527. SURGERY FOLLOWING ENDOSCOPIC RESECTION OF EARLY OESOPHAGO-GASTRIC CANCER AT ONE LARGE TERTIARY UNIT: A RETROSPECTIVE AUDIT

Abstract Background Endoscopic resection (ER) is a therapeutic option for early oesophago-gastric (OG) cancer. It is recommended as primary treatment for T1a cancers and as an option in T1b cancers. Following ER, surgery is recommended if high-risk features are identified on post-operative pathology. The aim of this retrospective audit is to evaluate the outcomes of patients who underwent curative intent surgery following ER in a tertiary centre in the United Kingdom, to inform patient selection. Methods Data were retrospectively collected from 2015-2020 at one large tertiary referral centre. Patients were included if they underwent EMR for T1 oesophageal or gastric cancer. Patient demographics, information regarding referral and diagnosis, histology, staging, treatment and outcomes were recorded. Patients were offered surgical resection after EMR after discussion at a multidisciplinary team meeting. Data were analysed descriptively. Results 186 patients underwent ER. Seventeen subsequently underwent curative surgery (Females, n=4), see Table 1 for further details. 41% experienced Clavien-Dindo complications Grade I-V. Final histology were: 24% no residual cancer, 35% T1a, 24% T1b, 18% T2. The final stage was upgraded in 29%, 47% had the same grade or downgraded. Lymph node metastases were found in 24% of cases. In patients with no residual cancer after oesophagectomy: two had malignant deep margins on ER histology (T1b), one was recommended surgery, and one underwent chemo-radiation. Two patients had clear margins on ER (T1a m1), one had poorly differentiated histology and proceeded to surgery, the other underwent surveillance. Both patients who did not initially undergo surgery had recurrence (8 and 48 months). Conclusion Almost 10% of patients underwent surgery following ER. Despite selection criteria following international guidelines, 25% of those who underwent major surgery had no residual cancer following ER although a similar portion had positive lymph nodes. Morbidity and mortality following OG cancer remains significant and further work is required to better identify patients for surveillance following ER.