N32: A Novel Mainstreaming Model For Lynch Syndrome Genetic Testing In Colorectal Cancer Patients

D. Georgiou1, B. Desouza2, A. F. Brady1, N. Ellery1, C. Berlin1, A. Latchford3, S. Clark3, H. J. Thomas4

1 – North West Thames Regional Genetics Service. 2 – South East Thames Regional Genetics Service. 3 – Polyposis Registry, St Marks Hospital. 4 – Family Cancer Clinic, St Marks Hospital.


Aim: New NICE guidance (2017) recommends universal tumour screening for Lynch syndrome (LS) in all patients with newly diagnosed colorectal cancer (CRC). Identifying CRCs with deficient DNA mismatch repair (dMMR) will guide further diagnostic testing for LS. Establishing a diagnosis of LS has important implications for the management of CRC patients. All CRC patients with suspected LS should have access to appropriate diagnostic testing performed within a suitable time frame.  Based on the anticipated rapid increase in clinical need, we have developed and implemented a novel mainstreaming model for LS genetic testing.

Method: Reflex IHC testing is undertaken in all newly diagnosed CRC cases; abnormal results are reviewed at the colorectal MDM, and eligible patients offered germline testing at their routine cancer appointments by appropriately trained cancer clinicians (i.e. oncologists and surgeons). Genetic results are fed back to patients by the cancer team, and all patients with a pathogenic variant or a variant of unknown significance are referred to clinical genetics for further management.

Results: We present the pathway as adopted at St Marks Hospital and the outcomes from the first year post implementation.

Conclusion: This pathway was effective at our hospital.