Germline variant testing in serrated polyposis syndrome.

BACKGROUND AND AIM: Serrated polyposis syndrome (SPS) is now known to be the commonest polyposis syndrome. Previous analyses for germline variants have shown no consistent positive findings. To exclude other polyposis syndromes, 2019 British Society of Gastroenterology (BSG) guidelines advise gene panel testing if the patient is under 50 years, there are multiple affected individuals within a family, or there is dysplasia within any of the polyps. METHODS: A database of SPS patients was established at the Oxford University Hospitals NHS Foundation Trust. Patients were referred for genetic assessment based on personal and family history and patient preference. The majority were tested for a hereditary colorectal cancer panel including MUTYH, APC, PTEN, SMAD4, BMPR1A, STK11, NTLH1, POLD1, POLE, GREM1 (40-kb duplication), PMS2, and Lynch syndrome mismatch repair genes. RESULTS: One hundred and seventy-three patients were diagnosed with SPS based on World Health Organization 2019 criteria between February 2010 and December 2020. The mean age of diagnosis was 54.2 ± 16.8 years. Seventy-three patients underwent genetic testing and 15/73 (20.5%) were found to have germline variants, of which 7/73 (9.6%) had a pathogenic variant (MUTYH n = 2, SMAD4 n = 1, CHEK2 n = 2, POLD1 n = 1, and RNF43 n = 1). Only 60% (9/15) of these patients would have been recommended for gene panel testing according to current BSG guidelines. CONCLUSIONS: A total of 20.5% of SPS patients tested were affected by heterozygous germline variants, including previously unreported associations with CHEK2 and POLD1. This led to a change in management in seven patients (9.6%). Current recommendations may miss SPS associated with germline variants, which is more common than previously anticipated.

Screening for Lynch syndrome and referral to clinical genetics by selective mismatch repair protein immunohistochemistry testing: an audit and cost analysis.

Lynch syndrome (LS) accounts for around 3% of colorectal cancers (CRCs) and is caused by germline mutations in mismatch repair (MMR) genes. Recently, screening strategies to identify patients with LS have become popular. We audited CRCs screened with MMR immunohistochemistry (IHC) in 2013. 209 tumours had MMR IHC performed at a cost of £12 540. 47/209 (21%) cases showed IHC loss of expression in at least one MMR protein. 28/44 cases with loss of MLH1 had additional BRAF V600E testing, at a cost of £5040. MMR IHC reduced the number of potential clinical genetics referrals from 209 to 47. BRAF mutation testing, performed in a subset of cases with MLH1 loss, further reduced this to 21. At a cost of £1340 per referral, this model of LS screening for clinical genetics referral had significant potential savings (£234 340) and can be easily implemented in parallel with MMR IHC done for prognostication in CRCs.

UK colorectal cancer patients are inadequately assessed for Lynch syndrome.

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.

The impact of obstructive sleep apnea on aortic disease in Marfan's syndrome.

BACKGROUND: Aortic dissection is a life-threatening manifestation of Marfan's syndrome. Preliminary evidence suggests that obstructive sleep apnea (OSA) is associated with aortic disease in Marfan's syndrome. OBJECTIVES: To study the effect of OSA on aortic events in Marfan's syndrome. METHODS: In patients with Marfan's syndrome, a sleep study was performed at baseline and OSA was defined as >5 events of apnea/hypopnea (A+H) per hour in bed. Operation because of progressive aortic dilatation and death because of aortic rupture were defined as 'aortic events'. Kaplan-Meier survival analyses were used to compare event-free survival in patients with and without OSA. Cox regression models were used to explore the effects of covariates on event-free survival. RESULTS: Data from 44 patients (mean age 37.4 years, 30 females) were available for analysis; 15 patients (34.1%) had OSA. The median follow-up time was 29 (interquartile range 24-36) months. Five patients had an aortic event within the follow-up time. Median event-free survival was 51.6 months. Event-free survival was significantly shorter in patients with OSA compared to patients without OSA (p = 0.012). In univariate analysis, A+H was associated with aortic events [hazard ratio (HR) 1.09, 95% confidence interval (CI) 1.01-1.18, p = 0.023]. Taking the interaction between BMI and A+H into account increased the HR for A+H (HR 1.75, 95% CI 1.003-3.048, p = 0.049). This association was no longer significant when other covariates were forced into the multivariate analysis. CONCLUSIONS: These data suggest that aortic event-free survival may be shorter in patients with Marfan's syndrome and OSA compared to patients without OSA, but more data from well-designed studies are needed to prove this association.