Phospho-ERK levels as predictors for chemotherapy of rectal carcinoma.

Treatment of rectal cancer has been vastly improved by advances in surgery and radiochemotherapy but remains an important cause of morbidity and mortality worldwide. A particular problem is the lack of predictive markers that can help to individualize treatment. The growth- and apoptosis-regulating signaling molecules ERK 1 and 2 are important to cancer growth and progression. They are activated through phosphorylation, which is initiated by a cascade involving the EGF receptor and RAS as upstream regulators. Moreover, in vitro studies indicate that phospho-ERKs interfere with 5-fluorouracil-based chemotherapy. Recently, we showed that high levels of phospho-ERKs in rectal cancer cells predict poor responses to neoadjuvant (preoperative) radiochemotherapy. We now report that preoperative phospho-ERK levels also can subdivide high-risk rectal cancer patients into a favorable and a poor prognostic group with respect to recurrence-free survival. Importantly, phospho-ERK levels were of predictive significance only in high-risk patients, who received adjuvant (postoperative) chemotherapy, but not in high-risk patients not receiving such therapy. Our results suggest that high cancer cell levels of phospho-ERK predict poor responsiveness to both preoperative and postoperative chemotherapy of rectal cancer.

Histological and Molecular Adipose Tissue Changes Are Related to Metabolic Syndrome Rather Than Lipodystrophy in Human Immunodeficiency Virus-Infected Patients: A Cross-Sectional Study.

Background: In human immunodeficiency virus (HIV)-infected patients on combination antiretroviral therapy (cART), lipodystrophy shares many similarities with metabolic syndrome, but only metabolic syndrome has objective classification criteria. We examined adipose tissue changes related to lipodystrophy and metabolic syndrome to clarify whether it may be acceptable to focus diagnosis on metabolic syndrome rather than lipodystrophy. Methods: This is a cross-sectional study of 60 HIV-infected men on cART and 15 healthy men. We evaluated lipodystrophy (clinical assessment) and metabolic syndrome (JIS-2009). We compared adipocyte size, leukocyte infiltration, and gene expression in abdominal subcutaneous adipose tissue biopsies of patients with and without lipodystrophy and with and without metabolic syndrome. Results: Lipodystrophy was only associated with increased macrophage infiltration (P = .04) and adiponectin messenger ribonucleic acid ([mRNA] P = .008), whereas metabolic syndrome was associated with larger adipocytes (P < .0001), decreased expression of genes related to adipogenesis and adipocyte function (P values between <.0001 and .08), increased leptin mRNA (P = .04), and a trend towards increased expression of inflammatory genes (P values between .08 and .6). Conclusions: Metabolic syndrome rather than lipodystrophy was associated with major unfavorable abdominal subcutaneous adipose tissue changes. In a clinical setting, it may be more relevant to focus on metabolic syndrome diagnosis in HIV-infected patients on cART with regards to adipose tissue dysfunction and risk of cardiometabolic complications.

Differential expression of CK20, ß-catenin, and MUC2/5AC/6 in Lynch syndrome and familial colorectal cancer type X.

BACKGROUND: Hereditary non-polyposis colorectal cancer comprises Lynch syndrome and familial colorectal cancer type X (FCCTX). Differences in genetics, demographics and histopathology have been extensively studied. The purpose of this study is to characterize their immunoprofile of markers other than MMR proteins. METHODS: We compared the expression patterns of cytokeratins (CK7 and CK20), mucins (MUC2/5 AC/6), CDX2 and ß-catenin in Lynch syndrome and FCCTX. RESULTS: Differences were identified for CK20 and nuclear ß-catenin, which were significantly more often expressed in FCCTX than in Lynch syndrome (p < 0.001), whereas MUC2, MUC5AC and MUC6 were overexpressed in Lynch syndrome tumors compared with FCCTX tumors (p = 0.001, < 0.01, and < 0.001, respectively). We observed no differences in the expression patterns of CK7 and CDX2. CONCLUSIONS: In summary, we identified significant differences in the immunoprofiles of colorectal cancers linked to FCCTX and Lynch syndrome with a more sporadic-like profile in the former group and a more distinct profile with frequent MUC6 positivity in the latter group.

Localization of active, dually phosphorylated extracellular signal-regulated kinase 1 and 2 in colorectal cancer with or without activating BRAF and KRAS mutations.

Colorectal cancers (CRC) often show activating mutations of the KRAS or BRAF genes, which stimulate the extracellular signal-regulated kinase (ERK) pathway, thus increasing cell proliferation and inhibiting apoptosis. However, immunohistochemical results on ERK activation in such tumors differ greatly. Recently, using a highly optimized immunohistochemical method, we obtained evidence that high levels of ERK activation in rectal adenocarcinomas were associated with resistance to radiochemotherapy. In order to determine whether KRAS and/or BRAF mutations correlate to immunohistochemically detectable increases in phosphorylation of ERK (pERK), we stained biopsies from 36 CRC patients with activating mutations in the BRAF gene (BRAFV600E: BRAF(m)), the KRAS gene (KRAS(m)) or in neither (BRAF/KRAS(n)) with this optimized method. Staining was scored in blind-coded specimens by two observers. Staining of stromal cells was used as a positive control. BRAF(m) or KRAS(m) tumors did not show higher staining scores than BRAF/KRAS(n) tumors. Although BRAFV600E staining occurred in over 90% of cancer cells in all 9 BRAF(m) tumors, 3 only showed staining for pERK in less than 10% of cancer cell nuclei. The same applied to 4 of the 14 KRAS(m) tumors. A phophorylation-insensitive antibody demonstrated that lack of pERK staining did not reflect defect expression of ERK1/2 protein. Thus, increased staining for pERK does not correlate to BRAF or KRAS mutations even with a highly optimized procedure. Further studies are required to determine whether this reflects differences in expression of counterregulatory molecules, including ERK phosphatases.

Fecal Calprotectin Predicts Relapse and Histological Mucosal Healing in Ulcerative Colitis.

BACKGROUND: Mucosal healing in ulcerative colitis leads to a decreased need for medication and decreased risk of disease relapse and colectomy. Histological healing seems to improve the disease prognosis even further. An assessment of both endoscopic and histological mucosal healing requires endoscopy, and the need for a reliable noninvasive biomarker to predict disease relapse is obvious. METHODS: Seventy patients were included and followed up for 12 months. Inclusion criteria were a total Mayo score ≤1 and a Mayo endoscopic score = 0. The patients underwent sigmoidoscopy with rectal biopsies. Fecal calprotectin (FC) was measured 2 to 3 days before the sigmoidoscopy. The tissue samples were evaluated for neutrophilic inflammation. We aimed at testing the predictive performance of FC and histological inflammatory activity on disease relapse. RESULTS: A baseline FC level of more than 321 mg/kg predicted disease relapse at both the 6- and 12-month follow-ups. Histological inflammatory activity, C-reactive protein, or length of remission was not predictive of relapse. Of note, 11.8% of all patients had histological inflammatory activity despite endoscopic remission and were found to have a higher level of FC (236.5 versus 56 mg/kg, P = 0.02). A receiver operating characteristic analysis estimated a cutoff level of ≤40.5 mg/kg for FC (area under the curve, 0.755 and confidence interval 95%, 0.5895-0.9208) for predicting a histological inflammatory activity score of 0. CONCLUSIONS: FC measurements can be used to identify patients with increased risk of relapse after 6 and 12 months and to predict histological mucosal healing. Regular measurement of FC may alter disease monitoring and improve prognosis, and may decrease the need for endoscopy.

CD3 immunohistochemical staining in diagnosis of lymphocytic colitis.

Microscopic colitis (MC) is a common cause of chronic watery diarrhea. Traditionally, MC encompasses the 2 subgroups lymphocytic colitis (LC) and collagenous colitis, but recently, an additional subgroup, MC incomplete, has been introduced. Distinguishing between the subgroups relies exclusively on histopathologic evaluation. In the present study, 4 pathologists evaluated 156 archived biopsies originally diagnosed as LC or LC incomplete (LCi). Each pathologist assigned a diagnosis of LC, LCi, or nonspecific inflammation to all cases at 2 independent assessments. At the first assessment, hematoxylin and eosin (HE) stainings were available. At the second assessment, a supplementary CD3 immunohistochemical staining was also available. The aim was to evaluate whether a supplementary CD3 would increase the diagnostic agreement among pathologists, and whether a CD3 stain would change the diagnosis based on HE staining only. After the complete assessment, the cases were divided into 3 groups, that is, full agreement, partial agreement, and disagreement. The CD3 staining increased the number of cases with full agreement from 60 to 78. One hundred thirty-one cases with agreement or partial diagnostic agreement based on HE + CD3 were compared with the HE diagnoses. In 44 (34%) of 131 cases, CD3 changed the diagnosis. Cases assigned to the LCi category based on HE were often changed by a supplementary CD3. Conclusively, it is recommended to use a CD3 before giving the histopathologic diagnosis of LCi.

Phospho-ERK1/2 levels in cancer cell nuclei predict responsiveness to radiochemotherapy of rectal adenocarcinoma.

Locally advanced rectal adenocarcinoma is treated with radiochemotherapy (RCT) before surgery. The response to RCT is heterogeneous and consensus regarding reliable predictors is lacking. Since the ERK pathway is implicated in radioprotection, we examined pretreatment biopsies from 52 patients by immunohistochemistry for phosphorylated ERK (pERK). Immunostaining for pERK was considerably enhanced by use of alkaline demasking. Nuclear staining occurred in both cancer cells and stromal cells. Blind-coded sections were scored by 2 independent investigators. In patients showing no residual tumor after RCT (TRG1), staining for pERK in cancer, but not stromal, cell nuclei was significantly weaker than in patients showing a poor RCT response (TRG1 vs TRG4: p = 0.0001). Nuclear staining for pERK predicted poor responders, as illustrated by receiver operating characteristic curves with an area under curve of 0.86 (p = 0.0007) and also predicted downstaging (area under curve: 0.76; p = 0.01). A number of controls documented the specificity of the optimized staining method and results were confirmed with another pERK antibody. Thus, staining for pERK in cancer cell nuclei can predict the response to RCT and may help spare poor responders this treatment. These results also raise the question whether inhibitors of ERK activation may serve as response modifiers of RCT.

Level of Fecal Calprotectin Correlates With Endoscopic and Histologic Inflammation and Identifies Patients With Mucosal Healing in Ulcerative Colitis.

BACKGROUND & AIMS: In patients with ulcerative colitis (UC), mucosal healing is an important goal of treatment. However, mucosal healing is difficult to determine on the basis of clinical evaluation alone, and endoscopy is uncomfortable and can cause complications. Fecal calprotectin (FC) is a marker of inflammation, and its levels have been associated with disease activity. We investigated the association between level of FC and mucosal healing and clinical disease activity in patients with UC. METHODS: We performed an observational cross-sectional study of 120 patients with active or inactive UC who underwent sigmoidoscopy at Copenhagen University Hospital Hvidovre from September 2012 through 2014. Endoscopic inflammation was evaluated by using the Mayo Endoscopic Score (MES) and Ulcerative Colitis Endoscopic Index of Severity (UCEIS) and histologic inflammatory activity by a slightly modified Harpaz Index, which measures acute inflammation. The Partial Mayo Score was used to measure the clinical disease activity. RESULTS: A cutoff level of FC of 192 mg/kg identified patients with endoscopic evidence of mucosal healing, which was based on the MES and UCEIS, with positive predictive values of 0.71 and 0.65, respectively; negative predictive values were 0.90 and 0.93, respectively. A cutoff level of 171 mg/kg identified patients with histologic evidence of mucosal healing, with positive predictive value of 0.75 and negative predictive value of 0.90. Levels of FC increased significantly with increases in endoscopic and histologic disease activity. There was high concordance between MES and UCEIS as well as between MES or UCEIS and histologic inflammatory activity. The histologic activity index had an interobserver variation of 4.35%. CONCLUSIONS: Level of FC identifies patients with UC who have endoscopic and histologic features of mucosal healing and correlates with endoscopic and histologic inflammatory activity. The UCEIS seems to be as accurate as the MES in identifying patients with mucosal healing and as easy to use. The histologic activity index had a high concordance with recognized endoscopic score systems.

Sebaceous neoplasms and the immunoprofile of mismatch-repair proteins as a screening target for syndromic cases.

INTRODUCTION: Muir-Torre syndrome (MTS), a subset of Lynch syndrome, is characterized by concurrent or sequential development of sebaceous neoplasms, and internal malignancies, specifically colorectal carcinoma (CRC), and can be related to mismatch-repair (MMR)-protein deficiency. In CRC context, p16-negativity in MLH1-deficient cases may denote methylation rather than mutation. The prime aim of this study was to evaluate the mismatch-repair (MMR)-protein deficiency and the p16 status among sebaceous neoplasms. MATERIAL AND METHOD: From January 1990 through October 2012, 26 sebaceous adenomas (SAs) and 6 sebaceous carcinomas (SCs) were accrued. The expression of MLH1, MSH2, MSH6, and PMS2 was recorded. MLH1-deficient cases were tested for p16 status. RESULTS: Eighteen (56%) of the 32 specimens with SA or SC displayed MMR-protein deficiency, comprising 17 (65.4%) SAs (MSH2/MSH6 loss in 12, MLH1/PMS2 loss in 3, MSH6 loss only in 2 cases) and 1 (16.7%) SC (MLH1/PMS2 loss). All 4 MLH1 deficient cases were p16-positive. CONCLUSION: A substantial proportion of sebaceous neoplasms were MMR-protein deficient and thus likely MTS candidates. Given the low prevalence of sebaceous neoplasms in Denmark, immunohistochemistry for the four MMR-proteins is recommended in the initial diagnostic approach. The addition of p16 was none-informative, but evaluation of its utility in larger series is warranted.

Monitoring mammary tumor progression and effect of tamoxifen treatment in MMTV-PymT using MRI and magnetic resonance spectroscopy with hyperpolarized [1-13C]pyruvate.

PURPOSE: To use dynamic magnetic resonance spectroscopy (MRS) of hyperpolarized (13)C-pyruvate to follow the progress over time in vivo of breast cancer metabolism in the MMTV-PymT model, and to follow the response to the anti-estrogen drug tamoxifen. METHODS: Tumor growth was monitored by anatomical MRI by measuring tumor volumes. Dynamic MRS of hyperpolarized (13)C was used to measure an "apparent" pyruvate-to-lactate rate constant (kp) of lactate dehydrogenase (LDH) in vivo. Further, ex vivo pathology and in vitro LDH initial reaction velocity were evaluated. RESULTS: Tamoxifen significantly halted the tumor growth measured as tumor volume by MRI. In the untreated animals, kp correlated with tumor growth. The kP was somewhat but not significantly lower in the treated group. Studies in vitro confirmed the effects of tamoxifen on tumor growth, and here the LDH reaction velocity was reduced significantly in the treated group. CONCLUSION: These hyperpolarized (13)C MRS findings indicate that tumor metabolic changes affects kP. The measured kp did not relate to treatment response to the same extent as did tumor growth, histological evaluation, and in vitro determination of LDH activity.

IQGAP1 in rectal adenocarcinomas: localization and protein expression before and after radiochemotherapy.

Treatment of rectal adenocarcinoma includes total mesorectal excision, which is preceded by radiochemotherapy (RCT) in cases of advanced disease. The response to RCT varies from total tumor regression to no effect but this heterogeneous response is unexplained. However, both radiation and treatment with 5-fluorouracil may induce treatment resistance through upregulation of the mitogen-activated protein kinase (MAPK) cascade. IQGAP1 is a scaffold protein that appears to be essential to MAPK signaling in cancers. We have therefore studied IQGAP1 protein expression in rectal adenocarcinomas before and after RCT. We demonstrate that cancer cells show increased apical staining for IQGAP1 following RCT. Interestingly, this increase is significantly higher in patients showing poor RCT responses. Our results also suggest that low levels of apical IQGAP1-staining in biopsies may predict the RCT response. Together, these data suggest that both the level and localization of IQGAP1 may influence the treatment response.

Heterogenous mismatch-repair status in colorectal cancer.

BACKGROUND: Immunohistochemical staining for mismatch repair proteins is efficient and widely used to identify mismatch repair defective tumors. The tumors typically show uniform and widespread loss of MMR protein staining. We identified and characterized colorectal cancers with alternative, heterogenous mismatch repair protein staining in order to delineate expression patterns and underlying mechanisms. METHODS: Heterogenous staining patterns that affected at least one of the mismatch repair proteins MLH1, PMS2, MSH2 and MSH6 were identified in 14 colorectal cancers. Based on alternative expression patterns macro-dissected and micro-dissected tumor areas were separately analyzed for microsatellite instability and MLH1 promoter methylation. RESULTS: Heterogenous retained/lost mismatch repair protein expression could be classified as intraglandular (within or in-between glandular formations), clonal (in whole glands or groups of glands) and compartmental (in larger tumor areas/compartments or in between different tumor blocks). These patterns coexisted in 9/14 tumors and in the majority of the tumors correlated with differences in microsatellite instability/MLH1 methylation status. CONCLUSIONS: Heterogenous mismatch repair status can be demonstrated in colorectal cancer. Though rare, attention to this phenomenon is recommended since it corresponds to differences in mismatch repair status that are relevant for correct classification. VIRTUAL SLIDES: The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1771940323126788.

Involvement of CDX2 in the cross talk between TNF-α and Wnt signaling pathway in the colon cancer cell line Caco-2.

Tumor necrosis factor-α (TNF-α) is highly upregulated in inflammation and reduces the expression of the intestinal transcription factor, Caudal-related homeobox transcription factor 2 (CDX2). Wnt/ß-catenin signaling is critical for intestinal cell proliferation, but a decreased CDX2 expression has influence on the Wnt signaling-related genes and progression of colorectal cancer. Although several inflammatory signaling pathways, including TNF-α, have been reported to promote Wnt/ß-catenin activity and development of cancer, the underlying molecular mechanisms remain unclear. The aim was to investigate the signaling pathways involved in the TNF-α-mediated downregulation of CDX2, and its influence on Wnt/ß-catenin signaling components in colon cancer cells. The expression of TNF-α and CDX2 at the invasive front were evaluated by immunohistochemical staining and showed reduced CDX2-positive cells in tumor buddings in areas with TNF-α expression in the surrounding inflammatory cells. In vitro studies revealed that TNF-α treatment showed a dose-dependent decrease of CDX2 messenger RNA (mRNA) and protein expression in Caco-2 cells. Inhibition of nuclear factor-kappaB or p38 pathways showed that these are involved in the TNF-α-dependent downregulation of CDX2. Furthermore, TNF-α-mediated downregulation of CDX2 was found to significantly decrease the mRNA levels of adenomatous polyposis coli (APC), axis inhibition protein 2 (AXIN2) and glycogen synthase kinase-3 beta (GSK3ß), whereas the mRNA levels of Wnt targets were significantly elevated in TNF-α-treated Caco-2 cells. These findings were associated with reduced binding of CDX2 to promoter or enhancer regions of APC, AXIN2 and GSK3ß. In conclusion, it was found that TNF-α induces the expression of Wnt signaling components through a downregulation of the CDX2 expression that might have a tumor-promoting effect on colon cancer cells.

Is the longitudinal margin of carcinoma-bearing colon resections a neglected parameter?

BACKGROUND: Resection of colon cancer with curative intent implies clear margins. An arbitrary requirement of 2 cm DtLM generally ensures surgical and pathological clearance. However, harvest of tumor-draining lymph nodes is related to DtLM. For this reason, an extended longitudinal margin becomes an issue. The major objective of the present study concerns quality development of colon resections, recording the status of DtLM, pT and pN stage, and the pathologists' reporting pattern. MATERIALS AND METHODS: The study comprised colectomy specimens obtained in 2010 to 2011 at Hvidovre Hospital with documented and suspected carcinoma. Specimens were stratified into 2 groups: DtLM < 5 cm and ≥ 5 cm. Data were correlated with lesional site, surgical approach, pT and pN stage and the pathologists' reporting approach. RESULTS: DtLM reporting was lacking in 6% of the specimens. DtLM was < 5 cm in 32% of the specimens. Sixty-three and 83.5% of the cancer specimens with DtLM < 5 cm were node-negative and stage pT3/4, respectively, compared with 49% and 87.5% of the ≥ 5 cm counterpart. The difference in percentage distribution of pN stage in the 2 groups was significant, and no significant difference was observed in relation to pT stage. CONCLUSION: This study suggests that DtLM < 5 cm in colon cancer surgery might result in diagnostic "understaging" and hence leaving metastasis in the patient.

Regulation of APC and AXIN2 expression by intestinal tumor suppressor CDX2 in colon cancer cells.

Wnt signaling is often constitutively active in colorectal cancer cells. The expression of the intestinal specific transcription factor CDX2 is found to be transiently decreased in invasive cells at the tumor/stroma interface. A recent ChIP-Seq study has indicated that several Wnt signaling-related genes are regulated by CDX2. The aim was to investigate the role of decreased CDX2 level on the expression of APC, AXIN2 and GSK3ß in migrating colon cancer cells at the invasive front. CDX2-bound promoter and enhancer regions from APC, AXIN2 and GSK3ß were analyzed for gene regulatory activity and the expression pattern of APC and GSK3ß at the invasive front was evaluated by immunohistochemical procedures. Transfection of intestinal and non-intestinal cell lines demonstrated that CDX2 activated APC and AXIN2 promoter activities via intestinal cell-specific enhancer elements. Suppressed CDX2 expression was associated with endogenous downregulation of APC and AXIN2 expression in Caco-2 cells but did not affect GSK3ß expression. Furthermore, elevated levels of nuclear ß-catenin and reduced levels of cytoplasmic APC were correlated to a low CDX2 expression in migrating colon cancer cells in vivo. These results suggest that a low CDX2 level has influence on the Wnt signaling in invasive colon cancer cells possibly promoting cellular migration.

The stem cell marker CD133 is highly expressed in sessile serrated adenoma and its borderline variant compared with hyperplastic polyp.

Non-dysplastic serrated polyps (ND-SP) represent a heterogeneous group of colorectal lesions that comprise hyperplastic polyp (HP) and the non-dysplastic subset of sessile serrated adenoma/polyp/lesion (SSA/P/L) and its borderline variant (BSSA/P/L). Given the observer variation in their histological typing, the identification of reliable markers that assist in the characterisation is warranted. Most important is the identification of polyp qualities that may reflect the patients' risk of developing colorectal cancer. To address these issues, CD133 may represent a potential adjunct. Here we studied the discriminatory value of CD133 expression in the classification of ND-SPs and its distribution pattern in relation to synchronous colorectal carcinoma (SCRC). 39 SSA/P/Ls, 27 BSSA/P/Ls and 21 matched HPs were immunostained for CD133. The data were further correlated to the presence of SCRC and to polyp site and size. Ignoring SCRC status, CD133 was expressed more prominently in SSA/P/Ls than in HPs. The values for BSSA/P/Ls fell in between, yet closer to the SSA/P/L scorings. This observation was retained in the context of SCRC and for SSA/P/Ls not associated with SCRC. Right-sidedness and large size of the polyps more commonly associated with increased CD133 expression. CD133 expression was not a significant discriminator as to the SCRC status. BSSA/P/Ls are more closely aligned to SSA/P/L and further that SSA/P/L and BSSA/P/Ls fundamentally differ from HP by their CD133 immunoprofile, a notion that can be exploited in the diagnostic routine practice. Recorded data further indirectly support the idea that SSA/P/Ls are more prone to neoplastic progression than are HPs.

Lynch syndrome-associated neoplasms: a discussion on histopathology and immunohistochemistry.

It was a century ago that Warthin, a pathologist, first described the clinical condition now known as Lynch syndrome. One hundred years later, our understanding of this syndrome has advanced significantly. Much of the progress took place over the last 25 years and was marked by a series of interacting developments from the disciplines of clinical oncology, pathology, and molecular genetics, with each development serving to guide or enhance the next. The advancement of our understanding about the pathology of Lynch syndrome associated tumors exemplifies such intimate interplay among disciplines. Today, accumulative knowledge has enabled surgical pathologists to detect tumors that are likely to be associated with Lynch syndrome, and the pathologist is playing an increasingly more important role in the care of these patients. The pathologist's ability is afforded primarily by information gained from tumor histopathology and by DNA mismatch repair protein immunohistochemistry. It is therefore pertinent both for the pathologists to accurately ascertain this morphologic information, and for all that are involved in the care of these patients to thoroughly understand the implications of such information. This article provides an overview of the development of histopathology and immunohistochemistry in Lynch syndrome-associated tumors, particularly in colorectal and endometrial cancers, and outlines the issues and current status of these specific pathologic aspects in not only the major tumors but also those less commonly seen or only newly reported in Lynch syndrome patients.

Qualities of sessile serrated adenoma/polyp/lesion and its borderline variant in the context of synchronous colorectal carcinoma.

AIMS: Although much data have accumulated on sessile serrated adenoma/polyp/lesion (SSA/P/L) in general, its characteristics in specified contexts are less well elucidated. This lack of knowledge is even more conspicuous concerning its borderline counterpart, referred to as BSSA/P/L. The previous histological observations of the authors on SSA/P/L and BSSA/P/L in general are here extended to encompass attributes of these polyps in the context of synchronous colorectal carcinoma (SCRC), with a focus on the place of BSSA/P/L in the spectrum of non-dysplastic serrated polyps. METHODS: 219 SSA/P/Ls, 206 BSSA/P/Ls and 170 hyperplastic polyps (HPs) were examined for SCRC. Demographics, polyp details (size, site, BRAF((V600E))) and advanced synchronous conventional adenomas were recorded. RESULTS: SCRC was present in 12.3% of SSA/P/Ls, 7.1% of HPs (p=0.09) and 8.3% of BSSA/P/Ls. Patients' ages were comparable. Gender distribution of SSA/P/L and BSSA/P/L was equal, which differed, albeit insignificantly, from a male predominance of HPs. More SSA/P/Ls and BSSA/P/Ls than HPs exceeded 4 mm (p≤0.0001). A proximal site characterised SSA/P/L compared with BBSA/P/L and HP (p<0.0001). BRAF mutation was more prevalent in SSA/P/Ls and BSSA/P/Ls, which further coexisted with advanced synchronous conventional adenomas less commonly than HPs. CONCLUSIONS: BSSA/P/L was like SSA/P/L in most respects. The lower SCRC prevalence of BSSA/P/L could fit the idea of BSSA/P/L as a precursor to SSA/P/L, a notion that deserves attention when formulating guidelines for CRC screening.

MSH6 mutations are frequent in hereditary nonpolyposis colorectal cancer families with normal pMSH6 expression as detected by immunohistochemistry.

INTRODUCTION: Hereditary nonpolyposis colorectal cancer (HNPCC) is an autosomal dominant condition accounting for 2% to 4% of all colorectal cancer cases worldwide. Families with germ line mutations in 1 of 6 mismatch repair genes are known as Lynch syndrome families. The largest number of mutations has been detected in the mismatch repair genes MLH1 and MSH2, but several mutations in MSH6 have also been demonstrated. AIM: : Whether HNPCC families are screened for mutations in mismatch repair genes often relies on their immunohistochemical profile. The aim of the present study was to evaluate this approach in Lynch families carrying mutations in MSH6. MATERIALS AND METHODS: Results of the screening of the MSH6 gene in HNPCC families were compared with those obtained on immunohistochemical protein analysis. RESULTS: In 56 (7%) of 815 families, at least 1 MSH6 mutation, 23 definitively pathogenic mutations and 38 missense mutations or unclassified variants, and several polymorphisms in the MSH6 gene were detected. In families carrying a pathogenic MSH6 mutation, 69.6% of 23 colon adenocarcinomas showed absence of pMSH6 in tumor tissue by immunohistochemical analysis. In 34.5%, all proteins could be detected, whereas in 34.5% pMSH6 was present and pMLH1/pPMS2 was absent. CONCLUSIONS: If genetic screening of HNPCC families depended on immunohistochemical results, a substantial number of families harboring a pathogenic mutation in MSH6 and the vast majority of families harboring an MSH6 unclassified variant would not be detected.