OGBN P02 Report of early experience from newly introduced Cytosponge service
Authors: Patel Maitreyi , Osei Stella , Amalesh Thangadorai , Mukherjee Samrat , Mukherjee Dipankar 
Published: December 2022

Abstract

Background
Barrett's oesophagus (BO) is a pre cancerous lesion associated with increased risk of oesophageal adenocarcinoma through intermediary stages of increasing abnormalities on histology. Approximatley 3–6% of individuals with Gastro oesophageal reflux disease could have underlying BO. However, only 20% are diagnosed. This prevents early detection of oesophageal adenocarcinoma, which could provide an opportunity to prevent progression to cancer. Devising a feasible large scale screening tool which is safe and acceptable is challenging. Cytosponge is a non endoscopic diagnostic tool which utilises biomarker test for Trefoil factor 3 (TFF3), that identifies intestinal metaplasia which can increase detection of BO ten times over current standard of care. It also assesses for dysplasia (atypia and p53). Cytosponge is an North East London cancer alliance initiative. Our Trust introduced cytosponge as an NHS England clinical pilot. It was introduced to screen reflux patients initially, but was subsequently extended for BO surveillance to address the pandemic related backlog. Early identification of patients with BO or dysplasia will help proritise patients with highest risk, whilst minimizing the number of gastroscopies.
We report the initial experience with the cytosponge service our Trust. The aim of this study was to assess the accuracy and safety of cytosponge.

Methods
We conducted a retrospective cross sectional study of patients referred for cytosponge test at a large acute care Centre in North East London from a prospectively maintained database. Adult patients who were either on endoscopic surveillance for Barrett's oesophagus as well as those with reflux disease were included. We assessed the successful detection of BO (determined by TFF3 positive), number of cases with dysplasia and the overall uptake of the cytosponge procedure .
Demographic and clinical information were collected for each patient. Additionally, results of any previous endoscopies were recorded. Number of swallow attempts and failure in swallowing the Cytosponge were noted. ‘Failure to swallow’ was stated when the device could not be swallowed despite three attempts. Uptake of Cytosponge was assessed as the number of patients who successfully swallowed the capsule.
The number of patients discharged following the test, or referred for endoscopy was assessed. Anonymized patient data was tabulated in a computerized database (Microsoft excel, 2016). Normally distributed data was presented as median with standard deviation (SD).

Results
106 patients were referred for cytosponge test. 72 were on BO surveillance and 34 belonged to reflux cohort. 47 (44.34%) were females. Four patients (3.78%) failed to complete the procedure. 101 patients completed the test successfully within a median time of 20+/- 6 minutes. There were no reported adverse events. Median number of swallow attempts was one. 84 (79.25%) tests were performed without use of local anaesthetic. Intestinal metaplasia was confirmed by positive TFF3 in 41 (38.68%) patients. Nine (8.5%) had inadequate sample and were referred for a repeat test. Four (3.77%) results were equivocal. Low grade dysplasia was detected in five (4.71%) patients on BO surveillance. 11 patients were referred for urgent endoscopy. 24 of the 34 patients (70.58%) with reflux were discharged on the basis of cytosponge results. Three patients with BO were discharged due to old age. 20 BO patients determined as high clinical risk were referred for endoscopic assessment of which seven had urgent endoscopic assessment.

Conclusions
Cytosponge offers a minimally invasive, safe and effective method for prioritizing patients for endoscopy. This procedure can therefore aid in a more proactive approach in detecting and thereby treating dysplasia at an early stage. Cytosponge service can be efficiently run at an Acute Care Hospital by appropriate patient screening for suitability to undergo the test. This has helped reduce the number of endoscopies required, thereby reducing the pressures on endoscopy waiting lists.