Leticia Moreira

Prevalence and risk factors of infections by multiresistant bacteria in cirrhosis: A prospective study†

Epidemiology, risk factors, and clinical effect of infections by multiresistant bacteria in cirrhosis are poorly known. This work was a prospective evaluation in two series of cirrhotic patients admitted with infection or developing infection during hospitalization. The first series was studied between 2005 and 2007 (507 bacterial infections in 223 patients) and the second between 2010 and 2011 (162 bacterial infections in 110 patients). In the first series, 32% of infections were community acquired (CA), 32% healthcare associated (HCA), and 36% nosocomial. Multiresistant bacteria (92 infections; 18%) were isolated in 4%, 14%, and 35% of these infections, respectively (P < 0.001). Extended‐spectrum β‐lactamase‐producing Enterobacteriaceae (ESBL‐E; n = 43) was the main multiresistant organism identified, followed by Pseudomonas aeruginosa (n = 17), methicillin‐resistant Staphylococcus aureus (n = 14), and Enterococcus faecium (n = 14). The efficacy of currently recommended empirical antibiotic therapy was very low in nosocomial infections (40%), compared to HCA and CA episodes (73% and 83%, respectively; P < 0.0001), particularly in spontaneous bacterial peritonitis, urinary tract infection, and pneumonia (26%, 29%, and 44%, respectively). Septic shock (26% versus 10%; P < 0.0001) and mortality rate (25% versus 12%; P = 0.001) were significantly higher in infections caused by multiresistant strains. Nosocomial origin of infection (hazard ratio [HR], 4.43), long‐term norfloxacin prophylaxis (HR, 2.69), recent infection by multiresistant bacteria (HR, 2.45), and recent use of β‐lactams (HR, 2.39) were independently associated with the development of multiresistant infections. Results in the second series were similar to those observed in the first series. Conclusions: Multiresistant bacteria, especially ESBL‐producing Enterobacteriaceae, are frequently isolated in nosocomial and, to a lesser extent, HCA infections in cirrhosis, rendering third‐generation cephalosporins clinically ineffective. New antibiotic strategies tailored according to the local epidemiological patterns are needed for the empirical treatment of nosocomial infections in cirrhosis. (HEPATOLOGY 2012)

Identification of Lynch syndrome among patients with colorectal cancer.

CONTEXT Lynch syndrome is the most common form of hereditary colorectal cancer (CRC) and is caused by germline mutations in DNA mismatch repair (MMR) genes. Identification of gene carriers currently relies on germline analysis in patients with MMR-deficient tumors, but criteria to select individuals in whom tumor MMR testing should be performed are unclear. OBJECTIVE To establish a highly sensitive and efficient strategy for the identification of MMR gene mutation carriers among CRC probands. DESIGN, SETTING, AND PATIENTS Pooled-data analysis of 4 large cohorts of newly diagnosed CRC probands recruited between 1994 and 2010 (n = 10,206) from the Colon Cancer Family Registry, the EPICOLON project, the Ohio State University, and the University of Helsinki examining personal, tumor-related, and family characteristics, as well as microsatellite instability, tumor MMR immunostaining, and germline MMR mutational status data. MAIN OUTCOME Performance characteristics of selected strategies (Bethesda guidelines, Jerusalem recommendations, and those derived from a bivariate/multivariate analysis of variables associated with Lynch syndrome) were compared with tumor MMR testing of all CRC patients (universal screening). RESULTS Of 10,206 informative, unrelated CRC probands, 312 (3.1%) were MMR gene mutation carriers. In the population-based cohorts (n = 3671 probands), the universal screening approach (sensitivity, 100%; 95% CI, 99.3%-100%; specificity, 93.0%; 95% CI, 92.0%-93.7%; diagnostic yield, 2.2%; 95% CI, 1.7%-2.7%) was superior to the use of Bethesda guidelines (sensitivity, 87.8%; 95% CI, 78.9%-93.2%; specificity, 97.5%; 95% CI, 96.9%-98.0%; diagnostic yield, 2.0%; 95% CI, 1.5%-2.4%; P < .001), Jerusalem recommendations (sensitivity, 85.4%; 95% CI, 77.1%-93.6%; specificity, 96.7%; 95% CI, 96.0%-97.2%; diagnostic yield, 1.9%; 95% CI, 1.4%-2.3%; P < .001), and a selective strategy based on tumor MMR testing of cases with CRC diagnosed at age 70 years or younger and in older patients fulfilling the Bethesda guidelines (sensitivity, 95.1%; 95% CI, 89.8%-99.0%; specificity, 95.5%; 95% CI, 94.7%-96.1%; diagnostic yield, 2.1%; 95% CI, 1.6%-2.6%; P < .001). This selective strategy missed 4.9% of Lynch syndrome cases but resulted in 34.8% fewer cases requiring tumor MMR testing and 28.6% fewer cases undergoing germline mutational analysis than the universal approach. CONCLUSION Universal tumor MMR testing among CRC probands had a greater sensitivity for the identification of Lynch syndrome compared with multiple alternative strategies, although the increase in the diagnostic yield was modest.

Colorectal cancers with microsatellite instability display unique miRNA profiles

Purpose: microRNAs (miRNA) are small noncoding transcripts that play an important role in carcinogenesis. miRNA expression profiles have been shown to discriminate between different types of cancers. The aim of this study was to analyze global miRNA signatures in various groups of colorectal cancers (CRC) based on the presence of microsatellite instability (MSI). Experimental Design: We analyzed genome-wide miRNA expression profiles in 54 CRC tissues [22 with Lynch syndrome, 13 with sporadic MSI due to MLH1 methylation, 19 without MSI (or microsatellite stable, MSS)] and 20 normal colonic tissues by miRNA microarrays. Using an independent set of MSI-positive samples (13 with Lynch syndrome and 20 with sporadic MSI), we developed a miRNA-based predictor to differentiate both types of MSI by quantitative reverse transcriptase PCR. Results: We found that the expression of a subset of nine miRNAs significantly discriminated between tumor and normal colonic mucosa tissues (overall error rate = 0.04). More importantly, Lynch syndrome tumors displayed a unique miRNA profile compared with sporadic MSI tumors; miR-622, miR-1238, and miR-192 were the most differentially expressed miRNAs between these two groups. We developed a miRNA-based predictor capable of differentiating between types of MSI in an independent sample set. Conclusions: CRC tissues show distinct miRNA expression profiles compared with normal colonic mucosa. The discovery of unique miRNA expression profiles that can successfully discriminate between Lynch syndrome, sporadic MSI, and sporadic MSS colorectal cancers provides novel insights into the role of miRNAs in colorectal carcinogenesis, which may contribute to the diagnosis, prognosis, and treatment of this disease. Clin Cancer Res; 17(19); 6239–49. ©2011 AACR.

A High Degree of LINE-1 Hypomethylation Is a Unique Feature of Early-Onset Colorectal Cancer

Objective Early-onset colorectal cancer (CRC) represents a clinically distinct form of CRC that is often associated with a poor prognosis. Methylation levels of genomic repeats such as LINE-1 elements have been recognized as independent factors for increased cancer-related mortality. The methylation status of LINE-1 elements in early-onset CRC has not been analyzed previously. Design We analyzed 343 CRC tissues and 32 normal colonic mucosa samples, including 2 independent cohorts of CRC diagnosed ≤50 years old (n = 188), a group of sporadic CRC >50 years (MSS n = 89; MSI n = 46), and a group of Lynch syndrome CRCs (n = 20). Tumor mismatch repair protein expression, microsatellite instability status, LINE-1 and MLH1 methylation, somatic BRAF V600E mutation, and germline MUTYH mutations were evaluated. Results Mean LINE-1 methylation levels (±SD) in the five study groups were early-onset CRC, 56.6% (8.6); sporadic MSI, 67.1% (5.5); sporadic MSS, 65.1% (6.3); Lynch syndrome, 66.3% (4.5) and normal mucosa, 76.5% (1.5). Early-onset CRC had significantly lower LINE-1 methylation than any other group (p<0.0001). Compared to patients with <65% LINE-1 methylation in tumors, those with ≥65% LINE-1 methylation had significantly better overall survival (p = 0.026, log rank test). Conclusions LINE-1 hypomethylation constitutes a potentially important feature of early-onset CRC, and suggests a distinct molecular subtype. Further studies are needed to assess the potential of LINE-1 methylation status as a prognostic biomarker for young people with CRC.

MSH6 and MUTYH Deficiency Is a Frequent Event in Early-Onset Colorectal Cancer

Purpose: Early-onset colorectal cancer (CRC) is suggestive of a hereditary predisposition. Lynch syndrome is the most frequent CRC hereditary cause. The MUTYH gene has also been related to hereditary CRC. A systematic characterization of these two diseases has not been reported previously in this population. Experimental Design: We studied a retrospectively collected series of 140 patients ≤50 years old diagnosed with nonpolyposis CRC. Demographic, clinical, and familial features were obtained. Mismatch repair (MMR) deficiency was determined by microsatellite instability (MSI) analysis, and immunostaining for MLH1, MSH2, MSH6, and PMS2 proteins. Germline MMR mutations were evaluated in all MMR-deficient cases. Tumor samples with loss of MLH1 or MSH2 protein expression were analyzed for somatic methylation. Germline MUTYH mutations were evaluated in all cases. BRAF V600E and KRAS somatic mutational status was also determined. Results: Fifteen tumors (11.4%) were MSI, and 20 (14.3%) showed loss of protein expression (7 for MLH1/PMS2, 2 for isolated MLH1, 3 for MSH2/MSH6, 7 for isolated MSH6, and 1 for MSH6/PMS2). We identified 11 (7.8%) germline MMR mutations, 4 in MLH1, 1 in MSH2, and 6 in MSH6. Methylation analysis revealed one case with somatic MLH1 methylation. Biallelic MUTYH mutations were detected in four (2.8%) cases. KRAS and BRAF V600E mutations were present in 39 (27.9%) and 5 (3.6%) cases, respectively. Conclusions: Loss of MSH6 expression is the predominant cause of MMR deficiency in early-onset CRC. Our findings prompt the inclusion of MSH6 and MUTYH screening as part of the genetic counseling of these patients and their relatives. Clin Cancer Res; 16(22); 5402–13. ©2010 AACR.

Cyclooxygenase as a target for colorectal cancer chemoprevention.

Colorectal cancer (CRC) is one of the most common neoplasia in Western countries and the second leading cause of cancer-related death. The vast majority of cases belong to sporadic forms, whereas a small but relevant proportion of them corresponds to inherited disorders, i.e. familial adenomatous polyposis and Lynch syndrome. These individuals with germline mutations in cancer-promoting genes, along with those who had already developed a colorectal neoplasm, either adenoma or carcinoma, stand to benefit from chemopreventive interventions. A large body of evidence indicates that the use of aspirin and other non-steroidal anti-inflammatory drugs (NSAID) can reduce the risk of CRC. Experimental studies have demonstrated that these drugs decrease the incidence of carcinogen-induced colon tumors in rodents, and several epidemiological investigations and therapeutic trials have also shown a 40-50% reduction in the risk of colorectal adenoma and cancer in individuals taking NSAIDs. Moreover, patients with familial adenomatous polyposis taking sulindac or celecoxib experience a reduction in adenoma size and number. The chemopreventive effects of NSAID are largely related to inhibition of cyclooxygenase-2 (COX-2), the inducible isoform of cyclooxygenase that catalyzes the conversion of arachidonic acid to prostaglandins. COX-2 overexpression is a frequent, but not universal event in colorectal neoplasms. Indeed, approximately 50% of adenomas and 80% of CRC express high levels of COX-2 mRNA and protein in neoplastic tissue. In this article, we will review the role of cyclooxygenase as a target for CRC chemoprevention, with special attention to the use of selective and non-selective COX-2 inhibitors in both individuals genetically predisposed and those who have already developed a colorectal neoplasm.

Prevalence of somatic mutl homolog 1 promoter hypermethylation in Lynch syndrome colorectal cancer.

Colorectal cancers (CRCs) that have microsatellite instability (MSI) and mutL homolog 1 (MLH1) immunoloss are observed in 3 clinical scenarios: Lynch syndrome (LS), sporadic MSI CRC, and Lynch‐like syndrome (LLS). v‐Raf murine sarcoma viral oncogene homolog B1 (BRAF) mutational analysis is used to differentiate LS from sporadic MSI CRC. The role of MLH1 promoter methylation status for the differential diagnosis of these clinical forms is not well established. The objectives of this study were: 1) to analyze MLH1 promoter methylation in MLH1‐deficient CRCs by pyrosequencing, and 2) to assess its role in the differential diagnosis of MLH1‐deficient CRCs.

The genetic basis of familial adenomatous polyposis and its implications for clinical practice and risk management

Familial adenomatous polyposis (FAP) is an inherited disorder that represents the most common gastrointestinal polyposis syndrome. Germline mutations in the APC gene were initially identified as responsible for FAP, and later, several studies have also implicated the MUTYH gene as responsible for this disease, usually referred to as MUTYH-associated polyposis (MAP). FAP and MAP are characterized by the early onset of multiple adenomatous colorectal polyps, a high lifetime risk of colorectal cancer (CRC), and in some patients the development of extracolonic manifestations. The goal of colorectal management in these patients is to prevent CRC mortality through endoscopic and surgical approaches. Individuals with FAP and their relatives should receive appropriate genetic counseling and join surveillance programs when indicated. This review is focused on the description of the main clinical and genetic aspects of FAP associated with germline APC mutations and MAP.

Colorectal cancer risk factors in patients with serrated polyposis syndrome: a large multicentre study

Objective Serrated polyposis syndrome (SPS) is associated with an increased colorectal cancer (CRC) risk, although the magnitude of the risk remains uncertain. Whereas intensive endoscopic surveillance for CRC prevention is advised, predictors that identify patients who have high CRC risk remain unknown. We performed a multicentre nationwide study aimed at describing the CRC risk in patients with SPS and identifying clinicopathological predictors independently associated with CRC. Design From March 2013 through September 2014, patients with SPS were retrospectively recruited at 18 Spanish centres. Data were collected from medical, endoscopy and histopathology reports. Multivariate logistic regression was performed to identify CRC risk factors. Results In 296 patients with SPS with a median follow-up time of 45 months (IQR 26–79.7), a median of 26 (IQR 18.2–40.7) serrated polyps and 3 (IQR 1–6) adenomas per patient were detected. Forty-seven patients (15.8%) developed CRC at a mean age of 53.9±12.8, and 4 out of 47 (8.5%) tumours were detected during surveillance (cumulative CRC incidence 1.9%). Patients with >2 sessile serrated adenomas/polyps (SSA/Ps) proximal to splenic flexure and ≥1 proximal SSA/P with high-grade dysplasia were independent CRC risk factors (incremental OR=2, 95% CI 1.22 to 3.24, p=0.006). Patients with no risk factors showed a 55% decrease in CRC risk (OR=0.45, 95% CI 0.24 to 0.86, p=0.01). Conclusions Patients with SPS have an increased risk of CRC, although lower than previously published. Close colonoscopy surveillance in experienced centres show a low risk of developing CRC (1.9% in 5 years). Specific polyp features (SSA/P histology, proximal location and presence of high-grade dysplasia) should be used to guide clinical management.

MicroRNAs for Detection of Pancreatic Neoplasia: Biomarker Discovery by Next-generation Sequencing and Validation in 2 Independent Cohorts.

Objective: The aim of our study was to analyze the miRNome of pancreatic ductal adenocarcinoma (PDAC) and its preneoplastic lesion intraductal papillary mucinous neoplasm (IPMN), to find new microRNA (miRNA)-based biomarkers for early detection of pancreatic neoplasia. Objective: Effective early detection methods for PDAC are needed. miRNAs are good biomarker candidates. Methods: Pancreatic tissues (n = 165) were obtained from patients with PDAC, IPMN, or from control individuals (C), from Hospital Clínic of Barcelona. Biomarker discovery was done using next-generation sequencing in a discovery set of 18 surgical samples (11 PDAC, 4 IPMN, 3 C). MiRNA validation was carried out by quantitative reverse transcriptase PCR in 2 different set of samples. Set 1—52 surgical samples (24 PDAC, 7 IPMN, 6 chronic pancreatitis, 15 C), and set 2—95 endoscopic ultrasound-guided fine-needle aspirations (60 PDAC, 9 IPMN, 26 C). Results: In all, 607 and 396 miRNAs were significantly deregulated in PDAC and IPMN versus C. Of them, 40 miRNAs commonly overexpressed in both PDAC and IPMN were selected for further validation. Among them, significant up-regulation of 31 and 30 miRNAs was confirmed by quantitative reverse transcriptase PCR in samples from set 1 and set 2, respectively. Conclusions: miRNome analysis shows that PDAC and IPMN have differential miRNA profiles with respect to C, with a large number of deregulated miRNAs shared by both neoplastic lesions. Indeed, we have identified and validated 30 miRNAs whose expression is significantly increased in PDAC and IPMN lesions. The feasibility of detecting these miRNAs in endoscopic ultrasound-guided fine-needle aspiration samples makes them good biomarker candidates for early detection of pancreatic cancer.