Colorectal Tumour Mucosa Microbiome Is Enriched in Oral Pathogens and Defines Three Subtypes That Correlate with Markers of Tumour Progression.

Long-term dysbiosis of the gut microbiome has a significant impact on colorectal cancer (CRC) progression and explains part of the observed heterogeneity of the disease. Even though the shifts in gut microbiome in the normal-adenoma-carcinoma sequence were described, the landscape of the microbiome within CRC and its associations with clinical variables remain under-explored. We performed 16S rRNA gene sequencing of paired tumour tissue, adjacent visually normal mucosa and stool swabs of 178 patients with stage 0-IV CRC to describe the tumour microbiome and its association with clinical variables. We identified new genera associated either with CRC tumour mucosa or CRC in general. The tumour mucosa was dominated by genera belonging to oral pathogens. Based on the tumour microbiome, we stratified CRC patients into three subtypes, significantly associated with prognostic factors such as tumour grade, sidedness and TNM staging, BRAF mutation and MSI status. We found that the CRC microbiome is strongly correlated with the grade, location and stage, but these associations are dependent on the microbial environment. Our study opens new research avenues in the microbiome CRC biomarker detection of disease progression while identifying its limitations, suggesting the need for combining several sampling sites (e.g., stool and tumour swabs).

Tumor microRNAs Identified by Small RNA Sequencing as Potential Response Predictors in Locally Advanced Rectal Cancer Patients Treated With Neoadjuvant Chemoradiotherapy.

BACKGROUND/AIM: Rectal cancer accounts for approximately one-third of all colorectal cancers. Currently, the standard treatment for locally advanced rectal cancer (LARC) is neoadjuvant chemoradiotherapy (CRT) with capecitabine or 5-fluorouracil followed by curative surgery. Unfortunately, only 20% of patients with LARC present complete pathological response after CRT, whereas in 20-40% cases the response is poor or absent. The aim of our study was to evaluate whether microRNAs (miRNAs) in tumor biopsy specimen have the potential to predict therapeutic response in LARC patients. PATIENTS AND METHODS: In total 87 LARC patients treated by CRT were enrolled in our prospective study. To identify predictive miRNAs, we used small RNA sequencing in 40 tumor biopsy samples of LARC patients (20 responders, 20 non-responders) and qPCR validation of selected miRNA candidates. RESULTS: In the discovery phase of the study, we identified 69 miRNAs to have significantly different expression between the group of responders (TRG 1,2) and a group of non-responders (TRG 4,5) to neoadjuvant CRT. Among these miRNAs, 48 showed a lower expression and 21 showed higher expression in tumor tissues from poorly responding LARC patients. Five miRNAs were selected for validation, but only miR-487a-3p was confirmed to have a significantly higher expression in the tumor biopsy specimens of non-responders to neoadjuvant CRT (p<0.0006, AUC=0.766). Gene Ontology (GO) clustering and pathway enrichment analysis of the miR-487a-3p mRNA targets, revealed potential mechanisms behind miR-487a-3p roles in chemoradioresistance (e.g. TGF-beta signaling pathway, protein kinase activity, double-stranded DNA binding, or microRNAs in cancer). CONCLUSION: By combination of miRNA expression profiling and integrative computational biology we identified miR-487a-3p as a potential predictive biomarker of CRT response in LARC patients.

Therapy and Prophylaxis of Peritoneal Metastases from Colorectal Cancer.

Stage IV colorectal cancer is associated with high mortality, and the prognosis is significantly worse for patients have peritoneal metastases. Peritoneal carcinomatosis from colorectal cancer was considered incurable with an infaust prognosis. Median survival of untreated patients is about 6 months and palliative systemic chemotherapy can prolonge this time up to 20 months. Patients with this disease were previously only surgically treated if they had severe clinical symptoms or complications. This view has changed dramatically over the past 15 years. Aggressive cytoreductive surgery in combination with intraperitoneal chemotherapy may prolong median survival for more than 40 months in selected patients. The Peritoneal Surface Oncology Group International (PSOGI), the international authority on the treatment of peritoneal tumors, recommends cytoreduction with intraperitoneal chemotherapy as the standard of care for selected patients with moderate-to-small volume peritoneal metastases secondary to colorectal cancer. Macroscopic cytoreduction appears to be essential; however, the role of hyperthermic intraperitoneal chemotherapy and the optimal chemotherapeutic agent for intraperitoneal lavage to treat peritoneal metastases from colorectal cancer remain unclear. The results of ongoing and future clinical trials are eagerly awaited.

Role of the Microbiome in the Formation and Development of Colorectal Cancer.

BACKGROUND: The clinical, histopathological, and molecular characteristics of colorectal cancer vary considerably. Factors associated with the heterogeneity of this disease and with understanding the effects of heterogeneity on disease progression and response to therapy are critical for the better stratification of patients and the development of new therapeutic methods. Although studies have focused mainly on tumor molecular profiling, current molecular predictive and prognostic factors are relevant to specific groups of colorectal cancer patients and are mostly used to predict the applicability of targeted biological agents rather than to predict their benefits. Molecular profiling fails to capture aspects important for tumor growth and aggressiveness, including the tumor microenvironment. The gut microbiome, consisting of specific communities of all commensal, symbiotic, and pathogenic microorganisms, has been shown to have a significant impact on the development of many diseases, including Crohns disease, type II diabetes, and obesity. Recent studies have indicated that long-term dysbiosis of the intestinal microflora can influence the development and progression of colorectal cancer, as well as tumor aggressiveness and response to treatment. CONCLUSION: This review article summarizes current knowledge of the gut microbiome in colorectal cancer, including the various mechanisms by which the gut microbiome affects the intestinal wall, thereby contributing to the development and progression of colorectal cancer. This work was supported by Ministry of Health of the Czech Republic (project AZV 16-31966A), project of Ministry of Education, Youth and Sports of the Czech Republic - NPU I - LO1413 a Ministry of Health of the Czech Republic - RVO (MMCI, 00209805). The authors declare they have no potential conflicts of interest concerning drugs, products, or services used in the study. The Editorial Board declares that the manuscript met the ICMJE recommendation for biomedical papers. Submitted: 15. 4. 2019 Accepted: 17. 6. 2019.

Circulating Myeloid-Derived Suppressor Cell Subsets in Patients with Colorectal Cancer - Exploratory Analysis of Their Biomarker Potential.

BACKGROUND: Myeloid-derived suppressor cells (MDSCs) contribute to tumor escape from host immune surveillance and to tumor progression by producing tumor-promoting factors. We focused on clinical and analytical MDSCs-related issues as potential biomarkers and immune regulators involved in tumor progression. PATIENTS AND METHODS: We analyzed 10 patients with advanced colorectal carcinoma (CRC) with (M1 subgroup) or without (M0 subgroup) distant metastases at diagnosis. Peripheral blood was collected at diagnosis prior to treatment and subsequently 12 months after therapy initiation. Using multicolor flow cytometry MDSC subsets were evaluated. Monocytic MDSCs (M-MDSCs) were detected as CD45+ CD11b+ CD33+ HLA-DRlow/ CD14+ CD15-, granulocytic MDSCs (CD33hi PMN-MDSC) were detected as CD45+ CD11b+ CD33hi HLA-DRlow/ CD14 CD15+. For analytical and preanalytical studies, random fresh blood specimens predominantly from cancer patients were analyzed. RESULTS: Levels of circulating M-MDSCs were not associated with metastatic disease within advanced CRC patients. Levels of circulating CD33hi PMN-MDSCs were elevated in patients with distant metastases compared to T3 M0 subgroup. Circulating M-MDSCs increased upon treatment initiation in 9 out of 10 patients. CD33hi PMN-MDSCs substantially dropped upon treatment initiation in 5 out of 10 patients and substantially increased in 2 out of 10 patients. Analytical part showed that absolute and relative counts within each MDSC subset are correlated. Coefficient of variation (CV) for repeatability was 6-11% for M-MDSCs and 25-44% for CD33hi PMN-MDSCs. CV for reproducibility was higher with 8-22% for M-MDSCs and 35-79% for CD33hi PMN-MDSCs demonstrating that delay in measurement of MDSCs in whole blood specimen may distort quantification of circulating MDSC subsets. CONCLUSION: The quantification of MDSC subsets is substantially dependent on the type of specimen examined and its preanalytical processing. Exploratory analysis of M-MDSCs and CD33hi PMN-MDSCs in CRC patients revealed different dynamics of M-MDSC and CD33hi PMN-MDSC subsets in the context anti-cancer treatment. Key words: myeloid-derived suppressor cells - preanalytics - colorectal cancer - flow cytometry - immune monitoring.

Focal necrosis mimicking breast cancer following coronary bypass grafting.

BACKGROUND: Breast cancer can be diagnosed easily in most cases. However, occasionally, we are faced with some conditions that can mimic it. These may include inflammations, benign tumors, cysts, hematomas, or, more rarely, focal necrosis. CASE PRESENTATION: This report presents a case of focal breast necrosis following myocardial revascularization with the left internal mammary artery, which is a very rare condition, with only few cases described in the literature. The necrosis becomes usually apparent a few days or weeks after the surgery and is often coincidental with the dehiscence of sternotomy with necrosis of wound edges. As it mostly affects the skin, it can be easily recognized. Also, our patient developed a dehisced sternotomy shortly after the surgery but there were no obvious objective changes on the breast. The condition was first dominated only by non-specific subjective symptom-pain. Later, a lump in the breast occurred, when the sternotomy had already healed. Moreover, an enlarged lymph node was palpable in the axilla. Because of non-typical symptoms, the condition was suggestive of breast cancer for a relatively long time. The patient had suffered from a very strong pain until she was treated by mastectomy with a good clinical result. CONCLUSIONS: Mammary necrosis following the coronary artery bypass is rare. In most cases, it manifests on the skin shortly after the surgery concurrently with dehisced sternotomy, so it can be easily diagnosed. However, in sporadic cases, the symptoms may occur later and may mimic breast cancer. Our objective is to raise awareness of this rare condition.