N83: Surveillance Recommendations For First-Degree Relatives Of Patients With Unexplained Multiple Colorectal Adenomas: A Nationwide Survey Of UK Regional Genetic Services

B. Desouza, A. Elniel, N. Jakharia-Shah, G. Norbury, A. Kulkarni, D. Ruddy, V. Tripathi, A. Shaw , L. Izatt

Guy’s Regional Genetics Service


Background: Patients with multiple colorectal adenomas (MCRA; 10-100 adenomas cumulatively) without a known genetic cause are increasingly being diagnosed in the UK. Germline monoallelic APC or biallelic MUTYH mutations are not identified in the majority of patients. Possible explanations include; APC mosaicism, cryptic mutations, mutations in other polyposis genes, and polygenic inheritance. Some guidelines have recommended regular colorectal surveillance for first-degree relatives of this patient group, but currently there is no national UK guidance.

Method: We conducted a national survey of UK regional genetic services to explore management practices for first-degree relatives of patients with MCRA without a known genetic cause. A web based-survey was sent by email to the cancer genetic lead clinicians at the 24 regional genetics services. The survey was primarily designed to assess surveillance recommendations for first-degree relatives of MRCA patients, and to determine whether recommendations varied according to the total number of adenomas and age of onset. Testing criteria and genetic investigations were also assessed for patients with MCRA.

Results: National survey results are presented.

Conclusion: The survey aims to highlight variation in the management of this patient group and their first-degree relatives in the UK.