Patient-centered REhabilitation Program to Advance REcovery

The goal of this clinical trial is to learn whether an app-based, patient-centered prehabilitation program improves preoperative functional capacity in adults scheduled for elective cancer surgery. The main questions it aims to answer are: Does the program increase the six-minute walk distance (6MWD) measured on the preoperative day (within 24-48 hours before surgery)? Compared with usual care, does the program improve preoperative adherence to home 6MWT practice and patient-reported anxiety/depression (HADS)? Researchers will compare an app-based prehabilitation program to usual care to see if the program improves preoperative functional capacity. Participants will: Use a study app to perform weekly home six-minute walk tests (6MWT) and complete brief daily check-ins (exercise, nutrition, psychological status) before surgery. Attend routine preoperative admission (no extra visit) for in-hospital 6MWT (primary endpoint) and brief assessments (grip strength, Timed Up \& Go, HADS, skeletal muscle mass by InBody where available/fee-free). Attend one routine postoperative outpatient visit at 3 or 6 months (site-standard timing) for follow-up assessments. No additional study-specific clinic visits are required outside usual care.