Array-based comparative genomic hybridization in ulcerative colitis neoplasia: single non-dysplastic biopsies distinguish progressors from non-progressors

A Phase IIa Trial of Metformin for Colorectal Cancer Risk Reduction among Individuals with History of Colorectal Adenomas and Elevated Body Mass Index

Obesity is associated with risk of colorectal adenoma (CRA) and colorectal cancer. The signaling pathway activated by metformin (LKB1/AMPK/mTOR) is implicated in tumor suppression in Apc^Min/+ mice via metformin-induced reduction in polyp burden, increased ratio of pAMPK/AMPK, decreased pmTOR/mTOR ratio, and decreased pS6^Ser235/S6^Ser235 ratio in polyps. We hypothesized that metformin would affect colorectal tissue S6^Ser235 among obese patients with recent history of CRA. A phase IIa clinical biomarker trial was conducted via the U.S. National Cancer Institute-Chemoprevention Consortium. Nondiabetic, obese subjects (BMI ≥30) ages 35 to 80 with recent history of CRA were included. Subjects received 12 weeks of oral metformin 1,000 mg twice every day. Rectal mucosa biopsies were obtained at baseline and end-of-treatment (EOT) endoscopy. Tissue S6^Ser235 and Ki-67 immunostaining were analyzed in a blinded fashion using Histo score (Hscore) analysis. Among 32 eligible subjects, the mean baseline BMI was 34.9. Comparing EOT to baseline tissue S6^Ser235 by IHC, no significant differences were observed. Mean (SD) Hscore at baseline was 1.1 (0.57) and 1.1 (0.51) at EOT; median Hscore change was 0.034 (P = 0.77). Similarly, Ki-67 levels were unaffected by the intervention. The adverse events were consistent with metformin's known side-effect profile. Among obese patients with CRA, 12 weeks of oral metformin does not reduce rectal mucosa pS6 or Ki-67 levels. Further research is needed to determine what effects metformin has on the target tissue of origin as metformin continues to be pursued as a colorectal cancer chemopreventive agent.

Precancer in ulcerative colitis: the role of the field effect and its clinical implications

Cumulative evidence indicates that a significant proportion of cancer evolution may occur before the development of histological abnormalities. While recent improvements in DNA sequencing technology have begun to reveal the presence of these early preneoplastic clones, the concept of 'premalignant field' was already introduced by Slaughter more than half a century ago. Also referred to as 'field effect', 'field defect' or 'field cancerization', these terms describe the phenomenon by which molecular alterations develop in normal-appearing tissue and expand to form premalignant patches with the potential to progress to dysplasia and cancer. Field effects have been well-characterized in ulcerative colitis, an inflammatory bowel disease that increases the risk of colorectal cancer. The study of the molecular alterations that define these fields is informative of mechanisms of tumor initiation and progression and has provided potential targets for early cancer detection. Herein, we summarize the current knowledge about the molecular alterations that comprise the field effect in ulcerative colitis and the clinical utility of these fields for cancer screening and prevention.

Biomarkers for colitis-associated colorectal cancer

Patients with extensive ulcerative colitis (UC) of more than eight years duration have an increased risk of colorectal cancer. Molecular biomarkers for dysplasia and cancer could have a great clinical value in managing cancer risk in these UC patients. Using a wide range of molecular techniques - including cutting-edge OMICS technologies - recent studies have identified clinically relevant biomarker candidates from a variety of biosamples, including colonic biopsies, blood, stool, and urine. While the challenge remains to validate these candidate biomarkers in multi-center studies and with larger patient cohorts, it is certain that accurate biomarkers of colitis-associated neoplasia would improve clinical management of neoplastic risk in UC patients. This review highlights the ongoing avenues of research in biomarker development for colitis-associated colorectal cancer.

Recurrence and survival rates of inflammatory bowel disease-associated colorectal cancer following postoperative chemotherapy: a comparative study

Background and Aim: Inflammatory bowel disease (IBD) is associated with an increased risk of colorectal cancer (CRC). Studies have shown tumorigenetic and histomorphological differences between IBD-associated CRC and non-IBD CRC, suggesting differences in tumor behavior and response to treatment. We aimed to compare tumor recurrence and survival rates following postoperative chemotherapy in CRC patients with and without IBD.

Methods: Search of the Cleveland Clinic’s CRC database revealed 65 patients who had IBD-associated CRC and received postoperative adjuvant chemotherapy between 1994 and 2010. Twenty-one patients were excluded due to incomplete clinical data. Propensity score-matching based on age, surgery intent, CRC site, tumor grade, American Joint Committee on Cancer (AJCC) stage and T stage was used to match IBD and non-IBD patients (1:4). Competing risk and Cox regression models were used to analyze differences in disease-free survival and overall survival, respectively.

Results: Forty-four patients with IBD-associated CRC were matched to 176 patients with non-IBD CRC. Among IBD patients, 29 (66%) had ulcerative colitis, 14 (32%) had Crohn’s disease, and one (2%) had indeterminate colitis. Mean IBD diagnosis age was 28.1 ± 14.5 years, and mean IBD duration at time of CRC treatment was 21.5 ± 12.6 years. Ten (23%) IBD patients had tumor recurrence compared with 34 (19%) non-IBD patients (P = .074). There was no significant difference in disease-free survival (hazard ratio [HR] = 0.60; 95% CI: 0.35–1.05; P = 0.074) or overall survival (HR = 0.87; 95% CI: 0.54–1.4; P = 0.58) between IBD and non-IBD patients.

Conclusion: Patients with IBD-associated CRC have comparable rates of tumor recurrence and survival following postoperative chemotherapy as CRC patients without IBD. Prospective studies are needed to confirm these findings and guide therapeutic decisions.

Pre-tumour clones, periodic selection and clonal interference in the origin and progression of gastrointestinal cancer: potential for biomarker development

Classically, the risk of cancer progression in premalignant conditions of the gastrointestinal tract is assessed by examining the degree of histological dysplasia. However, there are many putative pro-cancer genetic changes that have occurred in histologically normal tissue well before the onset of dysplasia. Here we summarize the evidence for such pre-tumour clones and the existing technology that can be used to locate these clones and characterize them at the genetic level. We also discuss the mechanisms by which pre-tumour clones may spread through large areas of normal tissue, and highlight emerging theories on how multiple clones compete and interact within the gastrointestinal mucosa. It is important to gain an understanding of these processes, as it is envisaged that certain pre-tumour changes may be powerful predictive markers, with the potential to identify patients at high risk of developing cancer at a much earlier stage.

Distinct clinicohistologic features of inflammatory bowel disease-associated colorectal adenocarcinoma: in comparison with sporadic microsatellite-stable and Lynch syndrome-related colorectal adenocarcinoma

Long-standing inflammatory bowel disease (IBD), either ulcerative colitis or Crohn disease, is associated with a high risk of developing colorectal adenocarcinoma (CAC). However, histomorphology of IBD-associated CAC has not been thoroughly examined, and it is unclear whether and how these patients should be screened for Lynch syndrome (LS). We evaluated the demographic and morphologic features of 108 IBD-associated CACs, including ulcerative colitis-associated (n = 95) and Crohn disease-associated CACs (n = 13), against 93 control cases of sporadic microsatellite-stable (MSS) CAC, 20 cases of sporadic microsatellite instability high (MSI-H) CAC, and 23 CAC cases of LS. The mean age of patients with IBD-associated CAC was 50 years, which was lower compared with the mean age of 63.7 years of the sporadic MSS controls and 76.5 years of the sporadic MSI-H group but not statistically different from that of the LS patients. Synchronous CACs were noted in 20.4% of the IBD patients and 13% of LS patients but in only 2.1% of the sporadic MSS controls and in none of the MSI-H patients. Right-sided CACs were significantly less frequent in the IBD group than in sporadic MSS controls, MSI-H group, and LS patients (P < 0.05 for all). In contrast to sporadic MSS CAC, IBD-associated CACs are characterized by lack of tumor necrosis, Crohn-like reaction, tumor histologic heterogeneity, the presence of mucin, and signet ring cell differentiation and tumor well differentiation. The histomorphologic similarity among IBD-associated and MSI-H tumors, either sporadic MSI-H or LS-related, is independent of MSI status. The young age of patients with IBD-associated CAC and the morphological similarities among IBD-associated, sporadic MSI-H, and LS-related CAC suggest that an age-based and morphology-based strategy before the screening test for LS may be less effective in IBD patients than in the non-IBD population.

Pan-colonic field defects are detected by CGH in the colons of UC patients with dysplasia/cancer

BAC arrays were used to evaluate genomic instability along the colon of patients with ulcerative colitis (UC). Genomic instability increases with disease progression and biopsies more proximal to dysplasia showed increased instability. Pan-colonic field copy number gain or loss involving small (<1Mb) regions were detected in most patients and were particularly apparent in the UC progressor patients who had dysplasia or cancer. Chromosomal copy gains or losses affecting large regions were mainly restricted to dysplastic biopsies. Areas of significant chromosomal losses were detected in the UC progressors on chromosomes 2q36, 3q25, 3p21, 4q34, 4p16.2, 15q22, and 16p13 (p-value⩽0.04). These results extend our understanding of the dynamic nature of pan-colonic genomic instability in this disease.

Dysplastic lesions in inflammatory bowel disease show increased positivity for the stem cell marker aldehyde dehydrogenase

The chronic inflammatory state in patients with inflammatory bowel disease places them at a substantially elevated risk for developing colorectal carcinoma. Moreover, distinguishing an inflammatory phenotype from dysplasia in inflammatory bowel disease can be difficult and has significant patient management implications. To this end, we studied the expression of the cancer stem cell marker aldehyde dehydrogenase to determine whether expression is increased in dysplastic lesions arising in inflammatory bowel disease. We studied 54 patients with inflammatory bowel disease who underwent surgical resection. Of the 54 patients, 13 exhibited high-grade dysplasia or adenocarcinoma, 19 exhibited low-grade dysplasia, and 22 displayed only inflammatory atypia. Staining for aldehyde dehydrogenase was evaluated in the cytoplasm of epithelial and stromal cells. We determined the intensity of staining (0 to 3+) and the percentage of cells staining positively. Positive staining for aldehyde dehydrogenase was observed in 92% (12/13) of cases with high-grade dysplasia/adenocarcinoma and in 95% (18/19) of cases with low-grade dysplasia. Cases with inflammatory atypia showed positive staining in 45% (10/22) of cases. The sensitivity for aldehyde dehydrogenase in epithelial cells as a marker for dysplasia was 95%; specificity was 55%. For stromal cells adjacent to dysplasia, sensitivity was 44%; and specificity was 68%. Although the sensitivity of aldehyde dehydrogenase for dysplasia was excellent, specificity was less than ideal. Our findings support the hypothesis that dysplasia in inflammatory bowel disease is associated with increased aldehyde dehydrogenase positivity, which supports the cancer stem cell hypothesis.

Passenger mutations as a marker of clonal cell lineages in emerging neoplasia

Cancer arises as the result of a natural selection process among cells of the body, favoring lineages bearing somatic mutations that bestow them with a proliferative advantage. Of the thousands of mutations within a tumor, only a small fraction functionally drive its growth; the vast majority are mere passengers of minimal biological consequence. Yet the presence of any mutation, independent of its role in facilitating proliferation, tags a cell's clonal descendants in a manner that allows them to be distinguished from unrelated cells. Such markers of cell lineage can be used to identify the abnormal proliferative signature of neoplastic clonal evolution, even at a stage which predates morphologically recognizable dysplasia. This article focuses on molecular techniques for assessing cellular clonality in humans with an emphasis on how they may be used for early detection of tumorigenic processes. We discuss historical as well as contemporary approaches and consider ways in which powerful new genomic technologies might be harnessed to develop a future generation of early cancer diagnostics.