Gender specificity of colorectal cancer in the Republic of Tatarstan

The purpose of the study: to develop an expert system based on the construction of a «decision tree» for predicting the 5-year survival rate of patients with colorectal cancer. Material and Methods. T he study included 654 patients with colorectal cancer (CRC) who were treated from 2013 to 2015, including 434 men and 220 women. The average age of patients was 64,1 ± 10,2 years. All patients underwent genetic analysis for the presence of a mutation in the K-ras gene from the primary tumor. Results. For the Republic of Tatarstan, there are regional features of mutation of the K-ras gene: the frequency of mutations in tumors in men was less frequent (20.3 %) than in women (37.7 %), in patients of Slavic nationality, mutations were slightly more frequent - 39 % than in Tatars - 21 %. The gender approach to assessing long-term treatment results showed that in men with colorectal cancer, the most favorable treatment results were observed in patients with tumors in stage T1-2N0M0, regardless of the differentiation of the tumor and its mutational status. Low-grade tumors with any T should be considered prognostically unfavorable in men, with the presence of regional metastases and mutation of the K-ras gene, even in the absence of distant metastases: no patient lived 5 years. Based on the construction of a «decision tree», the most favorable treatment results were observed in female patients with tumors in stage T1-2-3N0M0 at the age of 70 years (5-year survival rate of 90 %), with tumors T1-2N0M0 at the age of 70 years (5-year survival rate of 81.8 %), regardless of the tumor differentiation and its mutational status. Tumors of any differentiation are prognostically unfavorable for women of the T3-4N0 stage with the presence of distant metastases (6 % of patients lived 5 years) and lowdifferentiated stage T4N0M0 tumors (5-year survival rate of 8 %). Conclusion. G ender- and age-associated features of the development and course of CRC are relevant for oncologists to choose effective diagnostic and therapeutic measures

Analysis of the intestinal microbiome in colorectal cancer

Aim. To conduct a comparative analysis of the microbiome of biopsies of a tumor and normal intestinal epithelium of patients diagnosed with colorectal cancer and to identify of functional activities of the obtained bacterial isolates that affect the development of the tumor. Methods. The study included 50 patients with malignant neoplasms of the colon: 36 men and 24 women. The mean age of the patients was 64.1±10.2 years. To analyze the microbiota of the biopsies, DNA samples were obtained from the tissue of the unaffected colon mucosa and tumor of the patients. Bacterial 16S rRNA genes fragments were amplified using bar-coded primer bakt_341f. Metagenomic next-generation sequencing was performed using the MiSeq platform (Illumina, USA). The obtained data were processed by bioinformatic methods using the QIIME package. Recognition of microorganisms depending on the morphotype and gram staining of the microflora was carried out using combination differential media and biochemical tests. Statistical analysis was carried out using Microsoft Excel, Service Pack 2 for Office XP, Statistica 6.0 (StatSoft). A comparative analysis was performed with the Student's t-test and the Mann-Whitney test in case of unmet conditions of validity. Alpha diversity of bacterial communities was quantified by the Shannon diversity index and the UniFrac distance for beta diversity analysis. Results. In patients with colorectal cancer, 5 bacterial phyla were isolated, the predominant of which were Firmicutes and Bacteroidetes, while the content of Actinobacteria was low. In addition, a higher number of representatives of Fusobacteria was observed in the tumor tissue compared to the tissue of a healthy mucosa, at a distance of 5 centimeters proximal to the tumor. The results of this study indicate that the microbiome of a tumor and a healthy mucosa fundamentally differ from each other not only in morphotype and gram staining but also in antagonistic, hemolytic and ribonucleolytic activities. Conclusion. Colonization of the tumor by dominant aggressive Gram-negative bacteria leads to significant changes in the tumor microbiome composition compared with normal mucosa, whose representatives are displaced from the damaged epithelium by more aggressive strains