Joshua E. Melson

DNA methylation patterns in blood of patients with colorectal cancer and adenomatous colorectal polyps

Colorectal cancer (CRC) screening rates are currently suboptimal. Blood‐based screening could improve rates of earlier detection for CRC and adenomatous colorectal polyps. In this study, we evaluated the feasibility of plasma‐based detection of early CRC and adenomatous polyps using array‐mediated analysis methylation profiling of 56 genes implicated in carcinogenesis. Methylation of 56 genes in patients with Stages I and II CRC (N = 30) and those with adenomatous polyps (N = 30) were compared with individuals who underwent colonoscopy and were found to have neither adenomatous changes nor CRC. Composite biomarkers were developed for adenomatous polyps and CRC, and their sensitivity and specificity was estimated using five‐fold cross validation. Six promoters (CYCD2, HIC1, PAX 5, RASSF1A, RB1 and SRBC) were selected for the biomarker, which differentiated CRC patients and controls with 84% sensitivity and 68% specificity. Three promoters (HIC1, MDG1 and RASSF1A) were selected for the biomarker, which differentiated patients with adenomatous polyps and controls with sensitivity of 55% and specificity of 65%. Methylation profiling of plasma DNA can detect early CRC with significant accuracy and shows promise as a methodology to develop biomarkers for CRC screening.

Advanced adenoma detection rate is independent of nonadvanced adenoma detection rate.

OBJECTIVES:Adenoma detection rate (ADR) is the accepted rate marker in colonoscopy quality. Advanced adenomas detected at index colonoscopy, while less frequent than nonadvanced adenomas, carry greater risk for future advanced neoplasia during surveillance colonoscopy. This study aimed to determine the effect of the colonoscopist and other factors on advanced ADR and to define the correlation of advanced and nonadvanced ADRs among colonoscopists.METHODS:An observational study of a cohort of patients undergoing first-time colorectal cancer screening colonoscopy was conducted. Patient characteristics and colonoscopic findings were collected. Adenoma, advanced adenoma, and nonadvanced ADRs were calculated. Logistic regression was used to determine variable effects on advanced adenoma detection, and Spearmans rank-order correlation was used to evaluate the relationship between advanced and nonadvanced ADRs.RESULTS:A total of 1,944 patients had first-time screening colonoscopies by 14 colonoscopists. All colonoscopists had adequate (>20%) ADRs. The variability in the colonoscopist ranges of detection was 22.22 to 44.66% for adenomas and 2.00 to 18.18% for advanced adenomas. Logistic regression showed that increasing patient age (odds ratio (OR) 1.16 per 5-year increase, 95% confidence interval (CI) 1.05–1.28, P=0.008) and male gender (OR 2.15, 95% CI 1.51–3.06, P<0.0001) were variables associated with advanced adenoma detection. Colonoscopists were significantly different in detecting advanced adenomas by random effects model (P=0.002), adjusting for patient age, gender, race, year of colonoscopy, gastroenterology fellow participation during colonoscopy, and nonadvanced adenomas. Spearmans rank-order correlation coefficient of −0.42 (95% CI −0.77 to 0.14, P=0.13) was not significant and showed no correlation between advanced and nonadvanced adenoma detection by the group of colonoscopists.CONCLUSIONS:Advanced ADR is variable among colonoscopists with acceptable ADRs. Colonoscopists’ advanced ADRs are independent of their nonadvanced ADRs.

PI3K/AKT Signaling Is Essential for Communication between Tissue-Infiltrating Mast Cells, Macrophages, and Epithelial Cells in Colitis-Induced Cancer

Purpose: To understand signaling pathways that shape inflamed tissue and predispose to cancer is critical for effective prevention and therapy for chronic inflammatory diseases. We have explored phosphoinositide 3-kinase (PI3K) activity in human inflammatory bowel diseases and mouse colitis models. Experimental Design: We conducted immunostaining of phosphorylated AKT (pAKT) and unbiased high-throughput image acquisition and quantitative analysis of samples of noninflamed normal colon, colitis, dysplasia, and colorectal cancer. Mechanistic insights were gained from ex vivo studies of cell interactions, the piroxicam/IL-10−/− mouse model of progressive colitis, and use of the PI3K inhibitor LY294002. Results: Progressive increase in densities of pAKT-positive tumor-associated macrophages (TAM) and increase in densities of mast cells in the colonic submucosa were noted with colitis and progression to dysplasia and cancer. Mast cells recruited macrophages in ex vivo migration assays, and both mast cells and TAMs promoted invasion of cancer cells. Pretreatment of mast cells with LY294002 blocked recruitment of TAMs. LY294002 inhibited mast cell and TAM-mediated tumor invasion, and in mice, blocked stromal PI3K, colitis, and cancer. Conclusion: The PI3K/AKT pathway is active in cells infiltrating inflamed human colon tissue. This pathway sustains the recruitment of inflammatory cells through a positive feedback loop. The PI3K/AKT pathway is essential for tumor invasion and the malignant features of the piroxicam/IL-10−/− mouse model. LY294002 targets the PI3K pathway and hinders progressive colitis. These findings indicate that colitis and progression to cancer are dependent on stromal PI3K and sensitive to treatment with LY294002. Clin Cancer Res; 19(9); 2342–54. ©2013 AACR.

Endoscopic mis-sizing of polyps changes colorectal cancer surveillance recommendations.

BACKGROUND: Adenomatous polyps greater than 1 cm are defined as advanced adenomas. Inaccurate size estimation can lead to inappropriate surveillance recommendations of colorectal adenomas. OBJECTIVE: The aim of this study was to determine the impact of endoscopic polyp mis-sizing on colorectal cancer surveillance recommendations. DESIGN: This is a prospective study. SETTING: This study was conducted in a gastroenterology practice at a US academic medical center. PATIENTS: Patients undergoing colorectal cancer screening and surveillance colonoscopies from 2010 to 2011 were included. MAIN OUTCOME MEASUREMENTS: Endoscopic size estimates of polyps 10 to 25 mm were compared with postfixation histopathologic polyp measurements for 15 different gastroenterologists. Only adenomatous polyps removed in entirety by snare polypectomy were included in the analysis. Size variation was defined as (endoscopic estimate − histopathologic size)/(histopathologic size). Clinical mis-sizing was defined as a size variation of >33%. The mean size variation, the percentage of clinical mis-sizing, and the percentage of inappropriate surveillance recommendation due to size variation >33% were reported per endoscopist. RESULTS: Included for analysis were 4990 procedures from 15 gastroenterologists. A total of 230 polyps from 200 patients met inclusion criteria. The average age was 62.6 years (SD 10.1), and 52% were men. The mean size variation between the endoscopic polyp size estimation and the histopathologic polyp was 73.6% (range of mean size variation, 13%–127%). 62.6% (range, 0%–91%) of included polyps had clinical mis-sizing. Of included polypectomies, 35.2% (range, 0%–67%) resulted in an inappropriate surveillance recommendation due to clinical mis-sizing even after considering histology and synchronous polyps. LIMITATIONS: This was a single-center study. CONCLUSIONS: There is marked variation in endoscopists’ ability to accurately size adenomatous polyps. Some endoscopists rarely mis-size adenomas, and their surveillance recommendations are appropriate in regard to sizing. However, other endoscopists inaccurately size adenomas, and this leads to inappropriate surveillance of colorectal polyps. In this study, approximately 1 of 3 included polypectomies yielded inappropriate surveillance recommendations because of clinical mis-sizing.

Excess of Proximal Microsatellite-Stable Colorectal Cancer in African Americans from a Multiethnic Study

Purpose: African Americans (AA) have the highest incidence of colorectal cancer compared with other U.S. populations and more proximal colorectal cancers. The objective is to elucidate the basis of these cancer disparities. Experimental design: Of note, 566 AA and 328 non-Hispanic White (NHW) colorectal cancers were ascertained in five Chicago hospitals. Clinical and exposure data were collected. Microsatellite instability (MSI) and BRAF (V600E) and KRAS mutations were tested. Statistical significance of categorical variables was tested by the Fisher exact test or logistic regression and age by the Mann–Whitney U test. Results: Over a 10-year period, the median age at diagnosis significantly decreased for both AAs (68–61; P < 0.01) and NHWs (64.5– 62; P = 0.04); more AA patients were diagnosed before age 50 than NHWs (22% vs. 15%; P = 0.01). AAs had more proximal colorectal cancer than NHWs (49.5% vs. 33.7%; P < 0.01), but overall frequencies of MSI, BRAF and KRAS mutations were not different nor were they different by location in the colon. Proximal colorectal cancers often presented with lymphocytic infiltrate (P < 0.01) and were diagnosed at older ages (P = 0.02). Smoking, drinking, and obesity were less common in this group, but results were not statistically significant. Conclusions: Patients with colorectal cancer have gotten progressively younger. The excess of colorectal cancer in AAs predominantly consists of more proximal, microsatellite stable tumors, commonly presenting lymphocytic infiltrate and less often associated with toxic exposures or a higher BMI. Younger AAs had more distal colorectal cancers than older ones. These data suggest two different mechanisms driving younger age and proximal location of colorectal cancers in AAs. Clin Cancer Res; 20(18); 4962–70. ©2014 AACR.

Evaluation of Plasma miR-21 and miR-152 as Diagnostic Biomarkers for Common Types of Human Cancers.

Stable blood based miRNA species have allowed for the differentiation of patients with various types of cancer. Therefore, specific blood-based miRNA might be considered as a methodology which could be informative of the presence of cancer potentially from multiple distinct organ sites. Recently, miR-21 has been identified as an “oncomir” in various tumors while miR-152 as a tumor suppressor. In this study, we investigated whether circulating miR-21 and miR-152 can be used for early detection of lung cancer (LuCa), colorectal carcinoma (CRC), breast cancer (BrCa) and prostate cancer (PCa), with distinguishing cancer from various benign lesions on these organ sites. We measured the two miRNA levels by using real-time RT-PCR in plasma samples from a total of 204 cancer patients, 159 various benign lesions, and 228 normal subjects. We observed significantly elevated expression of miR-21 and miR-152 in LuCa, CRC, and BrCa when compared with normal controls. We also found upregulation of plasma miR-21 and miR-152 levels in patients with benign lesions of lung and breast, as compared to normal controls, respectively. No significant expression variation of the two miRNAs was observed in PCa or prostatic benign lesions as compared to healthy controls. Receiver operating characteristic (ROC) analyses revealed that miR-21 and/or miR-152 can discriminate LuCa, CRC and BrCa from normal controls. Our results suggest that plasma miR-21 and miR-152 may serve as non-specific noninvasive biomarkers for early screening of LuCa, CRC, and BrCa, but not PCa.

The Effects of Bowel Preparation on Microbiota-Related Metrics Differ in Health and in Inflammatory Bowel Disease and for the Mucosal and Luminal Microbiota Compartments.

OBJECTIVES:Bowel preparations (BPs) taken before colonoscopy may introduce a confounding effect on the results of gastrointestinal microbiota studies. This study aimed to determine the effect of bowel preparation on the mucosa-associated and luminal colonic microbiota in healthy subjects (HC) and inflammatory bowel disease (IBD) patients.METHODS:Biopsy samples (n=36) and fecal samples (n=30) were collected from 10 HC and 8 IBD subjects pre- and post-BP. 16S rRNA gene was pyrosequenced using 454 Titanium protocols. We compared the differences between the pre- and post-BP samples (i.e., comparisons-across-bowel-prep); we examined the effect of BP on the expected separation of the mucosal vs. the luminal compartments (i.e., comparisons-across-compartments). Last, we compared the baseline differences between the HC vs. IBD groups (a secondary analysis), and examined whether the differences between the HC vs. IBD changed after BP.RESULTS:In comparisons-across-bowel-prep, the Shannon’s index (SI) decreased only in the biopsy samples of IBD subjects post-BP (P=0.025) and phylogenetic diversity-whole tree (PD-WT) metric decreased in biopsy samples of HC subjects post-BP (P=0.021). In secondary comparisons, the subtle differences between the fecal samples of the HC vs. IBD groups, in terms of evenness and the SI, were not apparent post-BP. In terms of β-diversity, in comparisons-across-bowel-prep, the proportion of shared operational taxonomic units (OTUs) in pre- and post-BP samples was low (~30%) and unweighted Unifrac distances between pre- and post-BP specimens ranged from 0.52 to 0.66. HC biopsies were affected more than IBD biopsies with BP (P=0.004). In comparisons-across-compartments, the proportion of shared OTUs between biopsy and fecal samples increased and Unifrac distances decreased post-BP in IBD subjects, reducing the differences between the mucosal and luminal compartments of the gut microbiota. Interindividual differences in Unifrac distances were preserved even with BP effects, although the effects were greater on weighted Unifrac distances. Bacteroidetes and its subtypes increased post-BP in both the luminal and mucosal compartments.CONCLUSIONS:Bowel preparations affect the composition and diversity of the fecal and luminal microbiota in the short term, introducing potential bias into experiments examining the gut microbiota. The magnitude of the effect of BP is not greater than that of interindividual variation. Both the luminal and mucosal compartments of the gut microbiota get affected, and samples from controls and IBD subjects may get affected differently. Studies of the colonic microbiota should take into account the direction and the magnitude of the change introduced by BP during the design stage of the experiments, and consider sample sizes so that potential bias is minimized.

Commonality and differences of methylation signatures in the plasma of patients with pancreatic cancer and colorectal cancer

Profiling of DNA methylation status of specific genes is a way to screen for colorectal cancer (CRC) and pancreatic cancer (PC) in blood. The commonality of methylation status of cancer‐related tumor suppressor genes between CRC and PC is largely unknown. Methylation status of 56 cancer‐related genes was compared in plasma of patients in the following cohorts: CRC, PC and healthy controls. Cross validation determined the best model by area under ROC curve (AUC) to differentiate cancer methylation profiles from controls. Optimal preferential gene methylation signatures were derived to differentiate either cancer (CRC or PC) from controls. For CRC alone, a three gene signature (CYCD2, HIC and VHL) had an AUC 0.9310, sensitivity (Sens) = 0.826, specificity (Spec) = 0.9383. For PC alone, an optimal signature consisted of five genes (VHL, MYF3, TMS, GPC3 and SRBC), AUC 0.848; Sens = 0.807, Spec = 0.666. Combined PC and CRC signature or “combined cancer signature” was derived to differentiate either CRC and PC from controls (MDR1, SRBC, VHL, MUC2, RB1, SYK and GPC3) AUC = 0.8177, Sens = 0.6316 Spec = 0.840. In a validation cohort, N = 10 CRC patients, the optimal CRC signature (CYCD2, HIC and VHL) had AUC 0.900. In all derived signatures (CRC, PC and combined cancer signature) the optimal panel used preferential VHL methylation. In conclusion, CRC and PC differ in specific genes methylated in plasma other than VHL. Preferential methylation of VHL is shared in the optimal signature for CRC alone, PC alone and combined PC and CRC. Future investigations may identify additional methylation markers informative for the presence of both CRC and PC.

Dysplasia detection rate of confirmatory EGD in nondysplastic Barrett's esophagus.

Current guidelines for endoscopic surveillance of Barretts esophagus (BE) recommend that patients with newly diagnosed BE undergo confirmatory esophagogastroduodenoscopy (EGD) to exclude the presence of dysplasia. The extent to which confirmatory endoscopy alters management and detects missed dysplasia in newly diagnosed BE has not been reported. The frequency with which confirmatory endoscopy changed surveillance management in patients with newly diagnosed BE was assessed. A two center cohort analysis was conducted on patients newly diagnosed with BE. The rate of dysplasia on confirmatory endoscopy for patients who had nondysplastic BE was obtained. Demographic and endoscopic variables were assessed for association with dysplasia detection using Firth logistic regression model. Out of the 146 patients newly diagnosed with BE and initially determined to be without dysplasia, 12 had dysplasia on the confirmatory second EGD (8.2%). Eleven of 12 cases with dysplasia on confirmatory endoscopy had long-segment BE (LSBE). Among all the LSBE cases in our cohort, 11 had newly diagnosed dysplasia on confirmatory EGD, 29.7% (11/37). The average number of biopsies obtained from the 11 LSBE cases with dysplasia was comparable with the rest of the LSBE cases without dysplasia (6.73 and 5.42, respectively, P-value 0.205). The rate of dysplasia detection in short-segment BE (SSBE) was much lower, 0.95% (1 out of 105). There were no cases of high-grade dysplasia (HGD) or cancer detected in any SSBE case. HGD was detected on confirmatory EGD in two cases, both were LSBE. Segment length was the only statistically significant factor to predict the presence of dysplasia on confirmatory endoscopy (odds ratio 9.158, P. 0.008). Confirmatory EGD in newly diagnosed LSBE had significant rate of dysplasia detection (29.7%) in this cohort. Among patients with SSBE, there was a low rate of dysplasia detection with confirmatory EGD, less than 1% of cases. No additional cases of HGD or esophageal carcinoma in SSBE cases were detected. This suggests that the yield of confirmatory EGD is greater in patients with LSBE.

Histopathology predictors of medically refractory ulcerative colitis.

PURPOSE: The ability of ulcerative colitis histology to predict medically refractory disease was evaluated. METHODS: Twenty patients who underwent colectomy for medically refractory disease were compared with 48 medically managed patients. All patients were followed up for ≥6 months. The study design was a retrospective longitudinal observational chart review to determine whether specific histologic parameters were predictive of a later colectomy for medically refractory disease. RESULTS: On initial biopsy, medically refractory patients were more likely to have severe cryptitis, 75% vs 49%; lymphoid follicles, 78% vs 48%; and erosions, 35% vs 11%. There was no significant difference in the prevalence of crypt abscesses, mucin depletion, crypt distortion, or mucosal ulceration between medically refractory and medically managed patients. Active inflammation on endoscopy was not statistically different between groups (P = .192). In a recursive partition model, the strongest predictors of future colectomy were age dependent. Among older patients (>38 y), severe cryptitis was the strongest determinant of refractory disease. Only 1 of 21 (5%) of the patients who initially did not have severe cryptitis progressed to colectomy. In younger patients (≤38 y), the presence of lymphoid follicles was the strongest predictor of future colectomy; 9 of 14 (64%) patients with lymphoid follicles progressed to colectomy. CONCLUSIONS: Medically refractory ulcerative colitis was associated with initial biopsy findings of severe cryptitis, lymphoid follicles, and erosions. Refractory disease was not predicted by the severity or extent of endoscopic findings. In younger patients, the presence of lymphoid follicles, and in older patients, severe cryptitis, were the most important predictors of medically refractory disease.