Background:
Approximately one in twenty cases of colorectal cancer are caused by monogenic syndromes. Published guidelines recommend that patients with ten or more adenomas be referred for genetic testing, based on evidence that colorectal cancer risk is associated with adenoma multiplicity.

Objective:
The aim of this study was to determine adherence to guidelines on referral for genetic screening in patients with ten or more adenomas.

Design:
A cross-sectional study was performed of prospectively collected data from the United Kingdom Bowel Cancer Screening Program between May 2007 & June 2018. Only histologically confirmed adenomas were included. Clinicopathological data were recorded from patient records and referrals to clinical genetics services were ascertained.

Setting:
Data were obtained from three centres in London, United Kingdom.

Patients:
A total of 17,450 subjects underwent colonoscopy following an abnormal faecal occult blood test.

Main outcome measures:
We quantified patients with ten or more adenomas and the proportion referred for genetic screening.

Results:
The adenoma detection rate was 50.6% amongst 17,450 patients who underwent colonoscopy (8,831 had one or more adenomas). 347 patients (2.0%) had 10 or more adenomas. Patients with 10 or more adenomas were more likely to be male than those with less than 10 adenomas (76.9% vs. 53.4%; p<0.0001). A family history was collected in 37.8% of the multiple adenoma population. Of 347 patients with 10 or more adenomas, 28 (8.1%) were referred for genetic assessment.

Limitations:
All three screening centres were in a single city. No genetic outcome data were available to permit analysis of actual rates of inherited cancer syndromes in this population.

Conclusions:
In this study, almost one in fifty patients had ten or more adenomas. Despite guidelines advising genetic testing in this group, referral rates are low. A referral pathway and management strategies should be established to address this patient population. See Video Abstract at http://links.lww.com/DCR/B630.