional CAD scheme yielded a sensitivity of 25% at the same FP rate (the difference was statistically significant).

CONCLUSIONS

With the advanced MTANN CAD scheme, 58% of the polyps missed by radiologists in the original trial were detected and with a reasonable number of FPs. The results suggest that the use of an advanced MTANN CAD scheme may potentially enhance the detection of "difficult" polyps.

Performance of CT colonography for detecting small, diminutive, and flat polyps

The primary goal of colorectal cancer screening and prevention is the detection and removal of advanced neoplasia. Computerized tomography (CT) colonography is now well established as an effective screening test. Areas of greater uncertainty include the performance characteristics of CT colonography for detecting small (6-9 mm), diminutive (< or =5 mm), and flat (nonpolypoid) lesions. However, the actual clinical relevance of small, diminutive, and flat polyps has also been the source of debate. This article addresses these controversial and often misunderstood issues.

Colonoscopy screening for individuals aged 40-49 years with a family history of stomach cancer in Korea

BACKGROUND

For asymptomatic individuals aged 40-49 years, screening for colorectal cancer is recommended only if individuals are at an increased risk. A family history of colon cancer (FHCRC) is considered to increase risk, however, whether family history of stomach cancer (FHSC) increases the risk of adenoma is not well known. We aimed to see whether FHSC increases the risk in asymptomatic individuals aged 40-49 years in Korea.

METHODS

Among asymptomatic individual aged 40-49 years who underwent colonoscopy screening, risk of adenoma was assessed according to FHCRC or FHSC.

RESULTS

Of 3,160 individuals, male comprised 1,602 individuals (50.7%). FHCRC and FHSC was noticed in 163 (5.2%) and 227 (7.0%) individuals, respectively. Prevalence of adenoma was 31.9 %, 28.8%, and 22.3% for individuals with FHCRC, individuals with FHSC, and individuals without family history of cancer, respectively. FHSC was an independent risk factor for adenoma (odds ratio, 1.38; 95% confidence interval, 1.02-1.87, P = 0.039) in asymptomatic individuals aged 40-49 years. Compared with individuals with FHCRC, individuals with FHSC showed no difference in risk for adenoma (P = 0.347).

CONCLUSIONS

As with individuals with FHCRC, individuals with FHSC might need to be considered as an individual with increased risk for adenoma. Therefore, earlier screening might be needed for asymptomatic individuals aged 40-49 years with FHSC in Korea.

The role of CT colonography in a colorectal cancer screening program

Computed tomography colonography (CTC) has the potential to become a major component of colorectal cancer (CRC) screening programs and to have a significant effect on CRC prevention. This article describes the potential role of CTC within the framework of colorectal cancer screening. Current screening recommendations and traditional screening tests are reviewed, followed by a summary of recent study results on the use of CTC as a screening tool. Several factors that are affecting the acceptance and adoption of CTC are outlined. Although CTC is valuable and holds considerable promise as a way to increase the use of CRC screening, these issues need to be addressed before CTC becomes more widely disseminated as a screening modality.

Computer-aided Detection in Computed Tomography Colonography with Full Fecal Tagging: Comparison of Standalone Performance of 3 Automated Polyp Detection Systems

Purpose

We sought to compare the performance of 3 computer-aided detection (CAD) polyp algorithms in computed tomography colonography (CTC) with fecal tagging.

Methods

CTC data sets of 33 patients were retrospectively analysed by 3 different CAD systems: system 1, MedicSight; system 2, Colon CAD; and system 3, Polyp Enhanced View. The polyp database comprised 53 lesions, including 6 cases of colorectal cancer, and was established by consensus reading and comparison with colonoscopy. Lesions ranged from 6-40 mm, with 25 lesions larger than 10 mm in size. Detection and false-positive (FP) rates were calculated.

Results

CAD systems 1 and 2 could be set to have varying sensitivities with higher FP rates for higher sensitivity levels. Sensitivities for system 1 ranged from 73%–94% for all lesions (78%–100% for lesions ≥10 mm) and, for system 2, from 64%–94% (78%–100% for lesions ≥10 mm). System 3 reached an overall sensitivity of 76% (100% for lesions ≥10 mm). The mean FP rate per patient ranged from 8–32 for system 1, from 1–8 for system 2, and was 5 for system 3. At the highest sensitivity level for all polyps (94%), system 2 showed a statistically significant lower FP rate compared with system 1 ( P = .001). When analysing lesions ≥10 mm, system 3 had significantly fewer FPs than systems 1 and 2 ( P < .012).

Conclusions

Standalone CTC-CAD analysis in the selected patient collective showed the 3 systems tested to have a variable but overall promising performance with respect to sensitivity and the FP rate.

CT colonography: perforation rates and potential radiation risks

Computed tomographic colonography (CTC) has emerged as an alternative screening tool for colorectal cancer due to the potential to provide good efficacy combined with greater acceptability than optical colonoscopy or fecal occult blood testing. However, some organizations have raised concerns about the potential harms, including perforation rates and radiation-related cancer risks, and have not recommended that it currently be used as a screening tool in the general population in the US. In this article the authors review the current evidence for these potential harms from CTC and compare them to the potential harms from the alternatives including colonoscopy and double-contrast barium enema.

Establishing a CT colonography service

This article describes the steps involved in establishing a screening computed tomographic colonography (CTC) practice and integrating that practice within a gastroenterology practice. The standard operating procedures followed at the National Naval Medical Center's Colon Health Initiative are presented and are followed by a discussion of practical aspects of establishing a CTC practice, such as equipment specifications, CTC performance, and interpretation training requirements for radiologists and nonradiologists. Regulatory considerations involved in establishing a screening CTC program are examined along with the salient features of a CTC business plan. Finally, reimbursement issues, quality control, and the potential impact of screening CTC on colonoscopy practice are discussed.

Impact of gene patents and licensing practices on access to genetic testing for inherited susceptibility to cancer: comparing breast and ovarian cancers with colon cancers

Genetic testing for inherited susceptibility to breast and ovarian cancer can be compared with similar testing for colorectal cancer as a "natural experiment." Inherited susceptibility accounts for a similar fraction of both cancers and genetic testing results guide decisions about options for prophylactic surgery in both sets of conditions. One major difference is that in the United States, Myriad Genetics is the sole provider of genetic testing, because it has sole control of relevant patents for BRCA1 and BRCA2 genes, whereas genetic testing for familial colorectal cancer is available from multiple laboratories. Colorectal cancer-associated genes are also patented, but they have been nonexclusively licensed. Prices for BRCA1 and 2 testing do not reflect an obvious price premium attributable to exclusive patent rights compared with colorectal cancer testing, and indeed, Myriad's per unit costs are somewhat lower for BRCA1/2 testing than testing for colorectal cancer susceptibility. Myriad has not enforced patents against basic research and negotiated a Memorandum of Understanding with the National Cancer Institute in 1999 for institutional BRCA testing in clinical research. The main impact of patenting and licensing in BRCA compared with colorectal cancer is the business model of genetic testing, with a sole provider for BRCA and multiple laboratories for colorectal cancer genetic testing. Myriad's sole-provider model has not worked in jurisdictions outside the United States, largely because of differences in breadth of patent protection, responses of government health services, and difficulty in patent enforcement.

Radiation safety in abdominal computed tomography

The rapid technological developments in computed tomography (CT) have enabled many new clinical applications in the abdominal region. Abdomen CT is considered as a high radiation dose examination due to the large number of radiosensitive organs in the field of view. CT radiation dose has received a lot of attention not only by the medical specialties and researchers, but also by patients and media. This article reviews the situation on radiation dose and risk and provides practical guidelines to effectively manage the radiation dose without losing the benefits and maintaining diagnostic confidence in CT procedures.

What determines individuals' preferences for colorectal cancer screening programmes? A discrete choice experiment

INTRODUCTION

In many countries uptake of colorectal cancer (CRC) screening remains low.

AIM

To assess how procedural characteristics of CRC screening programmes determine preferences for participation and how individuals weigh these against the perceived benefits from participation in CRC screening.

METHODS

A discrete choice experiment was conducted among subjects in the age group of 50-75 years, including both screening-naïve subjects and participants of a CRC screening programme. Subjects were asked on their preferences for aspects of CRC screening programmes using scenarios based on pain, risk of complications, screening location, preparation, duration of procedure, screening interval and risk reduction of CRC-related death.

RESULTS

The response was 31% (156/500) for screening-naïve and 57% (124/210) for CRC screening participants. All aspects proved to significantly influence the respondents' preferences. For both groups combined, respondents required an additional relative risk reduction of CRC-related death by a screening programme of 1% for every additional 10 min of duration, 5% in order to expose themselves to a small risk of complications, 10% to accept mild pain, 10% to undergo preparation with an enema, 12% to use 0.75l of oral preparation combined with 12h fasting and 32% to use an extensive bowel preparation. Screening intervals shorter than 10 years were significantly preferred to a 10-year screening interval.

CONCLUSION

This study shows that especially type of bowel preparation, risk reduction of CRC related death and length of screening interval influence CRC screening preferences. Furthermore, improving awareness on CRC mortality reduction by CRC screening may increase uptake.

Preferences for colorectal cancer screening strategies: a discrete choice experiment

Background:

Guidelines underline the role of individual preferences in the selection of a screening test, as insufficient evidence is available to recommend one screening test over another. We conducted a study to determine the preferences of individuals and to predict uptake for colorectal cancer (CRC) screening programmes using various screening tests.

Methods:

A discrete choice experiment (DCE) questionnaire was distributed among naive subjects, yet to be screened, and previously screened subjects, aged 50–75 years. Subjects were asked to choose between scenarios on the basis of faecal occult blood test (FOBT), flexible sigmoidoscopy (FS), total colonoscopy (TC) with various test-specific screening intervals and mortality reductions, and no screening (opt-out).

Results:

In total, 489 out of 1498 (33%) screening-naïve subjects (52% male; mean age±s.d. 61±7 years) and 545 out of 769 (71%) previously screened subjects (52% male; mean age±s.d. 61±6 years) returned the questionnaire. The type of screening test, screening interval, and risk reduction of CRC-related mortality influenced subjects’ preferences (all P<0.05). Screening-naive and previously screened subjects equally preferred 5-yearly FS and 10-yearly TC (P=0.24; P=0.11), but favoured both strategies to annual FOBT screening (all P-values <0.001) if, based on the literature, realistic risk reduction of CRC-related mortality was applied. Screening-naive and previously screened subjects were willing to undergo a 10-yearly TC instead of a 5-yearly FS to obtain an additional risk reduction of CRC-related mortality of 45% (P<0.001).

Conclusion:

These data provide insight into the extent by which interval and risk reduction of CRC-related mortality affect preferences for CRC screening tests. Assuming realistic test characteristics, subjects in the target population preferred endoscopic screening over FOBT screening, partly, due to the more favourable risk reduction of CRC-related mortality by endoscopy screening. Increasing the knowledge of potential screenees regarding risk reduction by different screening strategies is, therefore, warranted to prevent unrealistic expectations and to optimise informed choice.

A retrograde-viewing device improves detection of adenomas in the colon: a prospective efficacy evaluation (with videos)

BACKGROUND

Colonoscopy may fail to detect neoplasia located on the proximal sides of haustral folds and flexures. The Third Eye Retroscope (TER) provides a simultaneous retrograde view that complements the forward view of a standard colonoscope.

OBJECTIVE

To evaluate the added benefit for polyp detection during colonoscopy of a retrograde-viewing device.

DESIGN

Open-label, prospective, multicenter study evaluating colonoscopy by using a TER in combination with a standard colonoscope.

SETTING

Eight U.S. sites, including university medical centers, ambulatory surgery centers, a community hospital, and a physician's office.

PATIENTS

A total of 249 patients (age range 55-80 years) presenting for screening or surveillance colonoscopy.

INTERVENTIONS

After cecal intubation, the disposable TER was inserted through the instrument channel of the colonoscope. During withdrawal, the forward and retrograde video images were observed simultaneously on a wide-screen monitor.

MAIN OUTCOME MEASUREMENTS

The number and sizes of lesions (adenomas and all polyps) detected with the standard colonoscope and the number and sizes of lesions found only because they were first detected with the TER.

RESULTS

In the 249 subjects, 257 polyps (including 136 adenomas) were identified with the colonoscope alone. The TER allowed detection of 34 additional polyps (a 13.2% increase; P < .0001) including 15 additional adenomas (an 11.0% increase; P < .0001). For lesions 6 mm or larger, the additional detection rates with the TER for all polyps and for adenomas were 18.2% and 25.0%, respectively. For lesions 10 mm or larger, the additional detection rates with the TER for all polyps and for adenomas were 30.8% and 33.3%, respectively. In 28 (11.2%) individuals, at least 1 additional polyp was found with the TER. In 8 (3.2%) patients, the polyp detected with the TER was the only one found. Every polyp that was detected with the TER was subsequently located with the colonoscope and removed. For all polyps and for adenomas, the additional detection rates for the TER were 9.7%/4.1% in the left colon (the splenic flexure to the rectum) and 16.5%/14.9% in the right colon (the cecum to the transverse colon), respectively.

LIMITATIONS

There was no randomization or comparison with a separate control group.

CONCLUSIONS

A retrograde-viewing device revealed areas that were hidden from the forward-viewing colonoscope and allowed detection of 13.2% additional polyps, including 11.0% additional adenomas. Additional detection rates with the TER for adenomas 6 mm or larger and 10 mm or larger were 25.0% and 33.3%, respectively. (

CLINICAL TRIAL REGISTRATION NUMBER

NCT00657371.).

Labeled versus unlabeled discrete choice experiments in health economics: an application to colorectal cancer screening

OBJECTIVES

Discrete choice experiments (DCEs) in health economics commonly present choice sets in an unlabeled form. Labeled choice sets are less abstract and may increase the validity of the results. We empirically compared the feasibility, respondents' trading behavior, and convergent validity between a labeled and an unlabeled DCE for colorectal cancer (CRC) screening programs in The Netherlands.

METHODS

A labeled DCE version presented CRC screening test alternatives as "fecal occult blood test,""sigmoidoscopy," and "colonoscopy," whereas the unlabeled DCE version presented them as "screening test A" and "screening test B." Questionnaires were sent to participants and nonparticipants in CRC screening.

RESULTS

Total response rate was 276 (39%) out of 712 and 1033 (46%) out of 2267 for unlabeled and labeled DCEs, respectively (P<0.001). The labels played a significant role in individual choices; approximately 22% of subjects had dominant preferences for screening test labels. The convergent validity was modest to low (participants in CRC screening: r=0.54; P=0.01; nonparticipants: r=0.17; P=0.45) largely because of different preferences for screening frequency.

CONCLUSION

This study provides important insights in the feasibility and difference in results from labeled and unlabeled DCEs. The inclusion of labels appeared to play a significant role in individual choices but reduced the attention respondents give to the attributes. As a result, unlabeled DCEs may be more suitable to investigate trade-offs between attributes and for respondents who do not have familiarity with the alternative labels, whereas labeled DCEs may be more suitable to explain real-life choices such as uptake of cancer screening.

Low risk of colorectal cancer and advanced adenomas more than 10 years after negative colonoscopy

BACKGROUND & AIMS

Screening colonoscopy is an effective method to reduce the incidence of and mortality from colorectal cancer (CRC). There is little empirical evidence available about the optimal interval for screening, making this a subject of debate. We associated the prevalence of advanced colorectal neoplasms with time since negative colonoscopies.

METHODS

In a study of participants in the German colonoscopy screening program, we determined the prevalence of colorectal neoplasias detected at screening colonoscopy among subjects who had undergone a previous colonoscopy without detection of polyps (negative colonoscopy). Data were compared with that from subjects who had not received colonoscopies.

RESULTS

No CRCs were detected in participants who had a previous negative colonoscopy an average of 11.9 years previously (n = 553), compared with the 8.4 CRC cases expected based on age- and gender-specific prevalences among participants who had not received a colonoscopy (n = 2701; standardized prevalence ratio [SPR] = 0.00; 95% confidence interval [CI]: 0.00-0.55). Prevalence of advanced adenoma was also much lower among subjects who had previous colonoscopies (SPR = 0.42; 95% CI: 0.25-0.68). Adjusted prevalence ratios (95% CIs) for detecting an advanced adenoma were 0.38 (95% CI: 0.16-0.90), 0.34 (95% CI: 0.15-0.74), 0.38 (95% CI: 0.16-0.90), and 0.53 (95% CI: 0.27-1.04) among participants with a negative colonoscopy conducted 1-5, 6-10, 11-15, and >16 years ago, respectively, compared to participants with no previous colonoscopy.

CONCLUSIONS

The low risk of CRC and advanced adenomas after a negative colonoscopy supports suggestions that screening intervals be extended to > or =10 years.

Impact of experience with a retrograde-viewing device on adenoma detection rates and withdrawal times during colonoscopy: the Third Eye Retroscope study group

BACKGROUND

Colonoscopy has been adopted as the preferred method to screen for colorectal neoplasia in the United States. However, lesions can be missed because of numerous factors, including location on the proximal aspect of folds or flexures, where they may be difficult to detect with the forward-viewing colonoscope. The Third Eye Retroscope (TER) is a disposable device that is passed through the instrument channel of a standard colonoscope to provide a retrograde view that complements the forward view of the colonoscope during withdrawal.

OBJECTIVE

To evaluate whether experience with the TER affects polyp detection rates and procedure times in experienced endoscopists who had not previously used the equipment.

DESIGN, SETTING, PATIENTS

This was an open-label, prospective, multicenter study at 9 U.S. sites, involving 298 patients presenting for colonoscopy, evaluating the use of the TER in combination with a standard colonoscope.

INTERVENTIONS

After cecal intubation, the TER was inserted through the instrument channel of the colonoscope. During withdrawal, the forward and retrograde video images were observed simultaneously on a wide-screen monitor.

MAIN OUTCOME MEASUREMENTS

Primary outcome measures were the number and size of adenomas and all polyps detected with the standard colonoscope and with the colonoscope combined with the TER. Secondary outcome measures were withdrawal phase time and total procedure time. Each endoscopist examined 20 subjects, divided into quartiles according to the order of their procedures, and results were compared among quartiles.

RESULTS

Overall, 182 polyps were detected with the colonoscope and 27 additional polyps with the TER, a 14.8% increase (P < .001). A total of 100 adenomas were detected with the colonoscope and 16 more with the TER, a 16.0% increase (P < .001). For procedures performed after each endoscopist had completed 15 procedures while using the TER, the mean additional detection rates with the TER were 17.0% for all polyps (P < .001) and 25.0% for adenomas (P < .001). For lesions 6 mm or larger, the overall additional detection rates with the TER for all polyps and for adenomas were 23.2% and 24.3%, respectively. For lesions 10 mm or larger, the overall additional detection rates with the TER for all polyps and for adenomas were 22.6% and 19.0%, respectively. The mean withdrawal times in the first and fourth quartiles were 10.6 and 9.2 minutes, respectively (P = .044).

LIMITATIONS

There was no randomization or separate control group. The endoscopists judged whether each lesion could have been detected with the colonscope alone by using their standard technique.

CONCLUSIONS

Polyp detection rates improved significantly with the TER, especially after 15 procedures, when the mean additional detection rate for adenomas was 25.0%. Additional detection rates with the TER for medium-size and large adenomas were greater than for smaller lesions. These results suggest that, compared with a colonoscope alone, a retrograde-viewing device can increase detection rates for clinically significant adenomas without detriment to procedure time or procedure complications. (

CLINICAL TRIAL REGISTRATION NUMBER

NCT00969124.).

Population-based family history-specific risks for colorectal cancer: a constellation approach

BACKGROUND & AIMS

Colorectal cancer (CRC) risk estimates based on family history typically include only close relatives. We report familial relative risk (FRR) in probands with various combinations, or constellations, of affected relatives, extending to third-degree.

METHODS

A population-based resource that includes a computerized genealogy linked to statewide cancer records was used to identify genetic relationships among CRC cases and their first-, second-, and third-degree relatives (FDRs, SDRs, and TDRs). FRRs were estimated by comparing the observed number of affected persons with a particular family history constellation to the expected number, based on cohort-specific CRC rates.

RESULTS

A total of 2,327,327 persons included in > or =3 generation family histories were analyzed; 10,556 had a diagnosis of CRC. The FRR for CRC in persons with > or =1 affected FDR = 2.05 (95% CI, 1.96-2.14), consistent with published estimates. In the absence of a positive first-degree family history, considering both affected SDRs and TDRs, only 1 constellation had an FRR estimate that was significantly >1.0 (0 affected FDRs, 1 affected SDR, 2 affected TDRs; FRR = 1.33; 95% CI, 1.13-1.55). The FRR for persons with 1 affected FDR, 1 affected SDR, and 0 affected TDRs was 1.88 (95% CI, 1.59-2.20), increasing to FRR = 3.28 (95% CI, 2.44-4.31) for probands with 1 affected FDR, 1 affected SDR, and > or =3 affected TDRs.

CONCLUSIONS

Increased numbers of affected FDRs influences risk much more than affected SDRs or TDRs. However, when combined with a positive first-degree family history, a positive second- and third-degree family history can significantly increase risk.

Healthy colon, healthy life (colon sano, vida sana): colorectal cancer screening among Latinos in Santa Clara, California

Colorectal cancer (CRC) screening rates are low among Latinos. To identify factors associated with CRC screening, we conducted a telephone survey of Latino primary care patients aged 50-79 years. Among 1,013 participants, 38% were up-to-date (UTD) with fecal occult blood test (FOBT); 66% were UTD with any CRC screening (FOBT, sigmoidoscopy, or colonoscopy). Individuals less than 65, females, those less acculturated, and patients of female physicians were more likely to be UTD with FOBT. CRC screening among Latinos is low. Younger patients, women, and patients of female physicians receive more screening.

Informed decision making changes test preferences for colorectal cancer screening in a diverse population

PURPOSE

We wanted to better understand patient preferences and decision making about options for colorectal cancer screening. Consistency in patient preferences could improve patient-clinician communication about tests by simplifying and focusing discussions.

METHODS

In a cross-sectional sample of primary care patients, cognitive ranking tasks were used to estimate patient preferences for fecal occult blood testing, flexible sigmoidoscopy, colonoscopy, and double-contrast barium enema before and after consideration of 13 test attributes, such as accuracy and scientific evidence. Patients also ranked the 13 test attributes and attribute descriptions in terms of importance. Friedman's nonparametric test was used to measure overall discrimination among items, and the average Pearson correlation coefficient (r) among participants was used to measure the degree of consistency in choices.

RESULTS

Participants (n = 168) averaged 62.1 years of age, and 64.3% were of minority racial ethnicity. For test-specific attributes, preferences were for high test accuracy (r = 0.63, P < .001), amount of colon examined (r = 0.64, P < .001), strong scientific evidence for efficacy (r = 0.59, P < .001), minimum discomfort (r = 0.50, P < .001), and low risk of complications (r = 0.38, P < .001). When all 13 attributes were considered together, agreement dropped (r = 0.13, P < .001), but attributes considered most important for decision making were test accuracy, scientific evidence for efficacy, amount of colon examined, and need for sedation. Test preferences showed moderate agreement (r = 0.20, P < .001), and choices were fairly consistent before and after exposure to test-specific attributes (kappa = 0.17, P = .007). Initially the modal choice was fecal occult blood testing (59%); however, after exposure to test specific attributes, the modal choice was colonoscopy (54%).

CONCLUSION

Participants were clear about the attributes that they prefer, but no single test has those attributes. Preferences were varied across participants and were not predictable; clinicians should discuss the full range of recommended tests for colorectal cancer with all patients.

Serious complications within 30 days of screening and surveillance colonoscopy are uncommon

BACKGROUND & AIMS

The risk of serious complications after colonoscopy has important implications for the overall benefits of colorectal cancer screening programs. We evaluated the incidence of serious complications within 30 days after screening or surveillance colonoscopies in diverse clinical settings and sought to identify potential risk factors for complications.

METHODS

Patients age 40 and over undergoing colonoscopy for screening, surveillance, or evaluation based an abnormal result from another screening test were enrolled through the National Endoscopic Database (CORI). Patients completed a standardized telephone interview approximately 7 and 30 days after their colonoscopy. We estimated the incidence of serious complications within 30 days of colonoscopy and identified risk factors associated with complications using logistic regression analyses.

RESULTS

We enrolled 21,375 patients. Gastrointestinal bleeding requiring hospitalization occurred in 34 patients (incidence 1.59/1000 exams; 95% confidence interval [CI], 1.10-2.22). Perforations occurred in 4 patients (0.19/1000 exams; 95% CI, 0.05-0.48), diverticulitis requiring hospitalization in 5 patients (0.23/1000 exams; 95% CI, 0.08-0.54), and postpolypectomy syndrome in 2 patients (0.09/1000 exams; 95% CI, 0.02-0.30). The overall incidence of complications directly related to colonoscopy was 2.01 per 1000 exams (95% CI, 1.46-2.71). Two of the 4 perforations occurred without biopsy or polypectomy. The risk of complications increased with preprocedure warfarin use and performance of polypectomy with cautery.

CONCLUSIONS

Complications after screening or surveillance colonoscopy are uncommon. Risk factors for complications include warfarin use and polypectomy with cautery.

Characterization of forces applied by endoscopists during colonoscopy by using a wireless colonoscopy force monitor

BACKGROUND

To perform a colonoscopy, the endoscopist maneuvers the colonoscope through a series of loops by applying force to the insertion tube. Colonoscopy insertion techniques are operator dependent but have never been comprehensively quantified.

OBJECTIVE

To determine whether the Colonoscopy Force Monitor (CFM), a device that continually measures force applied to the insertion tube, can identify different force application patterns among experienced endoscopists.

DESIGN

Observational study of 6 experienced endoscopists performing routine diagnostic and therapeutic colonoscopy in 30 patients.

SETTING

Outpatient ambulatory endoscopy center.

PATIENTS

Adult male and female patients between 30 and 75 years of age undergoing routine colonoscopy.

INTERVENTIONS

CFM monitoring of force applied to the colonoscope insertion tube during colonoscopy.

MAIN OUTCOME MEASUREMENTS

Maximum and mean linear and torque force, time derivative of force, combined linear and torque vector force, and total manipulation time.

RESULTS

The CFM demonstrates differences among endoscopists for maximum and average push/pull and mean torque forces, time derivatives of force, combined push/torque force vector, and total manipulation time. Endoscopists could be grouped by force application patterns.

LIMITATIONS

Only experienced endoscopists using conscious sedation in the patients were studied. Sample size was 30 patients.

CONCLUSIONS

This study demonstrates that CFM allows continuous force monitoring, characterization, and display of similarities and differences in endoscopic technique. CFM has the potential to facilitate training by enabling trainees to assess, compare, and quantify their techniques and progress.

Diagnosing cancer in the symptomatic patient

Finding cancer at its earliest, most treatable stage gives patients the greatest chance of survival. For a number of cancers, screening tests allow for early detection and treatment, and thereby, reduce cancer-related mortality. However, many cancers are discovered by symptomatic presentation rather than screening. This article addresses several symptoms commonly reported in the primary care setting, including rectal bleeding, a breast lump, cough, lymphadenopathy, and weight loss, and offers an evidence-based approach to the consideration and possibly the diagnosis of cancer.

An examination of the psychosocial factors influencing colorectal cancer patients' communication of colorectal cancer patient risk with their siblings

This study examined psychosocial factors influencing colorectal cancer (CRC) patients' communication with their first-degree relatives regarding their CRC risk. Among a sample of CRC patients who were members of a colon registry in New York (n = 127), 60% reported discussing CRC risk with their siblings. These discussions were related to the CRC patients' age of diagnosis, such that those diagnosed before age 45 years were more likely to communicate with their siblings about CRC risk. Despite advances made in CRC prevention, compliance with screening recommendations among individuals who may be at familial risk for the disease is low. Perhaps this underrepresentation reflects how CRC patients communicate with their first-degree relatives about their potential risk for the disease. This study examined the psychosocial factors influencing whether CRC patients communicate with their siblings about CRC risk. The sample included CRC patients with siblings who enrolled in a colon disease registry at a NYC metropolitan hospital. Participants completed questionnaires regarding their current psychosocial functioning, perceived risk of sibling's development of CRC, and communication of CRC risk with their siblings. Patients were predominantly Caucasian, with a mean age of 60.4 years. Of the 127 patients, 60% engaged in discussions with their siblings regarding their CRC risk. Patients diagnosed with CRC before the age of 45 years were more likely to discuss the risk of CRC with their siblings (P < 0.01). These data suggest that CRC patients may serve as an effective vehicle to promote CRC screening and support the need for health care providers to not only educate patients of the familial risk of CRC, but to also encourage these patients to communicate this information with their siblings.

A blood-based biomarker panel for stratifying current risk for colorectal cancer

Colorectal cancer (CRC) is often curable and preventable using current screening modalities. Unfortunately, screening compliance remains low, partly due to patient dissatisfaction with faecal/endoscopic testing. Recent guidelines advise CRC screening should begin with risk stratification. A blood-based test providing clinically actionable CRC risk information would likely improve screening compliance and enhance clinical decision making. We analyzed 196 gene expression profiles to select candidate CRC biomarkers. qRT-PCR was performed on 642 samples to develop a 7-gene biomarker panel using 112 CRC/120 controls (training set) and 202 CRC/208 controls (independent, blind test set). Panel performance characteristics and disease prevalence (0.7%) were then used to develop a scale assessing an individual's current risk of having CRC based on his/her gene signature. A 7-gene panel (ANXA3, CLEC4D, LMNB1, PRRG4, TNFAIP6, VNN1 and IL2RB) discriminated CRC in the training set (area under the receiver-operating-characteristic curve (ROC AUC), 0.80; accuracy, 73%; sensitivity, 82%; specificity 64%). The independent blind test set confirmed performance (ROC AUC, 0.80; accuracy, 71%; sensitivity, 72%; specificity, 70%). Individual gene profiles were compared against the population results and used to calculate the current relative risk for CRC. We have developed a 7-gene, blood-based biomarker panel that can stratify subjects according to their current relative risk across a broad range in an average-risk population. Across the continuous spectrum of risk as defined by the current relative risk scale, it is possible to identify clinically meaningful reference points that can assist patients and physicians in CRC screening decision making.

Protection from right- and left-sided colorectal neoplasms after colonoscopy: population-based study

BACKGROUND

Colonoscopy is used for early detection and prevention of colorectal cancer, but evidence on the magnitude of overall protection and protection according to anatomical site through colonoscopy performed in the community setting is sparse. We assessed whether receiving a colonoscopy in the preceding 10-year period, compared with no colonoscopy, was associated with prevalence of advanced colorectal neoplasms (defined as cancers or advanced adenomas) at various anatomical sites.

METHODS

A statewide cross-sectional study was conducted among 3287 participants in screening colonoscopy between May 1, 2005, and December 31, 2007, from the state of Saarland in Germany who were aged 55 years or older. Prevalence of advanced colorectal neoplasms was ascertained by screening colonoscopy and histopathologic examination of any polyps excised. Previous colonoscopy history was obtained by standardized questionnaire, and its association with prevalence of advanced colorectal neoplasms was estimated, after adjustment for potential confounding factors by log-binomial regression.

RESULTS

Advanced colorectal neoplasms were detected in 308 (11.4%) of the 2701 participants with no previous colonoscopy compared with 36 (6.1%) of the 586 participants who had undergone colonoscopy within the preceding 10 years. After adjustment, overall and site-specific adjusted prevalence ratios for previous colonoscopy in the previous 10-year period were as follows: overall, 0.52 (95% confidence interval [CI] = 0.37 to 0.73); cecum and ascending colon, 0.99 (95% CI = 0.50 to 1.97); hepatic flexure and transverse colon, 1.21 (95% CI = 0.60 to 2.42); right-sided colon combined (cecum to transverse colon), 1.05 (95% CI = 0.63 to 1.76); splenic flexure and descending colon, 0.36 (95% CI = 0.16 to 0.82); sigmoid colon, 0.29 (95% CI = 0.16 to 0.53); rectum, 0.07 (95% CI = 0.02 to 0.40); left colon and rectum combined (splenic flexure to rectum, referred to as left-sided elsewhere), 0.33 (95% CI = 0.21 to 0.53).

CONCLUSION

Prevalence of left-sided advanced colorectal neoplasms, but not right-sided advanced neoplasms, was strongly reduced within a 10-year period after colonoscopy, even in the community setting.

Secondary Prevention of Colorectal Cancer: Is There an Optimal Follow-up for Patients with Colorectal Cancer?

Secondary prevention of colorectal cancer, as opposed to primary prevention, indicates that a person has already had the disease and there are steps being taken to prevent cancer recurrence, usually as metachronous tumors. This generally involves annual surveillance with colonoscopy after surgical removal of the initial cancer if some aspect of the colon remains. However, some familial cases may involve other modalities, such as cyclooxygenase inhibitors, as an adjunct after the initial operation. Genetic testing in suspected familial cases may identify candidates for secondary prevention. The timing for secondary prevention is critical to prevent recurrent advanced disease, which is detrimental to patient survival. Recommendations are often empiric, but some cases are based on the biological behavior of the tumor. Close follow-up with a competent health care provider, such as a gastroenterologist, is necessary to help prevent recurrence.

CT colonography with decreased purgation: balancing preparation, performance, and patient acceptance

OBJECTIVE

Reduction or elimination of catharsis with fecal tagging enhances the tolerability of CT colonography (CTC) and may increase compliance with colorectal cancer (CRC) screening recommendations. We systematically reviewed studies that prospectively evaluated performance and patient satisfaction with decreased-purgation CTC and with optical colonoscopy.

CONCLUSION

The nine studies reviewed showed moderate-to-good performance for decreased-purgation CTC; however, data are limited, and study design and data presentation are inconsistent. Further study of decreased-purgation CTC and standardization of terminology are needed.

ACR Colon Cancer Committee white paper: status of CT colonography 2009

PURPOSE

To review the current status and rationale of the updated ACR practice guidelines for CT colonography (CTC).

METHODS

Clinical validation trials in both the United States and Europe are reviewed. Key technical aspects of the CTC examination are emphasized, including low-dose protocols, proper insufflation, and bowel preparation. Important issues of implementation are discussed, including training and certification, definition of the target lesion, reporting of colonic and extracolonic findings, quality metrics, reimbursement, and cost-effectiveness.

RESULTS

Successful validation trials in screening cohorts both in the United States with ACRIN and in Germany demonstrated sensitivity > or = 90% for patients with polyps >10 mm. Proper technique is critical, including low-dose techniques in screening cohorts, with an upper limit of the CT dose index by volume of 12.5 mGy per examination. Training new readers includes the requirement of interactive workstation training with 2-D and 3-D image display techniques. The target lesion is defined as a polyp > or = 6 mm, consistent with the American Cancer Society joint guidelines. Five quality metrics have been defined for CTC, with pilot data entered. Although the CMS national noncoverage decision in May 2009 was a disappointment, multiple third-party payers are reimbursing for screening CTC. Cost-effective modeling has shown CTC to be a dominant strategy, including in a Medicare cohort.

CONCLUSION

Supported by third-party payer reimbursement for screening, CTC will continue to further transition into community practice and can provide an important adjunctive examination for colorectal screening.

Noninvasive radiologic imaging of the large intestine: a valuable complement to optical colonoscopy

PURPOSE OF REVIEW

Radiologic imaging of the large intestine continues to evolve and expand the potential for noninvasive diagnosis. The aim of this review is to provide an update on current and emerging clinical capabilities for a variety of radiologic diagnostic imaging tools for evaluating the colon and rectum.

RECENT FINDINGS

The utility of computed tomography for the evaluation of symptomatic inflammatory and neoplastic conditions of the colon is well established, but the clinical role of computed tomography colonography is rapidly evolving. In addition to a number of diagnostic indications, computed tomography colonography is emerging as a potential frontline colorectal screening test for cancer prevention. MRI has become increasingly valuable for rectal cancer staging and inflammatory bowel disease but has yet to gain momentum for polyp evaluation. PET imaging has been primarily utilized for oncologic indications, but also holds considerable potential for inflammatory conditions. Other imaging modalities, such as the barium enema, conventional radiography, and ultrasound, play a much more limited role.

SUMMARY

Advances in radiologic imaging of the colorectum will continue to expand the capabilities and clinical indications for noninvasive diagnosis, allowing for a greater emphasis on the complementary roles of tissue sampling and therapy with optical colonoscopy.

Colorectal cancer screening barriers and facilitators in older persons

BACKGROUND

This systematic review identifies factors that are most consistently mentioned as either barriers to or facilitators of colorectal cancer (CRC) screening in older persons.

METHODS

A systematic literature search (1995-2008) was conducted to identify studies that reported barriers to or facilitators of CRC screening uptake, compliance or adherence specifically for older persons (> or = 65 years). Information on study characteristics and barriers and facilitators related to subjects; healthcare providers; policies; and screening tests were then abstracted and analyzed.

RESULTS

Eighty-three studies met the eligibility criteria. Low level of education, African American race, Hispanic ethnicity, and female gender were the most frequently reported barriers, whereas being married or living with a partner was the most frequently reported facilitator. The most cited barrier related to healthcare providers was lack of screening recommendation by a physician; having a usual source of care was a commonly reported facilitator. Lack of health insurance, and dual coverage with Medicare and Medicaid were the most frequently reported barriers, whereas Medicare's coverage of screening colonoscopy was consistently reported as a facilitator.

CONCLUSIONS

Barriers to, and facilitators of, CRC screening among older persons are reported. Particular attention should be paid to modifiable factors that could become the focus of interventions aimed at increasing CRC screening participation in older persons.

Cost effectiveness of CT colonography for UK NHS colorectal cancer screening of asymptomatic adults aged 60-69 years

BACKGROUND

Screening of populations at risk for colorectal cancer (CRC) allows the detection and successful treatment of tumours and their precursor polyps. The current UK CRC screening programme is faecal occult blood testing (FOBT), despite evidence from modelling studies to suggest that more cost-effective technologies exist.

OBJECTIVE

To assess the cost effectiveness of CT colonography (CTC) for colorectal cancer screening from the perspective of the UK NHS.

METHODS

A state-transition Markov model was constructed to estimate lifetime costs and health outcomes of a cohort of individuals screened at age 60-69 years using four different CRC screening technologies: FOBT, flexible sigmoidoscopy, optical colonoscopy and CTC.

RESULTS

CTC screening offered every 10 years was cost saving compared with the current UK programme of biennial FOBT screening. This strategy also yielded greater health benefits (QALYs and life-years) than biennial FOBT screening. The model fit observed CRC epidemiology data well and was robust to changes in underlying parameter values. CTC remained cost effective under a range of assumptions in the univariate sensitivity analysis. However, in the probabilistic sensitivity analysis, CTC dominated FOBT in only 5.9% of simulations and was cost effective at a threshold of pound30,000 per QALY gained in 48% of simulations.

CONCLUSIONS

CTC has the potential to provide a cost-effective option for CRC screening in the UK NHS and may be cost saving compared with the current programme of biennial FOBT. Further analysis is required to assess the impact of introducing CTC to the UK CRC screening programme on the NHS budget and capacity.

Colorectal cancer screening

Colorectal cancer (CRC) constitutes the second leading cause of death from cancer in the United States. Increased screening for CRC have been associated with a decreased incidence in the past two decades. Continued efforts are necessary to maintain this trend. Appropriate risk stratification of individuals and compliance with recommended screening strategies are important. Colonoscopy continues to play an important role in screening; however, several different screening options are available for average-risk individuals. This article reviews the current options open to physicians to adequately screen patients for CRC based on inherit risks.

Comparison of a unidirectional panoramic 3D endoluminal interpretation technique to traditional 2D and bidirectional 3D interpretation techniques at CT colonography: preliminary observations

AIM

To compare the evaluation times and accuracy of unidirectional panoramic three-dimensional (3D) endoluminal interpretation to traditional two-dimensional (2D) and bidirectional 3D endoluminal techniques.

MATERIALS AND METHODS

Sixty-nine patients underwent computed tomography colonography (CTC) after bowel cleansing. Forty-five had no polyps and 24 had at least one polyp > or = 6 mm. Patients underwent same-day colonoscopy with segmental unblinding. Three experienced abdominal radiologists evaluated the data using one of three primary interpretation techniques: (1) 2D; (2) bidirectional 3D; (3) panoramic 3D. Mixed model analysis of variance and logistic regression for correlated data were used to compare techniques with respect to time and sensitivity and specificity.

RESULTS

Mean evaluation times were 8.6, 14.6, and 12.1 min, for 2D, 3D, and panoramic, respectively. 2D was faster than either 3D technique (p < 0.0001), and the panoramic technique was faster than bidirectional 3D (p = 0.0139). The overall sensitivity of each technique per polyp and per patient was 68.4 and 76.7% for 2D, 78.9 and 93.3% for 3D; and 78.9 and 86.7% for panoramic 3D.

CONCLUSION

2D interpretation was the fastest overall, the panoramic technique was significantly faster than the bidirectional with similar sensitivity and specificity. The sensitivity for a single reader was significantly lower using the 2D technique. Each reader should select the technique with which they are most successful.

Colorectal cancer screening practices among obstetrician/gynecologists and nurse practitioners

OBJECTIVE

Obstetrician/gynecologists (Ob/Gyn) and nurse practitioners (NP) are essential providers of primary and preventive care for their female patients. Therefore, colorectal cancer (CRC) screening should be part of their routine preventive practices. The purpose of our study is to evaluate the CRC screening practices of these providers.

METHODS

A self-administered survey was mailed to a national sample of 1130 Ob/Gyns and NPs to assess providers' demographics, current CRC screening practices, and familiarity with CRC guidelines.

RESULTS

Three hundred thirty-six providers (29.7%) returned our survey (54% Ob/Gyns and 46% NPs). Three fourths of providers routinely performed screening for CRC, compared with 95% for breast and cervical cancer. Routine CRC screening was more common among Ob/Gyns (87.2%) than NPs (61.7%) (p < 0.001). Slightly over half of providers correctly identified the recommended age to begin CRC screening for the average-risk patient, with no significant difference between provider types. Overall, Ob/Gyns scored higher than NPs on a series of questions assessing CRC screening (p < 0.03). Several provider factors were found to be significantly associated with screening practices, including practicing >10 years (p < 0.01), practicing in a multispecialty group (2.62 times more likely), and having an older patient population (p < 0.001).

CONCLUSIONS

Ob/Gyns and NPs underuse CRC screening compared with breast and cervical cancer screening and lack knowledge about appropriate use of CRC screening modalities. Opportunities to further educate Ob/Gyns and NPs should be sought to improve compliance with current CRC screening guidelines.

Normalized distance along the colon centerline: a method for correlating polyp location on CT colonography and optical colonoscopy

OBJECTIVE

The ability to accurately locate a polyp found on CT colonography (CTC) at subsequent optical colonoscopy (OC) is an important part of the successful implementation of CTC for colorectal cancer screening. The purpose of this study was to determine whether a polyp's normalized distance along the colon centerline derived from CTC data can accurately predict its location on OC.

MATERIALS AND METHODS

The polyp population consisted of 152 polyps in 121 patients. CTC polyp findings were verified by same-day segmentally-unblinded OC. Each polyp's normalized distance along the colon centerline was computed by dividing its distance from the anorectal junction measured along the colon centerline by the length of the colon at CTC. The predicted polyp location at OC was computed by multiplying the normalized distance along the colon centerline by the colon length at OC (i.e., the distance to the cecum as determined at full colonoscope insertion). The differences between the true and predicted polyp locations at OC were compared using paired Student's t tests, linear regression, prediction interval assessment, and Bland-Altman analyses.

RESULTS

The differences between the true and predicted polyp locations at OC using the supine and prone CTC-normalized distances along the colon centerline were 2.2 +/- 10.5 cm (mean +/- SD; n = 136) and 1.5 +/- 10.5 cm (n = 135), respectively. The predicted location was within 10 cm of its true location for 71.3% (97/136) to 74.8% (101/135) of polyps and within 20 cm of its true location for 93.3% (126/135) to 93.4% (127/136) of polyps.

CONCLUSION

By computing the normalized distance along the colon centerline of a polyp found at CTC, the location of a polyp at OC can be predicted to within 10 cm (i.e., 1 colonoscope mark) for the majority of polyps.

Clusterin in stool: a new biomarker for colon cancer screening?

OBJECTIVES

The identification of useful markers for early diagnosis of human colon cancer is a major goal still in progress. Clusterin is a pleiotropic protein with a broad range of functions. It has recently drawn much attention because of its association with cancer promotion and metastasis. It is involved in prosurvival and apoptosis processes that are carried out by two different isoforms. Secreted clusterin isoform (sCLU) is cytoprotective and its prosurvival function is the basis of the current phase I/II clinical trials against prostate, lung, and breast cancers. We have already shown that in colorectal cancer (CRC) there is an increased expression of sCLU. In this report, we investigated whether sCLU is released in the blood and stool of colon cancer patients in order to study sCLU as a potential diagnostic molecular marker for colon cancer screening.

METHODS

The quantitative expression of sCLU was determined by dot blot immunodosage in the serum and stool of CRC patients (n=63) and age-matched controls without clinical history of neoplasia, CRC, or systemic or bowel inflammatory disease (n=50). Unpaired t-tests and Mann-Whitney U-tests were used for continuous variables. The diagnostic performance of clusterin was appraised by means of receiver operating characteristic (ROC) curves.

RESULTS

We found a significant increase of sCLU in the serum and stool of CRC patients (P=0.0002 and P<0.000, respectively) as compared with controls. ROC curves provided cutoff points showing a trade-off between sensitivity and specificity. With a cutoff point of 88.5 microg/ml, sCLU in blood showed a 55.6% sensitivity and 100% specificity, and with a cutoff point of 34.6 microg/g, the stool test reached 66.7% sensitivity and 84% specificity in discriminating between nonneoplastic and colorectal neoplastic lesions. Human cancer xenografts in nude mice indicated a positive correlation between increasing serum clusterin level and tumor size.

CONCLUSIONS

This study highlights the potential of clusterin detection in stool to be a valuable tool to improve the effectiveness and efficiency of large-scale clinical cancer screening.