Neoplastic precursor lesions related to the development of cancer in inflammatory bowel disease

Gastrointestinal dysplasia

The term dysplasia (intraepithelial neoplasia) is used to refer to neoplastic but non-invasive epithelium. Dysplasia in the gastrointestinal tract is considered a carcinoma precursor and a marker of high cancer risk for the site at which it is found. It is diagnosed by pathologists using a set of cytological and architectural features. There are many pitfalls in the diagnosis of gastrointestinal dysplasia. One reason for difficulty in dysplasia diagnosis is the significant heterogeneity in the appearances of each grade of dysplasia. In addition, the features that characterise dysplasia are only subtly different from those of regenerating epithelium, particularly at the low end of the spectrum, making this distinction difficult. For these reasons, and because of significant implications of this diagnosis for patient care, the interpretations of biopsies taken for dysplasia surveillance are considered challenging by most pathologists. In this article, we review definition, classification, and histological features and grading of gastrointestinal dysplasia with focus on Barrett's oesophagus (BE) related dysplasia, gastric epithelial dysplasia (GED) and dysplasia arising in the background of inflammatory bowel disease (IBD). We also discuss observer variability and the role of adjunctive markers in dysplasia diagnosis, and limitation with regard to surveillance of patients with BE and IBD due to sampling error.

Precancerous lesions in inflammatory bowel disease

Reduction of mortality from colorectal cancer is a prime goal in the clinical management of patients with extensive, longstanding ulcerative colitis and colonic Crohn's disease. The cornerstone of current cancer prevention efforts is endoscopic surveillance for colorectal dysplasia, or intraepithelial neoplasia, the direct histological precursor of cancer. A diagnosis of dysplasia provides a reliable indicator of heightened cancer risk and an end-point for colonoscopic surveillance allowing most patients to undergo prophylactic colectomy before the development of incurable cancer. This article reviews the classification, pathological criteria and clinical implications of colorectal dysplasia, current recommendations for the performance of surveillance colonoscopy, recent technical advances in colonoscopic imaging to enhance the detection of dysplasia, and a summary of the molecular genetic events implicated in its development.

Dysplasia in inflammatory bowel diseases

In both Crohn's disease and ulcerative colitis, the secondary prevention of colorectal cancer basically relies on the histological detection of dysplasia. In inflammatory bowel diseases, dysplasia identifies the subgroup of patients eligible for stricter surveillance (or prophylactic colectomy). In clinical practice, a number of issues may influence the benefits of clinico-pathological surveillance for inflammatory bowel disease patients with dysplasia, including: sampling errors, inconsistent biopsy assessments, patients' compliance with follow-up requirements, and how heath care is organized. Even in such a multifaceted context, it has been demonstrated that dysplasia surveillance is effective in reducing colorectal cancer-related mortality and morbidity. This paper focuses on current issues concerning the histological assessment of inflammatory bowel disease-associated dysplastic lesions.

Tumor heterogeneity: mechanisms and bases for a reliable application of molecular marker design

Tumor heterogeneity is a confusing finding in the assessment of neoplasms, potentially resulting in inaccurate diagnostic, prognostic and predictive tests. This tumor heterogeneity is not always a random and unpredictable phenomenon, whose knowledge helps designing better tests. The biologic reasons for this intratumoral heterogeneity would then be important to understand both the natural history of neoplasms and the selection of test samples for reliable analysis. The main factors contributing to intratumoral heterogeneity inducing gene abnormalities or modifying its expression include: the gradient ischemic level within neoplasms, the action of tumor microenvironment (bidirectional interaction between tumor cells and stroma), mechanisms of intercellular transference of genetic information (exosomes), and differential mechanisms of sequence-independent modifications of genetic material and proteins. The intratumoral heterogeneity is at the origin of tumor progression and it is also the byproduct of the selection process during progression. Any analysis of heterogeneity mechanisms must be integrated within the process of segregation of genetic changes in tumor cells during the clonal expansion and progression of neoplasms. The evaluation of these mechanisms must also consider the redundancy and pleiotropism of molecular pathways, for which appropriate surrogate markers would support the presence or not of heterogeneous genetics and the main mechanisms responsible. This knowledge would constitute a solid scientific background for future therapeutic planning.

Neoplasia without dysplasia: lessons from Barrett esophagus and other tubal gut neoplasms

CONTEXT

Classic pathology teaching emphasizes that neoplastic lesions of the gastrointestinal tract are characterized by architectural and cytologic abnormalities that distinguish it from normal tissue. Recent studies suggest that many important-and in some cases clonal-molecular abnormalities that lead to dysregulation of cell proliferation and differentiation (neoplasia) occur before morphologic expression of dysplasia.

OBJECTIVE

To summarize the biologic and pathologic features of preneoplastic conditions of the tubal gut that reveal evidence of neoplastic alteration, but without the traditional morphologic features of dysplasia, in order to provide guidance on how to identify these lesions. Particular attention is given to Barrett esophagus, a chronic inflammatory condition in which early molecular and morphologic events that drive carcinogenesis are best understood.

DATA SOURCES

Selected references and abstracts were obtained by a PubMed (US National Library of Medicine) search by using the search headings neoplasia, preneoplasia, dysplasia, adenoma, serrated polyps, and Barrett's esophagus between the years 1980 and 2009.

CONCLUSIONS

Many types of lesions throughout the tubal gut fulfill the most basic and classic principles of a neoplastic precursor lesion but lack conventional morphologic evidence of dysplasia and/or maintain the capacity for cell differentiation and maturation. All of these lesions, such as squamous dysplasia of the esophagus, dysplasia in Barrett esophagus, and hyperplastic/serrated polyps of the colon, represent early neoplastic precursor lesions but without conventional histologic features of dysplasia. It is important for pathologists to be aware of these lesions, both for diagnostic and prognostic purposes, but also so that future studies can be performed with regard to risk stratification of patients.

Colorectal dysplasia in chronic inflammatory bowel disease: pathology, clinical implications, and pathogenesis

CONTEXT

Colorectal cancer, the most lethal long-term complication of chronic inflammatory bowel disease (IBD), is the culmination of a complex sequence of molecular and histologic derangements of the intestinal epithelium that are initiated and at least partially sustained by chronic inflammation. Dysplasia, the earliest histologic manifestation of this process, plays an important role in cancer prevention by providing the first clinical alert that this sequence is underway and serving as an endpoint in colonoscopic surveillance of patients at high risk for colorectal cancer.

OBJECTIVE

To review the histology, nomenclature, clinical implications, and molecular pathogenesis of dysplasia in IBD.

DATA SOURCE

Literature review and illustrations from case material.

CONCLUSIONS

The diagnosis and grading of dysplasia in endoscopic surveillance biopsies play a decisive role in the management of patients with IBD. Although interpathologist variation, endoscopic sampling problems, and incomplete information regarding the natural history of dysplastic lesions are important limiting factors, indirect evidence that surveillance may be an effective means of reducing cancer-related mortality in the population with IBD has helped validate the histologic criteria, nomenclature, and clinical recommendations that are the basis of current practice among pathologists and clinicians. Emerging technologic advances in endoscopy may permit more effective surveillance, but ultimately the greatest promise for cancer prevention in IBD lies in expanding our thus far limited understanding of the molecular pathogenetic relationships between neoplasia and chronic inflammation.

Appendiceal mucinous cystadenoma is a neoplastic complication of IBD: case-control study of primary appendiceal neoplasms

BACKGROUND

IBD is a risk factor for development of colorectal neoplasia. Although IBD frequently involves the appendix microscopically, it is uncertain whether it also predisposes to appendiceal neoplasia.

METHODS

We performed a retrospective case-control study of incidental appendiceal neoplasms in colectomy specimens of adults with and without IBD (cases and controls, respectively) based on surgical pathology records spanning 54 months. To minimize referral bias, patients were excluded if they had preoperative clinical evidence or a principal pathologic diagnosis of appendiceal disease. The pathologic diagnoses were confirmed retrospectively.

RESULTS

Eleven appendiceal cystadenomas and 6 appendiceal carcinoid tumors were identified among 705 IBD cases (377 ulcerative colitis, 317 Crohn's disease, 11 indeterminate colitis) and 498 non-IBD controls meeting our inclusion criteria. There was no significant difference in prevalence of cyst adenomas between the cases and controls (9/705 [1.3%] versus 2/498 [0.4%], respectively, OR 3.2 [95% CI 0.7-14.9]). However, cyst adenomas were 15-fold more prevalent among cases with synchronous colorectal neoplasia compared with controls (4/69 [5.8%] versus 2/498 [0.4%], OR 15.3 [95% CI 2.7-85]) and 8-fold higher compared with cases without synchronous neoplasia (4/69 [5.8%] versus 5/636 [0.8%], OR 7.8 [95% CI 2.0-29.6]). Appendiceal carcinoids were equally prevalent in cases and controls (4/705 [0.6%] versus 2/498 [0.4%], OR 1.4 [95% CI 0.3-7.8]), cases with synchronous neoplasia and controls (1/69 [1.4%] versus 2/498 [0.4%], OR 3.6 [95% CI 0.3-40.8]), and cases with and without synchronous colorectal neoplasia (1/69 [1.4%] versus 3/636 [0.5%], OR 3.1 [95% CI 0.3-30.2]).

CONCLUSIONS

IBD with synchronous colorectal dysplasia or cancer is a risk factor for development of appendiceal cystadenomas, implicating this tumor as a neoplastic complication of IBD. IBD does not predispose to the development of appendiceal carcinoids.

The microenvironments of multistage carcinogenesis

Overt neoplasia is often the result of a chronic disease process encompassing an extended segment of the lifespan of any species. A common pathway in the natural history of the disease is the appearance of focal proliferative lesions that are known to act as precursors for cancer development. It is becoming increasingly apparent that the emergence of such lesions is not a cell-autonomous phenomenon, but is heavily dependent on microenvironmental cues derived from the surrounding tissue. Specific alterations in the tissue microenvironment that can foster the selective growth of focal lesions are discussed herein. Furthermore, we argue that a fundamental property of focal lesions as it relates to their precancerous nature lies in their altered growth pattern as compared to the tissue where they reside. The resulting altered tissue architecture translates into the emergence of a unique tumor microenvironment inside these lesions, associated with altered blood vessels and/or blood supply which in turn can trigger biochemical and metabolic changes fueling tumor progression. A deeper understanding of the role(s) of tissue and tumor microenvironments in the pathogenesis of cancer is essential to design more effective strategies for the management of this disease.