Background: Although circulating tumour DNA has been detected in patients with different types of cancer, little is known of free RNA in cancer patients. Aims: We investigated the presence of RNA from epithelial tumours in plasma from patients with colorectal carcinomas, and its correlation with tumour characteristics and circulating tumour cells. Methods: β-actin mRNA was analysed to assess the viability of plasma RNA in samples from 53 patients with colonic cancer and 25 controls. Subsequently, nested primers were used to detect the presence of cytokeratin 19 (CK19) and carcinoembryonic antigen (CEA) RNA in the same samples. Nine clinicopathological parameters were studied to correlate the molecular and clinical parameters. Additionally, we investigated for micrometastases in blood in 18 of these patients and in 10 of the controls samples. Results: All samples had detectable quantities of β-actin RNA. In the controls, one case (4%) was positive for CEA and five (20%) for CK19 RNA; of the 53 patients, 17 cases (32%) were positive for CEA and 39 (73.6%) for CK19 RNA. This was statistically significant (p=0.000001). Advanced stages (p=0.03) and soluble CEA status (p=0.03) were associated with the presence of CEA, CK19, or both RNAs in plasma. Lymph node metastases (p=0.06) and vascular invasion (p=0.07) were almost significant. On the basis of these results, we examined the possible presence of micrometastases in blood in several of these patients. The presence of plasma tumour RNA was found to be associated with circulating tumour cells in blood (p=0.04). Conclusions: Epithelial tumour RNA is detectable in plasma from colon cancer patients. This molecular event is associated with advanced stages and circulating tumour cells. Our results could offer new approaches in the diagnosis and monitoring of colon cancer.

Background: Survival at the intermediate stage of colorectal cancer (CRC) is less predictable than in the early and advanced stages. Several genetic markers possibly involved in growth and progression of CRC can be used for prognosis. Aims: This study investigated the proportion of allelic loss (loss of heterozygosity (LOH)) at the BRCA1 locus in sporadic CRC and its value in patient prognosis. Patients and methods: A total of 314 patients were investigated for LOH at the BRCA1 locus using polymerase chain reaction by means of three intragenic polymorphic microsatellite markers. Allelic losses were compared with clinicopathological characteristics of patients, recurrence rate, disease free survival (DFS), and overall survival. Results: Twenty six patients were excluded because of microsatellite instability. Of the remaining 288 cases, 244 (84.7%) were informative, with 97 (39.8%) patients bearing BRCA1 LOH. Recurrence rate was higher in patients with LOH (p = 0.0003), and DFS was 73.3% (SEM 5.7) at five years in patients without LOH, and 49.2% (7.1) in cases with positive allelic loss (p = 0.0004). Retention of alleles at the BRCA1 locus was associated with a favourable DFS in stages I and II (p,0.05). The presence of LOH was also significantly associated with short overall survival (p = 0.02). Multivariate analysis in the complete series showed that stage (p = 0.006) and lymph node metastases (>4 nodes, p = 0.0001; 1-3 nodes, p = 0.038) were independent prognostic factors. However, multivariate study by stages revealed that BRCA1 LOH was an independent prognostic factor in stages I and II (p = 0.001). Conclusions: BRCA1 LOH is a molecular alteration present in CRC, with unfavourable repercussions for overall survival, that could be considered as an outstanding independent prognostic factor in stages I and II.

The objective of the present work is to promote a review of the main microbial markers for detection of colorectal cancer (CRC), as well as to explain the difficulties involved in their standardization. Several studies show the elevation of certain microorganisms to the detriment of the intestinal microbiome during the development of CRC and one of the reasons that favor them are virulence factors. Streptococcus galollyticus subs. gallolyticus and Clostridium symbosium are among the main microbial markers. However, isolates do not demonstrate the ideal sensitivity and specificity for CCR detection, and the result is optimized by associating some markers with the usual ones, such as human fecal hemoglobin (F-HB). These markers are promising, however, there is a need for further studies for their standardization.