Prehabilitation to Enhance Preoperative Function in Elderly Undergoing Abdominal Malignancy Surgery

The goal of this observational study is to evaluate the effectiveness of the multimodal prehabilitation program at the Siriraj Integrated Preoperative and Prehabilitation Center (SiPAP) on improving preoperative walking capacity and functional status in patients undergoing elective intraabdominal cancer surgery. The main question it aims to answer is: \- Does the prehabilitation program lead to a significant change in 6-minute walk distance (6MWD) at preoperative admission as compared to at baseline assessment? Participants will receive the structured multimodal prehabilitation program, which represents the standard of care for patients in the ERAS protocol at the study site. Outcomes will be measured at preoperative admission and at 1 and 3 months after surgery.