POP-UP: a Single-arm, Two-cohort Study: Trimodal Prehab for Upper GI and Pancreatic Cancer

This study, called POP-UP, is testing a three-part preparation program (exercise, nutrition, and psychological support) for people undergoing chemotherapy before surgery for pancreatic or stomach/esophageal cancer. The goal is to help patients get stronger before surgery to improve their recovery. **You may be eligible if...** - You are over 18 years old (if 75 or older, you must pass a geriatric fitness screen) - You have been diagnosed with localized pancreatic cancer or stomach/esophageal cancer confirmed by tissue sample - You are scheduled to receive at least 4 cycles (about 8 weeks) of chemotherapy before surgery - You are in reasonably good physical condition (ECOG score 0-1) - You have not had prior treatment for this cancer - You are enrolled in a national health insurance program **You may NOT be eligible if...** - Your cancer has spread to other parts of the body (metastatic disease) - Your tumor is not an adenocarcinoma (a specific type of cancer) - You have heart, lung, psychiatric, or musculoskeletal conditions that prevent safe exercise Talk to your doctor to see if this trial is right for you.