This clinical trial is focused on studying a type of cancer called ampullary adenocarcinoma, which occurs in the area where the bile duct and pancreatic duct meet the small intestine. The study is investigating the effectiveness of different chemotherapy treatments in patients who have had this cancer surgically removed. The treatments being studied include a combination therapy known as modified FOLFIRINOX, which includes the drugs oxaliplatin, irinotecan, fluorouracil, and calcium folinate, compared to single-agent therapies using either capecitabine or gemcitabine. These medications are used to help prevent the cancer from returning after surgery.

The purpose of the study is to determine which treatment is more effective in improving the chances of staying cancer-free for two years after surgery. Participants in the study will be randomly assigned to receive either the modified FOLFIRINOX combination or one of the single-agent therapies. The study will last for up to 24 months, during which time participants will receive their assigned treatment and be monitored for any signs of cancer recurrence. Some participants may receive a placebo as part of the study design.

Throughout the study, participants will have regular check-ups to monitor their health and the effectiveness of the treatment. The study will also assess the overall survival rate, which is the time from the start of the study until death from any cause, and the quality of life of participants using specific questionnaires. The trial aims to provide valuable information on the best treatment approach for patients with resected ampullary adenocarcinoma, potentially improving outcomes and quality of life for those affected by this condition.