Microsatellite instability as a marker of prognosis and response to therapy: a meta-analysis of colorectal cancer survival data

Exploring prognostic values of DNA ploidy, stroma-tumor fraction and nucleotyping in stage II colon cancer patients

PURPOSE

To assess the prognostic value of three novel biomarkers, DNA ploidy, stroma-tumor fraction, and nucleotyping, seeking for more accurate stratification in stage II colon cancer.

METHODS

A total of 417 patients with complete follow up information were enrolled in this study and divided into three clinical risk groups. IHC was performed to examine MSI status. DNA ploidy, stroma and nucleotyping were estimated using automated digital imaging system. Kaplan-Meier survival curves, Cox proportional hazards regression models, and correlation analyses were carried out to process our data.

RESULTS

In the whole cohort of stage II colon cancer, nucleotyping and DNA ploidy were significant prognostic factors on OS in univariate analyses. The combination of nucleotyping and DNA ploidy signified superior OS and DFS. Difference was not significant between low-stroma and high-stroma patients. In multivariable analyses, nucleotyping and the combination of nucleotyping and DNA ploidy were proven the dominant contributory factors for OS. In the low-risk group, we found the combination of nucleotyping and DNA ploidy as the independent prognostic factor statistically significant in both univariate and multivariable, while in the high-risk group, the nucleotyping.

CONCLUSIONS

Our study has proven nucleotyping and the combination of DNA ploidy and nucleotyping as independent prognostic indicators, thus expanding the application of nucleotyping as a predictor from high risk stage II colon cancer to whole risks.

A recurrence-predictive model based on eight genes and tumor mutational burden/microsatellite instability status in Stage II/III colorectal cancer

BACKGROUND

Although adjuvant chemotherapy (ACT) is widely used to treat patients with Stage II/III colorectal cancer (CRC), administering ACT to specific patients remains a challenge. The decision to ACT requires an accurate assessment of recurrence risk and absolute treatment benefit. However, the traditional TNM staging system does not accurately assess a patient's individual risk of recurrence.

METHODS

To identify recurrence risk-related genetic factors for Stage II/III CRC patients after radical surgery, we conducted an analysis of whole-exome sequencing of 47 patients with Stage II/III CRC who underwent radical surgery at five institutions. Patients were grouped into non-recurrence group (NR, n = 24, recurrence-free survival [RFS] > 5 years) and recurrence group (R, n = 23, RFS <2 years). The TCGA-COAD/READ cohort was employed as the validation dataset.

RESULTS

A recurrence-predictive model (G8plus score) based on eight gene (CUL9, PCDHA12, HECTD3, DCX, SMARCA2, FAM193A, AATK, and SORCS2) mutations and tumor mutation burden/microsatellite instability (TMB/MSI) status was constructed, with 97.87% accuracy in our data and 100% negative predictive value in the TCGA-COAD/READ cohort. For the TCGA-COAD/READ cohort, the G8plus-high group had better RFS (HR = 0.22, p = 0.024); the G8plus-high tumors had significantly more infiltrated immune cell types, higher tertiary lymphoid structure signature scores, and higher immunological signature scores. The G8plus score was also a predict biomarker for immunotherapeutic in advanced CRC in the PUCH cohort.

CONCLUSIONS

In conclusion, the G8plus score is a powerful biomarker for predicting the risk of recurrence in patients with stage II/III CRC. It can be used to stratify patients who benefit from ACT and immunotherapy.

Chemokine- and chemokine receptor-based signature predicts immunotherapy response in female colorectal adenocarcinoma patients

The clinical significance and comprehensive characteristics of chemokines and chemokine receptors in female patients with advanced colorectal adenocarcinoma have not ever been reported. Our study explored the expression profiles of chemokines and chemokine receptors and constructed a chemokine- and chemokine receptor-based signature in female patients with advanced colorectal adenocarcinoma. Four independent cohorts containing 1335 patients were enrolled in our study. Univariate Cox regression and least absolute shrinkage and selection operator (LASSO) analyses were performed to construct the signature. CIBERSORT was used to evaluate the landscape of immune cell infiltration. Thirty-two pairs of tissue specimens of female advanced colorectal cancer (CRC) patients and two CRC cell lines were used to validate the signature in vitro. Quantitative real-time PCR and western blotting were performed to validate the mRNA and protein expression levels of signature genes. EdU and colony formation assays were performed to examine proliferative ability. Transwell and wound healing assays were used to evaluate cell invasion and migration capacity. During the signature construction and validation process, we found that the signature was more applicable to female patients with advanced colorectal adenocarcinoma. Hence, the subsequent study mainly focused on the particular subgroup. Enrichment analyses revealed that the signature was closely related to immunity. The landscape of immune cell infiltration presented that the signature was significantly associated with T cells CD8 and neutrophils. Gene set enrichment analysis (GSEA) confirmed that the high-risk group was chiefly enriched in the tumor-promoting related pathways and biological processes, whereas the low-risk group was mainly enriched in anti-tumor immune response pathways and biological processes. The signature was closely correlated with CTLA4, PDL1, PDL2, TMB, MSI, and TIDE, indicating that our signature could serve as a robust biomarker for immunotherapy and chemotherapy response. ROC curves verified that our signature had more robust prognostic power than all immune checkpoints and immunotherapy-related biomarkers. Finally, we used 32 pairs of tissue specimens and 2 CRC cell lines to validate our signature in vitro. We first provided a robust prognostic chemokine- and chemokine receptor-based signature, which could serve as a novel biomarker for immunotherapy and chemotherapy response to guide individualized treatment for female patients with advanced colorectal adenocarcinoma.

Prognostic value of primary tumor location in colorectal cancer: an updated meta-analysis

The clinical, histological, and molecular differences between right-sided colon cancer (RCC) and left-sided colon cancer (RCC) have received considerable attention. Over the past decade, many articles have been published concerning the association between primary tumor location (PTL) of colorectal cancer and survival outcomes. Therefore, there is a growing need for an updated meta-analysis integrating the outcomes of recent studies to determine the prognostic role of right vs left-sidedness of PTL in patients with colorectal cancer. We conducted a comprehensive database review using PubMed, SCOPUS, and Cochrane library databases from February 2016 to March 2023 for prospective or retrospective studies reporting data on overall survival (OS) and cancer-specific survival (CSS) of RCC compared with LCC. A total of 60 cohort studies comprising 1,494,445 patients were included in the meta-analysis. We demonstrated that RCC is associated with a significantly increased risk of death compared with LCC by 25% (hazard ratio (HR), 1.25; 95% confidence interval (CI), 1.19-1.31; I2 = 78.4%; Z = 43.68). Results showed that patients with RCC have a worse OS compared with LCC only in advanced stages (Stage III: HR, 1.275; 95% CI 1.16-1.4; P = 0.0002; I2 = 85.8%; Stage IV: HR, 1.34; 95% CI 1.25-1.44; P < 0.0001; I2 = 69.2%) but not in primary stages (Stage I/II: HR, 1.275; 95% CI 1.16-1.4; P = 0.0002; I2 = 85.8%). Moreover, a meta-analysis of 13 studies including 812,644 patients revealed that there is no significant difference in CSS between RCC and LCC (HR, 1.121; 95% CI 0.97-1.3; P = 0.112). Findings from the present meta-analysis highlight the importance of PTL in clinical decision-making for patients with CRC, especially in advanced stages. We provide further evidence supporting the hypothesis that RCC and LCC are distinct disease entities that should be managed differently.

A nomogram was developed using clinicopathological features to predict postoperative liver metastasis in patients with colorectal cancer

PURPOSE

The objective of this study is to examine the risk factors that contribute to the development of liver metastasis (LM) in patients who have suffered radical resection for colorectal cancer (CRC), and to establish a nomogram model that can be used to predict the occurrence of the LM.

METHODS

The present study enrolled 1377 patients diagnosed with CRC between January 2010 and July 2021. The datasets were allocated to training (n = 965) and validation (n = 412) sets in a randomly stratified manner. The study utilized univariate and multivariate logistic regression analyses to establish a nomogram for predicting LM in patients with CRC.

RESULTS

Multivariate analysis revealed that T stage, N stage, number of harvested lymph nodes (LNH), mismatch repair (MMR) status, neutrophil count, monocyte count, postoperative carcinoembryonic antigen (CEA) levels, postoperative cancer antigen 125 (CA125) levels, and postoperative carbohydrate antigen 19-9 (CA19-9) levels were independent predictive factors for LM after radical resection. These factors were then utilized to construct a comprehensive nomogram for predicting LM. The nomogram demonstrated great discrimination, with an area under the curve (AUC) of 0.782 for the training set and 0.768 for the validation set. Additionally, the nomogram exhibited excellent calibration and significant clinical benefit as confirmed by the calibration curves and the decision curve analysis, respectively.

CONCLUSION

This nomogram has the potential to support clinicians in identifying high-risk patients who may develop LM post-surgery. Clinicians can devise personalized treatment and follow-up plans, ultimately leading to an improved prognosis for patients.

Clinical trials of neoadjuvant immune checkpoint inhibitors for early-stage operable colon and rectal cancer

BACKGROUND

Immune checkpoint inhibitors (ICI) have become first-line treatment for metastatic colorectal cancer (CRC) with deficient mismatch repair (dMMR). Despite the remarkable response reported in preliminary trials, the role of ICI in patients with early-stage, operable CRC remains unclear. The aim of this study was to investigate trials on neoadjuvant ICI in operable CRC.

MATERIALS AND METHODS

Scoping review of clinical trial registries (Clinicaltrials.gov and EU clinical trial registers) and PubMed/Medline database of trials on neoadjuvant ICI for operable CRC was done up to December 2022.

RESULTS

Some 40 trials investigating neoadjuvant ICI for early-stage, operable CRC were identified, including five published trials and three conference abstracts. Preclinical phase I/II trial predominated with only three clinical phase III trials. Few trials investigated neoadjuvant ICI as the only intervention (monotherapy). Trials in rectal cancer were designed for combined ICI with chemo(radio)therapy, only 8 trials stating an MSI/dMMR status for inclusion, one designed for MSS/pMMR only and, the rest agnostic for MMR status. Thirty-eight (95%) trials investigated programmed cell death protein 1 (PD-1) or programmed cell death ligand 1 (PD-L1) inhibitors. PD-1/PD-L1 inhibitors were combined with vascular endothelial growth factor (VEGF) inhibitor or with cytotoxic T-lymphocyte-associated protein-4 (CTLA-4) inhibitor, in two trials each, respectively. Pathological complete response as primary outcome after surgery was the most frequently used study endpoint. In rectal cancer, six trials included a "watch and wait" strategy for patients with complete clinical response. No "watch and wait" study design for colon cancer after neoadjuvant ICI were identified.

CONCLUSION

High response rates from neoadjuvant ICI in early-stage colon and rectal cancer are reported in phase I/II studies. Contemporary trial designs are heterogeneous, with few comparable inclusion criteria, use of several drug combinations and durations and, wide variation of endpoints reported. Harmonizing clinical and translational aspects including survival data is needed for improved future trial designs with clinical impact.

Lynch Syndrome Biopathology and Treatment: The Potential Role of microRNAs in Clinical Practice

Lynch syndrome (LS), also known as Hereditary Non-Polyposis Colorectal Cancer (HNPCC), is an autosomal dominant cancer syndrome which causes about 2-3% of cases of colorectal carcinoma. The development of LS is due to the genetic and epigenetic inactivation of genes involved in the DNA mismatch repair (MMR) system, causing an epiphenomenon known as microsatellite instability (MSI). Despite the fact that the genetics of the vast majority of MSI-positive (MSI+) cancers can be explained, the etiology of this specific subset is still poorly understood. As a possible new mechanism, it has been recently demonstrated that the overexpression of certain microRNAs (miRNAs, miRs), such as miR-155, miR-21, miR-137, can induce MSI or modulate the expression of the genes involved in LS pathogenesis. MiRNAs are small RNA molecules that regulate gene expression at the post-transcriptional level by playing a critical role in the modulation of key oncogenic pathways. Increasing evidence of the link between MSI and miRNAs in LS prompted a deeper investigation into the miRNome involved in these diseases. In this regard, in this study, we discuss the emerging role of miRNAs as crucial players in the onset and progression of LS as well as their potential use as disease biomarkers and therapeutic targets in the current view of precision medicine.

The prognostic significance of microsatellite instability in colorectal cancer: a Swedish multi-center study

PURPOSE

About 10 to 15% of patients with sporadic colorectal cancer display mutations in DNA mismatch repair (MMR) genes shown as microsatellite instability (MSI). Previous reports of colorectal cancer (CRC) indicate a better prognosis for patients with MSI tumors compared to patients with microsatellite stable (MSS) tumors. In this study, our aim was to investigate whether MSI is an independent prognostic factor in CRC.

PATIENTS AND METHODS

Patients with stage I-III colorectal cancer and subject to curative surgery during 2002-2006 in the Swedish low-risk colorectal cancer study group cohort were eligible for inclusion. Deficient MMR (dMMR) status was analyzed by immunohistochemistry (IHC) and/or by MSI testing with polymerase chain reaction (PCR). Prognostic follow-up and treatment data were retrieved from patient records. Statistical analyses to assess MSI-status and prognosis were done using logistic regression and survival analyses using the Kaplan-Meier method and Cox regression hazards models adjusted for age, sex, stage, comorbidity, and tumor location.

RESULTS

In total, 463 patients were included, MSI high tumors were present in 66 patients (14%), and the remaining 397 were MSS/MSI low. Within 6 years, distant recurrences were present in 9.1% and 20.2% (P = 0.049), and death occurred in 25.8% and 31.5% in MSI and MSS patients, respectively. There was no statistically significant difference in overall mortality (HR 0.80, 95% CI 0.46-1.38), relapse-free survival (HR 0.82, 95% CI 0.50-1.36), or cancer-specific mortality (HR 1.60, 95% CI 0.73-3.51).

CONCLUSION

Despite distant metastases being less common in patients with MSI, there was no association between MSI and overall, relapse-free, or cancer-specific survival.

Promising Therapeutic Impact of Immune Checkpoint Inhibitors in Type II Endometrial Cancer Patients with Deficient Mismatch Repair Status

Type II endometrial cancer (EC) is responsible for most endometrial cancer-related deaths due to its aggressive nature, late-stage detection, and high tolerance to standard therapies. Thus, novel treatment strategies for type II EC are imperative. For patients with mismatch repair-deficient (dMMR) tumors, immunotherapy with immune checkpoint inhibitors represents a promising therapeutic strategy. However, the prevalence of dMMR tumors in type II EC patients remains unclear. In this study, using immunohistochemistry, we evaluated the expression of mismatch repair (MMR) proteins, tumor-infiltrating lymphocytes (CD8+), and immune checkpoint molecules (PD-L1) in 60 patients with type II EC (16, 5, 17, and 22 were endometrioid G3, serous, de-differentiated, and carcinosarcoma cases, respectively) to investigate the therapeutic effect of immune checkpoint inhibitors. Approximately 24 cases (40%) had a loss of MMR protein expression. The positivity rate of CD8+ (p = 0.0072) and PD-L1 (p = 0.0061) expression was significantly associated with the dMMR group. These results suggest immune checkpoint inhibitors (anti-PD-L1/PD-1 antibodies) could effectively treat type II EC with dMMR. The presence of dMMR might be a biomarker for a positive response to PD-1/PD-L1 immunotherapy in type II EC.

Prevalence and Associations of Beta2-Microglobulin Mutations in MSI-H/dMMR Cancers

Microsatellite instability (MSI) has emerged as an important predictor of sensitivity for immunotherapy-based strategies. β-2-Microglobulin (B2M) contains microsatellites within the coding regions and is prone to somatic changes in MSI/mismatch repair deficiency (MSI/dMMR) tumors. To delineate prevalence and associations of B2M mutations in MSI-H/dMMR cancers, we investigated the mutational profile of B2M and clinical and pathological features in gastric cancer (GC), colorectal cancer (CRC), and endometrial cancer (EC) with a high incidence of microsatellite instability-high (MSI-H)/dMMR. Formalin-fixed paraffin-embedded (FFPE) tumor tissues along with matched normal tissues were collected from 108 MSI/dMMR patients with GC, CRC, and EC. Genomic profiling of tissue and blood samples were assessed next-generation sequencing (NGS). Immunohistochemistry (IHC) was used to examine the presence or absence of B2M protein. Alternations in the exonic microsatellite regions of B2M were observed at various but high frequencies (57.5% in CRC, 23.9% in GC, and 13.6% in EC) and in different forms. NGS assay revealed that genes involved in chromatin regulation, the PI3K pathway, the WNT pathway, and mismatch repair were extensively altered in the MSI-H cohort. Signature 6 and 26, 2 of 4 mutational signatures associated with defective DNA mismatch repair, featured with high numbers of small insertion/deletions (INDEL) dominated in all 3 types of cancer. Alternations in the exonic microsatellite regions of B2M were observed at various but high frequencies (57.5% in CRC, 23.9% in GC, and 13.6% in EC) and in different forms. Tumor mutational burden (TMB) was significantly higher in the patients carrying MSI-H/dMMR tumors with B2M mutation than that in patients with wild-type B2M (P = .026).The frame shift alteration occurring at the exonic microsatellite sties caused loss of function of B2M gene. In addition, a case with CRC carrying indels in B2M gene resisted the ICI treatment was reported. In conclusion, patients carrying MSI-H/dMMR tumors with B2M mutation showed significantly higher TMB. Prescription of ICIs should be thoroughly evaluated for these patients.

Association of Inflammatory Biomarkers With Survival Among Patients With Stage III Colon Cancer

Importance

The association of chronic inflammation with colorectal cancer recurrence and death is not well understood, and data from large well-designed prospective cohorts are limited.

Objective

To assess the associations of inflammatory biomarkers with survival among patients with stage III colon cancer.

Design, Setting, and Participants

This cohort study was derived from a National Cancer Institute-sponsored adjuvant chemotherapy trial Cancer and Leukemia Group B/Southwest Oncology Group 80702 (CALGB/SWOG 80702) conducted between June 22, 2010, and November 20, 2015, with follow-up ending on August 10, 2020. A total of 1494 patients with plasma samples available for inflammatory biomarker assays were included. Data were analyzed from July 29, 2021, to February 27, 2022.

Exposures

Plasma inflammatory biomarkers (interleukin 6 [IL-6], soluble tumor necrosis factor α receptor 2 [sTNF-αR2], and high-sensitivity C-reactive protein [hsCRP]; quintiles) that were assayed 3 to 8 weeks after surgery but before chemotherapy randomization.

Main Outcomes and Measures

The primary outcome was disease-free survival, defined as time from randomization to colon cancer recurrence or death from any cause. Secondary outcomes were recurrence-free survival and overall survival. Hazard ratios for the associations of inflammatory biomarkers and survival were estimated via Cox proportional hazards regression.

Results

Of 1494 patients (median follow-up, 5.9 years [IQR, 4.7-6.1 years]), the median age was 61.3 years (IQR, 54.0-68.8 years), 828 (55.4%) were male, and 327 recurrences, 244 deaths, and 387 events for disease-free survival were observed. Plasma samples were collected at a median of 6.9 weeks (IQR, 5.6-8.1 weeks) after surgery. The median plasma concentration was 3.8 pg/mL (IQR, 2.3-6.2 pg/mL) for IL-6, 2.9 × 103 pg/mL (IQR, 2.3-3.6 × 103 pg/mL) for sTNF-αR2, and 2.6 mg/L (IQR, 1.2-5.6 mg/L) for hsCRP. Compared with patients in the lowest quintile of inflammation, patients in the highest quintile of inflammation had a significantly increased risk of recurrence or death (adjusted hazard ratios for IL-6: 1.52 [95% CI, 1.07-2.14]; P = .01 for trend; for sTNF-αR2: 1.77 [95% CI, 1.23-2.55]; P < .001 for trend; and for hsCRP: 1.65 [95% CI, 1.17-2.34]; P = .006 for trend). Additionally, a significant interaction was not observed between inflammatory biomarkers and celecoxib intervention for disease-free survival. Similar results were observed for recurrence-free survival and overall survival.

Conclusions and Relevance

This cohort study found that higher inflammation after diagnosis was significantly associated with worse survival outcomes among patients with stage III colon cancer. This finding warrants further investigation to evaluate whether anti-inflammatory interventions may improve colon cancer outcomes.

Trial Registration

ClinicalTrials.gov Identifier: NCT01150045.

Body mass index and molecular subtypes of colorectal cancer

BACKGROUND

Obesity is an established risk factor for colorectal cancer (CRC), but the evidence for the association is inconsistent across molecular subtypes of the disease.

METHODS

We pooled data on body mass index (BMI), tumor microsatellite instability status, CpG island methylator phenotype status, BRAF and KRAS mutations, and Jass classification types for 11 872 CRC cases and 11 013 controls from 11 observational studies. We used multinomial logistic regression to estimate odds ratios (OR) and 95% confidence intervals (CI) adjusted for covariables.

RESULTS

Higher BMI was associated with increased CRC risk (OR per 5 kg/m2 = 1.18, 95% CI = 1.15 to 1.22). The positive association was stronger for men than women but similar across tumor subtypes defined by individual molecular markers. In analyses by Jass type, higher BMI was associated with elevated CRC risk for types 1-4 cases but not for type 5 CRC cases (considered familial-like/Lynch syndrome microsatellite instability-H, CpG island methylator phenotype-low or negative, BRAF-wild type, KRAS-wild type, OR = 1.04, 95% CI = 0.90 to 1.20). This pattern of associations for BMI and Jass types was consistent by sex and design of contributing studies (cohort or case-control).

CONCLUSIONS

In contrast to previous reports with fewer study participants, we found limited evidence of heterogeneity for the association between BMI and CRC risk according to molecular subtype, suggesting that obesity influences nearly all major pathways involved in colorectal carcinogenesis. The null association observed for the Jass type 5 suggests that BMI is not a risk factor for the development of CRC for individuals with Lynch syndrome.

A Standardized Pathology Report for Gastric Cancer: 2nd Edition

The first edition of 'A Standardized Pathology Report for Gastric Cancer' was initiated by the Gastrointestinal Pathology Study Group of the Korean Society of Pathologists and published 17 years ago. Since then, significant advances have been made in the pathologic diagnosis, molecular genetics, and management of gastric cancer (GC). To reflect those changes, a committee for publishing a second edition of the report was formed within the Gastrointestinal Pathology Study Group of the Korean Society of Pathologists. This second edition consists of two parts: standard data elements and conditional data elements. The standard data elements contain the basic pathologic findings and items necessary to predict the prognosis of GC patients, and they are adequate for routine surgical pathology service. Other diagnostic and prognostic factors relevant to adjuvant therapy, including molecular biomarkers, are classified as conditional data elements to allow each pathologist to selectively choose items appropriate to the environment in their institution. We trust that the standardized pathology report will be helpful for GC diagnosis and facilitate large-scale multidisciplinary collaborative studies.

Tissue-resident memory T cells in gastrointestinal tumors: turning immune desert into immune oasis

Tissue-resident memory T cells (Trm) are a particular type of T cell subgroup, which stably reside in tissues and have been revealed to be the most abundant memory T cell population in various tissues. They can be activated in the local microenvironment by infection or tumor cells and rapidly clean them up to restore homeostasis of local immunity in gastrointestinal tissues. Emerging evidence has shown that tissue-resident memory T cells have great potential to be mucosal guardians against gastrointestinal tumors. Therefore, they are considered potential immune markers for immunotherapy of gastrointestinal tumors and potential extraction objects for cell therapy with essential prospects in clinical translational therapy. This paper systematically reviews the role of tissue-resident memory T cells in gastrointestinal tumors and looks to the future of their prospect in immunotherapy to provide a reference for clinical application.

A standardized pathology report for gastric cancer: 2nd edition

The first edition of 'A Standardized Pathology Report for Gastric Cancer' was initiated by the Gastrointestinal Pathology Study Group of the Korean Society of Pathologists and published 17 years ago. Since then, significant advances have been made in the pathologic diagnosis, molecular genetics, and management of gastric cancer (GC). To reflect those changes, a committee for publishing a second edition of the report was formed within the Gastrointestinal Pathology Study Group of the Korean Society of Pathologists. This second edition consists of two parts: standard data elements and conditional data elements. The standard data elements contain the basic pathologic findings and items necessary to predict the prognosis of GC patients, and they are adequate for routine surgical pathology service. Other diagnostic and prognostic factors relevant to adjuvant therapy, including molecular biomarkers, are classified as conditional data elements to allow each pathologist to selectively choose items appropriate to the environment in their institution. We trust that the standardized pathology report will be helpful for GC diagnosis and facilitate large-scale multidisciplinary collaborative studies.

epialleleR: an R/Bioconductor package for sensitive allele-specific methylation analysis in NGS data

Low-level mosaic epimutations within the BRCA1 gene promoter occur in 5-8% of healthy individuals and are associated with a significantly elevated risk of breast and ovarian cancer. Similar events may also affect other tumor suppressor genes, potentially being a significant contributor to cancer burden. While this opens a new area for translational research, detection of low-level mosaic epigenetic events requires highly sensitive and robust methodology for methylation analysis. We here present epialleleR, a computational framework for sensitive detection, quantification, and visualization of mosaic epimutations in methylation sequencing data. Analyzing simulated and real data sets, we provide in-depth assessments of epialleleR performance and show that linkage to epihaplotype data is necessary to detect low-level methylation events. The epialleleR is freely available at https://github.com/BBCG/epialleleR and https://bioconductor.org/packages/epialleleR/ as an open-source R/Bioconductor package.

PD-1 expression, among other immune checkpoints, on tumor-infiltrating NK and NKT cells is associated with longer disease-free survival in treatment-naïve CRC patients

A variety of variables, such as microsatellite instability or inflammatory mediators, are critical players in the development and progression of colorectal cancer (CRC). Natural killer (NK) and natural killer T (NKT) cells are involved in the prognoses of CRC. Immunological components of the tumor microenvironment (TME) impact cancer progression and therapeutic responses. We report that CRC patients with higher frequencies of tumor-infiltrating PD-1+ NK and NKT cells had significantly longer disease-free survival (DFS) than patients with lower frequencies. In agreement with that, patients with higher frequencies of tumor-infiltrating PD-1− NK and NKT cells showed shorter DFS. There were no significant associations between tumor-infiltrating PD-1+TIM-3+, PD-1+TIGIT+, PD-1+ICOS+, PD-1+LAG-3+ NK cells, and PD-1+TIM-3+, PD-1+TIGIT+, and PD-1+LAG-3+ NKT cells with DFS. This study highlights the significance of PD-1 expression on tumor-infiltrating NK and NKT cells and its association with disease prognoses in CRC patients.

Validation of the prognostic value of CD3 and CD8 cell densities analogous to the Immunoscore® by stage and location of colorectal cancer: an independent patient cohort study

In addition to the traditional staging system in colorectal cancer (CRC), the Immunoscore® has been proposed to characterize the level of immune infiltration in tumor tissue and as a potential prognostic marker. The aim of this study was to examine and validate associations of an immune cell score analogous to the Immunoscore® with established molecular tumor markers and with CRC patient survival in a routine setting. Patients from a population-based cohort study with available CRC tumor tissue blocks were included in this analysis. CD3+ and CD8+ tumor infiltrating lymphocytes in the tumor center and invasive margin were determined in stained tumor tissue slides. Based on the T-cell density in each region, an  immune cell score closely analogous to the concept of the Immunoscore® was calculated and tumors categorized into IS-low, IS-intermediate, or IS-high. Logistic regression models were used to assess associations between clinicopathological characteristics with the immune cell score, and Cox proportional hazards models to analyze associations with cancer-specific, relapse-free, and overall survival. From 1,535 patients with CRC, 411 (27%) had IS-high tumors. Microsatellite instability (MSI-high) was strongly associated with higher immune cell score levels (p < 0.001). Stage I-III patients with IS-high had better CRC-specific and relapse-free survival compared to patients with IS-low (hazard ratio [HR] = 0.42 [0.27-0.66] and HR = 0.45 [0.31-0.67], respectively). Patients with microsatellite stable (MSS) tumors and IS-high had better survival (HR_CSS  = 0.60 [0.42-0.88]) compared to MSS/IS-low patients. In this population-based cohort of CRC patients, the immune cell score was significantly associated with better patient survival. It was a similarly strong prognostic marker in patients with MSI-high tumors and in the larger group of patients with MSS tumors. Additionally, this study showed that it is possible to implement an analogous immune cell score approach and validate the Immunoscore® using open source software in an academic setting. Thus, the Immunoscore® could be useful to improve the traditional staging system in colon and rectal cancer used in clinical practice.

Effects of deficient mismatch repair on the prognosis of patients with stage II and stage III colon cancer during different postoperative periods

Background

We evaluated the prognostic role of deficient mismatch repair (dMMR) systems in stage II and stage III colon cancer patients during different postoperative periods. We also assessed whether patients aged ≥75 could benefit from chemotherapy.

Methods

This retrospective study was conducted across three medical centers in China. Kaplan–Meier survival methods and Cox proportional hazards models were used to evaluate the differences in overall survival (OS) and disease-free survival (DFS) rates. Propensity score matching was performed to reduce imbalances in the baseline characteristics of the patients. Landmark analysis was performed to evaluate the role of dMMR during different postoperative periods.

Results

The median follow-up time for all patients was 45.0 months (25–75 IQR: 38.0–82.5). There was no significant OS (p = 0.350) or DFS (p = 0.752) benefit associated with dMMR for stage II and III patients during the first postoperative year. However, significant OS (p < 0.001) and DFS (p < 0.001) benefits were observed from the second postoperative year until the end of follow-up. These differences remained after propensity score matching. Moreover, chemotherapy produced no OS (HR = 0.761, 95% CI: 0.43–1.34, p = 0.341) or DFS (HR = 0.98, 95% CI: 0.51–1.88, p = 0.961) benefit for patients aged ≥75 years.

Conclusion

The benefits of dMMR in stage III patients were observed from the second postoperative year until the end of follow-up. However, the prognosis of patients with dMMR is not different from that of patients with proficient mismatch repair (pMMR) during the first postoperative year. In addition, elderly patients aged ≥75 years obtained no significant survival benefits from postoperative chemotherapy.

Analysing 11 years of incidence trends, clinicopathological characteristics, and forecasts of colorectal cancer in young and old patients: a retrospective cross-sectional study in an Indonesian national referral hospital

OBJECTIVE

To obtain annual incidence trends, understand clinicopathological characteristics, and forecast the future burden of colorectal cancer (CRC) in Indonesia.

DESIGN

11-year retrospective cross-sectional study.

SETTING

A national referral hospital in Jakarta, Indonesia.

PARTICIPANTS

Data from 1584 eligible cases were recorded for trends and forecasting analyses; 433 samples were analysed to determine clinicopathological differences between young (<50 years) and old (≥50 years) patients.

METHODS

Trend analyses were done using Joinpoint software, expressed in annual percentage change (APC), and a regression analysis was executed to generate a forecasting model. Patients' characteristics were compared using χ2 or non-parametric tests.

MAIN OUTCOMES

Analysis of trends, forecasting model, and clinicopathological features between the age groups.

RESULTS

A significant increase in APC was observed among old patients (+2.38%) for CRC cases. Colon cancer increased remarkably (+9.24%) among young patients; rectal cancer trends were either stable or declining. The trend for right-sided CRC increased in the general population (+6.52%) and old patients (+6.57%), while the trend for left-sided CRC was stable. These cases are expected to be a significant health burden within the next 10 years. Patients had a mean age of 53.17±13.94, 38.1% were young, and the sex ratio was 1.21. Prominent characteristics were left-sided CRC, tumour size ≥5 cm, exophytic growth, adenocarcinoma, histologically low grade, pT3, pN0, inadequately dissected lymph nodes (LNs), LN ratio <0.05, no distant metastasis, early-stage cancer, no lymphovascular invasion, and no perineural invasion (PNI). Distinct features between young and old patients were found in the histological subtype, number of dissected LN, and PNI of the tumour.

CONCLUSIONS

Epidemiological trends and forecasting analyses of CRC cases in Indonesian patients showed an enormous increase in colon cancer in young patients, a particularly concerning trend. Additionally, young patients exhibited particular clinicopathological characteristics that contributed to disease severity.

Associations of cigarette smoking, alcohol drinking and body mass index with survival after colorectal cancer diagnosis by anatomic subsite: a prospective patient cohort study in Japan

BACKGROUND

Cigarette smoking, alcohol drinking and obesity are known to be risk factors for colorectal cancer. These factors may affect survival after diagnosis, but evidence has been inconsistent. We investigated subsite-specific associations between prediagnosis smoking, alcohol drinking and body mass index and survival in colorectal cancer.

METHODS

Subjects were 1300 patients (colon 778; rectum 502; concurrent 20) with histologically confirmed colorectal cancer diagnosed during 1997-2013 at a single institution in Japan. Histories of smoking and alcohol drinking, height and prediagnosis weight were assessed using a self-administered questionnaire. Using Cox proportional hazards model, hazard ratios and 95% confidence intervals of mortality were estimated.

RESULTS

During a median follow-up period of 6.7 years, 479 deaths were documented. Ever-smoking was associated with an increased risk of all-cause death among patients with colon cancer (hazard ratio: 1.47; 95% confidence interval: 1.07-2.02 compared with never-smoking). According to colon subsite, this increased risk was clear in patients with proximal colon cancer (hazard ratio: 2.09; 95% confidence interval: 1.28-3.40). There was no association between smoking and rectal cancer survival. Alcohol drinking was not associated with survival for either colon or rectal cancer. Among patients with rectal cancer, higher body mass index was associated with a lower risk of all-cause (Ptrend = 0.0006) and disease-specific death (Ptrend = 0.02). For colon cancer, lower body mass index tended to be associated with a higher risk of all-cause death (Ptrend = 0.05).

CONCLUSIONS

The results indicate that lifestyles identified as risk factors for colorectal cancer may impact differently on patient survival according to anatomic subsite.

Survival outcomes associated with Lynch syndrome colorectal cancer and metachronous rate after subtotal/total versus segmental colectomy: Meta-analysis

BACKGROUND

Lynch syndrome is associated with the most common form of heritable bowel cancer. There remains limited level 1 evidence on survival outcomes and rate of metachronous tumor associated with Lynch syndrome colorectal cancer.

METHODS

A systematic literature search of original studies was performed on Ovid searching MEDLINE, Embase, Cochrane Database of Systematic Reviews, American College of Physicians ACP Journal Club, Database of Abstracts of Reviews of Effects DARE, and Clinical Trials databases from inception of database to February 2021. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses reporting guideline was followed. The data were pooled using a random-effects model. All of the P values were 2-tailed, and statistical analysis was performed using RevMan v. 5.3 Cochrane Collaboration.

RESULTS

From 1,942 studies, 15 studies met the inclusion criteria and were included for qualitative and quantitative synthesis. The five-year overall survival was 89.5% (82.0-94.1%), P < .01; I² = 89%. The ten-year overall survival was 80.5% (68.7-88.6%), P < .01; I² = 81%. The fifteen-year overall survival was 70% (33.7%-91.5%), P < .01; I² = 93%. Univariate meta-regression analysis showed no statistically significant difference in 5-year overall survival by sex, age, MLH1, MSH2, MSH6, nor tumor location (right versus left colon). The metachronous tumor rate was 12% to 33% with a follow-up period of up to 15 years, significantly lower in patients who underwent subtotal/total colectomy (0-6%).

CONCLUSION

The overall survival of patients with colorectal cancer with Lynch syndrome was approximately 90% at 5 years, 80% at 10 years, and 70% at 15 years. The metachronous tumor rate was approximately 10% to 30% at up to 15 years, significantly improved by subtotal/total colectomy.

Association of microsatellite instability (MSI) status with the 5-year outcome and genetic ancestry in a large Brazilian cohort of colorectal cancer

Colorectal cancer (CRC) has a high incidence and mortality worldwide. Microsatellite instability (MSI) is crucial in CRC, with distinct molecular and clinicopathological features in patients. Nowadays, it is a predictive marker for immunotherapy. We proposed to evaluate the 5-year outcome of MSI status in 1002 Brazilian CRC, and associate it with genetic ancestry, molecular and clinicopathological features. MSI evaluation was performed using molecular markers. MSI+ tumors were analyzed for alterations in 23 MSI-targeted genes. Genetic ancestry was evaluated using an Ancestry-Informative markers panel. MSI status was analyzed in relation to CRC specific survival and other clinical and genetic variables. MSI+ status was observed in 10.5% of cases. MSI+ status was significantly associated with the anatomic site right colon, mucinous histological type, clinical stage II, histological grade III/undifferentiated, no recurrence of disease, and live cases without cancer. No association of MSI status with genetic ancestry components was observed. MSI-targeted genes analyses showed the most frequently altered genes: ATM, EGFR, MRE11, ROCK1, and TGFBRII. There was a statistically significant difference in cancer-specific survival between cases according to MSI status. This study constitutes the most comprehensive analyses of the MSI impact on the Brazilian CRC. MSI+ frequency in Brazilian CRC agreed with the literature and was associated with several clinicopathological features related with less aggressive tumors, independently of their genetic ancestry.

Circulating and Tumor-Infiltrating Immune Checkpoint-Expressing CD8+ Treg/T Cell Subsets and Their Associations with Disease-Free Survival in Colorectal Cancer Patients

Simple Summary

Colorectal cancer is one of the leading causes of global cancer-related mortality. Tumor-infiltrating effector immune cells play critical roles in tumor control, and their activity can dictate disease outcomes. In this study, we provide evidence of the associations between different CD8⁺ T cell subpopulations with disease-free survival (DFS) in CRC patients. We report associations between higher levels of certain circulating and tumor-infiltrating CD8⁺ T cell subsets and improved clinical outcomes in CRC patients.

Abstract

T cells in the tumor microenvironment (TME) have diverse roles in anti-tumor immunity, including orchestration of immune responses and anti-tumor cytotoxic attack. However, different T cell subsets may have opposing roles in tumor progression, especially in inflammation-related cancers such as colorectal cancer (CRC). In this study, we phenotypically characterized CD3⁺CD4^- (CD8⁺) T cells in colorectal tumor tissues (TT), normal colon tissues (NT) and in circulation of CRC patients. We investigated the expression levels of key immune checkpoints (ICs) and Treg-related markers in CD8⁺ T cells. Importantly, we investigated associations between different tumor-infiltrating CD8⁺ T cell subpopulations and disease-free survival (DFS) in CRC patients. We found that FoxP3 expression and ICs including PD-1, CTLA-4, TIM-3, and LAG-3 were significantly increased in tumor-infiltrating CD8⁺ T cells compared with NT and peripheral blood. In the TME, we found that TIM-3 expression was significantly increased in patients with early stages and absent lymphovascular invasion (LVI) compared to patients with advanced stages and LVI. Importantly, we report that high levels of certain circulating CD8⁺ T cell subsets (TIM-3-expressing, FoxP3⁻Helios⁻TIM-3⁺ and FoxP3⁻Helios⁺TIM-3⁺ cells) in CRC patients were associated with better DFS. Moreover, in the TME, we report that elevated levels of CD25⁺ and TIM-3⁺ T cells, and FoxP3⁺Helios⁻TIM-3⁺ Tregs were associated with better DFS.

Microsatellite instability in rectal cancer: what does it mean? A study of two randomized trials and a systematic review of the literature

Currently, compelling evidence illustrates the significance of determining microsatellite instability (MSI) in colorectal cancer (CRC). The association of MSI with proximal CRC is well established, however, its implications in patients with rectal cancer remain undefined. We therefore aimed to determine the role of MSI with respect to incidence and outcome in patients with rectal cancer, by the examination of patients from two prospective phase III trials: TME trial and PROCTOR-SCRIPT trial (n=1250). No differences in terms of overall survival (HR 1.00, 95%CI 0.69-1.47) and disease-free survival (HR 1.00, 95%CI 0.68-1.45) were observed in patients with MSI compared to microsatellite stable (MSS) rectal cancer. In addition, we performed a literature review to evaluate the overall prevalence, the effect on survival and the response to neo-adjuvant treatment in patients with MSI rectal cancer compared with MSS rectal cancer. The total number of MSI cases in the included studies (including our own) was 1220 (out of 16526 rectal cancer patients), with an overall prevalence of 6.7% (SE 1.19%). Both for overall survival as for disease-free survival there was no impact of MSI status on prognosis (HR 1.00, 95%CI 0.77-1.29 and HR 0.86, 95% CI 0.60-1.22, respectively). The risk ratio for downstaging and pCR showed also no impact of MSI status (RR 1.15, 95% CI 0.86-1.55 and RR 0.81, 95% CI 0.54-1.22 respectively). In conclusion, rectal cancer patients with MSI form a distinct and rare subcategory, however, there is no prognostic effect of MSI in rectal cancer patients.

Impact of microsatellite status in early-onset colonic cancer

BACKGROUND

The molecular profile of early-onset colonic cancer is undefined. This study evaluated clinicopathological features and oncological outcomes of young patients with colonic cancer according to microsatellite status.

METHODS

Anonymized data from an international collaboration were analysed. Criteria for inclusion were patients younger than 50 years diagnosed with stage I-III colonic cancer that was surgically resected. Clinicopathological features, microsatellite status, and disease-specific outcomes were evaluated.

RESULTS

A total of 650 patients fulfilled the criteria for inclusion. Microsatellite instability (MSI) was identified in 170 (26.2 per cent), whereas 480 had microsatellite-stable (MSS) tumours (relative risk of MSI 2.5 compared with older patients). MSI was associated with a family history of colorectal cancer and lesions in the proximal colon. The proportions with pathological node-positive disease (45.9 versus 45.6 per cent; P = 1.000) and tumour budding (20.3 versus 20.5 per cent; P = 1.000) were similar in the two groups. Patients with MSI tumours were more likely to have BRAF (22.5 versus 6.9 per cent; P < 0.001) and KRAS (40.0 versus 24.2 per cent; P = 0.006) mutations, and a hereditary cancer syndrome (30.0 versus 5.0 per cent; P < 0.001; relative risk 6). Five-year disease-free survival rates in the MSI group were 95.0, 92.0, and 80.0 per cent for patients with stage I, II, and III tumours, compared with 88.0, 88.0, and 65.0 per cent in the MSS group (P = 0.753, P = 0.487, and P = 0.105 respectively).

CONCLUSION

Patients with early-onset colonic cancer have a high risk of MSI and defined genetic conditions. Those with MSI tumours have more adverse pathology (budding, KRAS/BRAF mutations, and nodal metastases) than older patients with MSI cancers.

Risk factors for metachronous peritoneal carcinomatosis after radical resection for patients with nonmetastatic pT3-4 colon cancer

BACKGROUND

Patients with nonmetastatic pT3-4 colon cancers are prone to develop metachronous peritoneal carcinomatosis (mPC). Risk factors for mPC and the influence of mutant kirsten rat sarcoma viral oncogene (KRAS)/neuroblastoma rat sarcoma (NRAS)/v-raf murine sarcoma viral oncogene homolog B1 (BRAF) and DNA mismatch repair (MMR) status on mPC remain to be described in these patients.

METHOD

All enrolled patients were identified from the prospectively collected colorectal cancer database of a tertiary referral hospital between 2013 and 2018. Multivariate analysis was used to identify risk factors associated with mPC.

RESULTS

Of the 1689 patients with nonmetastatic pT3-4 colon carcinoma, 8.4% (142/1689) progressed to mPC. Endoscopic obstruction (HR = 3.044, p < 0.001), elevated CA125 (HR = 1.795, p = 0.009), pT (T4a vs. T3, HR = 2.745, p < 0.001; T4b vs. T3, HR = 3.167, p = 0.001), pN (N1 vs. N0, HR = 2.592, p < 0.001; N2 vs. N0, HR = 4.049, p < 0.001), less than 12 lymph nodes harvested (HR = 2.588, p < 0.001), mucinous or signet ring cell carcinoma (HR = 1.648, p = 0.038), perineural invasion (HR = 1.984, p < 0.001), and adjuvant chemotherapy (HR = 1.522, p = 0.039) were strongly related to mPC but that mutant KRAS/NRAS/BRAF and MMR status was not associated with mPC.

CONCLUSION

This study identified the high-risk factors for mPC in patients with nonmetastatic pT3-4 colon carcinoma, and these factors should be considered in selective preventive therapy and close follow-up for patients subsequently deemed to have high risk for mPC.

Correlation of mismatch repair deficiency with clinicopathological features and programmed death-ligand 1 expression in thyroid carcinoma

BACKGROUND

Mutations in DNA mismatch repair (MMR) genes associated with thyroid carcinoma (TC) have rarely been reported, especially in East Asian populations.

METHODS

We examined tumor tissue from a cohort of 241 patients diagnosed with TC between 2008 and 2020. MMR proteins were detected using tissue microarray-based immunohistochemistry in order to identify MMR-protein-deficient (MMR-D) and MMR-protein-intact (MMR-I) tumors. We retrospectively summarized the clinicopathologic characteristics of patients with MMR-D TC, measured the expression of PD-L1, and recorded overall survival (OS) and other clinical outcomes.

RESULTS

In our cohort, there were 18 (7.5%) MMR-D (MLH1, MSH2, MSH6, and PMS2) patients, including 12 with papillary TC (PTC) (6.7%), 2 with poorly differentiated TC (PDTC) (4.7%), and 4 with anaplastic TC (ATC) (22.2%). Half of them (9/18) showed a specific deletion in MSH6, and 6 of them also carried variants in the MSH6 and PMS2 gene. Survival was significantly better in patients with MMR-D ATC than in those with MMR-I tumors (p = 0.033). Four of the 18 MMR-D patients (22%) were found to be PD-L1 positive. Their OS was much shorter than that of PD-L1-negative patients.

CONCLUSIONS

MMR-D and PD-L1 positivity appear to be associated with clinicopathological characteristics and prognosis in TC. The results indicate that MMR status may have important prognostic significance in TC. Therefore, immune checkpoint inhibitors that target the PD-1/PD-L1 pathway may be a treatment option for TCs.

A chemoresistance lncRNA signature for recurrence risk stratification of colon cancer patients with chemotherapy

Chemotherapy is considered the nonsurgical treatment of choice for colon cancer patients. However, no precise molecular markers are available to determine which patients can actually benefit from it. In this study, we identified 55 chemotherapy-specific long non-coding RNAs (lncRNAs) of colon cancer patients through a systematic assessment of lncRNA expression profiles from a public database. These were taken from multiple cohorts of colon cancer patients who had received chemotherapy, or not. Based on these data, a chemoresistance lncRNA signature, named CRLSig, was constructed and successfully applied to divide chemotherapy patients into two groups with different recurrence-free survival (RFS) rates. Gene set enrichment analysis revealed that patients with low CRLSig had more infiltrating CD8+ T cells and macrophages, while those with high CRLSig had more infiltrating natural killer T cells. KEGG pathway analysis revealed that the low CRLSig group had more activated metabolic pathways compared with those in the high CRLSig group, indicating better response to chemotherapy. Single-cell sequencing analysis revealed that stromal cells and epithelial cells had higher CRLSig. Thus, we have constructed an auxiliary prognostic tool, CRLSig, able to discriminate patients at high risk of RFS, despite having received standard adjuvant chemotherapy treatment.

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A CRLSig was constructed for the first time

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CRLSig revealed chemotherapy patients with different RFS rates

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Low CRLSig group had more activated metabolic pathways

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ScRNA-seq analysis revealed stromal cells and epithelial cells had higher CRLSig

Current Perspectives on the Importance of Pathological Features in Prognostication and Guidance of Adjuvant Chemotherapy in Colon Cancer

There is not a clear consensus on which pathological features and biomarkers are important in guiding prognosis and adjuvant therapy in colon cancer. The Pathology in Colon Cancer, Prognosis and Uptake of Adjuvant Therapy (PiCC UP) Australia and New Zealand questionnaire was distributed to colorectal surgeons, medical oncologists and pathologists after institutional board approval. The aim of this study was to understand current specialist attitudes towards pathological features in the prognostication of colon cancer and adjuvant therapy in stage II disease. A 5-scale Likert score was used to assess attitudes towards 23 pathological features for prognosis and 18 features for adjuvant therapy. Data were analysed using a rating scale and graded response model in item response theory (IRT) on STATA (Stata MP, version 15; StataCorp LP). One hundred and sixty-four specialists (45 oncologists, 86 surgeons and 33 pathologists) participated. Based on IRT modelling, the most important pathological features for prognosis in colon cancer were distant metastases, lymph node metastases and liver metastases. Other features seen as important were tumour rupture, involved margin, radial margin, CRM, lymphovascular invasion and grade of differentiation. Size of tumour, location, lymph node ratio and EGFR status were considered less important. The most important features in decision making for adjuvant therapy in stage II colon cancer were tumour rupture, lymphovascular invasion and microsatellite instability. BRAF status, size of tumour, location, tumour budding and tumour infiltrating lymphocytes were factored as lesser importance. Biomarkers such as CDX2, EGFR, KRAS and BRAF status present areas for further research to improve precision oncology. This study provides the most current status on the importance of pathological features in prognostication and recommendations for adjuvant therapy in Australia and New Zealand. Results of this nationwide study may be useful to help in guiding prognosis and adjuvant treatment in colon cancer.

The Emerging Role of Tissue-Resident Memory CD8+ T Lymphocytes in Human Digestive Tract Cancers

Malignant digestive tract tumors are a great threat to human public health. In addition to surgery, immunotherapy brings hope for the treatment of these tumors. Tissue-resident memory CD8⁺ T (Trm) cells are a focus of tumor immunology research and treatment due to their powerful cytotoxic effects, ability to directly kill epithelial-derived tumor cells, and overall impact on maintaining mucosal homeostasis and antitumor function in the digestive tract. They are a group of noncirculating immune cells expressing adhesion and migration molecules such as CD69, CD103, and CD49a that primarily reside on the barrier epithelium of nonlymphoid organs and respond rapidly to both viral and bacterial infection and tumorigenesis. This review highlights new research exploring the role of CD8⁺ Trm cells in a variety of digestive tract malignant tumors, including esophageal cancer, gastric cancer, colorectal cancer, and hepatocellular carcinoma. A summary of CD8⁺ Trm cell phenotypes and characteristics, tissue distribution, and antitumor functions in different tumor environments is provided, illustrating how these cells may be used in immunotherapies against digestive tract tumors.

Identification of a 3-gene signature for predicting the prognosis of stage II colon cancer based on microsatellite status

Background

Though colon cancer (CC) is one of the most malignant tumors across the world, CC patients with microsatellite instability-high (MSI-H) in stage II seem to have a better prognosis. However, the molecular mechanisms underlying the phenomena haven't been elucidated yet.

Methods

This study enrolled 322 CCs with known microsatellite status from GSE143985, GSE39582 and GSE92921 in the Gene Expression Omnibus (GEO) database. Robust rank aggregation (RRA) analysis, univariate Cox regression analysis and multivariate Cox stepwise regression analysis were performed to identify genes and construct risk score signature. Kaplan-Meier and receiver operating characteristic (ROC) curves analyses were used to evaluate the prognostic value of the signature. The potential mechanisms underlying this signature were assessed in the Metascape database, gene set enrichment analysis (GSEA) and immune infiltration analysis.

Results

RRA analysis identified 40 differently expressed genes (DEGs). A 3-gene risk score signature (MKQ signature) associated with disease-free survival (DFS) was generated. DFS was significantly longer in CC patients with lower than higher scores (P=0.0046). The areas under curves (AUCs) of the time-dependent ROC curves of MKQ signature at 1-, 3- and 5-year DFS were 1, 0.963 and 0.961 respectively. Recurrence-free survival (RFS) was significantly longer in patients in GSE39582 with lower than higher risk scores (P=0.032). The AUCs for 1-, 3- and 5-year RFS in GSE39582 were 0.63, 0.618 and 0.583, respectively, validating the value of the MKQ signature. Functional annotation and GSEA revealed that the MKQ signature was associated with multiple immune-related pathways. Immune cell infiltration was found to differ in patients differing in the MKQ signature.

Conclusions

Gene expression and microsatellite status identified a 3-gene signature (MKQ signature) that could facilitate risk-stratified management in patients with stage II CC. Dysregulation of MSMB, KRT23, and QPRT can serve as prognostic markers in stage II CC.

Systematic review and meta-analysis of tumour microsatellite-instability status as a predictor of response to fluorouracil-based adjuvant chemotherapy in colorectal cancer

PURPOSE

Colorectal cancer (CRC) can be classified according to the chromosomal-instability pathway (a microsatellite-stable (MSS) pathway) and the microsatellite-instability (MSI) pathway. Adjuvant therapy after surgery in advanced CRC is usually based on fluoropyrimidine 5-fluorouracil (5-FU) alone or combined with other agents. Controversy however remains on the use of 5-FU-based regimens in treating MSI-related tumours.

AIMS

To systematically investigate the relationship between tumour microsatellite profile and 5-year overall survival in patients with CRC treated with 5-FU.

METHODS

A systematic literature review of PubMed and Embase databases was conducted. Pre-specified criteria determined study inclusion/exclusion. The PRISMA and QUADAS-2 criteria were used to assess study suitability and quality respectively. Patients were categorised as having either MSI or MSS CRC. Overall 5-year survival was estimated from Kaplan-Meier curves. Publication bias was assessed using funnel-plots and Egger's test.

RESULTS

1807 studies were identified, with meta-analysis performed using nine studies. 5-FU treated individuals with CRC who died at 5 years were found to be 0.31 times less likely to have MSI than those who were alive, although this was not statistically significant. There was an insufficient number of studies to enable subgroup analysis by stage.

CONCLUSIONS

In this meta-analysis, MSI status does not alter 5-year survival of patients with CRC patients treated with adjuvant 5-FU, however there is significant heterogeneity in the design of individual studies in the data synthesis. More studies are necessary to clarify whether CRC patients with MSI CRC, in particular early stage, should be offered 5-FU based adjuvant chemotherapy.

Clinical Significance of Fusobacterium nucleatum and Microsatellite Instability in Evaluating Colorectal Cancer Prognosis

OBJECTIVE

Both genetic and microbial factors play important roles in colorectal cancer (CRC) development. The effects of Fusobacterium nucleatum (F. nucleatum) and microsatellite instability (MSI) on CRC prognosis require more clinical evidence. We aimed to investigate the role of F. nucleatum and MSI as biomarkers in predicting the prognosis of CRC.

METHODS

CRC patients in various TNM stages were enrolled. MSI status and F. nucleatum were detected by immunohistochemical staining of formalin-fixed paraffin-embedded (FFPE) specimens. The associations between MSI status and F. nucleatum and clinical parameters were analyzed.

RESULTS

MSI tumors were more frequently observed in the colon than in the rectum. Cancerous tissues had higher levels of F. nucleatum than adjacent noncancerous tissues. There were no significant differences in F. nucleatum abundance in different age, sex, tumor stage, location, and tumor marker groups. MSI status was associated with tumor location and stage. Survival analyses revealed that disease-free survival (DFS) was significantly longer in the F. nucleatum-negative, younger age, and TNM stage I-II groups (p< 0.05), and age, advanced TNM stage (III and IV), and F. nucleatum status were independent factors for poor prognosis. Multivariate Cox regression and receiver operating characteristic (ROC) curve analyses showed that conventional tumor biomarkers of CRC had more prognostic value than F. nucleatum and MSI.

CONCLUSION

Age, advanced TNM stage, and F. nucleatum positivity were independent factors of poor prognosis, suggesting that F. nucleatum and MSI may contribute to the identification of new strategies for the prevention and treatment of CRC.

Pathological Features and Prognostication in Colorectal Cancer

The prognostication of colorectal cancer (CRC) has traditionally relied on staging as defined by the Union for International Cancer Control (UICC) and American Joint Committee on Cancer (AJCC) TNM staging classifications. However, clinically, there appears to be differences in survival patterns independent of stage, suggesting a complex interaction of stage, pathological features, and biomarkers playing a role in guiding prognosis, risk stratification, and guiding neoadjuvant and adjuvant therapies. Histological features such as tumour budding, perineural invasion, apical lymph node involvement, lymph node yield, lymph node ratio, and molecular features such as MSI, KRAS, BRAF, and CDX2 may assist in prognostication and optimising adjuvant treatment. This study provides a comprehensive review of the pathological features and biomarkers that are important in the prognostication and treatment of CRC. We review the importance of pathological features and biomarkers that may be important in colorectal cancer based on the current evidence in the literature.

Do tumor localization, microsatellite instability and mismatch repair deficiency have an impact on the prognosis of colorectal cancer?

Background

Recent reports have shown that left-and right-sided colon cancers display different clinical and biological features. Chromosomal instability, epigenetic alterations, and defects in the deoxyribonucleic acid (DNA) mismatch repair (MMR) system may lead to the development of colorectal cancer (CRC). Besides microsatellite instability (MSI) caused by DNA MMR activity degradation increases the risk for CRC.

Aim

We aimed to show the differences between CRCs in different locations, to research the cause of these differences, to present whether there is a relation between MMR and MSI, and to evaluate their effects on prognosis.

Patients and Methods

641 CRC cases were divided into three groups: Group 1 (right-sided), Group 2 (left-sided), and Group 3 (rectum). Demographics, cancer stages, location of the tumors, number of the lymph nodes removed, MMR deficiency or proficiency, MSI status, and survival were assessed by retrospective review of the patients.

Results

Among 641 patients, 64.9% were males. Group 1, 2, and 3 comprised 31.2%, 45.7%, and 23.1% of all the cases, respectively. There was a significant difference in terms of survival and location only in stage II tumors. Stage II left colon cancer (LCCs) had a statistically significant lower survival rate. There was no significant difference in survival between both MSI and MMR statuses. In addition, cases were also stratified by stages. According to this data, 10.1, 45.7, and 44.2% of the patients had stages I, II, and III disease, respectively.

Conclusions

Although it was not statistically significant, tumors with MMR deficiency (dMMR) and high microsatellite instability (MSI-H) are more common in right-sided colon tumors.

Rate of dissemination and prognosis in early and advanced stage colorectal cancer based on microsatellite instability status: systematic review and meta-analysis

INTRODUCTION

For the past two decades, microsatellite instability (MSI) has been reported as a robust clinical biomarker associated with survival advantage attributed to its immunogenicity. However, MSI is also associated with high-risk adverse pathological features (poorly differentiated, mucinous, signet cell, higher grade) and exhibits a double-edged sword phenomenon. We performed a systematic review and meta-analysis to evaluate the rate of dissemination and the prognosis of early and advanced stage colorectal cancer based on MSI status.

METHODS

A systematic literature search of original studies was performed on Ovid searching MEDLINE, Embase, Cochrane Database of Systematic Reviews, American College of Physicians ACP Journal Club, Database of Abstracts of Reviews of Effects DARE, Clinical Trials databases from inception of database to June 2019. Colorectal cancer, microsatellite instability, genomic instability and DNA mismatch repair were used as key words or MeSH terms. The Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) reporting guideline was followed. Data were pooled using a random-effects model with odds ratio (OR) as the effect size. Statistical analysis was performed using RevMan ver 5.3 Cochrane Collaboration.

RESULTS

From 5288 studies, 136 met the inclusion criteria (n = 92,035; MSI-H 11,746 (13%)). Overall, MSI-H was associated with improved OS (OR, 0.81; 95% CI 0.73-0.90), DFS (OR, 0.73; 95% CI 0.66-0.81) and DSS (OR, 0.69; 95% CI 0.52-0.90). Importantly, MSI-H had a protective effect against dissemination with a significantly lower rate of lymph node and distant metastases. By stage, the protective effect of MSI-H in terms of OS and DFS was observed clearly in stage II and stage III. Survival in stage I CRC was excellent irrespective of MSI status. In stage IV CRC, without immunotherapy, MSI-H was not associated with any survival benefit.

CONCLUSIONS

MSI-H CRC was associated with an overall survival benefit with a lower rate of dissemination. Survival benefit was clearly evident in both stage II and III CRC, but MSI-H was neither a robust prognostic marker in stage I nor stage IV CRC without immunotherapy.

Prevalence of cancer susceptibility variants in patients with multiple Lynch syndrome related cancers

Along with early-onset cancers, multiple primary cancers (MPCs) are likely resulting from increased genetic susceptibility; however, the associated predisposition genes or prevalence of the pathogenic variants genes in MPC patients are often unknown. We screened 71 patients with MPC of the stomach, colorectal, and endometrium, sequencing 65 cancer predisposition genes. A subset of 19 patients with early-onset MPC of stomach and colorectum were further evaluated for variants in cancer related genes using both normal and tumor whole exome sequencing. Among 71 patients with MPCs, variants classified to be pathogenic were observed in 15 (21.1%) patients and affected Lynch Syndrome (LS) genes: MLH1 (n = 10), MSH6 (n = 2), PMS2 (n = 2), and MSH2 (n = 1). All carriers had tumors with high microsatellite instability and 13 of them (86.7%) were early-onset, consistent with LS. In 19 patients with early-onset MPCs, loss of function (LoF) variants in RECQL5 were more prevalent in non-LS MPC than in matched sporadic cancer patients (OR = 31.6, 2.73–1700.6, p = 0.001). Additionally, there were high-confidence LoF variants at FANCG and CASP8 in two patients accompanied by somatic loss of heterozygosity in tumor, respectively. The results suggest that genetic screening should be considered for synchronous cancers and metachronous MPCs of the LS tumor spectrum, particularly in early-onset. Susceptibility variants in non-LS genes for MPC patients may exist, but evidence for their role is more elusive than for LS patients.

A template to quantify the location and density of CD3 + and CD8 + tumor-infiltrating lymphocytes in colon cancer by digital pathology on whole slides for an objective, standardized immune score assessment

BACKGROUND

In colon cancer, the location and density of tumor-infiltrating lymphocytes (TILs) can classify patients into low and high-risk groups for prognostication. While a commercially available 'Immunoscore®' exists, the incurred expenses and copyrights may prevent universal use. The aim of this study was to develop a robust and objective quantification method of TILs in colon cancer.

METHODS

A consecutive, unselected series of specimens from patients with colon cancer were available for immunohistochemistry and assessment of TILs by automated digital pathology. CD3 + and CD8 + cells at the invasive margin and in tumor center were assessed on consecutive sections using automated digital pathology and image analysis software (Visiopharm®). An algorithm template for whole slide assessment, generated cell counts per square millimeters (cells/mm2), from which the immune score was calculated using distribution volumes. Furthermore, immune score was compared with clinical and histopathological characteristics to confirm its relevance.

RESULTS

Based on the quantified TILs numbers by digital image analyses, patients were classified into low (n = 83, 69.7%), intermediate (n = 14, 11.8%) and high (n = 22, 18.5%) immune score groups. High immune score was associated with stage I-II tumors (p = 0.017) and a higher prevalence of microsatellite instable (MSI) tumors (p = 0.030). MSI tumors had a significantly higher numbers of CD3 + TILs in the invasive margin and CD8 + TILs in both tumor center and invasive margin, compared to microsatellite stable (MSS) tumors.

CONCLUSION

A digital template to quantify an easy-to-use immune score corresponds with clinicopathological features and MSI in colon cancer.

Microsatellite Instability as a Predictor of Outcomes in Colorectal Cancer in the Era of Immune-Checkpoint Inhibitors

The microsatellite instable phenotype resulting from errors in DNA mismatch repair proteins accounts for as far as 15 to 20% of non-hereditary colon cancers but is scarce in rectal cancer. It has been shown that the increased existence of tumor-specific neoantigens in hypermutated tumors is correlated with higher tumor-infiltrating lymphocytes (TILs) and overexpression of immune checkpoint receptors and ligands, mainly PD-1 and PD-L1. In particular, the data gained up to now gives evidence that neoantigen recognition constitutes a dominant component in the course of immunotherapies. This review's primary objective is to describe current approvals and summarize present knowledge about the outcomes of immuno-oncology treatment of microsatellite instable colorectal cancer (CRC). The secondary objective is to give a narrative report about testing methodologies, prognostics, and the predictive value of microsatellite instability. For this purpose, a literature review was performed, focusing on published clinical trial results, ongoing clinical trials and timelines, testing methods, and prognostic and predictive value of MSI. Following four recent FDA approvals of immunotherapy of MSI-high CRC, further work should be warranted by pathology societies towards standardization and rising concordance and reproducibility across the IHC/MSI testing landscape in order to facilitate professionals to offer better survival options for patients with CRC.

A Simple, Accurate and Cost-Effective Capillary Electrophoresis Test with Computational Methods to Aid in Universal Microsatellite Instability Testing

Background: Microsatellite instability (MSI) testing is important for the classification of Lynch syndrome, as a prognostic marker and as a guide for adjuvant chemotherapy in colorectal cancer (CRC). The gold standard for determining MSI status has traditionally been fluorescent multiplex polymerase chain reaction (PCR) and capillary gel electrophoresis (CGE). However, its use in the clinical setting has diminished and has been replaced by immunohistochemical (IHC) detection of loss of mismatch repair protein expression due to practicability and cost. The aim of this study was to develop a simple, cost-effective and accurate MSI assay based on CGE. Method: After amplification of microsatellites by polymerase chain reaction (PCR) using the National Cancer Institute (NCI) panel (BAT 25, BAT26, D5S346, D2S123, D17S250) of MSI markers, parallel CGE was utilized to classify colorectal cancers as MSI-H, MSI-L and MSS using the 5200 Fragment Analyzer System. Cell lines and patient cancer specimens were tested. DNA from 56 formalin-fixed paraffin-embedded cancer specimens and matched normal tissue were extracted and CGE was performed. An automated computational algorithm for MSI status determination was also developed. Results: Using the fragment analyser, MSI status was found to be 100% concordant with the known MSI status of cell lines and was 86% and 87% concordant with immunohistochemistry (IHC) from patient cancer specimens using traditional assessment and our MSI scoring system, respectively, for MSI determination. The misclassification rate was mainly attributed to IHC, with only one (1.8%) sampling error attributed to CGE testing. CGE was also able to distinguish MSI-L from MSI-H and MSS, which is not possible with IHC. An MSI score based on total allelic variability that can accurately determine MSI status was also successfully developed. A significant reduction in cost compared with traditional fluorescent multiplex PCR and CGE was achieved with this technique. Conclusions: A simple, cost-effective and reliable method of determining MSI status and an MSI scoring system based on an automatic computational algorithm to determine MSI status, as well as degree of allelic instability in colorectal cancer, has been developed using the 5200 Fragment Analyzer System.

Methylated circulating tumor DNA as a biomarker for colorectal cancer diagnosis, prognosis, and prediction

Worldwide, colorectal cancer (CRC) is a deadly disease whose death rate ranks second among cancers though its incidence ranks third. Early CRC detection is key and is associated with improved survival outcomes. However, existing tests for CRC diagnosis have several weaknesses thus rendering them inefficient. Moreover, reliable prognostic tests that can predict the overall cancer outcome and recurrence of the disease as well as predictive markers that can assess effectiveness of therapy are still lacking. Thus, shifting to noninvasive liquid biopsy or blood-based biomarkers is vital to improving CRC diagnosis, prognosis, and prediction. Methylated circulating tumor DNA (ctDNA) has gained increased attention as a type of liquid biopsy that is tumor-derived fragmented DNA with epigenetic alterations. Methylated ctDNA are more consistently present in blood of cancer patients as compared to mutated ctDNA. Hence, methylated ctDNA serves as a potential biomarker for CRC that is worth investigating. In this review, we explore what has been reported about methylated ctDNA as a biomarker for CRC diagnosis that can distinguish between CRC patients or those having adenoma and healthy controls as validated specifically through ROC curves. We also examine methylated ctDNA as a biomarker for CRC prognosis and prediction as confirmed through robust statistical analyses. Finally, we discuss the major technical challenges that limits the use of methylated ctDNA for clinical application and suggest possible recommendations to enhance its usage.

Genome profiling of mismatch repair genes in eight types of tumors

Mismatch repair (MMR) plays an important role in the occurrence and development of tumors. At present, it is widely believed that MMR is a protective mechanism of tumors that plays a critical role in the progresses of cancer. In this study, 34 genes related to MMR selected from Gene Ontology (GO) database were scored by single sample Gene sets enrichment analysis (ssGSEA), and eight cancers were screened from 23 TCGA solid cancers to investigate the clinical significance of MMR score. MMR had different effects on the prognosis of the eight tumors, with a protective effect in three cancers and functioning as a risk factor in the remaining five cancers. We used unsupervised clustering to divide the patients into four clusters. We found that the immune and metabolic status of the four clusters were extremely different, among which cluster1 had the lowest tumor purity and the most complex microenvironment; this may explain its poor prognosis and immunotherapy effect. In summary, MMR scores can improve the predictive ability and provide effective guidance for immunotherapy in individual type of tumors.

Cytotoxic CD8+ T cells and tissue resident memory cells in colorectal cancer based on microsatellite instability and BRAF status

BACKGROUND

Recent studies in non-colorectal malignancy have associated T resident memory (T_RM) cells with improved patient survival. It is unknown if T_RM plays a role in colorectal cancer (CRC).

AIM

To examine the potential role of T_RM cells in providing immunogenicity in CRC stratified by microsatellite instability (MSI) and BRAF status.

METHODS

Patients with known MSI and BRAF mutation status were eligible for inclusion in this study. CRC tumour sections stained with haematoxylin and eosin were microscopically reviewed and the images scanned prior to assessment for location of invading edge and core of tumour. Sequential sections were prepared for quantitative multiplex immunohistochemistry (IHC) staining. Opal Multiplex IHC staining was performed with appropriate positive and negative controls and imaged using a standard fluorescent microscope fitted with a spectral scanning camera (Mantra) in conjunction with Mantra snap software. Images were unmixed and annotated in inForm 2.2.0. Statistical analysis was performed using Graphpad Prism Version 7 and Stata Version 15.

RESULTS

Seventy-two patients with known MSI and BRAF status were included in the study. All patients were assessed for MSI by IHC and high resolution capillary electrophoresis testing and 44 of these patients successfully underwent quantitative multiplex IHC staining. Overall, there was a statistically significant increase in CD8+ T_RM cells in the MSI (BRAF mutant and wild type) group over the microsatellite stable (MSS) group. There was a statistically significant difference in CD8+ T_RM between high level MSI (MSI-H):BRAF mutant [22.57, 95% confidence interval (CI): 14.31-30.84] vs MSS [8.031 (95%CI: 4.698-11.36)], P = 0.0076 andMSI-H:BRAF wild type [16.18 (95%CI: 10.44-21.93)] vs MSS [8.031 (95%CI: 4.698-11.36)], P = 0.0279. There was no statistically significant difference in CD8 T cells (both CD8+CD103- and CD8+CD103+T_RM) between MSI-H: BRAF mutant and wild type CRC.

CONCLUSION

This study has shown that CD8+ T_RM are found in greater abundance in MSI-H CRC, both BRAF mutant and MSI-H:BRAF wild type, when compared with their MSS counterpart. CD8+ T_RM may play a role in the immunogenicity in MSI-H CRC (BRAF mutant and BRAF wild type). Further studies should focus on the potential immunogenic qualities of T_RM cells and investigate potential immunotherapeutic approaches to improve treatment and survival associated with CRC.

Morphology Matters: A Critical Reappraisal of the Clinical Relevance of Morphologic Criteria From the 2019 WHO Classification in a Large Colorectal Cancer Cohort Comprising 1004 Cases

The 2019 World Health Organization (WHO) classification of colorectal carcinoma (CRC) profoundly reclassified CRC subtypes and introduces tumor budding as a second major grading criterion, while condensing conventional grade into a 2-tiered system. So far it remains largely unexplored how these parameters interact with each other and whether they truly have an independent impact on patient prognosis. We reclassified a large single-center cohort of 1004 CRCs spanning 2 decades for adjusted WHO grade (low vs. high), tumor budding (Bd1/Bd2/Bd3), and CRC subtype (adenocarcinoma not otherwise specified, micropapillary, mucinous, serrated, medullary, adenoma-like, signet-ring cell, mixed adenoneuroendocrine carcinoma/neuroendocrine carcinoma, undifferentiated) according to the criteria of the 2019 WHO classification. We investigated the interaction of these parameters, their connection to stage/microsatellite status, and their significance for patient survival in the different subgroups. Specific subtypes other than adenocarcinoma not otherwise specified represented one third of all CRCs and were unevenly distributed throughout stage and microsatellite subgroups. Subtypes, WHO grade and tumor budding profoundly impacted all survival parameters (P<0.001 for all analyses), with CRC subtypes and tumor budding-but not WHO grade-being stage-independent prognosticators for all survival comparisons. WHO grade had very limited prognostic value in CRC subtypes, while tumor budding retained its strong prognostic impact in most scenarios. Accurate delineation of CRC subtypes introduced in the 2019 WHO classification provides strong stage-independent prognostic information, arguing that they should be considered in pathology reports and in clinical trials. Of the morphology-based grading schemes included in the 2019 WHO, tumor budding outperforms WHO grade.

Assessment of mismatch repair deficiency, CDX2, beta-catenin and E-cadherin expression in colon cancer: molecular characteristics and impact on prognosis and survival - an immunohistochemical study

Microsatellite instability (MSI) or the deficiency of mismatch repair (MMR) proteins is one of the molecular pathways of colorectal tumorigenesis and may have important clinical implications in predicting the treatment response. We evaluated the relationship between clinicopathological features and MMR proteins [mutL homologue 1 (MLH1), mutS homologue 2 (MSH2), mutS homologue 6 (MSH6), postmeiotic segregation increased 2 (PMS2)], adhesion molecules (E-cadherin, beta-catenin) and caudal-type homeobox 2 (CDX2) in 31 patients with colon adenocarcinoma, using immunohistochemistry. We also aimed to assess the prognostic value of the studied proteins. MLH1 loss was correlated to PMS2 loss (p=0.006) and MSH2 loss (p=0.023); MSH2 loss was significantly associated to MSH6 loss (p=0.011). Tumors with MSH6 loss, together with tumors with PMS2 loss, covered all the patients with MSI status. We found a significant correlation between MSI tumors and mucinous histological type (p=0.03), but no significant associations with other clinicopathological features or with survival rate. There was a significant correlation between E-cadherin expression and differentiation degree (p=0.018) and between beta-catenin expression and lymph node invasion (p=0.046). No significant association between CDX2 loss and any clinical or pathological features was found (p>0.05). No significant differences were identified in overall survival according to E-cadherin, beta-catenin or CDX2 expression (p>0.05). In our study, PMS2 loss was significantly correlated with CDX2 loss (p=0.03). In conclusion, the molecular analysis of biological markers for colon cancer may be important for patient stratification, in order to select the optimal treatment algorithm. Our results suggest that probably the double panel (MSH6 and PMS2) is enough to detect the MSI status, instead of using the quadruple panel.

Microsatellite Instability in Colorectal Cancer Liquid Biopsy-Current Updates on Its Potential in Non-Invasive Detection, Prognosis and as a Predictive Marker

Colorectal cancer (CRC) is the third most commonly-diagnosed cancer in the world and ranked second for cancer-related mortality in humans. Microsatellite instability (MSI) is an indicator for Lynch syndrome (LS), an inherited cancer predisposition, and a prognostic marker which predicts the response to immunotherapy. A recent trend in immunotherapy has transformed cancer treatment to provide medical alternatives that have not existed before. It is believed that MSI-high (MSI-H) CRC patients would benefit from immunotherapy due to their increased immune infiltration and higher neo-antigenic loads. MSI testing such as immunohistochemistry (IHC) and PCR MSI assay has historically been a tissue-based procedure that involves the testing of adequate tissue with a high concentration of cancer cells, in addition to the requirement for paired normal tissues. The invasive nature and specific prerequisite of such tests might hinder its application when surgery is not an option or when the tissues are insufficient. The application of next-generation sequencing, which is highly sensitive, in combination with liquid biopsy, therefore, presents an interesting possibility worth exploring. This review aimed to discuss the current body of evidence supporting the potential of liquid biopsy as a tool for MSI testing in CRC.

Assessment of the Circulating Tumor Cells and Microsatellite Instability in Colorectal Cancer Patients: Prognostic and Diagnostic Value

Background

Microsatellite instability (MSI) and circulating tumor cells (CTCs) play important roles in the diagnosis, prognosis and management of colorectal cancer (CRC) patients.

Methods

CTCs and MSI were assessed in the blood and representative tumor tissues of 100 CRC patients by flow cytometry (FCM) and PCR amplification. The data were correlated to relevant clinicopathological features of the patients, progression-free survival (PFS) and overall survival (OS) rates.

Results

MSI-high was detected in 44 (44.0%) patients, MSI-low in 37 (37%), and microsatellite stable (MSS) in 19 (19.0%) patients (P=0.007). The baseline CTCs count (<4 cells/7mL blood) was reported in 39% of the patients, and CTCs ≥4 cells/7mL blood in 61% of the patients (P=0.028). Improved PFS and OS rates were associated significantly with MSI-high (P<0.001), decreased CTC levels during the course of treatment (P<0.001) and post-treatment CTCs (P=0.008). There was no significant association between MSI-high and PFS or OS in early-stage patients (P=0.187 and P=0.187; respectively); however, it was associated significantly with better PFS and OS in late-stage patients (P<0.001). Multivariate analysis showed that only a change in serial CTC levels is considered an independent prognostic factor for OS (P<0.012). Post-treatment CTCs level, serial CTCs level changes during the course of treatment, lymph nodes and distant metastasis were independent prognostic factors for PFS (P<0.001, P= 0.047, P=0.001 and P<0.001; respectively).

Conclusion

MSI and CTCs could be used as accurate, reliable and sensitive diagnostic and prognostic biomarkers for CRC patients’ survival rates and outcomes.

The effect of smoking, obesity and diabetes on recurrence-free and overall survival in patients with stage III colon cancer receiving adjuvant chemotherapy

Background

The association between smoking, diabetes and obesity and oncological outcomes in patients with stage III colon cancer treated with surgery and adjuvant chemotherapy is unclear.

Aim

To evaluate whether smoking, obesity and diabetes are associated with the disease‐free survival and overall survival rates of patients with stage III colon cancer who have received adjuvant chemotherapy.

Methods

Patients were selected from the prospectively maintained Australian Cancer Outcomes and Research Database (ACCORD). All stage III colon cancer patients who received adjuvant chemotherapy between January 2003 to December 2015 were retrospectively analyzed. The three primary exposures of interest were smoking status, body mass index (BMI) and diabetic (DM) status. The primary outcomes of interest were disease‐free survival (DFS) and overall survival (OS).

Results

A total of 785 patients between 2003 and 2015 were included for analysis. Using Kaplan‐Meier survivorship curves, there was no association between OS and smoking (P = .71), BMI (P = .3) or DM (P = .72). Similarly, DFS did not reveal an association with smoking (P = .34), BMI (P = .2) and DM (P = .34). Controlling for other covariates the results did not reach statistical significance in adjusted multiple regression models.

Conclusion

Smoking, obesity and DM were not shown to influence DFS or OS for patients with stage III colon cancer who have received adjuvant chemotherapy.

Pembrolizumab in unresectable or metastatic MSI-high colorectal cancer: safety and efficacy

INTRODUCTION

Microsatellite instability-high (MSI-H) colorectal cancer (CRC) represents a unique subset of CRC characterized by elevated neoantigen expression and a high degree of intraepithelial T-cell infiltrate. These characteristics make MSI-H tumors particularly susceptible to immune checkpoint inhibitors (ICIs) such as pembrolizumab which inhibit the negative regulation of cytotoxic T-cells and promote T-cell mediated anti-tumor activity.

AREAS COVERED

We discuss the drug development of pembrolizumab including the seminal studies which enabled the drug to garner FDA approvals in the refractory and first-line settings for patients with MSI-H CRC, the pharmacokinetic & pharmacodynamic profile of the agent, and the adverse event profile of the ICI. We also discuss unmet needs in the arena of ICIs including strategies to overcome tumor resistance and to increase the applicability of the agents to a broader population of CRC patients.

EXPERT OPINION

Despite the anti-tumor activity of pembrolizumab in patients with MSI-H CRC, 30-35% of patients fail to derive any benefit. Ongoing research efforts are seeking to identify ICI combinations, which can overcome CRC resistance to pembrolizumab, move ICIs into the treatment paradigm for patients with localized MSI-H CRC and enable ICIs to become meaningful treatment options for patients with microsatellite stable CRC.