Objective To establish whether colorectal cancer patients in two centres in the UK are screened appropriately for Lynch syndrome, in accordance with current international guidance.

Design Patients newly diagnosed with colorectal cancer over an 18-month period were identified from the UK National Bowel Cancer Audit Programme. Their records and management were reviewed retrospectively.

Setting Two university teaching hospitals, Imperial College Healthcare and Oxford Radcliffe Hospitals NHS Trusts.

Outcomes measured Whether patients were screened for Lynch syndrome—and the outcome of that evaluation, if it took place—were assessed from patients' clinical records. The age, tumour location and family history of screened patients were compared to those of unscreened patients.

Results Five hundred and fifty three patients with newly diagnosed colorectal cancer were identified. Of these, 97 (17.5%) satisfied the revised Bethesda criteria, and should have undergone further assessment. There was no evidence that those guidelines had been contemporaneously applied to any patient. In practice, only 22 of the 97 (22.7%) eligible patients underwent evaluation. The results for 14 of those 22 (63.6%) supported a diagnosis of Lynch syndrome, but only nine of the 14 (64.3%) were referred for formal mismatch repair gene testing. No factors reliably predicted whether or not a patient would undergo Lynch syndrome screening.

Conclusions Colorectal teams in the UK do not follow international guidance identifying the patients who should be screened for Lynch syndrome. Patients and their families are consequently excluded from programmes reducing colorectal cancer incidence and mortality. Multidisciplinary teams should work with their local genetics services to develop reliable algorithms for patient screening and referral.