A case-cohort study for the disease natural history of adenoma-carcinoma and de novo carcinoma and surveillance of colon and rectum after polypectomy: implication for efficacy of colonoscopy

Down-regulation of HLA-A mRNA in peripheral blood mononuclear cell of colorectal cancer

PURPOSE

It has been demonstrated that the alteration of human leukocyte antigen (HLA) class I expression frequently occurs in colorectal tumor. Previous studies mainly focused on the expression of HLA-A in tumor cells. The expression of HLA-A in peripheral blood mononuclear cells (PBMC) was unknown. To develop a non-invasive diagnostic method for colorectal cancer (CRC), this work investigated the expression of HLA-A mRNA in PBMC in patients with CRC.

METHODS

Real-time quantitative RT-PCR was used to study the expression of HLA-A mRNA in PBMC from 48 patients with colorectal cancer, 38 patients with benign colorectal lesions, 20 patients with rheumatoid arthritis, 20 patients with esophageal cancer and 40 healthy individuals. Protein chip was utilized to detect the levels of serum CEA, CA 19-9, and CA 242 in all the cases. Overall results from the two methods were compared.

RESULTS

The relative expression of HLA-A mRNA in PBMC was 1.11 ± 0.45 in healthy group, 0.81 ± 0.42 in benign colorectal lesion group, and 0.39 ± 0.34 in cancer group, respectively. The diagnostic sensitivity of HLA-A mRNA, CEA, CA19-9, and CA242 was 81%, 59%, 61%, and 63%, and their diagnostic specificity was 75%, 64%, 52%, and 67%, respectively.

CONCLUSIONS

The expression of HLA-A mRNA in PBMC from colorectal cancer group was significantly lower than those in both benign group and healthy group (P < 0.001). It could be potentially developed as a tumor assistant marker in future.

Different bowel preparation schedule leads to different diagnostic yield of proximal and nonpolypoid colorectal neoplasm at screening colonoscopy in average-risk population

BACKGROUND

Accumulating evidence indicates that the timing of bowel preparation is crucial, but its impact on the diagnostic yield of proximal or nonpolypoid colorectal neoplasm remains unclear.

OBJECTIVE

This study aimed to investigate the impact of the timing of bowel preparation on the adenoma detection rate for nonpolypoid colorectal neoplasm at colonoscopy.

DESIGN

This study is a retrospective analysis of a screening colonoscopy cohort database.

SETTING

The investigation was conducted at a screening colonoscopy unit in an university hospital.

PATIENTS

A consecutive series of 3079 subjects who received primary screening colonoscopy with different timing of bowel preparation was analyzed.

INTERVENTION

Different timing of bowel preparation (same day vs prior day) was studied.

MAIN OUTCOME MEASURES

The main outcomes measured were patient demographics, timing of bowel preparation, colon-cleansing levels, diagnostic yields of colonoscopy, including adenoma, advanced adenoma, and nonpolypoid colorectal neoplasm.

RESULTS

There were a total of 1552 subjects in the morning group and 1527 in the evening group. More subjects had proximal adenoma (175, 11.3% vs 138, 9.0%, P = .04), advanced adenoma (68, 4.4% vs 46, 13.0%, P = .044), nonpolypoid colorectal neoplasm (98, 6.3% vs 67, 4.4%, P = .018), proximal nonpolypoid colorectal neoplasm (71, 4.6% vs 40, 2.6%, P = .004), and advanced nonpolypoid colorectal neoplasm (25, 1.6% vs 12, 0.8%, P = .036) detected by same-day preparation. On multivariate regression analysis, the adenoma detection rate was significantly higher in the same-day group regarding overall and proximal adenoma (OR 1.23, 95% CI: 1.00-1.50; OR 1.35, 95% CI: 1.05-1.74), advanced adenoma (OR 1.53, 95% CI: 1.04-2.28), overall, proximal, and advanced nonpolypoid colorectal neoplasm (OR 1.48, 95% CI: 1.06-2.08; OR 1.82, 95% CI: 1.20-2.75; OR 1.96, 95% CI: 1.12-3.37). The adenoma detection rate was also significantly different among endoscopists.

LIMITATION

This was a single-center, nonrandomized trial.

CONCLUSIONS

Improving bowel preparation quality by same-day preparation may lead to enhanced detection of overall, proximal, and advanced nonpolypoid colorectal neoplasm.

Colorectal cancers detected after colonoscopy frequently result from missed lesions

BACKGROUND & AIMS

Colorectal cancers (CRCs) that are detected in patients who have received colonoscopies (interval cancers) arise from missed lesions, incomplete resections of adenomas, or de novo. We estimated rates of interval cancer from missed lesions.

METHODS

Adenoma miss rates, cancer prevalence among patients with adenoma (based on size), and rates of adenoma-to-cancer transitions were estimated from the literature. We used a model to apply these risk estimates to a hypothetical average-risk population that received screening colonoscopies. We calculated the proportion of individuals with tumors missed at the baseline colonoscopy and tumors that arose from missed adenomas during a 5-year follow-up period. Sensitivity analyses were performed to assess robustness.

RESULTS

We found that 0.7 per 1000 persons undergoing a screening colonoscopy had a cancer that was missed at the baseline colonoscopy and an additional 1.1 per 1000 subsequently developed cancer from a missed adenoma. Therefore, the expected rate of individuals with CRC, based on missed adenomas, was 1.8 per 1000 persons within 5 years. By using the most conservative assumptions-a low miss rate and low prevalence of cancer in adenomas-0.5 per 1000 persons would have a detectable CRC within 5 years after a screening colonoscopy. In contrast, using the highest reported miss rates and cancer prevalence, CRCs from missed lesions would occur in 3.5 per 1000 screened persons.

CONCLUSIONS

A significant number of patients undergoing a screening colonoscopy that did not detect cancer actually have a malignant lesion or adenoma that could progress in a short interval. Most interval cancers might reflect missed rather than new lesions. Improving adenoma detection could reduce the rate of interval cancers.

A resect and discard strategy would improve cost-effectiveness of colorectal cancer screening

BACKGROUND & AIMS

A "resect and discard" policy has been proposed for diminutive polyps detected by screening colonoscopy, because hyperplastic and adenomatous polyps can be distinguished, in vivo, by using narrow-band imaging (NBI). We modeled the cost-effectiveness of this policy.

METHODS

Markov modeling was used to compare the cost-effectiveness of universal pathology evaluations with a resect and discard policy for colonoscopy screening. In a resect and discard approach, diminutive lesions (≤5 mm), classified by endoscopy with high confidence, were not analyzed by a pathologist. Base case assumptions of an 84% rate of high-confidence classification, with a sensitivity and specificity for adenomas of 94% and 89%, respectively, were used. Census data were used to project outputs of the model onto the US population, assuming 23% as the current rate of adherence to a colonoscopy screening.

RESULTS

With universal referral of resected polyps to pathology, colonoscopy screening costs an estimated $3222/person, with a gain of 51 days/person. Endoscopic polypectomy accounted for $179/person, of which $46/person was related to pathology examination. Adoption of a resect and discard policy for eligible diminutive polyps resulted in a savings of $25/person, without any meaningful effect on screening efficacy. Projected onto the US population, this approach would result in an undiscounted annual savings of $33 million. In the sensitivity analysis, the rate of high-confidence diagnosis and the accuracy for endoscopic polyp determination were the most meaningful variables.

CONCLUSIONS

In a simulation model, a resect and discard strategy for diminutive polyps detected by screening colonoscopy resulted in a substantial economic benefit without an impact on efficacy.

The natural history of non-polypoid colorectal neoplasms

Despite their importance, little is known about the natural history of non-polypoid colorectal neoplasms (NP-CRN). This article will summarize the available data to gain some estimates of the natural history of NP-CRN.

Incorporating frailty in a multi-state model: application to disease natural history modelling of adenoma-carcinoma in the large bowel

Homogeneous multi-state models of disease progression have been widely used for designing and evaluating cancer screening programs. However, in screening for premalignant conditions of the cervix or large bowel, it is unlikely that all premalignant lesions have the same underlying propensity for progression. Incorporating frailty into multi-state models raises practical difficulties as it precludes the derivation of finite transition probabilities by matrix solution of the Kolmogorov equations. We address this problem by formulating a heterogeneous process as a series of homogeneous processes linked by transitions which are subject to heterogeneity (frailty). Continuous frailty and discrete mover—stayer models were developed. We applied these to the example of progression of adenoma to colorectal cancer in a three-state model and to a five-state model including consideration of adenoma size. Results were compared with those of purely homogeneous models in a previous study in terms of cumulative risk of malignant transformation from adenoma to invasive colorectal cancer.

[Development of colorectal advanced neoplasia/adenomas in the long-term follow-up of patients submitted to colonoscopy with polipectomy]

CONTEXT

Colonoscopy with polypectomy reduces the incidence of colorectal cancer and its associated mortality. The ideal interval between surveillance examinations is determined by clinical features and endoscopic findings considered as risk factors to the development of advanced colonic neoplasias.

OBJECTIVE

To determine the development rate of advanced neoplasia in patients submitted to surveillance colonoscopy in a tertiary referral center.

METHODS

Three hundred and ninety two patients who underwent two or more complete colonoscopies between 1995 and 2005, and who have at least one diagnosed colorectal adenoma entered into the study. The endoscopic findings of the first and subsequent colonoscopies of each patient were analysed, considering advanced neoplasia as the main outcome. The patients enrolled were divided in accordance to the first colonoscopy findings in groups 1 or high risk; 2 or low risk; and 3 or without adenoma at the first colonoscopy. The development of advanced colorectal neoplasia and the period of surveillance until the outcome were analysed and compared among groups.

RESULTS

Twenty eight per cent of patients had advanced adenomas at index colonoscopy; 57.8% presented with low grade dysplasia neoplastic lesions and 14.1% had no adenoma at the first examination. The mean age was 59.54 +/- 11.74 years. Twenty six point four per cent of subjects from group 1 presented with advanced neoplasia during the surveillance period, while this outcome occurred in 10.9% and 5.3% of patients from groups 2 and 3, respectively (P<0,05). The mean period of surveillance was 123.35 months, and the mean time between the first examination and the one which presented with the outcome statistically differed among group 1 and the others, being 104.02, 115.31 and 120.61 months, respectively.

CONCLUSIONS

Patients with advanced neoplasia at index colonoscopy presented with a higher probability of harbouring this condition during the follow-up when compared with other two groups. These lesions also occur earlier in this patients than in the ones without these lesions at the first examination.

CT colonography to screen for colorectal cancer and aortic aneurysm in the Medicare population: cost-effectiveness analysis

OBJECTIVE

CT colonography (CTC) is a recommended test for colorectal cancer (CRC) screening according to the updated 2008 American Cancer Society guidelines. CTC can also accurately detect abdominal aortic aneurysm (AAA). This collaborative gastroenterology-radiology project evaluated the cost-effectiveness and clinical efficacy of CTC in the Medicare population.

MATERIALS AND METHODS

A computerized Markov model simulated the development of CRC and AAA in a hypothetical cohort of 100,000 U.S. adults > or = 65 years old. Screening with CTC at 5- and 10-year intervals using a 6-mm size threshold for polypectomy was compared with primary optical colonoscopy screening every 10 years and with no screening. Base case costs for CTC and optical colonoscopy were $674 and $795, respectively. The costs of the imaging workup for extracolonic findings at CTC were also included.

RESULTS

CTC resulted in 7,786 and 7,027 life-years gained at 5- and 10-year intervals, respectively, compared with 6,032 life-years gained with 10-year optical colonoscopy. The increase in overall efficacy with CTC was primarily due to prevention of AAA rupture because CRC prevention and CRC detection rates were similar for CTC and optical colonoscopy. All three strategies were highly cost-effective compared with no screening, with an incremental cost-effectiveness ratio (ICER) of $6,088, $1,251, and $1,104 per life-year gained for 5-year CTC, 10-year CTC, and 10-year optical colonoscopy strategies, respectively. The ICER of 5-year CTC and 10-year CTC versus optical colonoscopy was $23,234 and $2,144 per life-year gained, respectively.

CONCLUSION

Because of its ability to simultaneously screen for both CRC and AAA, CTC is a highly cost-effective and clinically efficacious screening strategy for the Medicare population.

Impact of whole-body CT screening on the cost-effectiveness of CT colonography

PURPOSE

To analyze the impact of adding computed tomographic (CT) imaging of the chest on the clinical effectiveness and cost-effectiveness of CT colonography to determine whether performing CT colonography and whole-body CT is a more clinically and cost-effective strategy than CT colonography alone when screening average-risk subjects.

MATERIALS AND METHODS

A Markov model simulated the occurrence of colorectal neoplasia, extracolonic abominal-pelvic malignancy, lung cancer, coronary artery disease (CAD), and abdominal aortic aneurysm (AAA) in a cohort of 100,000 U.S. subjects aged 50 to 100 years. Cost-effectiveness of CT colonography and whole-body CT was compared with that of CT colonography alone; each test was assumed to be repeated every 10 years between ages of 50 and 80 years.

RESULTS

Performing CT colonography and whole-body CT was more effective and costly than was CT colonography alone. The addition of chest CT was associated with a 22% increase in efficacy (life-years gained: 14,662 vs 11,990) and with a 48% increase in cost per person ($13,605 vs $9,223). Both strategies were cost effective as compared with no screening, with an incremental cost-effectiveness ratio (ICER) of $17,672 (CT colonography alone) and $44,337 (CT colonography and whole-body CT), respectively, but performing CT colonography and whole-body CT was not a cost-effective option when compared with CT colonography alone (ICER, $164,020). This was mainly a result of the high cost of false-positive follow-up for CAD and to the poor efficacy of lung cancer screening. Expected value of perfect information was $520 per patient.

CONCLUSION

The addition of chest CT to CT colonography does not appear to be a cost-effective alternative. Further research is needed before whole-body CT can be recommended in clinical practice.

Prevalence and characteristics of nonpolypoid colorectal neoplasm in an asymptomatic and average-risk Chinese population

BACKGROUND AND AIMS

Evidence from Japanese studies suggests that nonpolypoid colorectal neoplasia (NP-CRN) tends to be more pathologically advanced than polypoid neoplasia. However, data are limited regarding the prevalence of NP-CRN in an average-risk population. In addition, the diagnostic yield of the fecal occult blood test (FOBT) in relation to different types of colorectal neoplasms remains unclear. We prospectively investigated the prevalence and characteristics of polypoid and nonpolypoid colorectal lesions in an asymptomatic and average-risk Chinese population.

METHODS

The study included 12,731 asymptomatic Chinese subjects (8372 of whom were average-risk subjects) who underwent screening colonoscopy. The prevalence, histopathologic findings, and topographic distribution of polypoid and nonpolypoid colorectal lesions were determined and analyzed. The diagnostic yield of FOBT, in relation to lesion morphology, also was assessed.

RESULTS

NP-CRN was detected in 552 (4.3%) asymptomatic and 348 (4.2%) average-risk subjects. The prevalence of depressed NP-CRN was 0.18% in both asymptomatic and average-risk subjects. A higher proportion of smaller-sized but high-grade dysplasia and invasive carcinoma beyond the submucosal layer was noted for depressed NP-CRN compared with flat NP-CRN or polypoid neoplasia. The diagnostic yield of FOBT was comparable in depressed lesions and their polypoid counterparts.

CONCLUSIONS

The prevalence of NP-CRN is substantial in both asymptomatic and average-risk Chinese individuals. Some subcategories of NP-CRN in this population tend to have more advanced pathologic characteristics. These findings may lead to modification of screening and prevention strategies for colorectal cancer.

A comparative study of standard vs. high definition colonoscopy for adenoma and hyperplastic polyp detection with optimized withdrawal technique

BACKGROUND

Colonoscopy has a known miss rate for polyps and adenomas. High definition (HD) colonoscopes may allow detection of subtle mucosal change, potentially aiding detection of adenomas and hyperplastic polyps.

AIM

To compare detection rates between HD and standard definition (SD) colonoscopy.

METHODS

Prospective, cohort study with optimized withdrawal technique (withdrawal time >6 min, antispasmodic, position changes, re-examining flexures and folds). One hundred and thirty patients attending for routine colonoscopy were examined with either SD (n = 72) or HD (n = 58) colonoscopes.

RESULTS

Groups were well matched. Sixty per cent of patients had at least one adenoma detected with SD vs. 71% with HD, P = 0.20, relative risk (benefit) 1.32 (95% CI 0.85-2.04). Eighty-eight adenomas (mean +/- standard deviation 1.2 +/- 1.4) were detected using SD vs. 93 (1.6 +/- 1.5) with HD, P = 0.12; however more nonflat, diminutive (<6 mm) adenomas were detected with HD, P = 0.03. Twenty-three proximal hyperplastic polyps (0.32 +/- 0.58) were detected with SD vs. 31 (0.53 +/- 0.86) with HD, P = 0.35. Overall prevalence of proximal large (>9 mm) hyperplastic polyps was 7% (0.09 +/- 0.36).

CONCLUSIONS

High definition did not lead to a significant increase in adenoma or hyperplastic polyp detection, but may help where comprehensive lesion detection is paramount. High detection rates appear possible with either SD or HD, when using an optimized withdrawal technique.

A deterministic model for estimating the reduction in colorectal cancer incidence due to endoscopic surveillance

There is evidence that the removal of adenomas, by endoscopy, from the large bowel can prevent the occurrence of colorectal cancer (CRC). However, the reduction in cancer incidence due to endoscopic surveillance is difficult to estimate. Studies of cohorts of adenoma patients typically rely on comparisons with groups of historical controls. We present a model for disease progression which enables estimation of this quantity without direct comparison to a reference group. Models are applied to data from the National Polyp Study. Rates of adenoma recurrence and progression to carcinoma are estimated based on study data and relevant literature. This allows calculation of the number of cancers expected in the absence of surveillance and, thus, the number of cancers prevented. Results are compared with the original analysis. Models estimate that surveillance reduced CRC incidence by at least 97% in this cohort. The majority of the effect was due to the initial removal of adenomas rather than the follow-up surveillance. These results are similar to those produced in the original analysis when using the most appropriate reference groups. They indicate that polypectomy and follow-up surveillance can lead to large reductions in cancer incidence which may have been under-estimated in previous studies.

Deciphering the genetics of hereditary non-syndromic colorectal cancer

Previously we have localized to chromosome 3q21-q24, a predisposition locus for colorectal cancer (CRC), through a genome-wide linkage screen (GWLS) of 69 families without familial adenomatous polyposis or hereditary non-polyposis CRC. To further investigate Mendelian susceptibility to CRC, we extended our screen to include a further GWLS of an additional 34 CRC families. We also searched for a disease gene at 3q21-q24 by linkage disequilibrium mapping in 620 familial CRC cases and 960 controls by genotyping 1676 tagging SNPs and sequencing 30 candidate genes from the region. Linkage analysis was conducted using the Affymetrix 10K SNP array. Data from both GWLSs were pooled and multipoint linkage statistics computed. The maximum NPL score (3.01; P=0.0013) across all families was at 3q22, maximal evidence for linkage coming from families segregating rectal CRC. The same genomic position also yielded the highest multipoint heterogeneity LOD (HLOD) score under a dominant model (HLOD=2.79; P=0.00034), with an estimated 43% of families linked. In the case-control analysis, the strongest association was obtained at rs698675 (P=0.0029), but this was not significant after adjusting for multiple testing. Analysis of candidate gene mapping to the region of maximal linkage on 3q22 failed to identify a causal mutation. There was no evidence for linkage to the previously reported 9q CRC locus (NPL=0.95, P=0.23; HLOD(dominant)=0.40, HLOD(recessive)=0.20). Our findings are consistent with the hypothesis that variation at 3q22 contributes to the risk of CRC, but this is unlikely to be mediated through a restricted set of alleles.

A Markov regression random-effects model for remission of functional disability in patients following a first stroke: a Bayesian approach

Few attempts have been made to model the dynamics of stroke-related disability. It is possible though, using panel data and multi-state Markov regression models that incorporate measured covariates and latent variables (random effects). This study aimed to model a series of functional transitions (following a first stroke) using a three-state Markov model with or without considering random effects. Several proportional hazards parameterizations were considered. A Bayesian approach that utilizes the Markov Chain Monte Carlo (MCMC) and Gibbs sampling functionality of WinBUGS (a Windows-based Bayesian software package) was developed to generate the marginal posterior distributions of the various transition parameters (e.g. the transition rates and transition probabilities). Model building and comparisons was guided by reference to the deviance information criteria (DIC). Of the four proportional hazards models considered, exponential regression was preferred because it led to the smallest deviances. Adding random effects further improved the model fit. Of the covariates considered, only age, infarct size, and baseline functional status were significant. By using our final model we were able to make individual predictions about functional recovery in stroke patients.

Risk factors for high-grade dysplasia or carcinoma in colorectal adenoma cases treated with endoscopic polypectomy

OBJECTIVE

Our aim is to establish the risk factors for carrying high-grade dysplasia or carcinoma by analyzing endoscopically treated adenoma cases.

METHODS

Patients who underwent endoscopic polypectomy at our hospitals between January 2003 and August 2004 were analyzed.

RESULTS

A total of 889 patients (mean age: 63+/-11 years), and 1486 adenomas resected from these patients, were included in the analysis. Seventy-five adenomas (5%) from 72 patients (8%) were found to have high-grade dysplasia or carcinoma. Among patient factors, female sex [odds ratio (OR) 2.25, 95% confidence intervals (CI)=1.34-3.76], presence of multiple adenomas (OR=2.15, 95% CI=1.15-4.00), older age (OR=1.02, 95% CI=1.00-1.04), and rectal bleeding as the indication for colonoscopy (OR=2.57, 95% CI=1.34-4.92) were identified as the significant risk factors for carrying high-grade dysplasia or carcinoma using the multivariate analysis. In addition, a size of > or = 10 mm (OR=10.83, 95% CI=5.86-20.0), flat appearance (OR=3.91, 95% CI=2.20-6.95), and location on the left side of the colon (OR=1.80, 95% CI=1.03-3.13) were identified as tumor risk factors.

CONCLUSION

Distinct factors were proved to be associated with high-grade dysplasia or carcinoma. These results are useful to select lesions that require immediate treatment. Moreover, female sex as a risk factor raises an interesting problem regarding the progression from adenoma to carcinoma.

Q&A on diagnosis, screening and follow-up of colorectal neoplasia

The impressive and brisk evolution of medical science prevents many physicians from a thorough update on all the research fields. Colorectal cancer diagnosis, screening and follow-up is well known to require a multi-disciplinary approach, as it is faced by several specialties such as primary care physicians, gastroenterologists, non-gastroenterologist internists, radiologists and surgeons. To address this issue in a mutual perspective, we focused on the main points of the epidemiology, diagnosis, screening and follow-up of colorectal neoplasia by using a simple "Question & Answers" structure.

Small and diminutive polyps detected at screening CT colonography: a decision analysis for referral to colonoscopy

OBJECTIVE

The objective of this study was to assess the clinical and economic impact of colonoscopic referral for small and diminutive polyps detected at CT colonography (CTC) screening.

MATERIALS AND METHODS

A decision analysis model was constructed incorporating the expected polyp distribution, advanced adenoma prevalence, colorectal cancer (CRC) risk, CTC performance, and costs related to CRC screening and treatment. The model conservatively assumed that CRC risk was independent of advanced adenoma size. The number of diminutive (< or = 5 mm), small (6-9 mm), and large (> or = 10 mm) CTC-detected polyps needed to be removed to detect one advanced adenoma or prevent one CRC over a 10-year time horizon was calculated. The cost-effectiveness of polypectomy was also assessed.

RESULTS

The estimated 10-year CRC risk for unresected diminutive, small, and large polyps was 0.08%, 0.7%, and 15.7%, respectively. The number of diminutive, small, and large polyps needed to be removed to avoid leaving behind one advanced adenoma was 562, 71, and 2.5, respectively; similarly, 2,352, 297, and 10.7 polypectomies would be needed, respectively, to prevent one CRC over 10 years. The incremental cost-effectiveness ratio of removing all diminutive and small CTC-detected polyps was $464,407 and $59,015 per life-year gained, respectively. Polypectomy for large CTC-detected polyps yielded a cost-saving of $151 per person screened.

CONCLUSION

For diminutive polyps detected at CTC screening, the very low likelihood of advanced neoplasia and the high costs associated with polypectomy argue against colonoscopic referral, whereas removal of large CTC-detected polyps is highly effective. The yield of colonoscopic referral for small polyps is relatively low, suggesting that CTC surveillance may be a reasonable management option.

Tubulovillous adenoma in an Indiana pouch urinary diversion managed by endoscopic resection

We present a case of a tubulovillous adenoma in an Indiana pouch managed by endoscopic resection. A 66-year-old male underwent a cystectomy with creation of an Indiana pouch urinary diversion for invasive small cell carcinoma of the bladder. Seven years following his initial surgery, the patient noted several episodes of gross hematuria. The evaluation revealed a 2.5 cm tubulovillous adenoma with high-grade dysplasia within the Indiana pouch. The patient had significant comorbidities precluding an open operative procedure. He underwent en endoscopic resection of the tumor, and subsequently has been managed with surveillance pouchoscopy, biopsies, and fulguration every 3 months.

Cost-effectiveness of colorectal cancer screening with computed tomography colonography: the impact of not reporting diminutive lesions

BACKGROUND

Prior cost-effectiveness models analyzing computed tomography colonography (CTC) screening have assumed that patients with diminutive lesions (<or=5 mm) will be referred to optical colonoscopy (OC) for polypectomy. However, consensus guidelines for CTC recommend reporting only polyps measuring >or=6 mm. The purpose of the current study was to assess the potential harms, benefits, and cost-effectiveness of CTC screening without the reporting of diminutive lesions compared with other screening strategies.

METHODS

The cost-effectiveness of screening with CTC (with and without a 6-mm reporting threshold), OC, and flexible sigmoidoscopy (FS) were evaluated using a Markov model applied to a hypothetical cohort of 100,000 persons age 50 years.

RESULTS

The model predicted an overall cost per life-year gained relative to no screening of $4361, $7138, $7407, and $9180, respectively, for CTC with a 6-mm reporting threshold, CTC with no threshold, FS, and OC. The incremental costs associated with reporting diminutive lesions at the time of CTC amounted to $118,440 per additional life-year gained, whereas the incidence of colorectal cancer was reduced by only 1.3% (from 36.5% to 37.8%). Compared with primary OC screening, CTC with a 6-mm threshold resulted in a 77.6% reduction in invasive endoscopic procedures (39,374 compared with 175,911) and 1112 fewer reported OC-related complications from perforation or bleeding.

CONCLUSIONS

CTC with nonreporting of diminutive lesions was found to be the most cost-effective and safest screening option evaluated, thereby providing further support for this approach. Overall, the removal of diminutive lesions appears to carry an unjustified burden of costs and complications relative to the minimal gain in clinical efficacy.

Findings at Follow-up Endoscopies in Subjects With Suspected Colorectal Abnormalities: Effects of Baseline Findings and Time to Follow-up

PURPOSE

Guidelines for colonoscopic surveillance after the removal of colorectal polyps already exist in the United Kingdom and United States. However, there is a continuing need to build up an evidence base on the likely effect of different follow-up policies for specific current findings. This article reports on the colonoscopic surveillance of a cohort of patients in Taiwan. The risk of various outcomes at the second examination is assessed according to findings at the first examination and the interval between examinations.

PATIENTS AND METHODS

Data from baseline and follow-up examinations for 2,287 individuals attending the National Taiwan University Hospital were collected retrospectively. Multivariate logistic regression was used to identify risk factors for the following 4 outcomes: any positive findings; multiple (> or =3) polyps; large (> or =10 mm) polyp(s); or villous adenoma(s) or cancer. The effect of the interval between examinations was assessed in all models.

RESULTS

Older age was an independent risk factor for all outcomes. The number of baseline polyps was a significant risk factor for both positive results and multiple polyps, more severe baseline histology was a risk factor for large polyps and villous adenomas/cancer, and larger baseline polyps were a risk factor for large polyps at follow-up. Interval time was only an independent risk factor for villous adenomas/cancer, which tended to be found at shorter follow-up times. The total number of abnormalities found at follow-up was significantly related to the number of follow-up examinations but not to the total follow-up time.

CONCLUSIONS

Results suggest that, with the possible exception of subjects with villous adenomas at baseline, most reexaminations can safely be delayed for > or =5 years. In the majority of cases staff at the hospital were correctly identifying those subjects at particularly high risk and assigning shorter follow-up intervals accordingly. Models indicate that many of the findings seen at follow-up were due to missed baseline findings.

Colon cancer prevention in Italy: cost-effectiveness analysis with CT colonography and endoscopy

BACKGROUND

Colorectal cancer (CRC) is a major cause of mortality in Italy. Although prevention of CRC is possible, its cost-effectiveness when applied to the Italian population is unknown. Recently, computerized tomographic colonography (CTC) has been proposed for CRC screening.

AIM

To compare the efficacy and cost-effectiveness of CTC screening in a simulated Italian population with those of colonoscopy and flexible sigmoidoscopy (FS).

METHODS

The cost-effectiveness of different screening strategies was compared using a Markov process computer model, in which in a hypothetical population of 100,000 50 year-olds were investigated by CTC, colonoscopy or FS every decade. Outcomes were projected to the Italian national level.

RESULTS

CRC incidence reduction was calculated at 40.9%, 38.2%, and 31.8% with colonoscopy, CTC and FS, respectively. As compared to no screening, all screening programs were shown to be cost-saving, allowing a saving of 11 Euro, 17 Euro, and 48 Euro per person with colonoscopy, FS and CTC, respectively. FS appeared to be less cost-effective than CTC, whilst colonoscopy appeared to be an expensive option as compared to CTC. Undiscounted national expenditure was calculated to be 1,042,489,512 Euro, 1,093,268,285 Euro, and 1,198,783,428 Euro for FS, CTC and colonoscopy, respectively, as compared to 695,818,078 Euro without screening.

CONCLUSION

CRC screening is cost-saving in Italy, irrespective of the technique applied. CTC appeared to be more cost-effective than FS, and it may also become a valid alternative to colonoscopy.

The management of small polyps found by virtual colonoscopy: results of a decision analysis

BACKGROUND & AIMS

There is a firm consensus that larger (> or =10 mm) colonic polyps should be removed; however, the importance of removing smaller polyps (<10 mm) is more controversial. If computed tomographic colonography (CTC) is used for colorectal cancer screening, the majority of polypoid lesions identified will be less than 10 mm in size. Decision-analytic techniques were used to compare the outcomes of 2 management strategies for smaller (6-9 mm) polyps discovered by CTC.

METHODS

Hypothetic average-risk patients who had undergone a CTC examination and found to have a small (6-9 mm) polyp were simulated to either: (1) undergo immediate colonoscopy for polypectomy (COLO), or (2) wait 3 years for a repeat CTC examination (WAIT). A Markov model was constructed to analyze outcomes including the number of deaths and cancers after a 3-year follow-up period or time horizon. Values for the model parameters were derived from the published literature and from Surveillance Epidemiology and End Results data, and an extensive sensitivity analysis was performed.

RESULTS

The COLO strategy resulted in 14 total deaths per 100,000 patients compared with 79 total deaths in the WAIT strategy, for a difference of 65 deaths. The COLO strategy resulted in 39 cancers per 100,000 patients vs 773 in the WAIT strategy, for a difference of 734 cancers. Sensitivity analysis found that model findings were robust and only sensitive at extreme parameter values.

CONCLUSIONS

Managing smaller polyps detected on a screening CTC with another CTC examination 3 years later likely will result in more deaths and cancers than immediate colonoscopy and polypectomy.

Optical adjuncts for enhanced colonoscopic diagnosis

Background

Optical techniques using previously unexploited properties of light interaction with tissue may be valuable in the detection, diagnosis and staging of colorectal neoplasia.

Methods

A Medline search (1990 to present) was conducted on optical diagnostics in the detection of colorectal neoplasia. The reference list of each identified article was reviewed for further relevant papers.

Results and conclusion

Chromoendoscopy is the only optical adjunct to colonoscopy that has been tested in large randomized clinical trials. It improves the detection of small and flat colorectal adenomas, and of neoplasia in chronic ulcerative colitis and hereditary non-polyposis colorectal cancer. All other techniques are the subject of ongoing research and the practicality of population screening with any of the methods has yet to be established. Optical techniques may, however, permit immediate clinical diagnosis, removing the need for histological analysis. They may also improve the diagnosis of early colonic neoplasia.

Evaluation of the accuracy of serum MMP-9 as a test for colorectal cancer in a primary care population

BACKGROUND

Bowel cancer is common and is a major cause of death. Meta-analysis of randomised controlled trials estimates that screening for colorectal cancer using faecal occult blood (FOB) test reduces mortality from colorectal cancer by 16%. However, FOB testing has a low positive predictive value, with associated unnecessary cost, risk and anxiety from subsequent investigation, and is unacceptable to a proportion of the target population. Increased levels of an enzyme called matrix metalloproteinase 9 (MMP-9) have been found to be associated with colorectal cancer, and this can be measured from a blood sample. Serum MMP-9 is potentially an accurate, low risk and cost-effective population screening tool. This study aims to evaluate the accuracy of serum MMP-9 as a test for colorectal cancer in a primary care population.

METHODS/DESIGN

People aged 50 to 69 years, who registered in participating general practices in the West Midlands Region, will be asked to complete a questionnaire that asks about symptoms. Respondents who describe any colorectal symptoms (except only abdominal bloating and/or anal symptoms) and are prepared to provide a blood sample for MMP9 estimation and undergo a colonoscopy (current gold standard investigation) will be recruited at GP based clinics by a research nurse. Those unfit for colonoscopy will be excluded. Colonoscopies will be undertaken in dedicated research clinics. The accuracy of MMP-9 will be assessed by comparing the MMP-9 level with the colonoscopy findings, and the combination of factors (e.g. symptoms and MMP-9 level) that best predict a diagnosis of malignancy (invasive disease or polyps) will be determined.

DISCUSSION

Colorectal cancer is a major cause of morbidity and mortality. Most colorectal cancers arise from adenomas and there is a period for early detection by screening, but available tests have risks, are unacceptable to many, have high false positive rates or are expensive. This study will establish the potential of serum MMP-9 as a screening test for colorectal cancer. If it is confirmed as accurate and acceptable, this serum marker has the potential to assist with reducing the morbidity and mortality from colorectal cancer.

Proportion of de novo cancers among colorectal cancers in Japan

BACKGROUND & AIMS

Adenomatous polyps are main precursors of colorectal cancers (CRCs). In Japan, de novo cancers, which do not arise from preexisting adenomas, are considered to account for a substantial number of CRCs, but the relative importance of de novo carcinogenesis remains controversial. This study estimated the proportion of de novo cancers among CRCs in Japan.

METHODS

The subjects were persons 40-79 years of age who were relatively similar to those in the general population. The subjects underwent colonoscopy between 1997 and 2001. Early cancers among CRCs detected in this study were classified as de novo cancers or polyp cancers derived from adenomas. The age-specific incidence of the early CRCs was calculated, and the proportion of de novo cancers was estimated. The lifetime risk of early CRCs was estimated.

RESULTS

The study group comprised 14,817 persons. CRCs were diagnosed in 189 subjects, including 83 early cancers. There were no differences with regard to size and location between de novo cancers and polyp cancers, but morphology differed. Eighty-four percent (16/19) of de novo cancers were flat elevated or depressed. The expected lifetime risk of developing early CRCs was 5.27% for men and 3.21% for women. Among persons with early cancers, the expected probabilities of developing de novo cancer were 18.6% for men, 27.4% for women.

CONCLUSIONS

De novo cancers account for a considerable proportion in Japan. This information suggests that the recommended interval for colonoscopic examination in Japan should be shorter than that in the United States.

Prevention of colitis-associated carcinogenesis in a mouse model by diet supplementation with ursodeoxycholic acid

Bile acids in the intestinal lumen contribute to the homeostatic regulation of proliferation and death of the colonic epithelial cells: Deoxycholic acid (DCA) appears to enhance and ursodeoxycholic acid (UDCA) to attenuate the process of chemically induced carcinogenesis. We studied the effects of UDCA on colitis-related colorectal carcinogenesis. Three groups of 25 mice were given 0.7% dextran sulphate in drinking water for 7 days and pure water for 10 days and were fed a standard diet containing double iron concentration. In 2 groups, the diet was supplemented with 0.2% cholic acid (CA), the precursor of DCA, or with 0.4% UDCA. After 15 cycles, the histology, the expression of MUC2, beta-catenin, p27 and p16 and the fecal water concentration of DCA and UDCA were investigated. All animals showed colitis with similar severity and histologic as well as immunophenotypic alterations, resembling those of human colitis. Among the animals fed the nonsupplemented diet, 46% developed colorectal adenocarcinomas and 54% anal-rectal squamous cell carcinomas. The prevalence of dysplasia and carcinomas did not change significantly in the animals given CA. Among the mice fed with UDCA, none developed adenocarcinomas and 20% squamous carcinomas. Dysplastic lesions were found in 88%, 67% and 40% of each group, respectively. The prevalence of dysplasia as well as of carcinoma showed an inverse relationship to the UDCA concentration in the fecal water. These data indicate that UDCA suppresses colitis-associated carcinogenesis. This model is suitable for investigation of the mechanism of the anticarcinogenic effect of UDCA in vivo.

History of negative colorectal endoscopy and risk of rectosigmoid neoplasms at screening flexible sigmoidoscopy

BACKGROUND AND AIMS

Screening sigmoidoscopy can reduce incidence of colorectal cancer and mortality. The optimal re-screening interval has not yet been defined. This study is aimed at estimating the risk of distal advanced adenomas (diameter >/=10 mm, villous component >20%, high-grade dysplasia) and cancer at screening flexible sigmoidoscopy in subjects aged 55-64 years who reported pre-screening negative colorectal endoscopy.

PATIENTS

Eight thousands two hundred two subjects aged 55-64 years who underwent screening flexible sigmoidoscopy within the SCORE trial in Italy and who were able to report their previous history of colorectal endoscopy.

RESULTS

Eight hundred eighty three of 8,202 subjects (10.8%) reported at least one prescreening negative endoscopy: among them, after 3-5 years, 6-10 years and >10 years intervals between last reported examination and screening endoscopy, the Absolute Risk of advanced adenomas was 1.5%, 0.9% and 0.9%; one cancer was detected (0.1%). Among the 7,319 subjects who did not report prescreening endoscopy the risks of advanced adenoma and cancer were 3.2% and 0.4%, respectively. Subjects with a previous colorectal examination had a 65% decreased risk of advanced adenomas (OR=0.35, 95%CI 0.18-0.66) and a 71% decreased risk of cancer (OR=0.29, 95%CI 0.04-1.12) as compared to those who did not. For subjects without family history of colorectal cancer the statistically significant decrease of the risk persisted up to ten years. The observed benefit seems not to apply to subjects with family history of colorectal cancer.

CONCLUSIONS

Our results are consistent with the hypothesis that the interval between screening sigmoidoscopies could be safely expanded beyond 5 years for subjects without specific risk factors for colorectal cancer.

Poor correlation between clinical impression, the small colonic polyp and their neoplastic risk

BACKGROUND AND OBJECTIVES

Significance of the small colonic polyp is unclear and its removal is frequently determined by the proceduralist's clinical impression. Our aims were to determine if clinical discernment is accurate, and the likelihood that lesions < 10 mm are histologically advanced.

METHOD

We prospectively collected 1988 lesions from 854 subjects (2215 consecutive colonoscopies). Lesion size, location, patient age, sex and the colonoscopist's clinical impression was recorded.

RESULTS

Clinical assessment for neoplasia had a sensitivity of 87.4%, specificity of 65.0%, positive predictive value of 76.0% and negative predictive value of 80.2%, resulting in an accuracy of 73.4%. Factors predictive of correct clinical impression were polyp size, location in the rectum and being pedunculated, but not the patient's age, sex or the endoscopist's experience. Of the 1434 lesions < or = 5 mm in size, 44.5% were neoplastic and 3.5% were histologically advanced. Of the 266 lesions 6-9 mm, 79.3% were neoplastic, 19.9% were histologically advanced, five demonstrated high-grade dysplasia and three were malignant. Only two patients with an adenocarcinoma or high-grade dysplasia in a polyp <10 mm had a lesion > or =10 mm elsewhere in the colon. Of the 288 lesions > or =10 mm in size, 92.7% were neoplastic, 29.5% had a villous component, 6.9% demonstrated high-grade dysplasia and 29.2% were malignant. Factors predictive of neoplasia were patient age, polyp size and sessile nature of the lesion.

CONCLUSION

Polyps < 10 mm had a significant risk of neoplasia and advanced histology and, in general, clinical impression correlated poorly with neoplasia. Removal of all lesions proximal to the rectum, regardless of size, should therefore be considered.

Increasing incidence of colorectal cancer in Asia: implications for screening

Many Asian countries, including China, Japan, South Korea, and Singapore, have experienced an increase of two to four times in the incidence of colorectal cancer during the past few decades. The rising trend in incidence and mortality from colorectal cancer is more striking in affluent than in poorer societies and differs substantially among ethnic groups. Although changes in dietary habits and lifestyle are believed to be the reasons underlying the increase, the interaction between these factors and genetic characteristics of the Asian populations might also have a pivotal role. Non-polypoidal (flat or depressed) lesions and colorectal neoplasms arising without preceding adenoma (de novo cancers) seem to be more common in Asian than in other populations. The absence of polypoid growth preceding malignancy has posed difficulties in screening for early colorectal cancer by radiological imaging or even endoscopic techniques. Although epidemiological data are scanty, most Asian populations are not aware of the growing problem of colorectal cancer. More work is needed to elucidate the magnitude of the problem in Asia.

Incidental colonic focal lesions detected by FDG PET/CT

OBJECTIVE

The aim of this study was to assess the performance of FDG PET/CT for the detection of colonic lesions, especially advanced neoplasms (villous or >10-mm adenomas, carcinomas). Because of 18F FDG accumulation in adenomatous polyps, PET using FDG can detect early premalignant colorectal lesions.

MATERIALS AND METHODS

FDG PET/CT studies performed for a 1-year period in 1,716 consecutive patients with various malignant diseases, except colorectal cancer, were retrospectively reviewed. PET images obtained 1 hr after FDG injection and non-contrast CT images used for attenuation correction were fused for analysis. Of 45 patients showing intense focal colonic FDG uptake, 20 patients (with 21 foci) underwent a colonoscopic investigation, and, when necessary, polyp resection. The intensity of FDG uptake was quantified using the standardized uptake value (SUV(max)).

RESULTS

The FDG colonic foci were associated with 18 colonoscopic abnormalities in 15 patients, with no colonic abnormality detected in five patients (false-positive [FP] results). Histopathologic findings revealed advanced neoplasms in 13 patients (13 villous adenomas and three carcinomas) and two cases of hyperplastic polyps. A difference in the mean SUV(max) was found between FP and true-positive colonic FDG foci but was not statistically significant (p = 0.14).

CONCLUSION

Presence of a focal colonic FDG uptake incidental finding on a PET/CT scan justifies a colonoscopy to detect (pre-)malignant lesions. The fusion of PET and CT images allows an accurate localization of the lesions. PET/CT is a useful tool to differentiate pathologic from physiologic FDG uptake.

Laser photoablation of colorectal adenomas: a 12-year experience

BACKGROUND

We analyze laser photoablation as an alternative treatment of large sessile polyps in inoperable patients.

METHODS

Ninety-four colorectal polyps (mean diameter 3.09 +/- 2.7 cm, range 1-15 cm) were treated using high-energy lasers (Nd:YAG and diode). Grade of dysplasia was low in 51, high in 35, with focally invasive cancer in eight.

RESULTS

After 405 laser sessions (4.3 per polyp) five procedure-related complications were observed: two strictures, two bleedings, and one perforation. The last needed a surgical resection; the others were successfully treated by endoscopic therapy. Fifty-seven polyps (61%) were completely eradicated and the growth was controlled in all but two (98%). No degeneration was found after 28-month follow-up of treated adenomas with low- or high-grade dysplasia. Outcome of treatment was dependent on the dimension and grade of the dysplasia (p < 0.05), but not on the polyps' position (rectum or colon). Relief of rectal bleeding was obtained in 90%, of mucus discharge in 77%, and of tenesmus in 100% of cases.

CONCLUSIONS

Laser photoablation of colonic adenomas can be considered a valid procedure not only to relieve symptoms, but also to control the risk of degeneration in patients unfit for surgery or when surgical treatment is considered excessively invalidating.

Differential labeling by monoclonal antibodies Adnab-9 and anti-alpha-defensin 5 based on the distribution and adenomatous tissue content of colonic polyps

We sought a correlation between site and morphology of colonic polyps by labeling with neoplastic and general Paneth cell markers, monoclonal antibodies Adnab-9 and anti-alpha-defensin 5, respectively. Proportions labeled by Adnab-9 and anti-alpha-defensin 5 were, respectively, 42 and 85% for adenomas, 39 and 63% for early tubular adenomas, 41 and 44% for serrated, 34 and 20% for mixed, and 11 versus 2.7% for hyperplastic polyps. Compared with hyperplastic polyps, the proportion of other polyps labeled by Adnab-9 or anti-alpha-defensin 5 was higher but this difference was more significant for distal (P = 0.008 for Adnab-9 and P = 0.0001 for anti-alpha-defensin 5) than proximal (P = 0.645 and P = 0.154, respectively) polyps. While increased labeling of all proximal polyps compared to distal ones mirrored the colonic distribution of Paneth cells, distal adenomas tended to have a higher proportion labeled by Adnab-9, suggesting that Adnab-9 labels Paneth cells associated with increased neoplastic potential.

SAS macro program for non-homogeneous Markov process in modeling multi-state disease progression

Writing a computer program for modeling multi-state disease process for cancer or chronic disease is often an arduous and time-consuming task. We have developed a SAS macro program for estimating the transition parameters in such models using SAS IML. The program is very flexible and enables the user to specify homogeneous and non-homogeneous (i.e. Weibull distribution, log-logistic, etc.) Markov models, incorporate covariates using the proportional hazards form, derive transition probabilities, formulate the likelihood function, and calculate the maximum likelihood estimate (MLE) and 95% confidence interval within a SAS subroutine. The program was successfully applied to an example of a three-state disease model for the progression of colorectal cancer from normal (disease free), to adenoma (pre-invasive disease), and finally to invasive carcinoma, with or without adjusting for covariates. This macro program can be generalized to other k-state models with s covariates.