Systematic review of microsatellite instability and colorectal cancer prognosis

Research progress of DNA methylation in colorectal cancer (Review)

DNA methylation is one of the earliest and most significant epigenetic mechanisms discovered. DNA methylation refers, in general, to the addition of a methyl group to a specific base in the DNA sequence under the catalysis of DNA methyltransferase, with S‑adenosine methionine as the methyl donor, via covalent bonding and chemical modifications. DNA methylation is an important factor in inducing cancer. There are different types of DNA methylation, and methylation at different sites plays different roles. It is well known that the progression of colorectal cancer (CRC) is affected by the methylation of key genes. The present review did not only discuss the potential relationship between DNA methylation and CRC but also discussed how DNA methylation affects the development of CRC by affecting key genes. Furthermore, the clinical significance of DNA methylation in CRC was highlighted, including that of the therapeutic targets and biomarkers of methylation; and the importance of DNA methylation inhibitors was discussed as a novel strategy for treatment of CRC. The present review did not only focus upon the latest research findings, but earlier reviews were also cited as references to older literature.

Potent therapeutic strategy in gastric cancer with microsatellite instability-high and/or deficient mismatch repair

Gastric cancer (GC) is a common malignancy that presents challenges in patient care worldwide. The mismatch repair (MMR) system is a highly conserved DNA repair mechanism that protects genome integrity during replication. Deficient MMR (dMMR) results in an increased accumulation of genetic errors in microsatellite sequences, leading to the development of a microsatellite instability-high (MSI-H) phenotype. Most MSI-H/dMMR GCs arise sporadically, mainly due to MutL homolog 1 (MLH1) epigenetic silencing. Unlike microsatellite-stable (MSS)/proficient MMR (pMMR) GCs, MSI-H/dMMR GCs are relatively rare and represent a distinct subtype with genomic instability, a high somatic mutational burden, favorable immunogenicity, different responses to treatment, and prognosis. dMMR/MSI-H status is a robust predictive biomarker for treatment with immune checkpoint inhibitors (ICIs) due to high neoantigen load, prominent tumor-infiltrating lymphocytes, and programmed cell death ligand 1 (PD-L1) overexpression. However, a subset of MSI-H/dMMR GC patients does not benefit from immunotherapy, highlighting the need for further research into predictive biomarkers and resistance mechanisms. This review provides a comprehensive overview of the clinical, molecular, immunogenic, and therapeutic aspects of MSI-H/dMMR GC, with a focus on the impact of ICIs in immunotherapy and their potential as neoadjuvant therapies. Understanding the complexity and diversity of the molecular and immunological profiles of MSI-H/dMMR GC will drive the development of more effective therapeutic strategies and molecular targets for future precision medicine.

Personalized treatment using predictive biomarkers in solid organ malignancies: A review

In recent years, the influence of specific biomarkers in the diagnosis and prognosis of solid organ malignancies has been increasingly prominent. The relevance of the use of predictive biomarkers, which predict cancer response to specific forms of treatment provided, is playing a more significant role than ever before, as it affects diagnosis and initiation of treatment, monitoring for efficacy and side effects of treatment, and adjustment in treatment regimen in the long term. In the current review, we explored the use of predictive biomarkers in the treatment of solid organ malignancies, including common cancers such as colorectal cancer, breast cancer, lung cancer, prostate cancer, and cancers associated with high mortalities, such as pancreatic cancer, liver cancer, kidney cancer and cancers of the central nervous system. We additionally analyzed the goals and types of personalized treatment using predictive biomarkers, and the management of various types of solid organ malignancies using predictive biomarkers and their relative efficacies so far in the clinical settings.

Microsatellite instability evaluation by a novel PCR-based 8-loci test kit in colorectal cancer

Microsatellite instability (MSI) assessment is strongly recommended for colorectal cancer patients, as MSI status is crucial in determining optimal treatment and predicting prognosis. This study evaluated the reliability and accuracy of a novel polymerase chain reaction (PCR)-based 8-loci MSI test kit, a rapid test kit designed to detect MSI, by comparing its performance with immunohistochemistry (IHC) and the National Cancer Institute (NCI) 2B3D Panel. MSI status was determined in 186 formalin-fixed paraffin-embedded (FFPE) colorectal cancer tissue samples with known mismatch repair (MMR) status by IHC using the novel PCR-based 8-loci MSI test kit. Additionally, the consistency between the NCI 2B3D Panel and the novel PCR-based 8-loci panel was compared using 69 FFPE tumor tissues paired with adjacent non-cancerous tissue. The novel PCR-based 8-loci MSI test kit and IHC demonstrated high concordance (overall agreement: 97.8%). However, four samples displayed discordant results, exhibiting MMR deficiency using IHC and microsatellite stability using the novel PCR-based 8-loci MSI test kit. Of the 69 samples reanalyzed using the NCI 2B3D Panel, high concordance with the novel PCR-based 8-loci MSI test kit was observed in 67 of 69 cases (overall agreement: 97.1%). The novel PCR-based 8-loci MSI test kit is a rapid and reliable tool for accurately detecting MSI status in colorectal cancer.

Stratification of Stage II Colon Cancer Using Recurrence Prediction Value: A Multi-institutional International Retrospective Study

OBJECTIVE

To create a recurrence prediction value (RPV) of high-risk factor and identify the patients with high risk of cancer recurrence.

BACKGROUND

There are several high-risk factors known to lead to poor outcomes. Weighting each high-risk factor based on their association with increased risk of cancer recurrence can provide a more precise understanding of risk of recurrence.

METHODS

We performed a multi-institutional international retrospective analysis of patients with stage II colon cancer patients who underwent surgery from 2010 to 2020. Patient data from a multi-institutional database were used as the Training data, and data from a completely separate international database from 2 countries were used as the Validation data. The primary endpoint was recurrence-free survival.

RESULTS

A total of 739 patients were included from Training data. To validate the feasibility of RPV, 467 patients were included from Validation data. Training data patients were divided into RPV low (n=564) and RPV high (n=175). Multivariate analysis revealed that risk of recurrence was significantly higher in the RPV high than the RPV low [hazard ratio (HR) 2.628; 95% confidence interval (CI) 1.887-3.660; P <0.001). Validation data patients were divided into 2 groups (RPV low, n=420) and RPV high (n=47). Multivariate analysis revealed that risk of recurrence was significantly higher in the RPV high than the RPV low (HR 3.053; 95% CI 1.962-4.750; P <0.001).

CONCLUSIONS

RPV can identify stage II colon cancer patients with high risk of cancer recurrence worldwide.

Risk Without Reward: Differing Patterns of Chemotherapy Use Do Not Improve Outcomes in Stage II Early-Onset Colon Cancer

PURPOSE

Rising rates of early-onset colon cancer (EOCC) present challenges in deciding how to optimally treat patients. Although standard of care for stage II CC is surgical resection, adding chemotherapy for high-risk disease, evidence suggests treatment selection may differ by age. We investigated whether adjuvant chemotherapy (AC) administration rates differ between patients with early- and later-onset stage II CC.

METHODS

Data originated from the nationwide Flatiron Health electronic health record (EHR)-derived deidentified database spanning January 1, 2003, to August 1, 2021. Adults with stage II CC were grouped as age 18-49 years (EOCC) and those age 50 years or older (later-onset colon cancer [LOCC]). Demographics, Eastern Cooperative Oncology Group score, tumor stage and site, and chemotherapy were included. Primary outcomes included rates of AC administration by age and ethnicity; secondary outcomes included overall survival (OS) and time to metastatic disease (TTMD). Univariate and multivariable logistic regression models evaluated relationships between chemotherapy administration, age, and ethnicity, adjusting for significant covariates.

RESULTS

One thousand sixty-five patients were included. Median age of patients with EOCC was 45.0 years versus 69.0 years for patients with LOCC. Adjusted multivariate analysis showed patients with EOCC received AC significantly more often than patients with LOCC. Non-Hispanic patients received AC at significantly lower rates than Hispanic patients in both cohorts. Subanalysis of stage IIA patients showed that patients with EOCC were more likely to receive AC than patients with LOCC. No significant differences in OS or TTMD were observed by age regardless of AC administration in stage II overall; however, patients with stage IIA EOCC receiving AC had significantly longer TTMD than those not receiving AC.

CONCLUSION

AC was given preferentially in stage II EOCC, even in stage IIA, despite deviation from guidelines. This may expose low-risk patients to unnecessary toxicities and suggests bias toward treating younger patients more aggressively, despite unclear evidence for better outcomes.

Barriers in early detection of colorectal cancer and exploring potential solutions

This editorial discusses the literature review article by Tonini and Zanni, the paper was published in January 2024, and the authors provided very interesting conclusions regarding existing barriers to the early diagnosis of colon cancer. Many cancers do not have identifiable precursors, or there are currently no screening tests to find them. Therefore, these cancers do not have preventive screening options. Early detection is crucial for reducing mortality rates by identifying cancer at an earlier stage through screening, as opposed to no screening. Colorectal cancer develops from precancerous lesions, which can be detected early and potentially prevented and cured. Early detection leads to improved survival rates, decreased complications, and reduced healthcare expenses. This editorial provides a brief description of the biology of colon cancer, emphasizing the contrast in outcomes between early detection and late detection. We also describe screening programs around the globe and examine the barriers in each program. Finally, we explore potential future solutions to enhance inclusion in screening programs and improve patient compliance.

Cellular and molecular events in colorectal cancer: biological mechanisms, cell death pathways, drug resistance and signalling network interactions

Colorectal cancer (CRC) is a leading cause of cancer-related deaths worldwide, affecting millions each year. It emerges from the colon or rectum, parts of the digestive system, and is closely linked to both genetic and environmental factors. In CRC, genetic mutations such as APC, KRAS, and TP53, along with epigenetic changes like DNA methylation and histone modifications, play crucial roles in tumor development and treatment responses. This paper delves into the complex biological underpinnings of CRC, highlighting the pivotal roles of genetic alterations, cell death pathways, and the intricate network of signaling interactions that contribute to the disease's progression. It explores the dysregulation of apoptosis, autophagy, and other cell death mechanisms, underscoring the aberrant activation of these pathways in CRC. Additionally, the paper examines how mutations in key molecular pathways, including Wnt, EGFR/MAPK, and PI3K, fuel CRC development, and how these alterations can serve as both diagnostic and prognostic markers. The dual function of autophagy in CRC, acting as a tumor suppressor or promoter depending on the context, is also scrutinized. Through a comprehensive analysis of cellular and molecular events, this research aims to deepen our understanding of CRC and pave the way for more effective diagnostics, prognostics, and therapeutic strategies.

TGF-β Modulated Pathways in Colorectal Cancer: New Potential Therapeutic Opportunities

Colorectal cancer (CRC) is the third most commonly diagnosed cancer worldwide, with 20% of patients presenting with metastatic disease at diagnosis. TGF-β signaling plays a crucial role in various cellular processes, including growth, differentiation, apoptosis, epithelial-mesenchymal transition (EMT), regulation of the extracellular matrix, angiogenesis, and immune responses. TGF-β signals through SMAD proteins, which are intracellular molecules that transmit TGF-β signals from the cell membrane to the nucleus. Alterations in the TGF-β pathway and mutations in SMAD proteins are common in metastatic CRC (mCRC), making them critical factors in CRC tumorigenesis. This review first analyzes normal TGF-β signaling and then investigates its role in CRC pathogenesis, highlighting the mechanisms through which TGF-β influences metastasis development. TGF-β promotes neoangiogenesis via VEGF overexpression, pericyte differentiation, and other mechanisms. Additionally, TGF-β affects various elements of the tumor microenvironment, including T cells, fibroblasts, and macrophages, promoting immunosuppression and metastasis. Given its strategic role in multiple processes, we explored different strategies to target TGF-β in mCRC patients, aiming to identify new therapeutic options.

Clinical significance of combined tumour-infiltrating lymphocytes and microsatellite instability status in colorectal cancer: a systematic review and network meta-analysis

BACKGROUND

Microsatellite instability (MSI) status and tumour-infiltrating lymphocytes (TIL) are established prognostic factors in colorectal cancer. Previous studies evaluating the combination of TIL and MSI status identified distinct colorectal cancer subtypes with unique prognostic associations. However, these studies were often limited by sample size, particularly for MSI-high (MSI-H) tumours, and there is no comprehensive summary of the available evidence. We aimed to review the literature to compare the survival outcomes associated with the subtypes derived from the integrated MSI-TIL classification in patients with colorectal cancer.

METHODS

In this systematic review and network meta-analysis, we searched PubMed, Embase, Scopus, and the Cochrane Library without language restrictions, for articles published between Jan 1, 1990, and March 13, 2024. Patient cohorts comparing different combinations of TIL (high or low) and MSI status (MSI or microsatellite stable [MSS]) in patients with surgically resected colorectal cancer were included. Studies were excluded if they focused on neoadjuvant therapy or on other immune markers such as B cells or macrophages. Methodological quality assessment was done with the Newcastle-Ottawa scale; data appraisal and extraction was done independently by two reviewers. Summary estimates were extracted from published reports. The primary outcomes were overall survival, disease-free survival, and cancer-specific survival. A frequentist network meta-analysis was done to compare hazard ratios (HRs) and 95% CI for each outcome. The MSI-TIL subgroups were prognostically ranked based on P-score, bias, magnitude, and precision of associations with each outcome. The protocol is registered with PROSPERO (CRD42023461108).

FINDINGS

Of 302 studies initially identified, 21 studies (comprising 14 028 patients) were included in the systematic review and 19 (13 029 patients) in the meta-analysis. Nine studies were identified with a low risk of bias and the remaining ten had a moderate risk of bias. The MSI-TIL-high (MSI-TIL-H) subtype exhibited longer overall survival (HR 0·45, 95% CI 0·34-0·61; I2=77·7%), disease-free survival (0·43, 0·32-0·58; I2=61·6%), and cancer-specific survival (0·53, 0·43-0·66; I2=0%), followed by the MSS-TIL-H subtype for overall survival (HR 0·53, 0·41-0·69; I2=77·7%), disease-free survival (0·52, 0·41-0·64; I2=61·6%), and cancer-specific survival (0·55, 0·47-0·64; I2=0%) than did patients with MSS-TIL-low tumours (MSS-TIL-L). Patients with the MSI-TIL-L subtype had similar overall survival (0·88, 0·66-1·18; I2=77·7%) and disease-free survival (0·93, 0·69-1·26; I2=61·6%), but a modestly longer cancer-specific survival (0·72, 0·57-0·90; I2=0%) than did the MSS-TIL-L subtype. Results from the direct and indirect evidence were strongly congruous.

INTERPRETATION

The findings from this network meta-analysis suggest that better survival was only observed among patients with TIL-H colorectal cancer, regardless of MSI or MSS status. The integrated MSI-TIL classification should be further explored as a predictive tool for clinical decision-making in early-stage colorectal cancer.

FUNDING

German Research Council (HO 5117/2-2).

Large-scale external validation and meta-analysis of gene methylation biomarkers in tumor tissue for colorectal cancer prognosis

BACKGROUND

DNA methylation biomarkers in colorectal cancer (CRC) tissue hold potential as prognostic indicators. However, individual studies have yielded heterogeneous results, and external validation is largely absent. We conducted a comprehensive external validation and meta-analysis of previously suggested gene methylation biomarkers for CRC prognosis.

METHODS

We performed a systematic search to identify relevant studies investigating gene methylation biomarkers for CRC prognosis until March 2024. Our external validation cohort with long-term follow-up included 2303 patients with CRC from 22 hospitals in southwest Germany. We used Cox regression analyses to assess associations between previously suggested gene methylation biomarkers and prognosis, adjusting for clinical variables. We calculated pooled hazard ratios (HRs) and their 95% confidence intervals (CIs) using random-effects models.

FINDINGS

Of 151 single gene and 29 multiple gene methylation biomarkers identified from 121 studies, 37 single gene and seven multiple gene biomarkers were significantly associated with CRC prognosis after adjustment for clinical variables. Moreover, the directions of these associations with prognosis remained consistent between the original studies and our validation analyses. Seven single biomarkers and two multi-biomarker signatures were significantly associated with CRC prognosis in the meta-analysis, with a relatively strong level of evidence for CDKN2A, WNT5A, MLH1, and EVL.

INTERPRETATION

In a comprehensive evaluation of the so far identified gene methylation biomarkers for CRC prognosis, we identified candidates with potential clinical relevance for further investigation.

FUNDING

The German Research Council, the Interdisciplinary Research Program of the National Center for Tumor Diseases (NCT), Germany, the German Federal Ministry of Education and Research.

Mismatch Repair (MMR) Gene Mutation Carriers Have Favorable Outcome in Colorectal and Endometrial Cancer: A Prospective Cohort Study

Germline (Lynch syndrome, LS) and somatic deficiencies of mismatch repair proteins (MMRd) are linked to colorectal and endometrial cancer; however, their prognostic impact in Asian populations remains unclear. This prospective cohort study aimed to determine the prevalence and outcome of germline and somatic MMRd in cancer patients suspected of LS. Patients with colorectal or endometrial cancer suspected of LS were enrolled and underwent gene sequencing for germline MMRd (gMMRd) and immunohistochemistry staining of MMR proteins in a subset of the pathological samples (pMMRd). Among the 451 enrolled patients, 36 patients were gMMRd (+). Compared with gMMRd (-) patients, the 10-year relapse-free survival in gMMRd (+) patients was significantly higher (100% vs. 77.9%; p = 0.006), whereas the 10-year overall survival was similar (100% vs. 90.9%; p = 0.12). Among the 102 gMMRd (-) patients with available pMMR status, 13.7% were pMMRd (+). The 5-year relapse-free survival was 62.9% in gMMRd (-) pMMRd (+) patients and 35.0% in gMMRd (-) pMMRd (-) patients, both lower than gMMRd (+) patients (100%; p < 0.001). This study showed that having LS confers a favorable outcome in colorectal and endometrial cancer patients and highlights the importance of germline genetic testing following the detection of somatic MMRd.

The Association of Mismatch Repair Status with Microscopically Positive (R1) Margins in Stage III Colorectal Cancer: A Retrospective Cohort Study

BACKGROUND

There is mounting evidence that microscopically positive (R1) margins in patients with colorectal cancer (CRC) may represent a surrogate for aggressive cancer biology rather than technical failure during surgery. However, whether detectable biological differences exist between CRC with R0 and R1 margins is unknown. We sought to investigate whether mismatch repair (MMR) status differs between Stage III CRC with R0 or R1 margins.

METHODS

Patients treated for Stage III CRC from January 1, 2016 to December 31, 2019 were identified by using the Danish Colorectal Cancer Group database. Patients were stratified according to MMR status (proficient [pMMR] vs. deficient [dMMR]) and margin status. Outcomes of interest included the R1 rate according to MMR and overall survival.

RESULTS

A total of 3636 patients were included, of whom 473 (13.0%) had dMMR colorectal cancers. Patients with dMMR cancers were more likely to be elderly, female, and have right-sided cancers. R1 margins were significantly more common in patients with dMMR cancers (20.5% vs. 15.2%, p < 0.001), with the greatest difference seen in the rate of R1 margins related to the primary tumour (8.9% vs. 4.7%) rather than to lymph node metastases (11.6% vs. 10.5%). This association was seen in both right- and left-sided cancers. On multivariable analyses, R1 margins, but not MMR status, were associated with poorer survival, alongside age, pN stage, perineural invasion, and extramural venous invasion.

CONCLUSIONS

In patients with Stage III CRC, dMMR status is associated with increased risks of R1 margins following potentially curative surgery, supporting the use of neoadjuvant immunotherapy in this patient group.

Associations with other cancer-related biomarkers might contribute to poor outcomes in RAS-altered, younger patients with colorectal cancer

Colorectal cancer (CRC) is a common cancer in younger adults. In patients undergoing liver resection with RAS-altered CRCs, there is evidence suggesting younger patients have worse outcomes than older patients. To explain this pattern, differences in associations between RAS status and other cancer-related biomarkers in tumors from younger versus older patients with CRC were evaluated in a cohort of 925 patients with CRC, 277 (30.0%) of whom were ≤50 years old, and 454 (49.1%) who had RAS-altered tumors. For 3 biomarkers, RNF43, APC, and microsatellite instability (MSI), the association with RAS status was significantly modified by age after adjustment for multiple testing. Specifically, younger patients with RAS-altered tumors were more likely to be MSI-high, RNF43 mutated, and APC wild type. These differences might contribute to the observed pattern of diminished survival in younger versus older patients with CRC with RAS-mutated tumors undergoing liver metastasis resection.

Right-sided versus left-sided colorectal cancer in elderly patients: a sub-analysis of a large multicenter case-control study in Japan

PURPOSE

This study investigated the impact of sidedness of colorectal cancer (CRC) in elderly patients on the prognosis.

METHODS

In a sub-analysis of a multicenter case-control study of CRC patients who underwent surgery at ≥ 80 years old conducted in Japan between 2003 and 2007, both short- and long-term outcomes were compared between right-sided colon cancers (RCCs) and left-sided colorectal cancers (LCCs). RCCs were defined as those located from the cecum to the transverse colon.

RESULTS

Among the 1680 patients who underwent curative surgery, 812 and 868 had RCCs and LCCs, respectively. RCCs were more frequent than LCCs in those who were female, had renal comorbidities, and had a history of abdominal surgery. Regarding tumor characteristics, RCCs were larger, invaded more deeply, and were diagnosed as either mucinous or signet ring-cell carcinoma more frequently than LCCs. Regarding the prognosis, patients with RCCs had a significantly longer cancer-specific survival (CS-S) and cancer-specific relapse-free survival (CS-RFS) than those with LCCs. Furthermore, sidedness was determined to be an independent prognostic factor for CS-S and CS-RFS.

CONCLUSION

RCCs, which accounted for half of the cases in patients ≥ 80 years old, showed better long-term outcomes than LCCs.

Transfer Learning in Cancer Genetics, Mutation Detection, Gene Expression Analysis, and Syndrome Recognition

Artificial intelligence (AI), encompassing machine learning (ML) and deep learning (DL), has revolutionized medical research, facilitating advancements in drug discovery and cancer diagnosis. ML identifies patterns in data, while DL employs neural networks for intricate processing. Predictive modeling challenges, such as data labeling, are addressed by transfer learning (TL), leveraging pre-existing models for faster training. TL shows potential in genetic research, improving tasks like gene expression analysis, mutation detection, genetic syndrome recognition, and genotype-phenotype association. This review explores the role of TL in overcoming challenges in mutation detection, genetic syndrome detection, gene expression, or phenotype-genotype association. TL has shown effectiveness in various aspects of genetic research. TL enhances the accuracy and efficiency of mutation detection, aiding in the identification of genetic abnormalities. TL can improve the diagnostic accuracy of syndrome-related genetic patterns. Moreover, TL plays a crucial role in gene expression analysis in order to accurately predict gene expression levels and their interactions. Additionally, TL enhances phenotype-genotype association studies by leveraging pre-trained models. In conclusion, TL enhances AI efficiency by improving mutation prediction, gene expression analysis, and genetic syndrome detection. Future studies should focus on increasing domain similarities, expanding databases, and incorporating clinical data for better predictions.

Molecular Approach to Colorectal Carcinoma: Current Evidence and Clinical Application

Colorectal carcinoma is one of the most common cancer types in men and women, responsible for both the third highest incidence of new cancer cases and the third highest cause of cancer deaths. In the last several decades, the molecular mechanisms surrounding colorectal carcinoma's tumorigenesis have become clearer through research, providing new avenues for diagnostic testing and novel approaches to therapeutics. Laboratories are tasked with providing the most current information to help guide clinical decisions. In this review, we summarize the current knowledge surrounding colorectal carcinoma tumorigenesis and highlight clinically relevant molecular testing.

Mechanisms of metastatic colorectal cancer

Despite extensive research and improvements in understanding colorectal cancer (CRC), its metastatic form continues to pose a substantial challenge, primarily owing to limited therapeutic options and a poor prognosis. This Review addresses the emerging focus on metastatic CRC (mCRC), which has historically been under-studied compared with primary CRC despite its lethality. We delve into two crucial aspects: the molecular and cellular determinants facilitating CRC metastasis and the principles guiding the evolution of metastatic disease. Initially, we examine the genetic alterations integral to CRC metastasis, connecting them to clinically marked characteristics of advanced CRC. Subsequently, we scrutinize the role of cellular heterogeneity and plasticity in metastatic spread and therapy resistance. Finally, we explore how the tumour microenvironment influences metastatic disease, emphasizing the effect of stromal gene programmes and the immune context. The ongoing research in these fields holds immense importance, as its future implications are projected to revolutionize the treatment of patients with mCRC, hopefully offering a promising outlook for their survival.

Microsatellite Instability Testing and Prognostic Implications in Colorectal Cancer

Given the crucial predictive implications of microsatellite instability (MSI) in colorectal cancer (CRC), MSI screening is commonly performed in those with and at risk for CRC. Here, we compared results from immunohistochemistry (IHC) and the droplet digital PCR (ddPCR) MSI assay on formalin-fixed paraffin-embedded tumor samples from 48 patients who underwent surgery for colon and rectal cancer by calculating Cohen's kappa measurement (k), revealing high agreement between the methods (k = 0.915). We performed Kaplan-Meier survival analyses and univariate and multivariate Cox regression to assess the prognostic significance of ddPCR-based MSI and to identify clinicopathological features associated with CRC outcome. Patients with MSI-high had better overall survival (OS; p = 0.038) and disease-free survival (DFS; p = 0.049) than those with microsatellite stability (MSS). When stratified by primary tumor location, right-sided CRC patients with MSI-high showed improved DFS, relative to those with MSS (p < 0.001), but left-sided CRC patients did not. In multivariate analyses, MSI-high was associated with improved OS (hazard ratio (HR) = 0.221, 95% confidence interval (CI): 0.026-0.870, p = 0.042), whereas the loss of DNA mismatch repair protein MutL homolog 1 (MLH1) expression was associated with worse OS (HR = 0.133, 95% CI: 0.001-1.152, p = 0.049). Our results suggest ddPCR is a promising tool for MSI detection. Given the opposing effects of MSI-high and MLH1 loss on OS, both ddPCR and IHC may be complementary for the prognostic assessment of CRC.

Unraveling the Interplay of KRAS, NRAS, BRAF, and Micro-Satellite Instability in Non-Metastatic Colon Cancer: A Systematic Review

Microsatellite Instability (MSI-H) occurs in approximately 15% of non-metastatic colon cancers, influencing patient outcomes positively compared to microsatellite stable (MSS) cancers. This systematic review focuses on the prognostic significance of KRAS, NRAS, and BRAF mutations within MSI-H colon cancer. Through comprehensive searches in databases like MEDLINE, EMBASE, and others until 1 January 2024, we selected 8 pertinent studies from an initial pool of 1918. These studies, encompassing nine trials and five observational studies involving 13,273 patients, provided insights into disease-free survival (DFS), survival after recurrence, and overall survival. The pooled data suggest that while KRAS and BRAF mutations typically predict poorer outcomes in MSS colorectal cancer, their impact is less pronounced in MSI contexts, with implications varying across different stages of cancer and treatment responses. In particular, adverse effects of these mutations manifest significantly upon recurrence rather than affecting immediate DFS. Our findings confirm the complex interplay between genetic mutations and MSI status, emphasizing the nuanced role of MSI in modifying the prognostic implications of KRAS, NRAS, and BRAF mutations in colon cancer. This review underscores the importance of considering MSI alongside mutational status in the clinical decision-making process, aiming to tailor therapeutic strategies more effectively for colon cancer patients.

Somatic Mutations in Surgically Treated Colorectal Liver Metastases: An Overview

Colorectal cancer is the second most common cause of cancer death in the United States, and up to half of patients develop colorectal liver metastases (CRLMs). Notably, somatic genetic mutations, such as mutations in RAS, BRAF, mismatch repair (MMR) genes, TP53, and SMAD4, have been shown to play a prognostic role in patients with CRLM. This review summarizes and appraises the current literature regarding the most relevant somatic mutations in surgically treated CRLM by not only reviewing representative studies, but also providing recommendations for areas of future research. In addition, advancements in genetic testing and an increasing emphasis on precision medicine have led to a more nuanced understanding of these mutations; thus, more granular data for each mutation are reviewed when available. Importantly, such knowledge can pave the way for precision medicine with the ultimate goal of improving patient outcomes.

q-Diffusion leverages the full dimensionality of gene coexpression in single-cell transcriptomics

Unlocking the full dimensionality of single-cell RNA sequencing data (scRNAseq) is the next frontier to a richer, fuller understanding of cell biology. We introduce q-diffusion, a framework for capturing the coexpression structure of an entire library of genes, improving on state-of-the-art analysis tools. The method is demonstrated via three case studies. In the first, q-diffusion helps gain statistical significance for differential effects on patient outcomes when analyzing the CALGB/SWOG 80405 randomized phase III clinical trial, suggesting precision guidance for the treatment of metastatic colorectal cancer. Secondly, q-diffusion is benchmarked against existing scRNAseq classification methods using an in vitro PBMC dataset, in which the proposed method discriminates IFN-γ stimulation more accurately. The same case study demonstrates improvements in unsupervised cell clustering with the recent Tabula Sapiens human atlas. Finally, a local distributional segmentation approach for spatial scRNAseq, driven by q-diffusion, yields interpretable structures of human cortical tissue.

Circular RNA as a source of neoantigens for cancer vaccines

BACKGROUND

The effectiveness of somatic neoantigen-based immunotherapy is often hindered by the limited number of mutations in tumors with low to moderate mutation burden. Focusing on microsatellite-stable colorectal cancer (CRC), this study investigates the potential of tumor-associated circular RNAs (circRNAs) as an alternative source of neoepitopes in CRC.

METHODS

Tumor-associated circRNAs in CRC were identified using the MiOncoCirc database and ribo-depletion RNA sequencing of paired clinical normal and tumor samples. Candidate circRNA expression was validated by quantitative real-time PCR (RT-qPCR) using divergent primers. TransCirc database was used for translation prediction. Human leukocyte antigen binding affinity of open reading frames from potentially translatable circRNA was predicted using pVACtools. Strong binders from messenger RNA-encoded proteins were excluded using BlastP. The immunogenicity of the candidate antigens was functionally validated through stimulation of naïve CD8+ T cells against the predicted neoepitopes and subsequent analysis of the T cells through enzyme-linked immunospot (ELISpot) assay, intracellular cytokine staining (ICS) and granzyme B (GZMB) reporter. The cytotoxicity of T cells trained with antigen peptides was further tested using patient-derived organoids.

RESULTS

We identified a neoepitope from circRAPGEF5 that is upregulated in CRC tumor samples from MiOncoCirc database, and two neoepitopes from circMYH9, which is upregulated across various tumor samples from our matched clinical samples. The translation potential of candidate peptides was supported by Clinical Proteomic Tumor Analysis Consortium database using PepQuery. The candidate peptides elicited antigen-specific T cells response and expansion, evidenced by various assays including ELISpot, ICS and GZMB reporter. Furthermore, T cells trained with circMYH9 peptides were able to specifically target and eliminate tumor-derived organoids but not match normal organoids. This observation underscores the potential of circRNAs as a source of immunogenic neoantigens. Lastly, circMYH9 was enriched in the liquid biopsies of patients with CRC, thus enabling a detection-to-vaccination treatment strategy for patients with CRC.

CONCLUSIONS

Our findings underscore the feasibility of tumor-associated circRNAs as an alternative source of neoantigens for cancer vaccines targeting tumors with moderate mutation levels.

Aberrant PRDM2 methylation as an early event in serrated lesions destined to evolve into microsatellite-instable colorectal cancers

Up to 30% of colorectal cancers (CRCs) develop from sessile serrated lesions (SSLs). Within the serrated neoplasia pathway, at least two principally distinct oncogenetic routes exist generating microsatellite-stable and microsatellite-instable CRCs, respectively. Aberrant DNA methylation (DNAm) is found early in the serrated pathway and might play a role in both oncogenetic routes. We studied a cohort of 23 SSLs with a small focus (<10 mm) of dysplasia or cancer, 10 of which were MLH1 deficient and 13 MLH1 proficient. By comparing, for each SSL, the methylation status of (1) the region of dysplasia or cancer (SSL-D), (2) the nondysplastic SSL (SSL), and (3) adjacent normal mucosa, differentially methylated probes (DMPs) and regions (DMRs) were assessed both genome-wide as well as in a tumor-suppressor gene-focused approach. By comparing DNAm of MLH1-deficient SSL-Ds with their corresponding SSLs, we identified five DMRs, including those annotating for PRDM2 and, not unexpectedly, MLH1. PRDM2 gene promotor methylation was associated with MLH1 expression status, as it was largely hypermethylated in MLH1-deficient SSL-Ds and hypomethylated in MLH1-proficient SSL-Ds. Significantly increased DNAm levels of PRDM2 and MLH1, in particular at 'critical' MLH1 probe sites, were to some extent already visible in SSLs as compared to normal mucosa (p = 0.02, p = 0.01, p < 0.0001, respectively). No DMRs, nor DMPs, were identified for SSLs destined to evolve into MLH1-proficient SSL-Ds. Our data indicate that, within both arms of the serrated CRC pathway, the majority of the epigenetic alterations are introduced early during SSL formation. Promoter hypermethylation of PRDM2 and MLH1 on the other hand specifically initiates in SSLs destined to transform into MLH1-deficient CRCs suggesting that the fate of SSLs may not necessarily result from a stochastic process but possibly is already imprinted and predisposed.

Protocol of a first-in-human clinical trial to evaluate the safety, tolerability, and preliminary efficacy of the bispecific CD276xCD3 antibody CC-3 in patients with colorectal cancer (CoRe_CC-3)

Introduction

Colorectal cancer (CRC) is the third most common cancer worldwide in men and women. In the metastasized stage, treatment options and prognosis are limited. To address the high medical need of this patient population, we generated a CD276xCD3 bispecific antibody termed CC-3. CD276 is expressed on CRC cells and on tumor vessels, thereby allowing for a "dual" anticancer effect.

Methods and analysis

This first-in-human clinical study is planned as a prospective multicenter trial, enrolling patients with metastatic CRC after three lines of therapy. During the dose-escalation part, initially, an accelerated titration design with single-patient cohorts is employed. Here, each patient will receive a fixed dose level (starting with 50 µg for the first patient); however, between patients, dose level may be increased by up to 100%, depending on the decision of a safety review committee. Upon occurrence of any adverse events (AEs) grade ≥2, dose-limiting toxicity (DLT), or reaching a dose level of ≥800 µg, the escalation will switch to a standard 3 + 3 dose design. After maximum tolerated dose (MTD) has been determined, defined as no more than one of the six patients experiencing DLT, an additional 14 patients receive CC-3 at the MTD level in the dose-expansion phase. Primary endpoints are incidence and severity of AEs, as well as the best objective response to the treatment according to response evaluation criteria in solid tumors (RECIST) 1.1. Secondary endpoints include overall safety, efficacy, survival, quality of life, and pharmacokinetic investigations.

Ethics and dissemination

The CD276xCD3 study was approved by the Ethics Committee of the Medical Faculty of the Heinrich Heine University Düsseldorf and the Paul-Ehrlich-Institut (P00702). Clinical trial results will be published in peer-reviewed journals. Trial registration numbers: ClinicalTrials.cov Registry (NCT05999396) and EU ClinicalTrials Registry (EU trial number 2022-503084-15-00).

Comprehensive profiling of DNA methylation in Korean patients with colorectal cancer

Alterations in DNA methylation play an important pathophysiological role in the development and progression of colorectal cancer. We comprehensively profiled DNA methylation alterations in 165 Korean patients with colorectal cancer (CRC), and conducted an in-depth investigation of cancer-specific methylation patterns. Our analysis of the tumor samples revealed a significant presence of hypomethylated probes, primarily within the gene body regions; few hypermethylated sites were observed, which were mostly enriched in promoter-like and CpG island regions. The CpG Island Methylator PhenotypeHigh (CIMP-H) exhibited notable enrichment of microsatellite instability-high (MSI-H). Additionally, our findings indicated a significant correlation between methylation of the MLH1 gene and MSI-H status. Furthermore, we found that the CIMP-H had a higher tendency to affect the right-side of the colon tissues and was slightly more prevalent among older patients. Through our methylome profile analysis, we successfully verified the thylation patterns and clinical characteristics of Korean patients with CRC. This valuable dataset lays a strong foundation for exploring novel molecular insights and potential therapeutic targets for the treatment of CRC. [BMB Reports 2024; 57(2): 110-115].

Association of RNF43 Genetic Alterations With BRAFV600E and MSIhigh in Colorectal Cancer

PURPOSE

Recent studies have provided evidence for a predictive value of RNF43 genetic alterations (GAs) as biomarkers for targeted therapies in microsatellite-stable (MSS) colorectal cancer (CRC). These data have the potential to prioritize treatment strategies in patients with BRAFV600E-mutant CRC and help to identify a subgroup that is more likely to derive benefit versus those patients for whom alternative treatment approaches are needed. We were therefore interested in defining the precise frequency of BRAFV600E and RNF43 GAs and their respective overlap in a large cohort of patients with CRC.

METHODS

To address this question, we performed a retrospective analysis that included 52,969 patients diagnosed with CRC from the FoundationCORE database.

RESULTS

We observed a striking association of RNF43 GAs with MSI and tumor mutational burden status and BRAFV600E mutations. Overall, 23% of MSS patients with confirmed BRAFV600E mutation harbor an RNF43 GA-which accounts for 1.1% of all patients with CRC and for 15.7% of all CRC BRAFV600E cases.

CONCLUSION

Ongoing phase III clinical trials, such as BREAKWATER, should aim to incorporate broader genetic profiling to further validate the superior sensitivity of patients with RNF43-mutant, MSS BRAFV600E CRC to anti-EGFR-/BRAFi-based therapies.

Stromal localization of inactive CD8+ T cells in metastatic mismatch repair deficient colorectal cancer

BACKGROUND

The determinants of metastasis in mismatch repair deficiency with high levels of microsatellite instability (MSI-H) in colorectal cancer (CRC) are poorly understood. Here, we hypothesized that distinct immune and stromal microenvironments in primary tumors may discriminate between non-metastatic MSI-H CRC and metastatic MSI-H CRC.

METHODS

We profiled 46,727 single cells using high-plex imaging mass cytometry and analyzed both differential cell type abundance, and spatial distribution of fibroblasts and immune cells in primary CRC tumors with or without metastatic capacity. We validated our findings in a second independent cohort using immunohistochemistry.

RESULTS

High-plex imaging mass cytometry and hierarchical clustering based on microenvironmental markers separated primary MSI-H CRC tumors with and without metastatic capacity. Primary tumors with metastatic capacity displayed a high stromal content and low influx of CD8+ T cells, which expressed significantly lower levels of markers reflecting proliferation (Ki67) and antigen-experience (CD45RO) compared to CD8+ T cells in non-metastatic tumors. CD8+ T cells showed intra-epithelial localization in non-metastatic tumors, but stromal localization in metastatic tumors, which was validated in a second cohort.

CONCLUSION

We conclude that localization of phenotypically distinct CD8+ T cells within stroma may predict metastasis formation in MSI-H CRC.

HOXC6: A promising biomarker linked to an immunoevasive microenvironment in colorectal cancer based on TCGA analysis and cohort validation

HOXC6 plays an essential part of the carcinogenesis of solid tumors, but its functional relevance within the immune contexture in patients with colorectal cancer (CRC) is still uncertain. We intended to investigate the predictive value of HOXC6 expression for survival outcomes and its correlation with immune contexture in CRC patients by utilizing the Cancer Genome Atlas database (n = 619). Validation was performed in cohorts from Zhongshan Hospital (n = 200) and Shanghai Cancer Center (n = 300). Immunohistochemical (IHC) staining was utilized to compare the levels of immunocytes infiltrating the tumor between the groups with high and low expression of HOXC6. Elevated levels of HOXC6 expression in CRC tissues were linked to malignant progression and poor prognosis. HOXC6 as a risk factor for survival of CRC patients was confirmed. Receiver operating characteristic analysis confirmed its diagnostic value, and a reliable prognostic nomogram was constructed. KEGG analysis and GSEA showed that HOXC6 participated in immune regulation, and its expression was tightly linked to the abundance of infiltrating immunocytes. HOXC6 was upregulated in patients diagnosed with CRC within the two cohorts, and high HOXC6 levels were correlated with a worse prognosis. The high-HOXC6 expression group showed increased infiltration of Treg cells, CD68+ macrophages, CD66b+ neutrophils, and CD8+ T-cells and elevated levels of PD-L1 and PD-1, but decreased levels of granzyme B and perforin. These findings suggest that HOXC6 abundance in patients with CRC determines a poor prognosis, promotes an immunoevasive environment, and directs CD8+ T-cell dysfunction. HOXC6 is expected to become a prospective biomarker for the outcome of CRC.

Unique characteristics of the tumor immune microenvironment in young patients with metastatic colorectal cancer

Introduction

Metastatic colorectal cancer (mCRC) remains a common and highly morbid disease, with a recent increase in incidence in patients younger than 50 years. There is an acute need to better understand differences in tumor biology, molecular characteristics, and other age-related differences in the tumor microenvironment (TME).

Methods

111 patients undergoing curative-intent resection of colorectal liver metastases were stratified by age into those <50 years or >65 years old, and tumors were subjected to multiplex fluorescent immunohistochemistry (mfIHC) to characterize immune infiltration and cellular engagement.

Results

There was no difference in infiltration or proportion of immune cells based upon age, but the younger cohort had a higher proportion of programmed death-ligand 1 (PD-L1)+ expressing antigen presenting cells (APCs) and demonstrated decreased intercellular distance and increased cellular engagement between tumor cells (TCs) and cytotoxic T lymphocytes (CTLs), and between TCs and APCs. These trends were independent of microsatellite instability in tumors.

Discussion

Age-related differences in PD-L1 expression and cellular engagement in the tumor microenvironment of patients with mCRC, findings which were unrelated to microsatellite status, suggest a more active immune microenvironment in younger patients that may offer an opportunity for therapeutic intervention with immune based therapy.

Lymph Node Metastases and Associated Recurrence-Free Survival in Microsatellite Stable and Unstable Colon Cancer

BACKGROUND

In contrast to microsatellite stable (MSS) colon cancer, predictors of lymph node metastases and their association with recurrence are not well-defined in microsatellite instability (MSI) colon cancer.

METHODS

A cohort of nonmetastatic colon cancer patients undergoing surgery between 2015 and 2021 were evaluated for predictors of lymph node metastases (LNMs) and their association with recurrence-free survival (RFS).

RESULTS

Of 1466 patients included in the analyses, 361 (25 %) had MSI. Compared with MSS, MSI was associated with earlier stage, fewer LNMs in the patients with N1 or N2 disease, and fewer high-risk features. Compared with the T3-T4 MSS patients, the odds ratios for LNM were 0.52 (95% confidence interval [CI], 0.38-0.71) for the T3-T4 MSI patients, 0.27 (95% CI, 0.38-0.71) for the T1-T2 MSS patients, and 0.15 (95 % CI, 0.08-0.26) for the T1-T2 MSI patients. In both groups, LNMs were associated with T category, patient age, and venous, lymphatic, or perineural invasion. In the MSS patients, LNMs were additionally associated with patient sex and histologic grade. Compared with the MSS patients, the MSI patients with N0 and N1 disease had a better 3-year RFS. However, the MSI patients with N2 disease had a lower rate of 3-year RFS than the MSS patients (hazard ratio, 19.75 vs 4.49).

CONCLUSIONS

In MSI colon cancer, LNMs are 50 % less prevalent, but the factors associated with LNM are like those in MSS colon cancer. The improved prognosis traditionally associated with early-stage MSI colon cancers dissipates with four or more LNMs. These findings should be taken into consideration by clinicians selecting the most appropriate course of treatment for MSI colon cancer.

Does high [18F]FDG uptake always mean poor prognosis? Colon cancer with high-level microsatellite instability is associated with high [18F]FDG uptake on PET/CT

OBJECTIVES

High-level microsatellite instability (MSI-high) is generally associated with higher F-18 fluorodeoxyglucose ([18F]FDG) uptake than stable microsatellite (MSI-stable) tumors. However, MSI-high tumors have better prognosis, which is in contrast with general understanding that high [18F]FDG uptake correlates with poor prognosis. This study evaluated metastasis incidence with MSI status and [18F]FDG uptake.

METHODS

We retrospectively reviewed 108 right-side colon cancer patients who underwent preoperative [18F]FDG PET/CT and postoperative MSI evaluations using a standard polymerase chain reaction at five Bethesda guidelines panel loci. The maximum standard uptake value (SUVmax), SUVmax tumor-to-liver ratio (TLR), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) of the primary tumor were measured using SUV 2.5 cut-off threshold. Student's t-test or Mann-Whitney U test was performed for continuous variables, and χ2 test or Fisher's exact test was performed for categorical variables (p value of  < 0.05 for statistical significance). Medical records were reviewed for metastasis incidence.

RESULTS

Our study population had 66 MSI-stable and 42 MSI-high tumors. [18F]FDG uptake was higher in MSI-high tumors than MSI-stable tumors (TLR, median (Q1, Q3): 7.95 (6.06, 10.54) vs. 6.08 (4.09, 8.82), p = 0.021). Multivariable subgroup analysis demonstrated that higher [18F]FDG uptake was associated with higher risks of distant metastasis in MSI-stable tumors (SUVmax: p = 0.025, MTV: p = 0.008, TLG: p = 0.019) but not in MSI-high tumors.

CONCLUSION

MSI-high colon cancer is associated with high [18F]FDG uptake, but unlike MSI-stable tumors, the degree of [18F]FDG uptake does not correlate with the rate of distant metastasis.

CLINICAL RELEVANCE STATEMENT

MSI status should be considered during PET/CT assessment of colon cancer patients, as the degree of [18F]FDG uptake might not reflect metastatic potential in MSI-high tumors.

KEY POINTS

• High-level microsatellite instability (MSI-high) tumor is a prognostic factor for distant metastasis. • MSI-high colon cancers had a tendency of demonstrating higher [18F]FDG uptake compared to MSI-stable tumors. • Although higher [18F]FDG uptake is known to represent higher risks of distant metastasis, the degree of [18F]FDG uptake in MSI-high tumors did not correlate with the rate at which distant metastasis occurred.

WebSTR: A Population-wide Database of Short Tandem Repeat Variation in Humans

Short tandem repeats (STRs) are consecutive repetitions of one to six nucleotide motifs. They are hypervariable due to the high prevalence of repeat unit insertions or deletions primarily caused by polymerase slippage during replication. Genetic variation at STRs has been shown to influence a range of traits in humans, including gene expression, cancer risk, and autism. Until recently STRs have been poorly studied since they pose significant challenges to bioinformatics analyses. Moreover, genome-wide analysis of STR variation in population-scale cohorts requires large amounts of data and computational resources. However, the recent advent of genome-wide analysis tools has resulted in multiple large genome-wide datasets of STR variation spanning nearly two million genomic loci in thousands of individuals from diverse populations. Here we present WebSTR, a database of genetic variation and other characteristics of genome-wide STRs across human populations. WebSTR is based on reference panels of more than 1.7 million human STRs created with state of the art repeat annotation methods and can easily be extended to include additional cohorts or species. It currently contains data based on STR genotypes for individuals from the 1000 Genomes Project, H3Africa, the Genotype-Tissue Expression (GTEx) Project and colorectal cancer patients from the TCGA dataset. WebSTR is implemented as a relational database with programmatic access available through an API and a web portal for browsing data. The web portal is publicly available at https://webstr.ucsd.edu.

Histopathology and levels of proteins in plasma associate with survival after colorectal cancer diagnosis

BACKGROUND

The TNM system is used to assess prognosis after colorectal cancer (CRC) diagnosis. Other prognostic factors reported include histopathological assessments of the tumour, tumour mutations and proteins in the blood. As some of these factors are strongly correlated, it is important to evaluate the independent effects they may have on survival.

METHODS

Tumour samples from 2162 CRC patients were visually assessed for amount of tumour stroma, severity of lymphocytic infiltrate at the tumour margins and the presence of lymphoid follicles. Somatic mutations in the tumour were assessed for 2134 individuals. Pre-surgical levels of 4963 plasma proteins were measured in 128 individuals. The associations between these features and prognosis were inspected by a Cox Proportional Hazards Model (CPH).

RESULTS

Levels of stroma, lymphocytic infiltration and presence of lymphoid follicles all associate with prognosis, along with high tumour mutation burden, high microsatellite instability and TP53 and BRAF mutations. The somatic mutations are correlated with the histopathology and none of the somatic mutations associate with survival in a multivariate analysis. Amount of stroma and lymphocytic infiltration associate with local invasion of tumours. Elevated levels of two plasma proteins, CA-125 and PPP1R1A, associate with a worse prognosis.

CONCLUSIONS

Tumour stroma and lymphocytic infiltration variables are strongly associated with prognosis of CRC and capture the prognostic effects of tumour mutation status. CA-125 and PPP1R1A may be useful prognostic biomarkers in CRC.

Immune microenvironment and lymph node yield in colorectal cancer

BACKGROUND

Lymph node (LN) harvesting is associated with outcomes in colonic cancer. We sought to interrogate whether a distinctive immune milieu of the primary tumour is associated with LN yield.

METHODS

A total of 926 treatment-naive patients with colorectal adenocarcinoma with more than 12 LNs (LN-high) were compared with patients with 12 or fewer LNs (LN-low). We performed immunohistochemistry and quantification on tissue microarrays for HLA class I/II proteins, beta-2-microglobulin (B2MG), CD8, CD163, LAG3, PD-L1, FoxP3, and BRAF V600E.

RESULTS

The LN-high group was comprised of younger patients, longer resections, larger tumours, right-sided location, and tumours with deficient mismatch repair (dMMR). The tumour microenvironment showed higher CD8+ cells infiltration and B2MG expression on tumour cells in the LN-high group compared to the LN-low group. The estimated mean disease-specific survival was higher in the LN-high group than LN-low group. On multivariate analysis for prognosis, LN yield, CD8+ cells, extramural venous invasion, perineural invasion, and AJCC stage were independent prognostic factors.

CONCLUSION

Our findings corroborate that higher LN yield is associated with a survival benefit. LN yield is associated with an immune high microenvironment, suggesting that tumour immune milieu influences the LN yield.

Early-Onset Colon Cancer: A Narrative Review of Its Pathogenesis, Clinical Presentation, Treatment, and Prognosis

Colon cancer remains a leading cause of cancer-related deaths, and there has been a rise in the incidence of early-onset colon cancer or colon cancer diagnosed before the age of 50 years old. Early-onset colon cancer has several differences in clinical presentation, as well as histopathology, genetic alteration, and molecular profiling. Early-onset colon cancer can be differentiated into familial type that includes hereditary familial syndrome and sporadic type. Demographic variance also exists in both developing and developed countries. Due to the rising incidence of colon cancer diagnosed in younger age, it is imperative to examine the available evidence regarding the mortality rate of early-onset colon cancer. Colon cancer is affected by numerous modifiable and non-modifiable risk factors. Increasing obesity and lifestyle disorders in the younger population, such as smoking, may influence this increasing trend. There are existing guidelines for colon cancer screening in both average-risk and high-risk individuals. This narrative review aims to highlight the pathogenesis of early-onset CRC; its clinical presentation, treatment, prognosis; and how it differs from late-onset CRC.

Radiologic T staging of colon cancer: renewed interest for clinical practice

Radiologic imaging, especially MRI, has long been the mainstay for rectal cancer staging and patient selection for neoadjuvant therapy prior to surgical resection. In contrast, colonoscopy and CT have been the standard for colon cancer diagnosis and metastasis staging with T and N staging often performed at the time of surgical resection. With recent clinical trials exploring the expansion of the use of neoadjuvant therapy beyond the anorectum to the remainder of the colon, the current and future state of colon cancer treatment is evolving with a renewed interest in evaluating the role radiology may play in the primary T staging of colon cancer. The performance of CT, CT colonography, MRI, and FDG PET-CT for colon cancer staging will be reviewed. N staging will also be briefly discussed. It is expected that accurate radiologic T staging will significantly impact future clinical decisions regarding the neoadjuvant versus surgical management of colon cancer.

Immunotherapy for Colorectal Cancer with High Microsatellite Instability: The Ongoing Search for Biomarkers

Microsatellite instability (MSI) is a biological condition associated with inflamed tumors, high tumor mutational burden (TMB), and responses to immune checkpoint inhibitors. In colorectal cancer (CRC), MSI tumors are found in 5% of patients in the metastatic setting and 15% in early-stage disease. Following the impressive clinical activity of immune checkpoint inhibitors in the metastatic setting, associated with deep and long-lasting responses, the development of immune checkpoint inhibitors has expanded to early-stage disease. Several phase II trials have demonstrated a high rate of pathological complete responses, with some patients even spared from surgery. However, in both settings, not all patients respond and some responses are short, emphasizing the importance of the ongoing search for accurate biomarkers. While various biomarkers of response have been evaluated in the context of MSI CRC, including B2M and JAK1/2 mutations, TMB, WNT pathway mutations, and Lynch syndrome, with mixed results, liver metastases have been associated with a lack of activity in such strategies. To improve patient selection and treatment outcomes, further research is required to identify additional biomarkers and refine existing ones. This will allow for the development of personalized treatment approaches and the integration of novel therapeutic strategies for MSI CRC patients with liver metastases.

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.

Prognostic scoring system based on eosinophil- and basophil-related markers for predicting the prognosis of patients with stage II and stage III colorectal cancer: a retrospective cohort study

Background

Systemic inflammation is associated with the prognosis of colorectal cancer (CRC). The current study aimed to construct a comprehensively inflammatory prognostic scoring system named risk score (RS) based on eosinophil- and basophil-related markers and assess its prognostic value in patients with stage II and stage III CRC.

Patients and methods

A total of 3,986 patients were enrolled from January 2007 to December 2013. The last follow-up time was January 2019. They were randomly assigned to the training set and testing set in a 3:2 split ratio. Least absolute shrinkage and selection operator (LASSO)-Cox regression analysis was performed to select the optimal prognostic factors in the construction of RS. The Kaplan-Meier curve, time-dependent receiver operating characteristic (ROC), and Cox analysis were used to evaluate the association between RS and overall survival (OS).

Results

In the training set, all inflammatory markers showed certain prognostic values. Based on LASSO-Cox analysis, nine markers were integrated to construct RS. The Kaplan-Meier curve showed that a higher RS (RS > 0) had a significantly worse prognosis (log-rank p< 0.0001). RS (>0) remained an independent prognostic factor for OS (hazard ratio (HR): 1.70, 95% confidence interval (CI), 1.43-2.03, p< 0.001). The prognostic value of RS was validated in the entire cohort. Time-dependent ROC analysis showed that RS had a stable prognostic effect throughout the follow-up times and could enhance the prognostic ability of the stage by combination. Nomogram was established based on RS and clinicopathological factors for predicting OS in the training set and validated in the testing set. The area under the curve (AUC) values of the 3-year OS in the training and testing sets were 0.748 and 0.720, respectively. The nomogram had a satisfactory predictive accuracy and had better clinical application value than the tumor stage alone.

Conclusions

RS might be an independent prognostic factor for OS in patients with stage II and III CRC, which is helpful for risk stratification of patients. Additionally, the nomogram might be used for personalized prediction and might contribute to formulating a better clinical treatment plan.

Immunohistochemical Profiling of PD-1, PD-L1, CD8, MSI, and p53 and Prognostic Implications in Advanced Serous Ovarian Carcinoma: A Retrospective Study

Advanced high-grade serous ovarian carcinoma is a serious malignant neoplasm with a late diagnosis and high mortality rate. Even when treated with standard therapy, such as surgery followed by carboplatin and paclitaxel chemotherapy, the prognosis remains unfavorable. Immunotherapy is a treatment alternative that requires further study. Therefore, we aimed to evaluate the expression of PD-1, PD-L1, CD8, MSI (MLH1, MSH2, MSH6, and PMS2), and p53 in the paraffin samples of high-grade serous ovarian carcinoma. A retrospective study of 28 southern Brazilian patients with advanced serous ovarian carcinoma (EC III or IV) was conducted between 2009 and 2020. The expression of these proteins was evaluated using immunohistochemistry, and the results were correlated with the patients' clinicopathological data. At diagnosis, the mean age was 61 years, and the most common clinical stage (60%) was EC III. Among the cases, 84.6% exhibited p53 overexpression, 14.8% had MSI, 92.0% were sensitive to platinum, and more than 50.0% relapsed after treatment. Patients with MSI had a lower CD8/PD-1 ratio and more relapses (p = 0.03). In conclusion, analysis of immunotherapeutic markers in paraffin-embedded advanced serous ovarian carcinoma samples is feasible and may assist in prognosis.

Bayesian risk prediction model for colorectal cancer mortality through integration of clinicopathologic and genomic data

Routine tumor-node-metastasis (TNM) staging of colorectal cancer is imperfect in predicting survival due to tumor pathobiological heterogeneity and imprecise assessment of tumor spread. We leveraged Bayesian additive regression trees (BART), a statistical learning technique, to comprehensively analyze patient-specific tumor characteristics for the improvement of prognostic prediction. Of 75 clinicopathologic, immune, microbial, and genomic variables in 815 stage II-III patients within two U.S.-wide prospective cohort studies, the BART risk model identified seven stable survival predictors. Risk stratifications (low risk, intermediate risk, and high risk) based on model-predicted survival were statistically significant (hazard ratios 0.19-0.45, vs. higher risk; P < 0.0001) and could be externally validated using The Cancer Genome Atlas (TCGA) data (P = 0.0004). BART demonstrated model flexibility, interpretability, and comparable or superior performance to other machine-learning models. Integrated bioinformatic analyses using BART with tumor-specific factors can robustly stratify colorectal cancer patients into prognostic groups and be readily applied to clinical oncology practice.

Evaluating mismatch repair deficiency in colorectal cancer biopsy specimens

Mismatch repair (MMR) testing on all new cases of colorectal cancer (CRC) has customarily been preferably performed on surgical specimens, as more tissue is available; however, new clinical trials for the use of immune checkpoint inhibitors in the neoadjuvant setting require MMR testing on biopsy samples. This study aims at identifying advantages, disadvantages and any potential pitfalls in MMR evaluation on biopsy tissue and how to cope with them. The study is prospective-retrospective, recruiting 141 biopsies (86 proficient (p)MMR and 55 deficient (d)MMR) and 97 paired surgical specimens (48 pMMR; 49 dMMR). In biopsy specimens, a high number of indeterminate stains was observed, in particular for MLH1 (31 cases, 56.4%). The main reasons were a punctate nuclear expression of MLH1, relatively weak MLH1 nuclear expression compared to internal controls, or both (making MLH1 loss difficult to interpret), which was solved by reducing primary incubation times for MLH1. A mean of  ≥ 5 biopsies had adequate immunostains, compared to ≤ 3 biopsies in inadequate cases. Conversely, surgical specimens rarely suffered from indeterminate reactions, while weaker staining intensity (p < 0.007) for MLH1 and PMS2 and increased patchiness grade (p < 0.0001) were seen. Central artefacts were almost exclusive to surgical specimens. MMR status classification was possible in 92/97 matched biopsy/resection specimen cases, and all of these were concordant (47 pMMR and 45 dMMR). Evaluation of MMR status on CRC biopsy samples is feasible, if pitfalls in interpretation are known, making laboratory-specific appropriate staining protocols fundamental for high-quality diagnoses.

Pre- and Postoperative Levels of Carcinoembryonic Antigen in Microsatellite Stable Versus Instable Colon Cancer: a Retrospective Analysis

PURPOSE

The prognosis of microsatellite stable (MSS) versus instable (MSI) tumors is an ongoing matter of debate, with differences in expression of carcinoembryonic antigen (CEA) in these two tumor subsets being inconsistently reported to date. The aim of this study was to investigate CEA expression in the context of clinical parameters in MSS and MSI tumors.

METHODS

Clinical, pathological, and biochemical parameters of colon cancer patients who underwent curative surgery were documented in a database and compared between MSS and MSI cases. The pre- to postoperative trend of CEA was analyzed. Survival was assessed using the Kaplan-Meier (log rank) test.

RESULTS

One hundred sixty-nine patients were included in the study. Compared to those with MSS tumors, there was a higher proportion of preoperatively elevated CEA among those with MSI tumors (p = 0.067). Median CEA values decreased over the pre- to postoperative course with MSS (p = 0.01) but not MSI (p = 0.093) tumors. The distribution of N classification differed between MSS and MSI tumors (p = 0.014). Patients with MSI tumors had superior survival.

CONCLUSION

Despite the better prognosis, MSI tumors are associated with increases in CEA. Our findings shed light on discrepancies related to the prognostic evaluation of MSI tumors. Furthermore, in follow-up of colorectal cancers, CEA measurements should be interpreted differently for MSI and MSS tumors.

Microsatellite Instability and Immune Response: From Microenvironment Features to Therapeutic Actionability-Lessons from Colorectal Cancer

Microsatellite instability (MSI) can be found in 15-20% of all colorectal cancers (CRC) and is the key feature of a defective DNA mismatch repair (MMR) system. Currently, MSI has been established as a unique and pivotal biomarker in the diagnosis, prognosis, and treatment of CRC. MSI tumors display a strong lymphocytic activation and a shift toward a tumoral microenvironment restraining metastatic potential and ensuing in a high responsiveness to immunotherapy of MSI CRC. Indeed, neoplastic cells with an MMR defect overexpress several immune checkpoint proteins, such as programmed death-1 (PD-1) and programmed death-ligand 1(PD-L1), that can be pharmacologically targeted, allowing for the revival the cytotoxic immune response toward the tumor. This review aims to illustrate the role of MSI in the tumor biology of colorectal cancer, focusing on the immune interactions with the microenvironment and their therapeutic implications.

Is HLA type a possible cancer risk modifier in Lynch syndrome?

Lynch syndrome (LS) is the most common inherited cancer syndrome. It is inherited via a monoallelic germline variant in one of the DNA mismatch repair (MMR) genes. LS carriers have a broad 30% to 80% risk of developing various malignancies, and more precise, individual risk estimations would be of high clinical value, allowing tailored cancer prevention and surveillance. Due to MMR deficiency, LS cancers are characterized by the accumulation of frameshift mutations leading to highly immunogenic frameshift peptides (FSPs). Thus, immune surveillance is proposed to inhibit the outgrowth of MMR-deficient cell clones. Recent studies have shown that immunoediting during the evolution of MMR-deficient cancers leads to a counter-selection of highly immunogenic antigens. The immunogenicity of FSPs is dependent on the antigen presentation. One crucial factor determining antigen presentation is the HLA genotype. Hence, a LS carrier's HLA genotype plays an important role in the presentation of FSP antigens to the immune system, and may influence the likelihood of progression from precancerous lesions to cancer. To address the challenge of clarifying this possibility including diverse populations with different HLA types, we have established the INDICATE initiative (Individual cancer risk by HLA type, http://indicate-lynch.org/), an international network aiming at a systematic evaluation of the HLA genotype as a possible cancer risk modifier in LS. Here we summarize the current knowledge on the role of HLA type in cancer risk and outline future research directions to delineate possible association in the scenario of LS with genetically defined risk population and highly immunogenic tumors.