ACG colorectal cancer prevention action plan: update on CT-colonography

Prevention of malignant digestive system tumors should focus on the control of chronic inflammation

Chronic inflammation, through a variety of mechanisms, plays a key role in the occurrence and development of digestive system malignant tumors (DSMTs). In this study, we feature and provide a comprehensive understanding of DSMT prevention strategies based on preventing or controlling chronic inflammation. The development and evaluation of cancer prevention strategies is a longstanding process. Cancer prevention, especially in the early stage of life, should be emphasized throughout the whole life course. Issues such as the time interval for colon cancer screening, the development of direct-acting antiviral drugs for liver cancer, and the Helicobacter pylori vaccine all need to be explored in long-term, large-scale experiments in the future.

Knowledge of Polyp History and Recommended Follow-Up Among a Predominately African American Patient Population and the Impact of Patient Navigation

BACKGROUND AND AIMS

Colorectal screening (CRS) rates in minority and uninsured populations have increased through patient navigation (PN) interventions. However, patient knowledge of colonoscopy results and follow-up recommendations has not been described in an African American (AA) population or following PN. Our objectives were to determine patient knowledge of colonoscopy results and follow-up recommendations within an AA patient population and to compare post-colonoscopy knowledge among patients who received either PN or usual care.

METHODS

This is a prospective observational study of patients who completed a screening colonoscopy in 2014. A semi-structured telephone survey was completed by 96 participants (69 % AA, 78 % female, and mean age 63 years). The survey assessed patient recall of polyp results and follow-up recommendations. Responses were compared with the medical record.

RESULTS

Of 96 patients surveyed (response rate, 68 %), 83 % accurately reported if polyps were detected and 66 % accurately reported their recommended follow-up. The identification of adenomatous polyps on colonoscopy was a predictor of accurate recall of colonoscopy results and follow-up recommendations. Uninsured patients who completed PN (18 of 96) were more likely to accurately report polyp results (100 vs. 80 %; P = 0.036), but the rates of accurate follow-up recall were not statistically significant (44 vs. 71 %; P = 0.053) when compared to usual care patients.

CONCLUSIONS

In an AA population, post-colonoscopy polyp recall rates were similar to those described in white populations. Uninsured patients who completed PN were more likely than insured usual care patients to accurately report the presence of polyps on colonoscopy.

Fecal tag CT colonography with a limited 2-day bowel preparation following incomplete colonoscopy

PURPOSE

This study aimed to assess the feasibility and patient tolerance of a 2-day limited fecal tag bowel preparation in computed tomographic colonography (CTC) performed for incomplete conventional colonoscopy (CC) patients.

MATERIALS AND METHODS

Seventy-five patients who underwent a CTC examination fbecause of incomplete CC were included. A low-residue diet was given for 2 days before CTC. Fecal tagging (FT) was done using a barium sulfate suspension. The quality of the preparation, success of tagging and patient experience with the bowel preparation were investigated.

RESULTS

Four hundred fifty bowel segments were evaluated. The number of solid stool balls of 6-9 mm size was 284; the corresponding figure was 93 for solid stool balls ≥ 10 mm. Residual fluid was present in about one-third of the segments. The fecal tagging efficacy for ≥ 6 mm residual stool balls was 92 %. Overall, 16 (21.3 %) patients presented with colonic lesions at CTC. Three out of four colonic mass lesions had not been diagnosed with CC. Most patients reported mild discomfort.

CONCLUSION

FT-CTC performed after a limited 2-day bowel preparation seems to be a technically feasible, safe and acceptable procedure that allows a complete a colonic study in incomplete CC patients.

Comparison of a 4-Day versus 2-Day Low Fiber Diet Regimen in Barium Tagging CT Colonography in Incomplete Colonoscopy Patients

Our aim was to compare the amount of residual feces, residual fluid, the tagging quality, and patient compliance using 4-day versus 2-day low fiber diet regimen in barium tagging CT colonography in incomplete colonoscopy patients. Methods. A total of 101 patients who underwent CT colonography were assigned to 2-day diet group (n = 56) and 4-day diet group (n = 45). Fecal tagging was achieved with barium sulphate while bisacodyl and sennoside B were used for bowel preparation. Residual solid stool was divided into two groups measuring <6 mm and ≥6 mm. We graded the residual fluid, tagging quality for solid stool, and fluid per bowel segment. We performed a questionnaire to assess patient compliance. Results. 604 bowel segments were evaluated. There was no significant difference between 2-day and 4-day diet groups with respect to residual solid stool, residual fluid, tagging quality for stool, and fluid observed in fecal tag CT colonography (P > 0.05). The prevalence of moderate discomfort was significantly higher in 4-day group (P < 0.001). Conclusion. Our study shows that 2-day limited bowel preparation regimen for fecal tag CT colonography is a safe and reasonable technique to evaluate the entire colon, particularly in incomplete conventional colonoscopy patients.

Development and validation of a clinical score for predicting risk of adenoma at screening colonoscopy

BACKGROUND

Currently, no clinical tools use demographic and risk factor information to predict the risk of finding an adenoma in individuals undergoing colon cancer screening. Such a tool would be valuable for identifying those who would most benefit from screening colonoscopy.

METHODS

We used baseline data from men and women who underwent screening colonoscopy from the randomized, multicenter National Colonoscopy Study (NCS) to develop and validate an adenoma risk model. The study, conducted at three sites in the United States (Minneapolis, MN; Seattle, WA; and Shreveport, LA) asked all participants to complete baseline questionnaires on clinical risk factors and family history. Model parameters estimated from logistic regression yielded an area under the receiver operating characteristic curve (AUROCC) used to assess prediction.

RESULTS

Five hundred forty-one subjects were included in the development model, and 1,334 in the validation of the risk score. Variables in the prediction of adenoma risk for colonoscopy screening were age (likelihood ratio test for overall contribution to model, P < 0.001), male sex (P < 0.001), body mass index (P < 0.001), family history of at least one first-degree relative with colorectal cancer (P = 0.036), and smoking history (P < 0.001). The adjusted AUROCC of 0.67 [95% confidence interval (CI), 0.61-0.74] for the derivation cohort was not statistically significantly different from that in the validation cohort. The adjusted AUROCC for the entire cohort was 0.64 (95% CI, 0.60-0.67).

CONCLUSION

We developed and validated a simple well-calibrated risk score.

IMPACT

This tool may be useful for estimating risk of adenomas in screening eligible men and women.

[Korean guidelines for colorectal cancer screening and polyp detection]

Colorectal cancer is the second most common cancer in males and the fourth most common in females in Korea. Since the most of colorectal cancer occur through the prolonged transformation of adenomas into carcinomas, early detection and removal of colorectal adenomas are one of the most effective methods to prevent colorectal cancer. Considering the increasing incidence of colorectal cancer and polyps in Korea, it is very important to establish Korean guideline for colorectal cancer screening and polyp detection. Korean Multi-Society Take Force developed the guidelines with evidence-based methods. Parts of the statements drawn by systematic reviews and meta-analyses. Herein we discussed the epidemiology of colorectal cancers and adenomas in Korea, optimal screening methods for colorectal cancer, and detection for adenomas including fecal occult blood tests, radiologic tests, and endoscopic examinations.

Korean guidelines for colorectal cancer screening and polyp detection

Now colorectal cancer is the second most common cancer in males and the fourth most common cancer in females in Korea. Since most of colorectal cancers occur after the prolonged transformation of adenomas into carcinomas, early detection and removal of colorectal adenomas are one of the most effective methods to prevent colorectal cancer. Considering the increasing incidence of colorectal cancer and polyps in Korea, it is very important to establish Korean guideline for colorectal cancer screening and polyp detection. The guideline was developed by the Korean Multi-Society Take Force and we tried to establish the guideline by evidence-based methods. Parts of the statements were draw by systematic reviews and meta-analyses. Herein we discussed epidemiology of colorectal cancers and adenomas in Korea and optimal methods for screening of colorectal cancer and detection of adenomas including fecal occult blood tests, radiologic tests, and endoscopic examinations.

Computed tomographic colonography: ready for prime time?

Computed tomographic (CT) colonography is a noninvasive method to evaluate the colon and has received considerable attention in the last decade as a colon-imaging tool. The technique has also been proposed as a potential primary colon cancer-screening method in the United States. The accuracy of the technique for the detection of large lesions seems to be high, perhaps in the range of colonoscopy. Overall, the field is rapidly evolving. Available data suggest that CT colonography, although a viable colon cancer screening modality in the United States, is not ready for widespread implementation, largely because of the lack of standards for training and reading and the limited number of skilled readers.

A comparison of optical colonoscopy and CT colonography screening strategies in the detection and recovery of subcentimeter adenomas

OBJECTIVES

Evidence has shown that computerized tomographic colonography (CTC) and optical colonoscopy (OC) can detect advanced adenomas at an equal rate; however, a comparison of the subcentimeter adenoma detection has not been performed. The objective of this study is to compare CTC and OC screening programs, with a focus on the detection and recovery of subcentimeter adenomas.

METHODS

In all, 1,700 screening OC examinations in average-risk patients were compared with 1,307 CTC examinations in similar patients drawn from the same referral pool completed in 2006-2008. The detection rate for adenomas ≤ 5 mm, 6-9 mm, and <10 mm with advanced histology were compared.

RESULTS

In the OC group, 23.2% of patients had at least one adenoma removed; in the CTC screening group, 5.9% of patients had at least one adenoma detected and removed, P<0.001. There were significantly more ≤ 5 mm adenomas (detection rate 0.22, 378/1,700) detected by OC than by CTC (detection rate 0.04, 56/1,307), P<0.001. There were significantly more adenomas 6-9 mm (detection rate 0.12, 204/1,700) detected by OC than by CTC (detection rate 0.05, 67/1,307), with 70 patients with polyps of unknown histology in CTC surveillance, P<0.001. The number of advanced lesions <10 mm detected by OC (15/1,700) compared with CTC (4/1,307) were not significantly different, P=0.06. In the OC group, 27.1% of patients had non-adenomatous polyps removed; in the CTC group, 4.1% of patients had non-adenomatous polyps removed, P<0.001.

CONCLUSIONS

(i) An OC screening program detects and recovers a significant four and a half fold greater number of non-advanced adenomas compared with a CTC screening program. (ii) The primary difference between screening with OC and CTC is the recovery and management of the subcentimeter adenoma.

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.

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.

Management of small polyps detected by screening CT colonography: patient and physician preferences

BACKGROUND

Management of small polyps found on computed tomography (CT) colonography is controversial and critical to both cancer outcomes and cost. Patient and physician behavior are influenced by personal beliefs and prior experience. Thus, we aimed to understand patient and physician preferences after finding polyps on CT colonography.

METHODS

Patients were given a validated handout and survey asking for their preference for evaluation of a "pea-sized" polyp found on CT colonography. By using an Internet survey, physicians were asked how they would manage a 5-mm, 8-mm, or 12-mm polyp, or three 5-mm polyps found by CT colonography in a hypothetical 52-year-old patient of average colorectal cancer risk. Survey reliability was assessed using Cronbach's coefficient alpha.

RESULTS

Of the 305 patient respondents, 95% wanted to know if the polyp found on CT colonography was precancerous, 86% stated they would request endoscopic evaluation, and 85% wanted polypectomy. Of the 277 primary care physicians, 71% would refer a 5-mm sigmoid polyp for endoscopy, 86% would refer an 8-mm polyp, 97% would refer a 12-mm polyp, and 91% would refer three 5-mm polyps. Of the 461 gastroenterologists, 83% would refer a 5-mm sigmoid polyp for endoscopy, 96% would refer an 8-mm polyp, 97% would refer a 12-mm polyp, and 93% would refer three 5-mm polyps. Overall, 75% of physicians indicated the fear of missing a precancerous lesion would prompt referral for colonoscopy.

CONCLUSION

Both patients and physicians overwhelmingly preferred to follow up small polyps identified by CT colonography with endoscopy, suggesting that population-based CT colonography screening programs in which polyps are not removed might require significant patient and physician education before implementation.

Charity Colonoscopy Event to Commemorate the 185th Anniversary of Singapore General Hospital

Introduction: Colorectal cancer is now the cancer with the highest incidence in Singapore. However, the overall mortality rate is still about 50% because the majority of the patients present at a late stage of disease. A charity event of screening colonoscopy was offered to the public in conjunction with the 185th anniversary of Singapore General Hospital. The aim of this event was to raise awareness about early detection of colorectal cancer and the safety of colonoscopy. Materials and Methods: We conducted a one-off free screening event for colorectal cancer using colonoscopy. Four hundred and ninety individuals responded to a multimedia advertisement for the event. Of these, 220 individuals were selected for the screening based on National Guidelines for colorectal cancer screening and financial status. Results: One hundred and fifty-two individuals turned up for the colonoscopy. The median age was 55 years (range, 22 to 82), with 84 males. Significant pathology was found in 33% of the individuals (n = 51). Colorectal polyps were detected in 34 individuals (22%). A total of 45 polyps were removed, with 20 hyperplastic polyps and 25 adenomas. Eight out of 25 adenomas were located proximal to the splenic flexure. Rectal cancer was diagnosed in 1 individual (0.6%). One individual had a large dysplastic rectosigmoid ulcer and refused further intervention. There were no significant complications from any of the colonoscopies. Conclusions: Colonoscopy is an invaluable screening modality as it has a high pick-up rate for colorectal polyp and cancer in an asymptomatic population. It is also proven to be safe in our study. It has the added advantage over flexible sigmoidoscopy of detecting a significant number of proximal lesions. Also, therapeutic polypectomy can be performed in the same setting. Colorectal cancer is now the cancer with the highest incidence in Singapore. Similar to many developed countries, individuals here have a moderate to high risk of developing colorectal cancer in their lifetime. Key words: Cancer screening, Colonoscopy, Colorectal cancer, Colorectal polyps, Polypectomy

American College of Gastroenterology guidelines for colorectal cancer screening 2009 [corrected]

This document is the first update of the American College of Gastroenterology (ACG) colorectal cancer (CRC) screening recommendations since 2000. The CRC screening tests are now grouped into cancer prevention tests and cancer detection tests. Colonoscopy every 10 years, beginning at age 50, remains the preferred CRC screening strategy. It is recognized that colonoscopy is not available in every clinical setting because of economic limitations. It is also realized that not all eligible persons are willing to undergo colonoscopy for screening purposes. In these cases, patients should be offered an alternative CRC prevention test (flexible sigmoidoscopy every 5-10 years, or a computed tomography (CT) colonography every 5 years) or a cancer detection test (fecal immunochemical test for blood, FIT).

CT colonography can be an adjunct to optical colonoscopy in CRC screening

CT colonography or virtual colonoscopy is a fairly new modality that has the potential to play a significant role in screening for colon cancer. CT colonography is an attractive option for two specific reasons. First, it is non-invasive and, second, it obviates the need for sedation. It thus overcomes the two major drawbacks of optical colonoscopy. CT colonography cannot be a stand-alone technique for colorectal cancer screening because, unlike conventional colonoscopy, it does not possess a therapeutic option or a definite diagnostic capability. However, CT colonography can be a cost-effective complement to traditional colonoscopy if it is reasonably priced and if appropriate cut-off levels (>6 mm polyp) are used to increase its sensitivity.

The efficacy of intravenous contrast-enhanced 16-raw multidetector CT colonography for detecting patients with colorectal polyps in an asymptomatic population in Korea

PURPOSE

The purpose of this study is to compare the sensitivity of computed tomography (CT) colonography (CTC) with that of colonoscopy for detecting patients with colorectal polyps in an asymptomatic screening population in Korea, thus to evaluate a possibility, whether CTC could be used as a screening tool for colorectal polyps.

METHODS

A total of 241 asymptomatic adults underwent intravenous contrast-enhanced CTC and colonoscopy successively on the same day. Bowel preparation was performed by 4 L of polyethylene glycol (n=172) or 90 mL of sodium phosphate (n=69). The CTC findings were released to the colonoscopists after the first examination of each segment, a procedure known as segmental unblinded colonoscopy, and were used as the reference standard. The diagnostic performance of CTC for colorectal polyps was calculated.

RESULTS

The per-patient sensitivities of CTC were 68.5% (37/54) and 86.7% (13/15) for polyp > or = 6 and > or = 10 mm, inferior to those of colonoscopy, 92.6% (50/54) and 100% (15/15), respectively. The per-polyp sensitivities of CTC were 60.4% (61/101) and 72.7% (16/22) for polyp > or = 6 and > or = 10 mm, respectively. The low sensitivity of CTC was related with flat morphology. CTC detected only 37.5% (9/24) of flat polyps > or = 6 mm. Bowel preparation by sodium phosphate further decreased the positive predictive value and specificity than by polyethylene glycol.

CONCLUSIONS

Screening by CTC with asymptomatic population was not promising in Korea despite using advanced CT technology (16-row detector). Bowel preparation was one of the key determinants of the specificity of CTC.

Computed tomography colonography (virtual colonoscopy): climax of a new era of validation and transition into community practice

Colorectal cancer, which kills more than 50,000 patients every year in the United States and costs more than $6 billion in direct health costs, is a prime target for cancer prevention. Computed tomography colonography (CTC) has emerged as a minimally invasive, structural examination of the entire colon that can complement the current tools of cancer prevention and may improve patient compliance. Large trials have suggested a sensitivity of roughly 90% and specificity greater than 97% for CTC for patients with polyps >or= 10 mm. Bowel preparation by diet restriction, catharsis, and stool and fluid tagging are typically used. A prepless CTC protocol is an active area of research with a focus on improving patient compliance. Insurance coverage of CTC is a key factor affecting current dissemination and local and national coverage decisions are ongoing. CT examination of the abdomen allows visualization of extracolonic organs, where detection of additional disease must balance any unnecessary anxiety and testing. Estimates of CTC cost-effectiveness are generally favorable, but vary due to the high sensitivity of these models to costs, polyp sensitivity, compliance rates, and other parameters, which are difficult to accurately assess. Quality initiatives are being developed that will be key for implementation into community practice.

Advances in radiological imaging of gastrointestinal tumors

This article summarizes the recent advances in radiological imaging in the hepatogastrointestinal field in terms of detection, characterization and staging of tumors. Introduction of multidetector row computed tomography technology has helped computed tomography to excel in its already established indications, and has expanded its capabilities by adding new clinical applications, such as computed tomography angiography, liver perfusion, computed tomography enterography or enteroclysis, and virtual colonoscopy. Contrast-enhanced ultrasound has dramatically changed the role of ultrasound in liver tumor characterization, detection, and other applications. Combining the advantages of unsurpassed soft tissue contrast and lack of ionizing radiation, magnetic resonance imaging of the gastrointestinal tract has become increasingly used clinically. Moreover, substantial progress in molecular and cellular magnetic resonance imaging has been achieved in the past few years. Particularly, the increasing number of available specific contrast agents dedicated to the evaluation of the liver and lymph nodes shows promises in the area of oncologic abdominal imaging.

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

In the United States, colorectal cancer (CRC) is the third most common cancer diagnosed among men and women and the second leading cause of death from cancer. CRC largely can be prevented by the detection and removal of adenomatous polyps, and survival is significantly better when CRC is diagnosed while still localized. In 2006 to 2007, the American Cancer Society, the US Multi-Society Task Force on Colorectal Cancer, and the American College of Radiology came together to develop consensus guidelines for the detection of adenomatous polyps and CRC in asymptomatic average-risk adults. In this update of each organization's guidelines, screening tests are grouped into those that primarily detect cancer early and those that can detect cancer early and also can detect adenomatous polyps, thus providing a greater potential for prevention through polypectomy. When possible, clinicians should make patients aware of the full range of screening options, but at a minimum they should be prepared to offer patients a choice between a screening test that primarily is effective at early cancer detection and a screening test that is effective at both early cancer detection and cancer prevention through the detection and removal of polyps. It is the strong opinion of these 3 organizations that colon cancer prevention should be the primary goal of screening.

Computed tomographic colonography: clinical value

Computed tomographic colonography (CTC) has the potential to reliably detect polyps in the colon. Its clinical value is accepted for several indications. The main target is screening asymptomatic people for colorectal cancer (CRC). As in large multi-centre trials controversial results were obtained, acceptance of this indication on a large scale is still pending. Agreement exists that in experienced hands screening can be performed with CTC. This emphasizes the importance of adequate and intensive training. Besides this, other problems have to be solved. A low complication profile is mandatory. Perforation rate is very low. Ultra-low dose radiation should be used. When screening large patient cohorts, CTC will need a time-efficient and cost-effective management without too many false positives and additional exploration. Can therefore a cut-off size of polyp detection safely be installed? Is the flat lesion an issue? Can extra-colonic findings be treated efficiently? A positive relationship with the gastro-enterologists will improve the act of screening. Improvements of scanning technique and software with dose reduction, improved 3D visualisation methods and CAD are steps in the good direction. Finally, optimisation of laxative-free CTC could be invaluable in the development of CTC as a screening tool for CRC.

CT colonography with reduced bowel preparation after incomplete colonoscopy in the elderly

We prospectively assessed the feasibility and acceptance of computerized tomographic colonography (CTC) without bowel cathartic preparation in elderly patients after incomplete colonoscopy. A total of 136 patients underwent CTC without cathartic preparation. The time delay between conventional colonoscopy and CTC ranged between 3 and 20 days, depending on the clinical situation. Before CTC, fecal tagging was achieved by adding diatrizoate meglumine and diatrizoate sodium to regular meals. CTCs were interpreted using a primary two-dimensional (2D) approach and 3D images for further characterization. Patients were interviewed before and 2 weeks after CTC to assess preparation acceptance. CTC was feasible and technically successful in all the 136 patients. Fecal tagging was judged as excellent in 113 (83%) patients and sufficient in 23 (17%). Average CT image interpretation time was 14.8 min. Six (4.4%) cases of colorectal cancer and nine (6.6%) large polyps were detected, as well as 23 (11.3%) extracolonic findings of high clinical importance. No major side effect occurred, although 25% patients reported minor side effects, especially diarrhea. Overall, 76/98 patients replied that they would be willing to repeat the test if necessary. CTC without cathartic preparation is a technically feasible and safe procedure to complete a colonic study in the elderly, prompting its use in clinical practice.

Pathophysiology, clinical presentation, and management of colon cancer

Colon cancer is believed to arise from two types of precursor polyps via two distinct pathways: conventional adenomas by the conventional adenoma-to-carcinoma sequence and serrated adenomas according to the serrated adenoma-to-carcinoma theory. Conventional adenomas arise from mutation of the APC gene; progression to colon cancer is a multistep process. The fundamental genetic defect in serrated adenomas is unknown. Environmental factors can increase the risk for colon cancer. Advanced colon cancer often presents with symptoms, but early colon cancer and premalignant adenomatous polyps commonly are asymptomatic, rendering them difficult to detect and providing the rationale for mass screening of adults over age 50.

Reducing the incidence and mortality of colon cancer: mass screening and colonoscopic polypectomy

Most colon cancers arise from conventional adenomatous polyps (conventional adenoma-to-carcinoma sequence), while some colon cancers appear to arise from the recently recognized serrated adenomatous polyp (serrated adenoma-to-carcinoma theory). Because conventional adenomas and serrated adenomas are usually asymptomatic, mass screening of asymptomatic patients has become the cornerstone for detecting and eliminating these precursor lesions to reduce the risk of colon cancer. Colonoscopy has become the primary screening test because of its high sensitivity and specificity, and the ability to perform polypectomy. Other screening tests include guaiac tests or fecal immunochemical tests (FIT) for fecal occult blood, and flexible sigmoidoscopy. A minimal colonoscopic withdrawal time of 6 minutes is important to maximize polyp detection at colonoscopy. Chromoendoscopy is an experimental technique used to highlight abnormal colonic areas to identify neoplastic tissue and to potentially determine the histology of colonic polyps at colonoscopy based on superficial pit anatomy.

CT colonography: current status and future promise

CT colonography (CTC) is an innovative technology that entails CT examination of the entire colon and computerized processing of the raw data after colon cleansing and colonic distention. CTC could potentially increase the screening rate for colon cancer because of its relative safety, relatively low expense, and greater patient acceptance, but its role in mass colon cancer screening is controversial because of its highly variable sensitivity, the inability to sample polyps for histologic analysis, and lack of therapeutic capabilities. This article reviews the CTC literature, including imaging and adjunctive techniques, radiologic interpretation, procedure indications, contraindications, risks, sensitivity, interpretation pitfalls, and controversies.

Projected impact of colorectal cancer screening with computerized tomographic colonography on current radiological capacity in Europe

BACKGROUND

The impact of a primary colorectal cancer screening with computerized tomographic colonography on current radiological capacity is unknown. The multispecialty needs for computerized tomographic examinations raise some doubts on the feasibility of a mass colorectal cancer screening with computerized tomographic colonography.

AIM

To assess whether the number of available computerized tomographic units in Europe is adequate to cover population screening with computerized tomographic colonography.

METHODS

A mathematical and a Markov model were, respectively, used to assess the number of computerized tomographic colonography procedures needed to be performed each day in the start-up and in the steady-state phases of a colorectal cancer screening programme in Europe. Such outcome was divided for the total number of computerized tomographic machines aged <10 years estimated to be present in the European hospitals.

RESULTS

At a simulated 30% compliance, 28 760 130 European people would need to be screened by the 3482 available computerized tomographic units in a 5-year start-up period, corresponding to 6.6 CTC/CT unit/day. Assuming a 10-year repetition of computerized tomographic colonography between 50 and 80 years, the number of computerized tomographic colonography needed to be performed in the steady-state period appeared to be 4.3/CT unit/day.

CONCLUSIONS

The current radiological capacity may cover the need for a primary colorectal cancer screening with computerized tomographic colonography in a steady state. On the other hand, a substantial implementation of the current computerized tomographic capacity or a synergistic approach with other techniques seems to be necessary for the start-up period.

CT colonography versus colonoscopy for the detection of advanced neoplasia

BACKGROUND

Advanced neoplasia represents the primary target for colorectal-cancer screening and prevention. We compared the diagnostic yield from parallel computed tomographic colonography (CTC) and optical colonoscopy (OC) screening programs.

METHODS

We compared primary CTC screening in 3120 consecutive adults (mean [+/-SD] age, 57.0+/-7.2 years) with primary OC screening in 3163 consecutive adults (mean age, 58.1+/-7.8 years). The main outcome measures included the detection of advanced neoplasia (advanced adenomas and carcinomas) and the total number of harvested polyps. Referral for polypectomy during OC was offered for all CTC-detected polyps of at least 6 mm in size. Patients with one or two small polyps (6 to 9 mm) also were offered the option of CTC surveillance. During primary OC, nearly all detected polyps were removed, regardless of size, according to established practice guidelines.

RESULTS

During CTC and OC screening, 123 and 121 advanced neoplasms were found, including 14 and 4 invasive cancers, respectively. The referral rate for OC in the primary CTC screening group was 7.9% (246 of 3120 patients). Advanced neoplasia was confirmed in 100 of the 3120 patients in the CTC group (3.2%) and in 107 of the 3163 patients in the OC group (3.4%), not including 158 patients with 193 unresected CTC-detected polyps of 6 to 9 mm who were undergoing surveillance. The total numbers of polyps removed in the CTC and OC groups were 561 and 2434, respectively. There were seven colonic perforations in the OC group and none in the CTC group.

CONCLUSIONS

Primary CTC and OC screening strategies resulted in similar detection rates for advanced neoplasia, although the numbers of polypectomies and complications were considerably smaller in the CTC group. These findings support the use of CTC as a primary screening test before therapeutic OC.

Utility of computed tomographic colonography in surveillance for hereditary nonpolyposis colorectal cancer syndrome

Computed tomographic colonography (CTC) is suggested to be an alternative to colonoscopy as a surveillance tool in subjects with a high risk for colorectal cancer (CRC). To evaluate the utility of CTC we successively examined 78 subjects, all with a DNA mismatch repair gene mutation, by CTC and colonoscopy. We detected altogether 37 polyps or tumors in 28 subjects (prevalence 35.9%), adenomas in 13 subjects (16.7%), CRC in two (2.6%), and hyperplastic polyps in 13 (16.7%). A great majority of the polyps were diminutive. The per-patient sensitivity for detecting all lesions with CTC was 0.25 and 0.29 by two radiologists and the specificities 0.82 and 0.76. For lesions of 10 mm or larger the sensitivities were 0.6 and 1.0 and the specificities 0.96 by each examiner. Each diagnosed the two cancers correctly. We concluded that CTC has an acceptable accuracy for large lesions in the colon but the detection rate for small polyps is not comparable to that in colonoscopy. Therefore CTC remains a second choice in surveillance for use when colonoscopy for some reason is incomplete or unsuitable.

Will 3D Virtual Dissection Display Prove to Be the Display Format for Reviewing CT Colonography Examinations?

In the study by Kim et al, primary two-dimensional (2D) search with a three-dimensional (3D) problem-solving technique was compared with a 3D virtual dissection technique, with use of two independent reviewers. The authors observed no significant difference (P>.05) in sensitivity or specificity between the two techniques for the detection of polyps 6 mm or larger, whereas the median review time with virtual dissection was significantly (P<.05) shorter. This may have implications for the application of computed tomographic (CT) colonography for screening the asymptomatic average-risk population.