LYNCH SYNDROME CASCADE TESTING; REFERRAL PATTERNS AND TESTING OF FIRST-DEGREE RELATIVES IN A FAMILY SCREENING CLINIC

Aims To examine genetic testing/referral patterns in the first-degree relatives (FDRs) of Lynch Syndrome (LS) patients and assess if all high-risk patients are being captured.

Methods We examined the pedigrees of all LS patients to determine the number of FDRs referred, tested through the clinic, tested elsewhere, not tested or refused testing.

Results Lynch Syndrome is one of the commonest major genetic conditions worldwide and the commonest known genetic cause of colorectal cancer (CRC). Approximately 15,000 people in Ireland have LS, with 100 CRCs/year diagnosed. It is estimated 95% of people with LS are unaware they have it. As an autosomal dominant condition, 50% of patients’ first-degree relatives are at risk of inheritance. It is important that family members are offered appropriate screening and surveillance.

Number of LS patients included= 92. Number of distinct pedigrees= 32. Number of FDRs= 670. Mean number of FDRs per Patient: 7.28 (Range 2-17). Total number of FDRs referred to clinic: 265 (39.6% of total FDRs). Genetic tests of the FDRs referred (not including tested elsewhere); total=228, Gene + 169, Gene - 59. FDRs referred but not tested 27. Refused testing= 15.

Conclusions This study shows that over 60% of FDRs are not being referred on to clinic for further assessment. Although a proportion of these may be assessed elsewhere, it is likely that many are unaware of their risk. Strategies to increase public awareness will increase early detection of these cancers. A national database would support appropriate/efficient management of individuals at risk and optimise cascade testing.