To Investigate Risk of Colorectal Neoplasms in First-degree Relatives of Patients With Non-advanced Adenomas

The risk of CRC in families of patients with CRC is well established, but it is less well-defined for families of patients with adenomas. Screening recommendations to families when an index subject has an adenoma on colonoscopy are not clear. Previous studies demonstrating an increased CRC risk in close relatives of subjects with adenomas were mostly limited by the lack of a suitable comparison group, did not offer colonoscopy to all relatives or did not have verification on true status of adenoma history in the relatives. A systematic review has reported that most studies cited for risk of CRC in relatives with adenomas have not addressed the intended question. Currently International guidelines recommended screening colonoscopy in close relatives and at a younger age when there is a proband with an adenoma, however this recommendation has not been fully supported by all societies due to the lack of robust evidence. This gap in knowledge highlights the need of well-designed and adequately powered studies to estimate the risk of colorectal neoplasms in subjects who have first-degree relatives with adenomas. Up to 30% of average risk asymptomatic individuals 50 years or older will have at least one adenoma. Based on current guidelines, nearly half the population will be counseled to undergo a colonoscopy from 40 years old based on a positive family history of adenoma. This will have enormous burden on the healthcare system if screening is implicated in all these individuals. Secondly, not all adenomas carry the same risk. Large or villous adenomas are associated with a nearly 70% increased risk of CRC in first degree relatives (FDR) whereas small adenomas may be associated with a modest increased risk 19. It is therefore important to determine the risk of colorectal neoplasms in families of subjects with non-advanced adenomas to justify more intensive screening in these individuals. Investigators hypothesize that first-degree relatives of patients with non-advanced adenoma have an increased risk of both CRC and adenomas. Investigators aim to quantify this risk, and to identify other individual patient or neoplasm characteristics that may contribute to this increased risk. In addition, Investigators aim to determine molecular alteration profiles of colonic adenoma in siblings of patients with advanced neoplasm.

Sex

All

Minimum age

40 Years

Maximum age

70 Years

Inclusion Criteria:

* First-degree relatives (aged 40 to 70 years) of individuals diagnosed with non-advanced adenoma on screening colonoscopy as Cases
* FDR of patients with negative findings on colonoscopy identified during the same study period, who are of the same age group as the studied as Cohort

Exclusion Criteria:

* A FDR history of CRC
* A family history compatible with that of Hereditary Non-polyposis Colon Cancer (HNPCC) based on the Amsterdam criteria
* Known Familial Adenomatous Polyposis (FAP) syndrome
* Patients and siblings with known inflammatory bowel disease
* Undergone colonoscopy examinations in the past 5 years
* Severe cardio-pulmonary or other medical co-morbidities that preclude safe colonoscopic examination
* Pregnancy

• DERIVEDNg SC, Kyaw MH, Suen BY, Tse YK, Wong MCS, Hui AJ, Tak HY, Lau JYW, Sung JJY, Chan FKL. Prospective colonoscopic study to investigate risk of colorectal neoplasms in first-degree relatives of patients with non-advanced adenomas. Gut. 2020 Feb;69(2):304-310. doi: 10.1136/gutjnl-2018-318117. Epub 2019 Apr 26. PMID 31028155