key: cord-0926678-3leww7j4
authors: Pilonis, Nastazja Dagny; Killcoyne, Sarah; Tan, W Keith; O'Donovan, Maria; Malhotra, Shalini; Tripathi, Monika; Miremadi, Ahmad; Debiram-Beecham, Irene; Evans, Tara; Phillips, Rosemary; Morris, Danielle L; Vickery, Craig; Harrison, Jon; di Pietro, Massimiliano; Ortiz-Fernandez-Sordo, Jacobo; Haidry, Rehan; Kerridge, Abigail; Sasieni, Peter D; Fitzgerald, Rebecca C
title: Use of a Cytosponge biomarker panel to prioritise endoscopic Barrett's oesophagus surveillance: a cross-sectional study followed by a real-world prospective pilot
date: 2022-02-03
journal: Lancet Oncol
DOI: 10.1016/s1470-2045(21)00667-7
sha: 46245e093529f1e67471de6685f509f91eb1ba7a
doc_id: 926678
cord_uid: 3leww7j4

BACKGROUND: Endoscopic surveillance is recommended for patients with Barrett's oesophagus because, although the progression risk is low, endoscopic intervention is highly effective for high-grade dysplasia and cancer. However, repeated endoscopy has associated harms and access has been limited during the COVID-19 pandemic. We aimed to evaluate the role of a non-endoscopic device (Cytosponge) coupled with laboratory biomarkers and clinical factors to prioritise endoscopy for Barrett's oesophagus. METHODS: We first conducted a retrospective, multicentre, cross-sectional study in patients older than 18 years who were having endoscopic surveillance for Barrett's oesophagus (with intestinal metaplasia confirmed by TFF3 and a minimum Barrett's segment length of 1 cm [circumferential or tongues by the Prague C and M criteria]). All patients had received the Cytosponge and confirmatory endoscopy during the BEST2 (ISRCTN12730505) and BEST3 (ISRCTN68382401) clinical trials, from July 7, 2011, to April 1, 2019 (UK Clinical Research Network Study Portfolio 9461). Participants were divided into training (n=557) and validation (n=334) cohorts to identify optimal risk groups. The biomarkers evaluated were overexpression of p53, cellular atypia, and 17 clinical demographic variables. Endoscopic biopsy diagnosis of high-grade dysplasia or cancer was the primary endpoint. Clinical feasibility of a decision tree for Cytosponge triage was evaluated in a real-world prospective cohort from Aug 27, 2020 (DELTA; ISRCTN91655550; n=223), in response to COVID-19 and the need to provide an alternative to endoscopic surveillance. FINDINGS: The prevalence of high-grade dysplasia or cancer determined by the current gold standard of endoscopic biopsy was 17% (92 of 557 patients) in the training cohort and 10% (35 of 344) in the validation cohort. From the new biomarker analysis, three risk groups were identified: high risk, defined as atypia or p53 overexpression or both on Cytosponge; moderate risk, defined by the presence of a clinical risk factor (age, sex, and segment length); and low risk, defined as Cytosponge-negative and no clinical risk factors. The risk of high-grade dysplasia or intramucosal cancer in the high-risk group was 52% (68 of 132 patients) in the training cohort and 41% (31 of 75) in the validation cohort, compared with 2% (five of 210) and 1% (two of 185) in the low-risk group, respectively. In the real-world setting, Cytosponge results prospectively identified 39 (17%) of 223 patients as high risk (atypia or p53 overexpression, or both) requiring endoscopy, among whom the positive predictive value was 31% (12 of 39 patients) for high-grade dysplasia or intramucosal cancer and 44% (17 of 39) for any grade of dysplasia. INTERPRETATION: Cytosponge atypia, p53 overexpression, and clinical risk factors (age, sex, and segment length) could be used to prioritise patients for endoscopy. Further investigation could validate their use in clinical practice and lead to a substantial reduction in endoscopy procedures compared with current surveillance pathways. FUNDING: Medical Research Council, Cancer Research UK, Innovate UK.

Cytosponge specimens were processed centrally by the Addenbrooke's Hospital Human

Research Tissue Bank, as previously described for patients from the BEST2 and BEST3

cohorts (1) and by the Cyted Ltd laboratory, Huntingdon, UK for patients included as part of the DELTA study. To qualify for inclusion in the study all patients had endoscopic evidence of columnar epithelium in the distal oesophagus with a minimum length of 1 cm Glandular atypia included clear cut dysplasia and those graded as 'atypia of unknown significance'. A p53 staining with an intensity of 3 was considered significant, as previously published (4) . Although the absence of p53 staining also constitutes abnormal expression in a small proportion of patients with a TP53 mutation, this cannot be reliably ascertained due to a lack of wild type basal cell staining on Cytosponge samples.(5) Consensus agreement for p53 over-expression and atypia between pathologists was used in any case of uncertainty.

The endoscopies were carried out by local study endoscopists and biopsies were performed using the recommended Seattle biopsy protocol whereby 4-quadrant biopsies were taken every 2cm of BO length and targeted biopsies taken for any visible nodular lesion. 

Decision tree clinical parameters for the 'moderate' risk group were developed based on the published risks for long-segment BO, patient age, and sex (7, 8) . We performed additional analyses on our retrospective training cohort to identify cutoffs that maximised sensitivity for the primary and secondary endpoints. Of the 24 patients diagnosed with HGD/IMC that were negative for both atypia and p53, 7 had BO segments that were in the highest quantile for Prague lengths ( M>10cm or C>6), 12 patients had BO segments longer than the median (5cm) and were either male or over 60 years at the time of the test. These clinical variables captured 79% (19/24) of the biomarker negative patients with HGD/IMC. The remaining 5 patients were short segment BO (≤3cm) and while this could indicate sensitivity limitations with respect to short segments, 15 of the 132 biomarker-positive 'high' risk cases were ≤3cm and were not subsequently diagnosed with HGD/IMC. Suggesting that false positives may be more likely than false negatives in these cases. 

Members of the Registered Charities Heartburn Cancer UK and Action Against Heartburn have assisted with devising patient-facing materials for Cytosponge and are members of the DELTA trial steering committee. Supplemental Table 1 . Significant coefficients associated with the primary (HGD/IMC) and secondary (any dysplasia) endpoints. Of the clinical features examined only BO length in cm (M) and patient age in years were associated and considered in subsequent risk prediction. Atypia and p53 show a much larger effect as shown by the odds ratios in both models. Figure 2 : ROC AUC plots corresponding to Table 1 for three diagnostic models: biomarker-positive(+) only (atypia or p53), biomarker+ with age and BO length (M), compared to clinical factors alone (age and length) for the primary (HGD/IMC) outcome. The asterisk in each shows the best fit threshold (balancing the sensitivity and specificity) for each curve. An important note for the biomarker-positive(+) only curve is that this is based on a binary predictor (biomarker is positive or negative) resulting in only a single threshold and so is shown only to provide a comparison to the multi-predictor models. Table 1 for three diagnostic models: biomarker-positive(+) only (atypia or p53), biomarker+ with age and BO length (M), compared to clinical factors alone (age and length) for the secondary (any dysplasia) outcome. The asterisk in each shows the best fit threshold (balancing the sensitivity and specificity) for each curve. An important note for the biomarker-positive(+) only curve is that this is based on a binary predictor (biomarker is positive or negative) resulting in only a single threshold and so is shown only to provide a comparison to the multi-predictor models. year old male patient, with a C0M3 BO segment was positive for both biomarkers but the endoscopic biopsies did not show any abnormality. The clinical characteristics mean that this patient would not fulfil the moderate risk criteria, but the Cytosponge atypia and p53 abnormalities are concerning ( Figure 4C , middle panel). He will be re-scoped in 6 months on the basis that dysplasia may have been missed due to sampling bias at endoscopy. (C) A 70 year old female patient, with a C0M2 segment, also considered clinically low risk, was found to have atypia and p53 on Cytosponge with a nodule containing IMC confirmed at endoscopy.

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