Colon Cancer Tumor Location Defined by Gene Expression May Disagree With Anatomic Tumor Location

Right vs. Left colorectal cancer - Where do we draw the line?

PURPOSE

No consensus on the definition of right and left colorectal cancer (CRC) exists, nor studies offering histological or molecular basis for such categorisation. This study investigated the regional variations in the histological and molecular characteristics of CRCs, with the objective of determining an optimal division point between right and left CRCs.

MATERIALS AND METHODS

An observational study of consecutive patients who underwent CRC resection (1995-2022) at Concord Hospital, Sydney was performed. Clinicopathological data were extracted from a prospective database and seven permutations of right-left divisions considered. Logistic regression tested association between the right-left divisions and pathological characteristics. Receiver operating characteristic and area under the curve (AUC) analyses determined the discriminative ability of each division to predict 18 pathology characteristics.

RESULTS

3753 patients underwent a CRC resection (2120 male; mean 69.5yrs [SD12.6]). There was regional variation in tumours with respect to tumour infiltrating lymphocytes (TILs), mismatch repair deficiency (dMMR), and mutant BRAF (mBRAF). Left-sided tumours were less likely to demonstrate TILs (P < 0.001), be dMMR (P < 0.001), and express mBRAF (P < 0.001). Division at the descending-sigmoid junction yielded highest discriminative abilities: TILs - AUC 0.66, dMMR - AUC 0.76, and mBRAF - AUC 0.73.

CONCLUSION

This is the first study to provide a pathological basis on which right- and left-sided cancers may be defined, and found the optimal division point between the right and left colorectum to be at the descending-sigmoid junction. Further research is needed to determine whether this can facilitate individualised patient management.

Primary site and treatment impact in unresectable metastatic colorectal cancer

INTRODUCTION

Colorectal cancer is a heterogenous disease, with various clinical and molecular subtypes related to the primary site (left versus right colon) of the original tumour. Primary colon tumour side is both a prognostic and predictive marker in metastatic colorectal cancer.

AREAS COVERED

There is an increasing body of evidence for how primary site may impact treatment decisions in metastatic colorectal cancer. We reviewed the evidence for its prognostic and predictive value.

EXPERT OPINION

Primary site is a prognostic marker in metastatic colorectal cancer, with right colon tumours being associated with more aggressive disease behaviour and poorer outcomes. Primary site also appears to predict for outcomes to various treatments, in particular anti-EGFR antibodies. As our understanding and testing of the molecular and biological differences within colorectal cancer increases beyond primary site, this should be integrated into the current treatment algorithm to ensure an individualised patient-centred approach to care.

Single-cell atlas of the aging mouse colon

We performed massive single-cell sequencing in the aging mouse colonic epithelium and immune cells. We identified novel compartment-specific markers as well as dramatic aging-associated changes in cell composition and signaling pathways, including a shift from absorptive to secretory epithelial cells, depletion of naive lymphocytes, and induction of eIF2 signaling. Colon cancer is one of the leading causes of death within the western world, incidence of which increases with age. The colonic epithelium is a rapidly renewing tissue, tasked with water and nutrient absorption, as well as hosting intestinal microbes. The colonic submucosa is populated with immune cells interacting with and regulating the epithelial cells. However, it is unknown whether compartment-specific changes occur during aging and what impact this would cause. We show that both epithelial and immune cells differ significantly between colonic compartments and experience significant age-related changes in mice. We found a shift in the absorptive-secretory cell balance, possibly linked to age-associated intestinal disturbances, such as malabsorption. We demonstrate marked changes in aging immune cells: population shifts and interactions with epithelial cells, linking cytokines (Ifn-γ, Il1B) with the aging of colonic epithelium. Our results provide new insights into the normal and age-associated states of the colon.

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Mouse colon shows compartment-specific transcriptional and population differences

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Old animal colon switches to a pro-inflammatory state

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Changes in epithelium linked to changes in tissue-resident immune cells

Tumor-Associated Microbiota in Proximal and Distal Colorectal Cancer and Their Relationships With Clinical Outcomes

The proximal and distal subsites of colorectal cancer (CRC) have distinct differences in their embryonic origin, epidemiology, and prognosis. Therefore, they are not considered as the same disease. However, the possible difference in microbial characterization of the two subsites of CRC is still unclear. In this study, we explored tumor microbiota diversity and composition difference in patients with proximal (N = 187) and distal CRCs (N = 142). This was carried out on cancer tissues and adjacent tissues using bacterial 16S rRNA sequencing. The Kaplan–Meier method was used to analyze the correlation between differential flora and overall survival rate of the patients. It was found that there were significant differences in tumor microbial characteristics between the proximal and distal CRC tissues. The microbiota communities were distinctly richer in the proximal colon tumor tissues than in the distal CRC tissues. Microbial diversity and structure were relatively constant in the paracancerous normal tissues of the proximal and distal colorectum. Generally, microbial communities of CRC tumor tissues were composed of Proteobacteria, Firmicutes, Actinobacteria, and Bacteroidetes. Alpha diversity in the proximal and distal CRC tumor tissues was closely related to specific microflora. The abundance of Fusobacteria was associated with age of patient, tumor diameter, and tumor microsatellite instability (MSI) status of the patients. Moreover, Fusobacteria enrichment was associated with poor prognosis especially in patients with proximal colon cancers, but not in patients with distal CRC. In conclusion, proximal and distal subsites of the CRC present distinct microbiota diversity and community structures. The differences indicate that there are different risk factors across anatomical subsites of CRC, which may provide a new strategy for precise prevention and treatment of CRC in the future.

Clinical and Molecular Features in Patients Undergoing Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy for Peritoneal Carcinosis from Colorectal Cancer

PURPOSE

Careful patient selection plays a crucial role in avoiding overtreatment and further increases survival rates in patients undergoing cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) for colorectal cancer (CRC) with peritoneal metastases (PM).

METHODS

The clinical and molecular factors influencing survival in patients who had undergone CRS with HIPEC between January 2015 and December 2018 were analyzed.

RESULTS

Sixty-six patients underwent CRS with HIPEC during the study period. The median overall survival (OS) was 36 months, with a 3-year OS of 43%. Multivariate analysis revealed increased PCI (HR: 1.21; 95% CI: 1.02-1.41; p = 0.020), right-sided primary tumor (HR: 3.01; 95% CI: 1.27-7.13; p = 0.017), and BRAF V600E mutation (HR: 4.55; 95% CI: 1.21-17.21; p = 0.025) as independent predictors for worse OS.

CONCLUSION

In addition to confirming the prognostic role of PCI, our study extends the role of BRAF mutation and right primary tumor location as markers for worse prognosis.

Construction of a long noncoding RNA-based competing endogenous RNA network and prognostic signatures of left- and right-side colon cancer

Background

Cancers located on the right and left sides of the colon have distinct clinical and molecular characteristics. This study aimed to explore the regulatory mechanisms of location-specific long noncoding RNAs (lncRNAs) as competing endogenous RNAs (ceRNAs) in colon cancer and identify potential prognostic biomarkers.

Method

Differentially expressed lncRNAs (DELs), miRNAs (DEMs), and genes (DEGs) between right- and left-side colon cancers were identified by comparing RNA sequencing profiles. Functional enrichment analysis was performed for the DEGs, and a ceRNA network was constructed. Associations between DELs and patient survival were examined, and a DEL-based signature was constructed to examine the prognostic value of these differences. Clinical colon cancer tissues and Gene Expression Omnibus (GEO) datasets were used to validate the results.

Results

We identified 376 DELs, 35 DEMs, and 805 DEGs between right- and left-side colon cancers. The functional enrichment analysis revealed the functions and pathway involvement of DEGs. A ceRNA network was constructed based on 95 DEL–DEM–DEG interactions. Three DELs (LINC01555, AC015712, and FZD10-AS1) were associated with the overall survival of patients with colon cancer, and a prognostic signature was established based on these three DELs. High risk scores for this signature indicated poor survival, suggesting that the signature has prognostic value for colon cancer. Examination of clinical colon cancer tissues and GEO dataset analysis confirmed the results.

Conclusion

The ceRNA regulatory network suggests roles for location-specific lncRNAs in colon cancer and allowed the development of an lncRNA-based prognostic signature, which could be used to assess prognosis and determine treatment strategies in patients with colon cancer.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-021-01901-3.