Dysplastic lesions in ulcerative colitis: changing paradigms

Colon Cancer: Inflammation-Associated Cancer

Colitis-associated cancer is a relatively rare form of cancer with an unclear pathogenesis. Colitis-associated cancer serves as a prototype of inflammation-associated cancers. Advanced colonoscopic techniques are considered standard of care for surveillance in patients with long-standing colitis, especially those with other risk factors, including sclerosing cholangitis and a family history of colorectal cancer. When colitis-associated cancer is diagnosed, the standard operation involves total proctocolectomy. Restorative procedures and surveillance after colectomy require special considerations. In these contexts, new 3-dimensional human models may be used to usher in personalized medicine.

Surveillance of long-standing colitis: the role of image-enhanced endoscopy

Patients with long-standing inflammatory bowel disease of the colon are at an increased risk of developing colorectal carcinoma. Surveillance programs have been implemented with the aim of detecting neoplastic lesions in an early stage. Due to limitations of conventional white light endoscopy, several new techniques to enhance the detection of dysplastic lesions in this setting have been explored. These advanced endoscopic techniques use a variety of methods to improve visualization, such as pancolonic dye-spraying (chromoendoscopy), optical filters (narrow-band imaging) and autofluorescence of mucosal tissue (autofluorescence imaging). At present, most guidelines have adopted chromoendoscopy as the preferred method for surveillance, based on several controlled studies. It is currently unknown if widespread implementation of chromoendoscopy will lead to an improved clinical outcome. This review explores the current evidence on image-enhanced endoscopic techniques used in the detection of neoplastic lesions in patients with long standing colitis.

Low Prevalence of Colon Polyps in Chronic Inflammatory Conditions of the Colon

OBJECTIVES

Previous studies have reported a low prevalence of colon polyps in patients with microscopic colitis. The aim of the study was to test whether such inverse associations applied to other inflammatory diseases of the colon.

METHODS

In a case-control study among 130,204 patients undergoing colonoscopy for the work-up of diarrhea, we compared the prevalence of colon polyps in a case population of patients with inflammatory bowel disease (IBD), microscopic colitis, histologic signs of active colitis, diverticulitis, or ischemic colitis, and in a control population with normal colon mucosa. Case and control subjects were compared using odds ratios and their 95% confidence intervals adjusted for age and sex.

RESULTS

In 11,176 patients with microscopic colitis, the prevalence of hyperplastic polyps, serrated adenomas, and tubular adenomas were all reduced: odds ratios=0.46 (95% confidence intervals=0.43-0.49), 0.24 (0.19-0.30), and 0.35 (0.33-0.38), respectively. In 4,435 patients with IBD, the corresponding values were: 0.18 (0.15-0.21), 0.24 (0.16-0.35), and 0.18 (0.15-0.21), respectively. In 6,501 patients with histologically active colitis, the corresponding values were: 0.58 (0.53-0.63), 0.57 (0.46-0.70), and 0.63 (0.58-0.68), respectively. No such consistent reduction in polyp prevalence was found in patients with diverticulitis or ischemic colitis.

CONCLUSIONS

Chronic inflammatory conditions of the colon are associated with a decreased prevalence of colon polyps.

Colorectal cancer in patients with inflammatory bowel disease: the true impact of the risk

Patients with long-standing inflammatory bowel disease (IBD) have an increased risk of colorectal cancer (CRC). The association between IBD and CRC is well supported, but reported risk estimates vary widely. Although recent evidence from population-based studies reports a decline in risk, CRC accounts for 10-15% of all deaths in IBD. The potential causes of recent epidemiological trends and the real magnitude of risk of CRC in IBD are subjects of debate. The molecular pathway leading to CRC differs from the classic adenoma-to-CRC sequence. Chronic inflammation contributes to the development of low- and high-grade dysplasia which may further convert into CRC. Patients with a young age at onset, long-standing and extensive colitis with severe inflammatory burden, a family history of sporadic CRC, and concomitant primary sclerosing cholangitis are at greatest risk. The CRC risk in patients with colonic Crohn's disease is similar to that of ulcerative colitis. IBD-associated CRC can frequently be detected at late stages and at a younger age. The long-term prognosis of CRC may be poorer in patients with IBD than in those with sporadic CRC. Regular surveillance colonoscopies may permit earlier detection of CRC, with a corresponding improved prognosis. The interval between surveillance colonoscopies is dependent on each patient's personal risk profile.

Inflammatory bowel disease cancer surveillance in a tertiary referral hospital: attitudes and practice

BACKGROUND

Physician adherence to guidelines for colorectal cancer (CRC) surveillance in inflammatory bowel disease (IBD) is often poor. This may lead to adverse patient outcomes and excess endoscopic workload.

AIMS

To assess the attitudes and practice of IBD specialists in a tertiary centre towards colonoscopic surveillance.

METHODS

First, a questionnaire evaluating attitudes and approach to CRC surveillance was issued to 36 clinicians at one tertiary referral hospital. Second, a retrospective audit of IBD surveillance colonoscopy practice over a 2-year period was performed.

RESULTS

Questionnaire response rate was 97%. Sixty-nine per cent of respondents were aware of, and used, Australian guidelines. Surveillance was undertaken by all clinicians in patients with extensive colitis, 83% in patients with left-sided colitis and 51% in patients with proctitis. Seventy-six per cent used chromoendoscopy, and 47% took 10 to 20 random biopsies. Colectomy was considered appropriate in 0% for unifocal low-grade dysplasia, 35% for multifocal low-grade dysplasia and 83% for high-grade dysplasia. Sixty-six per cent would remove elevated dysplastic lesions endoscopically. The audit identified 103 surveillance colonoscopies in 81 patients. Chromoendoscopy was used in 21% of cases, and the median number of random biopsies was 13. Sixty-two per cent of colonoscopies were performed outside the guidelines in relation to colonoscopic frequency. Following colonoscopy, an appropriate recommendation for subsequent surveillance was documented in 40% of cases.

CONCLUSIONS

Knowledge and practice of CRC surveillance in IBD vary among specialist clinicians and often deviate from guidelines. Many clinicians perform surveillance earlier and more frequently than recommended. These findings have implications for patient outcomes and workload.

Consensus on the Prevention, Screening, Early Diagnosis and Treatment of Colorectal Tumors in China: Chinese Society of Gastroenterology, October 14-15, 2011, Shanghai, China

BACKGROUND

Colorectal cancer (CRC) is steadily increasing in China. Colorectal adenoma (CRA) is the most important precancerous disease of CRC. Screening for colorectal tumors can aid early diagnosis. Advances in endoscopic mucosal resection and endoscopic submucosal dissection can aid the early treatment of colorectal tumors. Furthermore, because of high risk of recurrence after removal of adenomas under endoscopy, factors contributing to recurrence, the follow-up mode and the interval established, and the feasibility of application and the time of various chemical preventions should be concerned. However, a relevant consensus on the screening, early diagnosis and treatment, and prevention of colorectal tumors in China is lacking.

SUMMARY

The consensus recommendations include epidemiology, pathology, screening, early diagnosis, endoscopic treatment, monitoring and follow-up, and chemoprevention of colorectal tumors in China.

KEY MESSAGE

This is the first consensus on the prevention, screening, early diagnosis and treatment of CRA and CRC in China based on evidence in the literature and on local data.

PRACTICAL IMPLICATIONS

Through reviewing the literature, regional data and passing the consensus by an anonymous vote, gastroenterology experts from all over China launch the consensus recommendations in Shanghai. The incidence and mortality of CRC in China has increased, and the incidence or detection rate of CRA has increased rapidly. Screening for colorectal tumors should be performed at age 50-74 years. Preliminary screening should be undertaken to find persons at high risk, followed by colonoscopy. A screening cycle of 3 years is recommended for persistent interventions. Opportunistic screening is a mode suitable for the current healthcare system and national situation. Colonoscopy combined with pathological examination is the standard method for the diagnosis of colorectal tumors. CRA removal under endoscopy can prevent CRC to some extent, but CRA has an obvious recurrence trend. The follow-up interval after the removal or surgery of colorectal tumors should be different with lesions. Primary prevention of CRA includes improved diet with more fiber, supplements containing calcium and vitamin D, supplements containing folic acid for those with low hemoglobin levels, and cessation of tobacco smoking. Non-steroidal anti-inflammatory drugs and selective cyclooxygenase-2 inhibitors have been recognized to prevent recurrence after adenoma removal.

Chronic ulcerative colitis and colorectal cancer

One of the most important consequences of chronically active ulcerative colitis (UC) or Crohn's disease (CD) - the two major forms of inflammatory bowel disease (IBD) - is the development of colorectal cancer (CRC). An increased risk for the occurrence of CRC in up to 30% of affected patients after 35years of UC has been reported. Recent evidence from population based studies indicates a lower risk. Nevertheless the incidence is still significantly increased as compared to individuals without chronic colitis. Colitis-associated CRC (CAC) does not display the adenoma-carcinoma sequence which is typical for sporadic CRC and the pathophysiology appears to be different. Chronic inflammation and the increased turnover of epithelial cells contribute to the development of low- and high-grade dysplasia which may further transform into CAC. Reactive oxygen species (ROS) generated by the inflammatory infiltrate are thought to contribute to the generation of dysplastic lesions. In sporadic CRC the sequence of mutations that finally lead to malignancy involves early activation of Wnt/β-catenin pathway (in 90% of cases) including mutations in adenomatous polyposis coli (APC) tumor suppressor gene, its regulating kinase GSK3β and β-catenin itself. β-catenin mutations are rarer in CAC and mutations in APC occur rather late during the disease progression, whereas there are earlier mutations in p53 and K-ras. Recent data indicate that the intestinal microbiome and its interaction with a functionally impaired mucosal barrier may also play a role in CAC development. CACs frequently show aggressive growth and early metastases. The treatment of CAC in patients with colitis always includes proctocolectomy with ileoanal anastomosis as meta- or synchronic lesions are frequent.