Could a smartphone app boost recovery before cancer surgery?

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * Adults ≥18 years. * Elective cancer surgery planned under general anesthesia at a participating site (e.g., gastrointestinal, hepatobiliary-pancreatic, thoracic, gynecologic, or other site-approved cancer operations). * Ambulatory: able to walk independently (assistive device such as a cane is allowed) and deemed safe to perform a six-minute walk test (6MWT) per investigator judgment. * Smartphone access and app use: owns/has regular access to a smartphone capable of running the study app and agrees to use the app (notifications, weekly home 6MWT logging, brief daily check-ins). * Preoperative lead-in: expected interval of ≈14 days or more between consent/randomization and surgery to allow prehabilitation exposure (shorter intervals may be screened but must allow minimum onboarding and at least one home 6MWT). * Able to understand study procedures and provide written informed consent (Korean or English literacy sufficient to follow app instructions). Exclusion Criteria: * Emergency surgery or surgery date that cannot accommodate even minimal prehabilitation onboarding. * ASA IV or higher, or any unstable/critical condition that, in the investigator's opinion, makes participation unsafe. * Contraindications to 6MWT/light walking, including but not limited to: unstable angina, recent myocardial infarction (≤30 days), decompensated heart failure, uncontrolled clinically significant arrhythmia, severe symptomatic aortic stenosis, severe uncontrolled pulmonary disease, or investigator-judged safety concerns (e.g., resting severe hypoxemia, high fall risk). * Non-ambulatory status or musculoskeletal/neurologic conditions that preclude performing a 6MWT. * Cognitive impairment or psychiatric/behavioral conditions that preclude informed consent or reliable app use. * Inability or unwillingness to install/use the study app (or lack of regular smartphone access). * Concurrent enrollment in another interventional clinical trial that would confound outcomes or burden participants (per investigator judgment). * Any other medical or logistical condition that, in the opinion of the investigator, would interfere with protocol adherence, outcome assessment on the preoperative day, or the routine postoperative follow-up visit.