Introduction: There is a lack of data on familial aggregation of Colorectal Cancer (CRC) in northeast of Iran. We aimed to determine the frequency of hereditary nonpolyposis Colorectal Cancer (HNPCC) and familial Colorectal Cancer (FCC) and to determine the frequency of extracolonic Cancers in these families in mashhad.Methods: We reviewed documents of 202 patients with a pathologically confirmed diagnosis of CRC which pathology block were available in referral emamreza hospital in mashhad between 2014-2015.We found HNPCC and FCC families based on the Amsterdam II criteria and revised Bethesda and also interviewed them for family history of CRC and extracolonic tumors. The family history was taken at least up to the second-degree relatives Results: During 2014-2015, a total of 202 CRC cases have been assesed. Clinical diagnosis of HNPCC was established in 4 (2%) probands with amesterdamII criteria and 83 (41.3%) with revised Bethesda criteria.26.7% (54) of our patients were under 45 years old.Family history of CRC was more frequently reported by early-onset (AGE<=45Y) than by late-onseT (AGE>45) patients (58.3% vs.31.1% p< 0.001).Right colon Cancer was the most frequent site (30.8%) observed in patients with positive family history of Colorectal Cancer.Conclusion: We found a relative high frequency of HNPCC (2%) amsterdamII among CRC cases in our region and 40.5% had revised Bethesda criteria which immunuhistochemical or molecular study to confirm HNPCC should performed. Further studies in this field and designing a specific screening and national Cancer registry program for HNPCC and FCC families in this area should be conducted.

Background: The importance of microbiome in the progression and development of Colorectal Cancer (CRC) has been discussed in the last decade. Like colon bacteria, other intestinal microorganisms, including archaea, could also be involved in the CRC progression, so it’ s important to work out the archaeal microbiome (archaeome) composition among CRC patients. Objectives: The aim of this study was to determine the archaeome composition of CRC and healthy controls based on age and gender. Methods: Total bacterial DNA was extracted from 30 biopsy samples (17 CRC and 13 healthy controls). Archaeome communities were profi led by 16S rRNA high throughput sequencing, then compared to clinicopathological features, including CRC patients’ gender and age. Results: In the CRC patients, archaeal methanogens including Methanobrevibacter (86%) and Methanomassiliicoccus (8%) were overrepresented at the genus level. In contrast in the healthy controls, only two genera of haloarchaea including Natronococcus (58%) and Haloterrigena (42%) were presented. The results showed that the number of archaeal genera in men is higher than women in both the CRC and healthy controls. moreover, our results showed that the most genera of archaea are present in the CRC-32-50 group, six archaeal genera. The diff erential abundance taxa analysis results showed signifi cant diff erences between healthy controls and CRC patients (P  0. 05). Conclusions: The high abundance of methanogens in the colon archaeome of CRC patients compared to healthy controls suggests that methanogens may be involved in CRC development.