Epidemiological, clinical and molecular characterization of Lynch-like syndrome: A population-based study.

Colorectal carcinomas that are mismatch repair (MMR)-deficient in the absence of MLH1 promoter methylation or germline mutations represent Lynch-like syndrome (LLS). Double somatic events inactivating MMR genes are involved in the etiology of LLS tumors. Our purpose was to define the clinical and broader molecular hallmarks of LLS tumors and the population incidence of LLS, which remain poorly characterized. We investigated 762 consecutive colorectal carcinomas operated in Central Finland in 2000-2010. LLS cases were identified by a stepwise protocol based on MMR protein expression, MLH1 methylation and MMR gene mutation status. LLS tumors were profiled for CpG Island Methylator Phenotype (CIMP) and somatic mutations in 578 cancer-relevant genes. Among 107 MMR-deficient tumors, 81 (76%) were attributable to MLH1 promoter methylation and 9 (8%) to germline mutations (Lynch syndrome, LS), leaving 14 LLS cases (13%) (3 remained unclassified). LLS carcinomas were diagnosed at a mean age of 65 years (vs. 44 years in LS, p < 0.001), had a proximal to distal ratio of 1:1, and all were BRAF V600E-negative. Two somatic events in MMR genes were identifiable in 11 tumors (79%). As novel findings, the tumors contained an average of 31 nonsynonymous somatic mutations/Mb and 13/14 were CIMP-positive. In conclusion, we establish the epidemiological, clinical and molecular characteristics of LLS in a population-based study design. Significantly more frequent CIMP-positivity and lower rates of somatic mutations make a distinction to LS. The absence of BRAF V600E mutation separates LLS colorectal carcinomas from MLH1-methylated colorectal carcinomas with CIMP-positive phenotype.

An improved image analysis method for cell counting lends credibility to the prognostic significance of T cells in colorectal cancer.

Numerous immunohistochemically detectable proteins, such as immune cell surface (CD) proteins, vascular endothelial growth factor, and matrix metalloproteinases, have been proposed as potential prognostic markers in colorectal cancer (CRC) and other malignancies. However, the lack of reproducibility has been a major problem in validating the clinical use of such markers, and this has been attributed to insufficiently robust methods used in immunohistochemical staining or its assessment. In this study, we assessed how computer-assisted image analysis might contribute to the reliable assessment of positive area percentage and immune cell density in CRC specimens, and subsequently, we applied the computer-assisted cell counting method in assessing the prognostic value of T cell infiltration in CRC. The computer-assisted analysis methods were based on separating hematoxylin and diaminobenzidine color layers and then applying a brightness threshold using open source image analysis software ImageJ. We found that computer-based analysis results in a more reproducible assessment of the immune positive area percentage than visual semiquantitative estimation. Computer-assisted immune cell counting was rapid to perform and accurate (Pearson r > 0.96 with exact manual cell counts). Moreover, the computer-assisted determination of peritumoral and stromal T cell density had independent prognostic value. Our results suggest that computer-assisted image analysis, utilizing freely available image analysis software, provides a valuable alternative to semiquantitative assessment of immunohistochemical results in cancer research, as well as in clinical practice. The advantages of using computer-assisted analysis include objectivity, accuracy, reproducibility, and time efficiency. This study supports the prognostic value of assessing T cell infiltration in CRC.

Absence of cytomegalovirus from the gastrointestinal tract of patients with active Crohn's disease.

BACKGROUND: Cytomegalovirus (CMV) infection reportedly is detectable in the gastrointestinal mucosa of patients with chronic inflammatory bowel disease. One view is that CMV infection is of clinical significance in patients with Crohn's disease with severe colitis not responding to steroid therapy. In this study, we evaluated the prevalence of CMV infection in our own patients with Crohn's disease treated with colon resection. PATIENTS AND METHODS: The study included 16 consecutive patients with Crohn's disease with colitis who underwent surgery for colonic disease. Histology and immunohistochemistry were used to examine the CMV infection in their surgical specimens by means of enzymatic antigen retrieval, mouse monoclonal antibody, clone CMV01, and a sensitive polymer detection system. RESULTS: All 16 patients underwent colon resection, three of them undergoing emergency surgery. No CMV infection was found in their surgical specimens. CONCLUSION: CMV infection seems not to play a major role in the pathogenesis of Crohn's colitis requiring surgery. However, further prospective studies with larger number of patients are needed to determine the role of CMV in active Crohn's colitis.