Immunohistochemical test for MLH1 and MSH2 expression predicts clinical outcome in stage II and III colorectal cancer patients

Colorectal cancer in the young: a possible role for immune surveillance?

BACKGROUND

Younger patients with colorectal cancer (CRC) generally have better survival in spite of worse clinical and pathological features.

METHODS

Twenty-six patients under 50 years operated for primary CRC were enrolled and matched 1:2:2 according to stage, tumor site and gender with 52 patients from 50 to 70 years and 52 patients over 70 years old.

RESULTS

Patients under 50 years had a significantly longer overall, cancer specific and disease free survival (p = .001, p = .007 and p = .05, respectively). However, they had more frequently lymphovascular invasion (p = .006) and they more frequently developed metachronous CRC at follow-up (p = .03). Nevertheless, preoperative lymphocytes blood count/white blood count (LBC/WBC) ratio inversely correlated with age at operation (rho = -.21, p = .04) and it predicted CRC recurrence with an accuracy of 70%, p < .001 (threshold value LBC/WBC = 0.21%) and better overall, cancer specific and disease free survival (p < .0001 for all). At multivariate analysis, stage and LBC/WBC ratio resulted independent predictors of disease free survival (p = .0001 and p = .01, respectively).

CONCLUSIONS

Patients under 50 years had a significantly longer survival with a higher LBC/WBC ratio. These results could suggest a possible role of immunosurveillance in neoplastic control.

Factors associated with short recurrence-free survival in completely resected colon cancer

Background: Several factors could affect disease recurrence in surgically resected colon cancer. While the role of certain factors such as cancer stage and grade is well established, the role of other factors (e.g., histological subtypes) is yet to be determined.

Objective:Therefore, we conducted a study to evaluate the impact of several factors in recurrence-free survival (RFS) in patients who were disease free following surgical resection of the colon cancer.

Design/Methods: Data were collected for patients with Stage I–III colon cancer who underwent complete surgical resection of the tumor between January 2010 and December 2015 in our institution. A total of 90 subjects met the inclusion criteria and were included in the study. The following factors were collected at the time of surgical resection of the colonic tumor: patient’s age, gender, colon cancer stage, grade and histological subtype, body mass index, hemoglobin A1c, and smoking history.

Results: A total of 28 patients (31%) developed recurrence and had a mean follow-up time of 19.8 months (range: 2–54.4 months). Median RFS was 54.4 months with a 5-year RFS of 49%. Advanced colonic cancer stage and mucinous histological subtype were associated with shorter RFS with an HR of 2.37, 95% CI = 1.38–4.06, and 95% CI = 1.02–5.90, respectively. Current smokers or those who quit less than 15 years earlier tended to have worse RFS with an HR of 2.47, 95% CI = 0.98–6.27.

Conclusion: Advanced colon cancer stage and mucinous histological subtype are independent risk factors for cancer recurrence and shorter RFS in completely resected colonic tumor.

Molecular Landscape and Treatment Options for Patients with Metastatic Colorectal Cancer

Over the last 20 years, median survival for patients with metastatic colorectal cancer (CRC) has remarkably improved from about 12 to over 30 months, mainly because of the development of new agents and patient selection using predictive biomarkers. However, the identification of the most effective treatment for an individual patient is still a challenge. Molecular profiling of CRC has made great progress, but it is limited by tumor heterogeneity and absence of driver mutation. However, RAS, BRAF, and microsatellite instability are validated biomarker recommended by NCCN and ESMO. In this review, we discuss recent advances and future developments.

Systematic immunohistochemical screening for mismatch repair and ERCC1 gene expression from colorectal cancers in China: Clinicopathological characteristics and effects on survival

BACKGROUND

We performed a systematic screening of colorectal cancer (CRC) tissues to investigate whether mismatch repair (MMR) status and ERCC1 protein expression could be predictive of clinical outcomes for these patients following the recommendation of The Evaluation of Genomic Applications in Practice of Prevention (EGAPP).

METHODS

The expression of four MMR genes and ERCC1 were assessed by immunohistochemistry (IHC) from cancer tissue samples of 2233 consecutive CRC patients.

RESULTS

We observed that most CRC patients with a proficient MMR (pMMR) status tended to have simultaneous ERCC1 protein expression (P< 0.001). Stage III CRC patients with deficient MMR (dMMR) had higher prognoses than the same stage patients with pMMR (DFS: 74% vs 65%, P = 0.04; OS: 79% vs 69%, P = 0.04). Here, dMMR is also associated with poorer survival for stage II patients after chemotherapy (DFS: 66% vs 78%, P = 0.04). Stage II and III patients that were shown to express ERCC1 protein had higher DFS and OS than those that were deficient in expression (stage II, DFS: 83% vs 70%, P = 0.006; OS 85% vs 73%, P = 0.02. Stage III, DFS: 67% vs56%, P = 0.03; OS: 71% vs 57%, P = 0.04).

CONCLUSIONS

Our results indicate that dMMR appeared to predictive of a survival benefit for stage III CRC patients. We also found the determination of ERCC1 expression to be useful for predicting DFS or OS for stage II and III CRC patients. In addition, the expression of MMR genes and ERCC1 showed a significant relationship.

Epigenetic silencing of MLH1 in endometrial cancers is associated with larger tumor volume, increased rate of lymph node positivity and reduced recurrence-free survival

OBJECTIVES

To determine the relationship between mismatch repair (MMR) classification and clinicopathologic features including tumor volume, and explore outcomes by MMR class in a contemporary cohort.

METHODS

Single institution cohort evaluating MMR classification for endometrial cancers (EC). MMR immunohistochemistry (IHC)±microsatellite instability (MSI) testing and reflex MLH1 methylation testing was performed. Tumors with MMR abnormalities by IHC or MSI and MLH1 methylation were classified as epigenetic MMR deficiency while those without MLH1 methylation were classified as probable MMR mutations. Clinicopathologic characteristics were analyzed.

RESULTS

466 endometrial cancers were classified; 75% as MMR proficient, 20% epigenetic MMR defects, and 5% as probable MMR mutations. Epigenetic MMR defects were associated with advanced stage, higher grade, presence of lymphovascular space invasion, and older age. MMR class was significantly associated with tumor volume, an association not previously reported. The epigenetic MMR defect tumors median volume was 10,220mm³ compared to 3321mm³ and 2,846mm³, for MMR proficient and probable MMR mutations respectively (P<0.0001). Higher tumor volume was associated with lymph node involvement. Endometrioid EC cases with epigenetic MMR defects had significantly reduced recurrence-free survival (RFS). Among advanced stage (III/IV) endometrioid EC the epigenetic MMR defect group was more likely to recur compared to the MMR proficient group (47.7% vs 3.4%) despite receiving similar adjuvant therapy. In contrast, there was no difference in the number of early stage recurrences for the different MMR classes.

CONCLUSIONS

MMR testing that includes MLH1 methylation analysis defines a subset of tumors that have worse prognostic features and reduced RFS.

Current and future biomarkers in the treatment of colorectal cancer

Colorectal cancer (CRC) is a leading cause of cancer deaths worldwide. CRC develops as a consequence of genomic instability, characterized by various genetic and epigenetic alterations. Its molecular heterogeneity explains the large variability in patient prognosis and treatment response, emphasizing the need for development of accurate prognostic and predictive biomarkers. This article delineates the different pathways of colorectal carcinogenesis and its molecular subtype classification. With this review, we aim to provide a comprehensive overview of the current and future biomarkers guiding clinical decision-making and CRC treatment.

Prognostic Value of E-cadherin-, CD44-, and MSH2-associated Nomograms in Patients With Stage II and III Colorectal Cancer

BACKGROUND

To evaluate the prognostic value of E-cadherin, CD44, and MSH2 expression for colorectal cancer (CRC) and construct nomograms that can predict prognosis.

METHODS

We retrospectively analyzed the expression of E-cadherin, CD44, and MSH2 in 223 paraffin-embedded stage II and III CRC specimens using immunohistochemistry in the training cohort. Their prognostic values were assessed using Kaplan-Meier curves and univariate and multivariate COX regression models. Moreover, a number of risk factors were used to form nomograms to evaluate survival, and Harrell's concordance index (C-index) was used to evaluate the predictive accuracy. Further validation of the nomograms was performed in an independent cohort of 115 cases.

RESULTS

Low E-cadherin expression and low CD44 expression were significantly associated with diminished overall survival (OS) and disease-free survival (DFS) in stage II and III CRC patients and patients with negative MSH2 expression had better clinical outcomes. Moreover, the multivariate COX analysis identified E-cadherin, CD44 and MSH2 expression as independent prognostic factors for DFS and OS. Using these three markers and three clinicopathological risk variables, two nomograms were constructed and externally validated for predicting OS and DFS (C-index: training cohort, 0.779 (95% CI 0.722-0.835) and 0.771 (0.720-0.822), respectively; validation cohort, 0.773 (0.709-0.837) and 0.670 (0.594-0.747), respectively).

CONCLUSION

The expression levels of E-cadherin, CD44 and MSH2 were independent prognostic factors for stage II and III CRC patients. By incorporating clinicopathological features and these biomarkers, we have established two nomograms that could be used to make individualized predictions for OS and DFS.

Rapid Disease Progression of Liver Metastases following Resection in a Liver-Transplanted Patient with Probable Lynch Syndrome – A Case Report and Review of the Literature

Solid organ transplantation provides life-saving therapy for patients with end-stage organ disease, and its outcomes have been improving dramatically over the past few decades. However, substantial morbidity results from chronic immunosuppressive therapy administered to prevent graft rejection. It predisposes patients to several life-threatening complications, such as opportunistic microbial infections and the development of different types of cancers. Here, we presented the case of a young man with probable Lynch syndrome, who developed an aggressive colon carcinoma after long-term immunosuppressive therapy due to a prior liver transplantation. Based on this case report, we attempt to find an answer to the question about the risk of cancer development or recurrence in patients with familial syndromes receiving long-term immunosuppressive therapy and to find out how it can be minimized. Answering these questions is particularly important, given the facts that disease course is substantially more aggressive among transplanted patients and that prognosis is poor due to lack of immunocompetence, especially in the setting of Lynch syndrome.

Molecular genetics of microsatellite-unstable colorectal cancer for pathologists

Background

Microsatellite-unstable colorectal cancers (CRC) that are due to deficient DNA mismatch repair (dMMR) represent approximately 15% of all CRCs in the United States. These microsatellite-unstable CRCs represent a heterogenous group of diseases with distinct oncogenesis pathways. There are overlapping clinicopathologic features between some of these groups, but many important differences are present. Therefore, determination of the etiology for the dMMR is vital for proper patient management and follow-up.

Main body

Epigenetic inactivation of MLH1 MMR gene (sporadic microsatellite-unstable CRC) and germline mutation in an MMR gene (Lynch syndrome, LS) are the two most common mechanisms in the pathogenesis of microsatellite instability in CRC. However, in a subset of dMMR CRC cases that are identified by screening tests, no known LS-associated genetic alterations are appreciated by current genetic analysis. When the etiology for dMMR is unclear, it leads to patient anxiety and creates challenges for clinical management.

Conclusion

It is critical to distinguish LS patients from other patients with tumors due to dMMR, so that the proper screening protocol can be employed for the patients and their families, with the goal to save lives while avoiding unnecessary anxiety and costs. This review summarizes the major pathogenesis pathways of dMMR CRCs, their clinicopathologic features, and practical screening suggestions. In addition, we include frequently asked questions for MMR immunohistochemistry interpretation.

Prediction of biological behavior and prognosis of colorectal cancer patients by tumor MSI/MMR in the Chinese population

Colorectal cancers (CRCs) exhibiting microsatellite instability (MSI) have special biological behavior. The clinical predictors for MSI and its survival relevance for the Chinese population were still unclear. Seven hundred ninety-five CRC patients were retrospectively assessed. Mismatch repair (MMR) proteins (MSH2, MSH6, PMS1, and MLH1) expression was detected by immunohistochemistry using tumor tissues of all patients. DNA MSI status was analyzed by polymerase chain reaction in 182 samples randomly selected from the 795 cases. Among all CRC tumor tissues, 97 cases (12.2%) were with an MMR protein-deficient (MMR-D) phenotype, whereas 698 cases (87.8%) were with an MMR proteins intact (MMR-I) phenotype. A total of 21 (11.5%) CRCs were identified as having high microsatellite instability, 156 (85.7%) tumors were having microsatellite stability (MSS), and five (2.7%) were having low microsatellite instability. Importantly, MMR status was demonstrated to be moderately consistent with MSI status (κ=0.845, 95% confidence interval [CI] 0.721, 0.969). Unconditional logistic regression analysis revealed age, number of lymph node, tumor diameter, and tumor site as predictors for MSI with a substantial ability to discriminate different MSI status by area under curve of 80.62% using receiver operation curve. Compared with MMR-I, MMR-D was an independent prognostic factor for longer overall survival (hazard ratio =0.340, 95% CI 0.126, 0.919; P=0.034). MMR-D is an independent prognostic factor for better outcome. Our results may provide evidence for individualized diagnosis and treatment of CRC, but this will require further validation in larger sample studies.

Associations of defect mismatch repair genes with prognosis and heredity in sporadic colorectal cancer

BACKGROUND

Microsatellite instability arises due to defect mismatch repair (MMR) and occurs in 10-20% of sporadic colorectal cancer. The purpose was to investigate correlations between defect MMR, prognosis and heredity for colorectal cancer in first-degree relatives.

MATERIAL AND METHODS

Tumour tissues from 318 patients consecutively operated for colorectal cancer were analysed for immunohistochemical expression of MLH1, MSH2 and MSH6 on tissue microarrays. Information on KRAS and BRAF mutation status was available for selected cases.

RESULTS

Forty-seven (15%) tumours displayed MSI. No correlation was seen between patients exhibiting MSI in the tumour and heredity (p = 0.789). Patients with proximal colon cancer and MSI had an improved cancer-specific survival (p = 0.006) and prolonged time to recurrence (p = 0.037). In a multivariate analysis including MSI status, gender, CEA, vascular and neural invasion, patients with MSS and proximal colon cancer had an impaired cancer-specific survival compared with patients with MSI (HR, 4.32; CI, 1.46-12.78). The same prognostic information was also seen in distal colon cancer; no recurrences seen in the eight patients with stages II and III distal colon cancer and MSI, but the difference was not statistically significant.

CONCLUSION

No correlation between MSI and heredity for colorectal cancer in first-degree relatives was seen. Patients with MSI tumours had improved survival.

The evolving role of microsatellite instability in colorectal cancer: A review

Microsatellite instability (MSI) is a molecular marker of a deficient mismatch repair (MMR) system and occurs in approximately 15% of colorectal cancers (CRCs), more frequently in early than late-stage of disease. While in sporadic cases (about two-thirds of MSI-H CRCs) MMR deficiency is caused by an epigenetic inactivation of MLH1 gene, the remainder are associated with Lynch syndrome, that is linked to a germ-line mutation of one of the MMR genes (MLH1, MSH2, MSH6, PMS2). MSI-H colorectal cancers have distinct clinical and pathological features such as proximal location, early-stage (predominantly stage II), poor differentiation, mucinous histology and association with BRAF mutations. In early-stage CRC, MSI can select a group of tumors with a better prognosis, while in metastatic disease it seems to confer a negative prognosis. Although with conflicting results, a large amount of preclinical and clinical evidence suggests a possible resistance to 5-FU in these tumors. The higher mutational load in MSI-H CRC can elicit an endogenous immune anti-tumor response, counterbalanced by the expression of immune inhibitory signals, such as PD-1 or PD-L1, that resist tumor elimination. Based on these considerations, MSI-H CRCs seem to be particularly responsive to immunotherapy, such as anti-PD-1, opening a new era in the treatment landscape for patients with metastatic CRC.

Mismatch repair gene defects in sporadic colorectal cancer enhance immune surveillance

Background

There is evidence that colorectal cancers (CRC) with DNA mismatch repair deficiency (MMR-D) are associated with a better prognosis than the generality of large bowel malignancies. Since an active immune surveillance process has been demonstrated to influence CRC outcome, we investigated whether MMR-D can enhance the immune response in CRC.

Patients and Methods

A group of 113 consecutive patients operated for CRC (42 stage I or II and 71 with stage III or IV) was retrospectively analyzed. The expression of MMR genes (MSH2, MLH1, MSH6 and PSM2) and co-stimulatory molecule CD80 was assessed by tissue microarray immunohistochemistry. In addition, tumor infiltrating mononuclear cells (TIMC) and T cell subpopulations (CD4, CD8, T-bet and FoxP-3) were quantified. The effect of specific siRNA (siMSH2, siMLH1, siMSH6 and siPSM2) transfection in HT29 on CD80 expression was quantified by flow cytometry. Non parametric statistics and survival analysis were used.

Results

Patients with MMR-D showed a higher T-bet/CD4 ratio (p = 0.02), a higher rate of CD80 expression and CD8 lymphocyte infiltration compared to those with no MMR-D. Moreover, in the MMR-D group, the Treg marker FoxP-3 was not expressed (p = 0.05). MMR-D patients with stage I or II and T-bet expression had a significant better survival (p = 0.009). Silencing of MSH2, MLH1 and MSH6, but not PSM2, significantly increased the rate of CD80+ HT29 cells (p = 0.007, p = 0.023 and p = 0.015, respectively).

Conclusions

CRC with MMR-D showed a higher CD80 expression, and CD8+ and Th1 T-cell infiltration. In vitro silencing of MSH2, MLH1 and MSH6 significantly increased CD80+ cell rate. These results suggest an enhanced immune surveillance mechanism in presence of MMR-D.

Microsatellite instability testing and its role in the management of colorectal cancer

Opinion statement: TNM stage remains the key determinant of patient prognosis after surgical resection of colorectal cancer (CRC), and informs treatment decisions. However, there is considerable stage-independent variability in clinical outcome that is likely due to molecular heterogeneity. This variability underscores the need for robust prognostic and predictive biomarkers to guide therapeutic decision-making including the use of adjuvant chemotherapy. Although the majority of CRCs develop via a chromosomal instability pathway, approximately 12-15 % have deficient DNA mismatch repair (dMMR) which is characterized in the tumor by microsatellite instability (MSI). Tumors with the dMMR/MSI develop from a germline mutation in an MMR gene (MLH1, MSH2, MSH6, PMS2), i.e., Lynch syndrome, or more commonly from epigenetic inactivation of MLH1 MMR gene. CRCs with dMMR/MSI status have a distinct phenotype that includes predilection for the proximal colon, poor differentiation, and abundant tumor-infiltrating lymphocytes. Consistent data indicate that these tumors have a better stage-adjusted survival compared to proficient MMR or microsatellite stable (MSS) tumors and may respond differently to 5-fluorouracil-based adjuvant chemotherapy. To increase the identification of dMMR/MSI patients in clinical practice that includes those with Lynch syndrome, it is recommended that all resected CRCs to be analyzed for MMR status. Available data indicate that patients with stage II dMMR CRCs have an excellent prognosis and do not benefit from 5-fluorouracil (FU)-based adjuvant chemotherapy which supports their recommended management by surgery alone. In contrast, the benefit of standard adjuvant chemotherapy with the FOLFOX regiment in stage III dMMR CRC patients awaits further study and therefore, all patients should be treated with standard adjuvant FOLFOX.

Implications of mismatch repair-deficient status on management of early stage colorectal cancer

For primary colorectal cancers (CRCs), tumor stage has been the best predictor of survival after resection and the key determinant of patient management. However, considerable stage-independent variability in clinical outcome is observed that is likely due to molecular heterogeneity. This is particularly important in early stage CRCs where patients can be cured by surgery alone and only a proportion derives benefit from adjuvant chemotherapy. Thus, the identification of molecular prognostic markers to supplement conventional pathologic staging systems has the potential to guide patient management and influence outcomes. CRC is a heterogeneous disease with molecular phenotypes reflecting distinct forms of genetic instability. The chromosomal instability pathway (CIN) is the most common phenotype, accounting for 85% of all sporadic CRCs. Alternatively, the microsatellite instability (MSI) phenotype represents ~15% of all CRCs and is caused by deficient DNA mismatch repair (MMR) as a consequence of germline mutations in MMR genes or, more commonly, epigenetic silencing of the MLH1 gene with frequent mutations in the BRAF oncogene. MSI tumors have distinct phenotypic features and are consistently associated with a better stage-adjusted prognosis compared with microsatellite stable (MSS) tumors. Among non-metastatic CRCs, the difference in prognosis between MSI and MSS tumors is larger for stage II than stage III patients. On the other hand, the predictive impact of MMR status for adjuvant chemotherapy remains a contentious issue in that most studies demonstrate a lack of benefit for 5-fluorouracil (5-FU)-based adjuvant chemotherapy in stage II MSI-H CRCs, whereas it remains unclear in MSI-H stage III tumors. Here, we describe the molecular aspects of the MMR system and discuss the implications of MMR-deficient/MSI-H status in the clinical management of patients with early stage CRC.

Systemic neutrophil-to-lymphocyte ratio in colorectal cancer: the relationship to patient survival, tumour biology and local lymphocytic response to tumour

Background:

Colorectal cancer (CRC) is a major cause of mortality and morbidity. The impact of inflammatory biomarkers (C-reactive protein etc.) on CRC is increasingly studied including systemic neutrophil-to-lymphocyte ratio (NLR) as they seem to predict outcome.

Methods:

All patients who underwent curative resection for CRC from 2000 to 2004 at Leeds Teaching Hospitals NHS Trust had pre-operative NLR calculated. Demographic, histopathological and survival data were collected. Tissue microarrays were created and stained to determine the mismatch repair (MMR) protein status of each tumour. Local lymphocytic response to the tumour was assessed and graded.

Results:

About 358 patients were eligible. Of these 88 had an NLR ⩾5, which predicted lower overall survival and greater disease recurrence. A high NLR is associated with higher pT- and pN-stage and a greater incidence of extramural venous invasion. MMR protein status was not associated with NLR. A pronounced lymphocytic reaction at the invasive margin (IM) indicated a better prognosis and was associated with a lower NLR.

Conclusion:

Neutrophil-to-lymphocyte ratio predicts disease-free and overall survival and is associated with a more aggressive tumour phenotype. The lymphocytic response to tumour at the IM is associated with NLR however dMMR is not. Neutrophil-to-lymphocyte ratio is a cheap, easy-to-access test that predicts outcome in CRC.

A microRNA molecular modeling extension for prediction of colorectal cancer treatment

Background

Several studies show that the regulatory impact of microRNAs (miRNAs) is an essential contribution to the pathogenesis of colorectal cancer (CRC). The expression levels of diverse miRNAs are associated with specific clinical diagnoses and prognoses of CRC. However, this association reveals very little actionable information with regard to how or whether to treat a CRC patient. To address this problem, we use miRNA expression data along with other molecular information to predict individual response of CRC cell lines and CRC patients.

Methods

A strategy has been developed to join four types of information: molecular, kinetic, genetic and treatment data for prediction of individual treatment response of CRC.

Results

Information on miRNA regulation, including miRNA target regulation and transcriptional regulation of miRNA, in integrated into an in silico molecular model for colon cancer. This molecular model is applied to study responses of seven CRC cell lines from NCI-60 to ten agents targeting signaling pathways. Predictive results of models without and with implemented miRNA information are compared and advantages are shown for the extended model. Finally, the extended model was applied to the data of 22 CRC patients to predict response to treatments of sirolimus and LY294002. The in silico results can also replicate the oncogenic and tumor suppression roles of miRNA on the therapeutic response as reported in the literature.

Conclusions

In summary, the results reveal that detailed molecular events can be combined with individual genetic data, including gene/miRNA expression data, to enhance in silico prediction of therapeutic response of individual CRC tumors. The study demonstrates that miRNA information can be applied as actionable information regarding individual therapeutic response.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-1437-0) contains supplementary material, which is available to authorized users.

Lack of Association between Membrane-Type 1 Matrix Metalloproteinase Expression and Clinically Relevant Molecular or Morphologic Tumor Characteristics at the Leading Edge of Invasive Colorectal Carcinoma

Colorectal cancer (CRC) is one of the leading causes of death from cancer in the western world, but tumor biology and clinical course show great interindividual variation. Molecular and morphologic tumor characteristics, such as KRAS/BRAF mutation status, mismatch repair (MMR) protein expression, tumor growth pattern, and tumor cell budding, have been shown to be of key therapeutic and/or prognostic relevance in CRC. Membrane-type 1 matrix metalloproteinase (MT1-MMP) is a membrane-anchored zinc-binding endopeptidase that is expressed at the leading edge of various invasive carcinomas and promotes tumor cell invasion through degradation of the extracellular matrix. The aim of this study was to investigate possible associations between MT1-MMP expression and molecular tumor characteristics as well as morphologic features of tumor aggressiveness in a consecutive series of 79 CRC tissue samples. However, although MT1-MMP was expressed in 41/79 samples (52%), there was no significant association between MT1-MMP expression and KRAS/BRAF mutation status, MMR protein expression, presence of lymphovascular invasion, tumor growth pattern, tumor-infiltrating lymphocytes, or tumor cell budding in our sample cohort (P > 0.05). Thus, we conclude that although MT1-MMP may play a role in CRC invasion, it is not of key relevance to the current models of CRC invasion and aggressiveness.

Systematic review of the predictive effect of MSI status in colorectal cancer patients undergoing 5FU-based chemotherapy

BACKGROUND

We systematically reviewed the evidence for the interaction of microsatellite instability status (MSI) and treatment with 5FU in colorectal cancer to determine how well MSI status predicts health outcomes in patients undergoing 5FU-based chemotherapy.

METHODS

We conducted a search of four electronic databases through June 2013. We considered studies that included both colorectal cancer patients treated with 5FU-based chemotherapy and untreated patients with survival outcomes presented by MSI status.

RESULTS

We identified 16 studies for qualitative analysis (9,212 patients) with 14 studies eligible for meta-analysis. The microsatellite stable (MSS) group showed an effect of 5FU treatment on disease-free survival (HR of 0.62 [95% CI: 0.54, 0.71]) and overall survival (HR of 0.65 [95% CI: 0.54, 0.79]), indicating that MSS patients who received 5FU treatment had longer survival than MSS patients who were untreated. The effect of 5FU treatment was not statistically significant for microsatellite high (MSI-H) patients for disease-free survival (HR of 0.84 [95% CI: 0.53, 1.32]) or overall survival (HR 0.66 [95% CI: 0.43, 1.03]). However, the summarized point estimates of the effects of 5FU treatment for the MSS and MSI-H groups were not different at a statistically significant level.

CONCLUSIONS

Our analyses indicate that treatment with 5FU-based chemotherapy improves disease-free and overall survival in CRC patients, but that there is no difference in the effect of treatment based on MSI status. Therefore, the use of MSI status to guide treatment decisions about the use of 5FU treatment for CRC has no significant benefits for patients.

Microsatellite instability and mutations in BRAF and KRAS are significant predictors of disseminated disease in colon cancer

BACKGROUND

Molecular alterations are well studied in colon cancer, however there is still need for an improved understanding of their prognostic impact. This study aims to characterize colon cancer with regard to KRAS, BRAF, and PIK3CA mutations, microsatellite instability (MSI), and average DNA copy number, in connection with tumour dissemination and recurrence in patients with colon cancer.

METHODS

Disease stage II-IV colon cancer patients (n = 121) were selected. KRAS, BRAF, and PIK3CA mutation status was assessed by pyrosequencing and MSI was determined by analysis of mononucleotide repeat markers. Genome-wide average DNA copy number and allelic imbalance was evaluated by SNP array analysis.

RESULTS

Patients with mutated KRAS were more likely to experience disease dissemination (OR 2.75; 95% CI 1.28-6.04), whereas the opposite was observed for patients with BRAF mutation (OR 0.34; 95% 0.14-0.81) or MSI (OR 0.24; 95% 0.09-0.64). Also in the subset of patients with stage II-III disease, both MSI (OR 0.29; 95% 0.10-0.86) and BRAF mutation (OR 0.32; 95% 0.16-0.91) were related to lower risk of distant recurrence. However, average DNA copy number and PIK3CA mutations were not associated with disease dissemination.

CONCLUSIONS

The present study revealed that tumour dissemination is less likely to occur in colon cancer patients with MSI and BRAF mutation, whereas the presence of a KRAS mutation increases the likelihood of disseminated disease.

Microsatellite instability in gallbladder carcinoma

The genetic abnormalities involved in the pathogenesis of gallbladder carcinoma (GBC) remain unclear. Microsatellite instability (MSI) has been described in many carcinomas, but little is known about the significance of mismatch repair in gallbladder carcinogenesis. Additionally, methylation status of long interspersed element-1 (LINE-1), a surrogate marker of global DNA methylation, has defined distinct subsets of other cancer types but has not been explored in GBC. Immunohistochemical expression of MSH2, MSH6, MLH1, and PMS2 and LINE-1 mRNA in situ hybridization was evaluated in 67 primary and 15 metastatic GBCs from 77 patients. Amplification of human epidermal growth factor receptor 2 (HER2) was evaluated by fluorescence in situ hybridization. Genotyping for 24 genes involved in carcinogenesis was performed using a multiplex PCR-based platform. MSI was present in 6 of 77 GBCs (7.8 %). Loss of MSH2/MSH6 was detected in five cases and loss of MLH1/PMS2 in one case. MSI status was not associated with Lynch syndrome, tumor grade, extracellular mucin, or tumor-infiltrating lymphocytes. There was no significant difference in mean overall survival of patients with and without MSI. Strong LINE-1 staining was identified in none of the GBC with MSI and in 36 of 69 (52 %) of those without MSI (p = 0.005), suggesting that LINE-1 in the former cohort was hypermethylated. All MSI tumors were negative for HER2 amplification, and TP53 and NRAS mutations were only found in GBC without MSI. MSI was identified in a minority of GBC cases. The strong correlation between global DNA methylation as measured by LINE-1 and loss of mismatch repair proteins suggests that methylation may account for the loss of these proteins. These hypermethylated tumors appear to represent a genetically unique cohort of gallbladder neoplasms, and the data suggests that demethylating agents may have a therapeutic value in this class of tumors.

Carcinoma microsatellite instability status as a predictor of benefit from fluorouracil-based adjuvant chemotherapy for stage II rectal cancer

PURPOSE

Rectal cancers with high microsatellite-instable have clinical and pathological features that differentiate them from microsatellite-stable or low- frequency carcinomas, which was studied rarely in stage II rectal cancer, promoting the present investigation of the usefulness of microsatellite-instability status as a predictor of the benefit of adjuvant chemotherapy with fluorouracil in stage II rectal cancer.

PATIENTS AND METHODS

Data of 460 patients who underwent primary anterior resection with a double stapling technique for rectal carcinoma at a single institution from 2008 to 2012 were retrospectively collected. All patients experienced a total mesorectal excision (TME) operation. Survival analysis were analyzed using the Cox regression method.

RESULTS

Five-year rate of disease-free survival (DFS) was noted in 390 (84.8%) of 460 patients with stage II rectal cancer. Of 460 tissue specimens, 97 (21.1%) exhibited high-frequency microsatellite instability. Median age of the patients was 65 (50-71) and 185 (40.2%) were male. After univariate and multivariate analysis, microsatellite instability (p= 0.001), female sex (p< 0.05) and fluorouracil-based adjuvant chemotherapy (p< 0.001), the 3 factors were attributed to a favorable survival status independently. Among 201 patients who did not receive adjuvant chemotherapy, those cancers displaying high-frequency microsatellite instability had a better 5-year rate of DFS than tumors exhibiting microsatellite stability or low-frequency instability (HR, 13.61 [95% CI, 1.88 to 99.28]; p= 0.010), while in 259 patients who received adjuvant chemotherapy, there was no DFS difference between the two groups (p= 0.145). Furthermore, patients exhibiting microsatellite stability or low-frequency instability who received adjuvant chemotherapy had a better 5-year rate of DFS than patients did not (HR, 5.16 [95% CI, 2.90 to 9.18]; p< 0.001), while patients exhibiting high-frequency microsatellite instability were not connected with increased DFS (p= 0.696). It was implied that female patients had better survival than male.

CONCLUSION

Survival status after anterior resection of rectal carcinoma is related to the microsatellite instability status, adjuvant chemotherapy and gender. Fluorouracil-based adjuvant chemotherapy benefits patients of stage II rectal cancer with microsatellite-stable or low microsatellite-instable, but not those with high microsatellite- instable. Additionally, free of adjuvant chemotherapy, carcinomas with high microsatellite-instable have a better 5-year rate of DFS than those with microsatellite-stable or low microsatellite-instable, and female patients have a better survival as well.

Colorectal cancer in Chinese patients: current and emerging treatment options

Colorectal cancer is the second most common cancer in Hong Kong and its incidence is rising in economically developed Chinese cities, including Hong Kong and Shanghai. Several studies conducted in the People's Republic of China have characterized the unique molecular epidemiology of familial colorectal cancer syndromes and molecular biomarkers such as microsatellite instability and genetic mutations (eg, KRAS, NRAS, BRAF, PIK3CA, ERCC1) in Chinese populations. Interethnic differences in anticancer drug response and toxicity have been well described in many cancers, and this review examined the literature with regard to the tolerance of Chinese patients to commonly used chemotherapeutic regimens and targeted therapies for metastatic colorectal cancer. Studies on the pharmacogenomic differences in drug metabolizing and DNA repair enzymes between Chinese, North Asians, and Caucasian patients were also reviewed.

Colorectal cancer in Chinese patients: current and emerging treatment options

Colorectal cancer is the second most common cancer in Hong Kong and its incidence is rising in economically developed Chinese cities, including Hong Kong and Shanghai. Several studies conducted in the People's Republic of China have characterized the unique molecular epidemiology of familial colorectal cancer syndromes and molecular biomarkers such as microsatellite instability and genetic mutations (eg, KRAS, NRAS, BRAF, PIK3CA, ERCC1) in Chinese populations. Interethnic differences in anticancer drug response and toxicity have been well described in many cancers, and this review examined the literature with regard to the tolerance of Chinese patients to commonly used chemotherapeutic regimens and targeted therapies for metastatic colorectal cancer. Studies on the pharmacogenomic differences in drug metabolizing and DNA repair enzymes between Chinese, North Asians, and Caucasian patients were also reviewed.

Should mismatch repair status be determined in all stage II and III colon cancer patients?

SUMMARY 

Microsatellite instability constitutes an important oncogenic molecular pathway in colon cancer (12–15%). Microsatellite instability is a molecular marker of deficient DNA mismatch repair (MMR), which occurs from somatic hypermethylation of the MLH1 promoter or less frequently as a result of germline mutations in MMR genes. The excellent prognosis of patients with stage II deficient MMR colon cancer today, makes this information mandatory in order to decide or not on adjuvant chemotherapy. MMR deficiency may also predict tumor chemoresistance to 5-fluorouracil adjuvant treatment. However, when looking at very recent data on 5-fluorouracil plus oxaliplatin-based adjuvant regimens, it seems that the benefit of this adjuvant therapy is similar between deficient and proficient MMR patients.

Biomarker-based treatment selection in early-stage rectal cancer to promote organ preservation

Background

Total mesorectal excision (TME) remains commonplace for T1–2 rectal cancer owing to fear of undertreating a small proportion of patients with node-positive disease. Molecular stratification may predict cancer progression. It could be used to select patients for organ-preserving surgery if specific biomarkers were validated.

Methods

Gene methylation was quantified using bisulphite pyrosequencing in 133 unirradiated rectal cancer TME specimens. KRAS mutation and microsatellite instability status were also defined. Molecular parameters were correlated with histopathological indices of disease progression. Predictive models for nodal metastasis, lymphovascular invasion (LVI) and distant metastasis were constructed using a multilevel reverse logistic regression model.

Results

Methylation of the retinoic acid receptor β gene, RARB, and that of the checkpoint with forkhead and ring finger gene, CHFR, was associated with tumour stage (RARB: 51·9 per cent for T1–2 versus 33·9 per cent for T3–4, P < 0·001; CHFR: 5·5 per cent for T1–2 versus 12·6 per cent for T3–4, P = 0·005). Gene methylation associated with nodal metastasis included RARB (47·1 per cent for N− versus 31·7 per cent for N+; P = 0·008), chemokine ligand 12, CXCL12 (12·3 per cent for N− versus 8·9 per cent for N+; P = 0·021), and death-associated protein kinase 1, DAPK1 (19·3 per cent for N− versus 12·3 per cent for N+; P = 0·022). RARB methylation was also associated with LVI (45·1 per cent for LVI− versus 31·7 per cent for LVI+; P = 0·038). Predictive models for nodal metastasis and LVI achieved sensitivities of 91·1 and 85·0 per cent, and specificities of 55·3 and 45·3 per cent, respectively.

Conclusion

This methylation biomarker panel provides a step towards accurate discrimination of indolent and aggressive rectal cancer subtypes. This could offer an improvement over the current standard of care, whereby fit patients are offered radical surgery. May assist selection for organ preservation

Prognostic Impact of Deficient DNA Mismatch Repair and Mutations in KRAS, and BRAFV600E in Patients with Lymph Node-Positive Colon Cancer

While tumor stage remains the key determinant of colorectal cancer (CRC) prognosis and treatment, there is considerable stage-independent variability in clinical outcome. Molecular markers hold promise for explaining variations in clinical behavior, and may identify patient subsets with differential efficacy and survival after adjuvant chemotherapy which is standard of care for patients with lymph node-positive, i.e., stage III, colon cancer. An increased understanding of the molecular evolution and progression of CRC has identified two major pathways of tumorigenesis that are characterized by chromosomal instability or microsatellite instability (MSI). MSI is a consequence of deficient DNA mismatch repair (MMR) that is generally due to epigenetic inactivation of MLH1 in tumors that often carry mutations in oncogenic BRAF^V600E . Activating BRAF^V600E and KRAS mutations are mutually exclusive and in this article, we review the current status of these mutations and MMR status as prognostic biomarkers in stage III colon cancers.

Prognostic and predictive significance of MSI in stages II/III colon cancer

In colon cancer, classic disease staging remains the key prognosis and treatment determinant. Although adjuvant chemotherapy has an established role in stage III colon cancer patients, in stage II it is still a subject of controversy due to its restriction to a small subgroup of patients with high-risk histopathologic features. Patients with stage II tumors form a highly heterogeneous group, with five-year relative overall survival rates ranging from 87.5% (IIA) to 58.4% (IIC). Identifying those for whom adjuvant chemotherapy would be appropriate and necessary has been challenging, and prognostic markers which could serve in the selection of patients more likely to recur or benefit from adjuvant chemotherapy are eagerly needed. The stronger candidate in this category seems to be microsatellite instability (MSI). The recently reported European Society for Medical Oncology guidelines suggest that MSI should be evaluated in stage II colorectal cancer patients in order to contribute in treatment decision-making regarding chemotherapy administration. The hypothetical predictive role of MSI regarding its response to 5-fluorouracil-based adjuvant chemotherapy has proven a much more difficult issue to address. Almost every possible relation between MSI and chemotherapy outcome has been described in the adjuvant colon cancer setting in the international literature, and the matter is far from being settled. In this current report we critically evaluate the prognostic and predictive impact of MSI status in patients with stage II and stage III colon cancer patients.

Chemotherapy of MMR-deficient colorectal cancer

Colorectal cancer (CRC) continues to rank as the third most common cancer in Western society and the second leading cause of cancer death in North America. There are at least three distinct, and relatively discreet, molecular pathways associated with this disease: chromosomal instability (CIN), microsatellite instability (MSI) and the cytosine polyguanine island methylator phenotype. Defects in the DNA mismatch repair system (MMR) account for the MSI phenotype and genotype of about 15 % of CRC. Although high frequency MSI tumors have better stage independent prognosis compared to those with CIN, MMR deficient CRC appears to be resistant to fluorouracil based treatment, but sensitive to other therapeutic regimens. This review summarises current literature on differential chemosensitivity of MMR-deficient CRC.

Molecular markers of chemotherapeutic response and toxicity in colorectal cancer

Outcomes in colorectal cancer have improved over the last 15 years; this is in part due to the optimization of 5-fluorouracil schedules and the introduction of new and effective chemotherapeutic agents, such as irinotecan and oxaliplatin. However, not all patients respond to these agents and a proportion may suffer severe side effects from particular chemotherapy drugs. These observations have resulted in a concerted research effort to identify markers of chemotherapy efficacy and toxicity. Here we review the evidence for using molecular markers to individualize chemotherapy treatment in colorectal cancer.

Translating genetic risk factors for prostate cancer to the clinic: 2013 and beyond

Prostate cancer (PrCa) is the most commonly diagnosed cancer in the male UK population, with over 40,000 new cases per year. PrCa has a complex, polygenic predisposition, due to rare variants such as BRCA and common variants such as single nucleotide polymorphisms (SNPs). With the introduction of genome-wide association studies, 78 susceptibility loci (SNPs) associated with PrCa risk have been identified. Genetic profiling could risk-stratify a population, leading to the discovery of a higher proportion of clinically significant disease and a reduction in the morbidity related to age-based prostate-specific antigen screening. Based on the combined risk of the 78 SNPs identified so far, the top 1% of the risk distribution has a 4.7-times higher risk of developing PrCa compared with the average of the general population.

Promoter methylation and immunohistochemical expression of hMLH1 and hMSH2 in sporadic colorectal cancer: a study from India

To determine the etiological factors of human colorectal cancer (CRC) we assessed the frequency and prognostic significance of hMLH1 and hMSH2 genes in conjunction with hMLH1 and hMSH2 protein expression in 30 Indian CRC patients. The protein expression and promoter methylation of hMLH1 and hMSH2; Mismatch Repair genes (MMR) were analyzed by immunohistochemistry and methylation-specific PCR (MSP), respectively. A loss of hMLH1 expression was recognized in 4(13.3%) and loss of hMSH2 expression was recognized in 2(6.6%) of 30 CRC cases whereas 50% tumors showed reduced expression of hMLH1 and 33.3% showed reduced expression of hMSH2 protein. One tumor showed a loss of both hMLH1 and hMSH2 expression. Normal nuclear staining pattern of hMLH1 and hMSH2 was observed in almost all the adjoining and normal mucosa. Promoter hypermethylation of the hMLH1 gene was detected in 15 of 30 CRC cases (50%) and of hMSH2 gene was only in 3 of 30 CRC cases (10%). No promoter methylation of hMLH1 and hMSH2 genes was observed in adjoining and normal mucosa. Combination of methylation of hMLH1 and hMSH2 gene was observed in two tumors (6.6%). A significant correlation between histological grade of the tumor, methylation and expression of hMLH1 gene (p < 0.05) was observed. Normal expression of hMLH1 and hMSH2 was seen in all of the unmethylated tumors (100%). Nuclear staining and promoter methylation of hMLH1 and hMSH2 did not significantly influence survival. hMLH1 methylation was common and was significantly correlated with loss of hMLH1 protein expression. In contrast, hMSH2 methylation was infrequent. These findings suggest that the inactivation of MMR gene expression probably via hypermethylation may lead to inactivation of their functions which finally leads to tumor aggressiveness and the immunostaining of hMLH1 protein can be used as a prognostic factor for determining the grade of the tumor.

Preoperative serum CA 72.4 as prognostic factor of recurrence and death, especially at TNM stage II, for colorectal cancer

Background

Nowadays, evaluation of colorectal cancer prognosis and decision-making for treatment continues to be based primarily on TNM tumour stage. Administration of adjuvant chemotherapy is especially challenging for stage II patients that can have very different disease-related outcomes. Therefore, more reliable prognostic markers need to be developed to improve the selection of stage II patients at high risk for recurrence. Our purpose is to assess the prognostic value of preoperative serum CA 72.4 to improve the risk stratification of CRC patients.

Methods

Preoperative sera collected from 71 unselected patients between January 1994 and February 1997 was assayed for CA 72.4 and CEA levels. Patients were followed-up for at least 30 months or until relapse. Survival curves were estimated by the Kaplan-Meier method and the prognostic value was determined using Log-Rank test and Cox regression analysis.

Results

Preoperative CA 72.4 levels above 7 U/mL correlate with a worse prognosis, with associated recurrence and death percentages exceeding the displayed by CEA. In a multivariate analysis, its combination with CEA proved the most important independent factor predicting survival. Remarkably, at stage II CA 72.4 also discriminates better than CEA those patients that will relapse or die from those with a favourable prognosis; however, CEA has not a negligible effect on survival.

Conclusions

The most outstanding finding of the present work is the correct classification of nearly every patient with bad prognosis (relapse or death) at TNM stage II when CEA and CA 72.4 are used altogether. This could improve the decision-making involved in the treatment of stage II colon cancer. Certainly further large-scale studies must be performed to determine whether CA 72.4 can be effectively used in the clinical setting.

Poorly differentiated colorectal cancers: correlation of microsatellite instability with clinicopathologic features and survival

OBJECTIVES

To evaluate the association of microsatellite instability (MSI) with clinicopathologic features and oncologic outcomes in patients with poorly differentiated colorectal cancer (PD).

METHODS

Study patients were divided into well-differentiated colorectal cancer (WD) and PD, which were compared according to histologic differentiation and MSI status.

RESULTS

Among 1,941 patients, PD was more frequent among microsatellite-unstable tumors (23.6%) than among microsatellite-stable (MSS) tumors (4.2%, P < .001). Patients with PD had worse 4-year overall survival rates than patients with WD (78.6% vs 88.2%, P = 0.010). Compared with MSS-PD tumors, MSI-PD tumors were characterized by right-colon predilection, larger size, and infrequent lymph node metastasis (P < .001 to P = .007).

CONCLUSIONS

The clinicopathologic characteristics of PD were closely associated with those of MSI. The outcomes of MSI-PD tumors were better than those of MSS-PD tumors, but this finding did not reach statistical significance.

Reduced expression of mutS homolog 2 and mutL homolog 1 affects overall survival in laryngeal squamous cell carcinoma patients: Investigation into a potential cause

The risk factors affecting the survival rates of laryngeal carcinoma are not well understood. In this study, we investigated the expression status of mutS homolog 2 (MSH2) and mutL homolog 1 (MLH1) and examined the relationship between these two molecules and overall survival rates in laryngeal cancer. We also explored the potential reason for the altered expression of these two genes. Using real-time polymerase chain reaction and western blotting, we detected MSH2 and MLH1 expression in laryngeal cancer tissue samples. We collected a retrospective cohort with 180 laryngeal cancer patients, and inspected MSH2 and MLH1 staining with tissue microarray immunohistochemistry. Prognostic value of clinicopathological characteristics was evaluated by statistical analysis. Laryngeal carcinoma cells were co-cultured with Helicobacter pylori (H. pylori) bacteria. MSH2 and MLH1 were expressed at lower levels compared to those of adjacent tissues in 21 laryngeal carcinoma patients. Patients with negative expression of MSH2 and MLH1 tended to have a higher risk of mortality compared to patients with positive expression (HR=4.38; HR=3.0, respectively). Cigarette smoking rate was higher in the MLH1 expression positive group. H. pylori infection reduced the MSH2 and MLH1 expression levels of laryngeal carcinoma cell lines within co-culture conditions. It is suggested that the altered expression levels of MSH2 and MLH1 probably affect the overall survival of laryngeal carcinoma patients. H. pylori infection may have an effect on the expression of MSH2 and MLH1 in laryngeal carcinoma patients.

Gender-specific profiling in SCN1A polymorphisms and time-to-recurrence in patients with stage II/III colorectal cancer treated with adjuvant 5-fluoruracil chemotherapy

This study was designed to analyze the gender-related association between SCN1A polymorphisms (voltage-gated sodium channels; α-subunit) and time-to-recurrence (TTR) in patients with colorectal cancer (CRC) treated with 5-fluoruracil (5-FU)-based adjuvant chemotherapy. We enrolled from a prospective database patients with stage II and III CRC treated with adjuvant 5-FU-based chemotherapy. Genotypes for SCN1A rs3812718 and rs229877 were determined by direct DNA sequencing. One hundred twenty-seven males and 107 females were included in the study. In the univariate and multivariate analysis, the shortest TTR was associated with female patients carrying the rs3812718-TT genotype (hazard ratio (HR): 2.26 (95% confidence interval (CI): 0.89, 5.70), P=0.039) but with male patients carrying the rs3812718-CC genotype (HR: 0.49 (95% CI: 0.18, 1.38), P=0.048). For rs229877 the CT genotype was associated with a trend for shorter TTR in both gender populations. The study validated gender-dependent association between genomic SCN1A rs3812718 polymorphism and TTR in CRC patients treated with adjuvant 5-FU-based chemotherapy. This study confirms that voltage-gated Na+ channels may be a potential therapeutic target and a useful predictive biomarker before 5-FU infusion.

Molecular markers in colorectal cancer: clinical relevance in stage II colon cancer

SUMMARY Colorectal cancer is the second most common cause of cancer death in developed countries. Adjuvant chemotherapy is standard for stage III colorectal cancer but its use in stage II is controversial. Several clinicopathological factors have been described to define a high-risk group among stage II colon cancers, which can aid the selection of patients who may benefit from chemotherapy. Local tumor invasion (T4), high histological grade, obstruction and perforation at diagnosis, and number of lymph nodes removed are the most widely accepted factors. Several molecular factors have been also investigated as prognostic candidate biomarkers. DNA ploidy, KRAS and TP53 mutations, thymidylate synthase, dihydropyrimidine dehydrogenase, thymidine phosphorylase, loss of heterozygosity on chromosome 18q and microsatellite instability have been widely investigated. The aim of this review is to analyze the current evidence and clinical applications of the classical molecular biomarkers as well as new ones such as BRAF, circulating tumor cells, genome expression signatures and DNA methylation.

Microsatellite instability and TARBP2 mutation study in upper urinary tract urothelial carcinoma

Microsatellite instability (MSI) contributes to the tumorigenesis of upper urinary tract urothelial carcinomas (UUT-UCs). In this study, we first used MLH1 and MSH2 immunohistochemistry to identify patients with loss of expression of either or both of these proteins in 132 UUT-UCs. We found a total loss of MSH2 expression in 4 patients. MSI was evaluated using 5 markers in these 4 cases. All of the tumors had high MSI (MSI-H) status. Trans-activation responsive RNA-binding protein 2, an integral component of DICER1-containing complex, was a putative target of DNA mismatch repair deficiency. Truncating mutation has been identified in gastrointestinal cancers with MSI. No previous study has evaluated the mutation status of this gene in MSI UUT-UCs. In this study, we analyze the mutation of TARBP2 in MSI-H UUT-UCs with reverse transcription polymerase chain reaction. No truncating mutations were identified in the MSI-H UUT-UCs.

Microsatellite instability testing in Korean patients with colorectal cancer

Microsatellite instability (MSI) testing is useful for identifying patients with hereditary nonpolyposis colorectal cancer and detecting sporadic colorectal cancer that develops through replication error pathways. A pentaplex panel is recommended by the National Cancer Institute for MSI testing, but simplified mononucleotide panels and immunohistochemistry of mismatch repair proteins are widely employed for convenience. This study was to evaluate the MSI status of colorectal cancer in Korean patients. This study included 1,435 patients with colorectal adenocarcinoma subjected to surgical resection. The pentaplex Bethesda panel was used for MSI testing. Seventy nine (5.5 %) carcinomas were classified as MSI-high (MSI-H) and 95 (6.6 %) as MSI-low (MSI-L). BAT-26 and BAT-25 were unstable in 73 and 75 of 79 MSI-H carcinomas, respectively. With the panel comprising these 2 mononucleotide markers, 72 carcinomas were diagnosed as MSI-H, compared to the Bethesda panel data (72/79, 91.1 %). In contrast, BAT-26 or BAT-25 were unstable in only 7 (7.4 %) of the 95 MSI-L tumors. In the panel with 2 dinucleotide markers, D17250 linked to p53 and D2S123 to hMSH2, detection rates were 89.9 % (71/79) for MSI-H and 80.0 % (76/95) for MSI-L carcinomas, compared to the Bethesda panel. Moreover, we compared the frequency of MSI tumor in our patients with those reported previously from Western countries. In conclusion, the frequency of MSI-H appears lower in colorectal cancer patients in Korea. A simplified panel for MSI testing with BAT-26 and BAT-25 seems not effective for the accurate evaluation of MSI status, particularly in MSI-L colorectal carcinomas, in our patients.

Mismatch repair status and clinical outcome in endometrial cancer: a systematic review and meta-analysis

BACKGROUND

The association between the deficiency in mismatch repair (MMR) genes and prognosis in women with endometrial cancer is unclear. Here we report a systematic review and meta-analysis exploring this association.

METHODS

We searched literature databases (MEDLINE, EMBASE, and Cochrane) from 1980 until December 2011 to identify studies evaluating the association between MMR status and clinical outcome in endometrial cancer. The main outcome measures were overall survival (OS) and disease-free survival (DFS).

RESULTS

Twenty-three studies met the inclusion criteria. The median sample size of studies was 112, 74% were retrospective case-series and 70% performed microsatellite instability (MSI) analysis to evaluate the status of MMR. Only 22% of studies used the panel of five microsatellite markers recommended by the National Cancer Institute. Seven studies used immunohistochemistry to define MMR deficiency, but only two of them determined the expression of all four MMR proteins. Overall, significant associations between MMR and outcome were observed in 32% of studies. There was marked inter-study heterogeneity for estimates of OS and DFS. Pooled analysis did not show any significant association between deficiency in MMR and worse OS (6 studies, hazard ratio [HR] 2.0, p=0.11) or DFS (4 studies, HR ratio 1.31, p=0.66).

CONCLUSION

There is no definitive evidence of a significant association between MMR status and detrimental survival in endometrial cancer.

Therapeutic implications of DNA mismatch repair in adjuvant colorectal cancer chemotherapy

SUMMARY Microsatellite instability (MSI) is a molecular marker of defective DNA mismatch repair (MMR) and constitutes an important oncogenic molecular pathway in colorectal cancer that is present in approximately 12–15% of all colorectal malignant tumors. Defective MMR status in colorectal cancer occurs as a result of germline mutations in MMR genes (less than one third of cases) or, more commonly, from somatic hypermethylation of the MLH1 promoter (more than two thirds). MMR deficiency accelerates colorectal oncogenesis by accumulation of secondary mutations in specific target genes. Patients with defective MMR tumors have distinct clinicopathologic characteristics and have been associated with a better stage-adjusted prognosis than patients with proficient MMR tumors. MMR deficiency may predict tumor chemoresistance to adjuvant 5-fluorouracil treatment. Preliminary clinical data suggested that adding oxaliplatin to 5-fluorouracil could restore the benefit of adjuvant chemotherapy in MSI patients. Further studies are needed to clarify the differential chemosensitivity of MSI patients depending on the mechanism of MMR deficiency and the adjuvant chemotherapeutic regimen used.