Low incidence of significant dysplasia in a successful endoscopic surveillance program of patients with ulcerative colitis

The risk of colorectal cancer in ulcerative colitis: a meta-analysis

BACKGROUND AND AIMS

Controversy surrounds the risk of colorectal cancer (CRC) in ulcerative colitis (UC). Many studies have investigated this risk and reported widely varying rates.

METHODS

A literature search using Medline with the explosion of references identified 194 studies. Of these, 116 met our inclusion criteria from which the number of patients and cancers detected could be extracted. Overall pooled estimates, with 95% confidence intervals (CI), of cancer prevalence and incidence were obtained using a random effects model on either the log odds or log incidence scale, as appropriate.

RESULTS

The overall prevalence of CRC in any UC patient, based on 116 studies, was estimated to be 3.7% (95% CI 3.2-4.2%). Of the 116 studies, 41 reported colitis duration. From these the overall incidence rate was 3/1000 person years duration (pyd), (95% CI 2/1000 to 4/1000). The overall incidence rate for any child was 6/1000 pyd (95% CI 3/1000 to 13/1000). Of the 41 studies, 19 reported results stratified into 10 year intervals of disease duration. For the first 10 years the incidence rate was 2/1000 pyd (95% CI 1/1000 to 2/1000), for the second decade the incidence rate was estimated to be 7/1000 pyd (95% CI 4/1000 to 12/1000), and in the third decade the incidence rate was 12/1000 pyd (95% CI 7/1000 to 19/1000). These incidence rates corresponded to cumulative probabilities of 2% by 10 years, 8% by 20 years, and 18% by 30 years. The worldwide cancer incidence rates varied geographically, being 5/1000 pyd in the USA, 4/1000 pyd in the UK, and 2/1000 pyd in Scandinavia and other countries. Over time the cancer risk has increased since 1955 but this finding was not significant (p=0.8).

CONCLUSIONS

Using new meta-analysis techniques we determined the risk of CRC in UC by decade of disease and defined the risk in pancolitics and children. We found a non-significant increase in risk over time and estimated how risk varies with geography.

Screening and surveillance colonoscopy in chronic Crohn's colitis

BACKGROUND & AIMS

Unlike ulcerative colitis, there are few reports on the efficacy of surveillance colonoscopy in patients with chronic Crohn's colitis and therefore little agreement as to whether routine surveillance is indicated. We report on 259 patients with chronic Crohn's colitis who underwent screening and subsequent surveillance colonoscopy and biopsy since 1980.

METHODS

Biopsies were performed at 10-cm intervals and from strictures and polypoid masses. Pathology was classified as normal, dysplasia (indefinite, low-grade, high-grade), or carcinoma.

RESULTS

A total of 663 examinations were performed on 259 patients. The median interval between examinations was 24 months; examinations were performed more frequently (1-6 months) in patients with dysplasia on biopsy. A thinner-caliber colonoscope was required to complete 12% of screening examinations and 23% of surveillance examinations. The pediatric colonoscope helped increase our yield of neoplasia by 19%. The screening and surveillance program detected dysplasia or cancer in 16% (10 indefinite, 23 low-grade, and 4 high-grade dysplasias and 5 cancers). A finding of definite dysplasia or cancer was associated with age >45 years and increased symptoms. By life table analysis, the probability of detecting dysplasia or cancer after a negative screening colonoscopy was 22% by the fourth surveillance examination.

CONCLUSIONS

Colonoscopic surveillance should be strongly considered in chronic extensive Crohn's colitis.

Chromosomal imbalances in Barrett's adenocarcinoma and the metaplasia-dysplasia-carcinoma sequence

To characterize cytogenetic alterations found in Barrett's adenocarcinoma (BA) and, more importantly, its premalignant stages, we studied chromosomal imbalances in various lesions in the histologically proposed metaplasia-dysplasia-carcinoma sequence using comparative genomic hybridization (CGH). Using 30 esophageal adenocarcinoma resection specimens, we were able to study 30 areas of Barrett's adenocarcinoma and 8 lymph node metastases (LN). In addition, we investigated 25 premalignant lesions adjacent to BA derived from a subset of 14 resection specimens including 11 areas of high grade dysplasia (HGD), 8 areas of low grade dysplasia (LGD), and 6 areas of intestinal metaplasia (IM), which were laser-microdissected and studied with CGH. To validate the CGH findings, fluorescence in situ hybridization analysis on 13 BA with probes specific for HER-2/neu and 20q13.2 were performed. The chromosomal alterations most often identified in BA were: gains on 8q (80%), 20q (60%), 2p, 7p and 10q (47% each), 6p (37%), 15q (33%) and 17q (30%). Losses were observed predominantly on the Y-chromosome (76%), 4q (50%), 5q and 9p (43% each), 18q (40%), 7q (33%) and 14q (30%). High-level amplifications were observed on 8q23-qter, 8p12-pter, 7p11-p14, 7q21-31, 17q11-q23. Recurrent chromosomal changes were also identified in metaplastic (gains on 8q, 6p, 10q, losses on 13q, Y, 9p) and dysplastic epithelium (gains on 8q, 20q, 2p, 10q, 15q, losses on Y, 5q, 9p, 13q, 18q). Novel amplified chromosomal regions on chromosomes 2p and 10q were detected in both Barrett's adenocarcinoma and premalignant lesions. An increase of the average number of detected chromosomal imbalances from IM (7.0 +/- 1.7), to LGD (10.8 +/- 2.2), HGD (13.4 +/- 1.1), BA (13.3 +/- 1.4), and LN (22 +/- 1.2) was seen. Although the detection of common chromosomal alterations in premalignant lesions and adjacent carcinomas suggest a process of clonal expansion, the occurrence of several chromosomal changes in an apparently random order relative to one another is striking evidence that clonal evolution is more complex than would be predicted by linear models. This is probably a reflection of the existence of many divergent neoplastic subpopulations and highlights one of the main problems associated with surveillance of Barrett's patients, namely sampling error.

The differentiation of true adenomas from colitis-associated dysplasia in ulcerative colitis: a comparative immunohistochemical study

Adenomas in areas involved by ulcerative colitis (UCA) are difficult to identify because of their morphological similarity to ulcerative colitis-associated dysplasia (UCD) and have an uncertain biology. Recently, a set of morphopathologic criteria were published for the diagnosis of UCA versus UCD. As a first step to analyze these criteria, we studied p53 and bcl-2 expression in groups of UCA and UCD along with a sporadic adenoma control group. Ninety lesions from UC areas (62 patients) were examined, including 24 UCA without high-grade dysplasia (HGD) and 66 UCD consisting of 43 polypoid and 23 flat dysplastic lesions (29 with HGD). Immunohistochemical p53 and bcl-2 expression were evaluated semiquantitatively. P53-positive cases were significantly less frequent in the UCA (4%) versus the UCD group (30%, P = .01) and the polypoid UCD subgroup (35%, P = .005). Moderate or strong bcl-2 expression was significantly more frequent in the UCA than in the UCD group (96% v 70%, P = .01) and in the UCA versus both polypoid and flat UCD subgroups. Comparison of UCA with low-grade dysplastic polypoid UCD cases alone showed a difference just below significance for p53 (P = .07). p53 and bcl-2 expression rates were very similar in the UCA group and the sporadic adenoma (n = 25) control group. These results show that UCA has phenotypic features more similar to sporadic adenomas than UCD and supports the concept that adenomas in UC have a biology different from UC-associated dysplasia.

Cancer risk in patients with inflammatory bowel disease

Patients with inflammatory bowel disease (IBD) are at increased risk for developing cancer of the gastrointestinal tract, particularly colorectal cancer. Because of the relative rarity of IBD in the general population, it has been difficult to quantify this risk. Efforts to reduce the risk have included both prophylactic surgery and endoscopic screening programs. Because of the potential impact on quality of life and life expectancy, the optimal strategy for reducing this risk has not been defined. This article reviews the current literature relating to the risk of cancer for patients with IBD and methods to reduce this risk.

Evolution of neoplastic cell lineages in Barrett oesophagus

It has been hypothesized that neoplastic progression develops as a consequence of an acquired genetic instability and the subsequent evolution of clonal populations with accumulated genetic errors. Accordingly, human cancers and some premalignant lesions contain multiple genetic abnormalities not present in the normal tissues from which the neoplasms arose. Barrett oesophagus (BE) is a premalignant condition which predisposes to oesophageal adenocarcinoma (EA) that can be biopsied prospectively over time because endoscopic surveillance is recommended for early detection of cancer. In addition, oesophagectomy specimens frequently contain the premalignant epithelium from which the cancer arose. Neoplastic progression in BE is associated with alterations in TP53 (also known as p53) and CDKN2A (also known as p16) and non-random losses of heterozygosity (LOH). Aneuploid or increased 4N populations occur in more than 90-95% of EAs, arise in premalignant epithelium and predict progression. We have previously shown in small numbers of patients that disruption of TP53 and CDKN2A typically occurs before aneuploidy and cancer. Here, we determine the evolutionary relationships of non-random LOH, TP53 and CDKN2A mutations, CDKN2A CpG-island methylation and ploidy during neoplastic progression. Diploid cell progenitors with somatic genetic or epigenetic abnormalities in TP53 and CDKN2A were capable of clonal expansion, spreading to large regions of oesophageal mucosa. The subsequent evolution of neoplastic progeny frequently involved bifurcations and LOH at 5q, 13q and 18q that occurred in no obligate order relative to each other, DNA-content aneuploidy or cancer. Our results indicate that clonal evolution is more complex than predicted by linear models.

Colonoscopy and biopsy

The place of colonoscopy in the management of ulcerative colitis is restricted to clinical situations where the information provided will change clinical management. The information provided will be answers to the questions?inflammatory bowel disease, o r, in the patient with known colitis: inflammatory bowel disease?type?activity extent?dysplasia. Biopsy is pivotal to the diagnosis and provides the certainty of tissue diagnosis, assessment of activity and detection of dysplasia. Sigmoidoscopy is sufficient for providing information for clinical management in most circumstances, but colonoscopy is important where clinical features are disproportionate to sigmoidoscopic findings and systemic parameters of inflammatory activity; to determine type and extent of inflammatory bowel disease and when surveillance needs to start; and for biopsy to detect dysplasia. Ileoscopy is an important aspect of colonoscopy for differential diagnosis, and is the unique definer of total colonoscopy.

Cancer surveillance in ulcerative colitis

During a 13-year period, 213 patients with ulcerative colitis who had no clinical or endoscopic evidence of colonic carcinoma were enrolled in a biopsy surveillance program for dysplasia and carcinoma. The aims of the study were to determine whether such a program could decrease the cancer risk in this group of patients, to determine whether patients with a low risk of carcinoma could be identified, thus enabling them to retain their colon, and to accomplish these goals with a reasonable expenditure of resources. Eighteen patients had dysplasia detected in the initial biopsy specimens; 15 of these patients underwent colectomy, and 7 had unsuspected carcinoma (1 Dukes' stage A, 2 stage B, and 4 stage C). Eleven patients had dysplasia detected during follow-up; 7 of these patients had colectomy, and only 1 patient had carcinoma (Dukes' B). Dysplasia developed in 5 of 20 patients with indefinite changes on initial biopsy samples; 3 of these patients underwent colectomy, and 1 patient had carcinoma (Dukes' B). There was no difference in the prevalence of dysplasia between patients with left-sided disease and patients with extensive disease. With the exception of 2 patients with inadequate surveillance, there has been no clinical evidence of carcinoma in any of the 148 patients whose biopsy results remained negative throughout the study; carcinoma has not developed in any of 175 patients without dysplasia on initial biopsy sample. All 4 patients who died of carcinoma had high-grade dysplasia in their initial colonoscopic biopsy samples. It is concluded that a biopsy surveillance program can be an effective aid in helping control the risk of carcinoma in patients with long-standing ulcerative colitis, that the short-term risk of carcinoma for patients with negative biopsy results is low and colectomy for risk of carcinoma can be deferred in this group, and that patients with extensive and left-sided disease share the same risk of the development of dysplasia.