Metformin as a Metabolic Intervention in Oesophageal Adenocarcinomas to Improve Response to Neoadjuvant Chemoradiotherapy

This study tests whether adding metformin — a medication usually used for diabetes — to standard pre-surgery chemoradiation therapy can improve treatment response in patients with operable esophageal or stomach-esophageal junction adenocarcinoma. **You may be eligible if...** - You have been diagnosed with surgically resectable esophageal or gastroesophageal junction adenocarcinoma (confirmed by biopsy) - You are planning to receive chemoradiation before surgery - You are 18 years or older - Your performance status is ECOG 0–1 (you are generally well enough to be active) - Your blood counts and organ function are within acceptable levels - You are willing to undergo two endoscopies for study purposes **You may NOT be eligible if...** - You already have diabetes and are taking anti-diabetic medication - You are allergic or intolerant to metformin - You have severe kidney disease - You drink alcohol excessively - You take certain medications that interact with metformin - You have had prior treatment (radiation or chemotherapy) to the esophagus - You are pregnant or planning to become pregnant Talk to your doctor to see if this trial is right for you.