Endoscopic submucosal dissection (ESD) is a relatively new technique to treat superficial cancers in the upper gastrointestinal (GI) tract. Previous studies reported high en bloc resection rates (95%-97%). However, R0 resection rates (84.5%) suggest that the tumour is not radically removed in all cases, resulting in a risk of tumour recurrence. One of the key challenges is the limited accuracy in determining the depth of cancer invasion. To reduce the risk of tumour recurrence, the endoscopist would greatly benefit from proper and complete visualization of the tumour margin and depth during ESD. Several studies have shown that near-infrared quantified fluorescence molecular endoscopy (qFME) could serve as a red flag detection method and might be a useful imaging tool for tumour demarcation in the upper GI tract. The aim of this study is to evaluate the feasibility of ICG-enhanced near-infrared qFME to determine tumour demarcation and tumour depth in upper GI tumours (e.g. superficial esophageal and/or gastric adenocarcinoma (T1)) during ESD.