Patient-Reported Quality of Life and Fatigue After a Theory-of-Planned-Behavior-Informed Multicomponent Exercise Intervention During Systemic Treatment for Colorectal Cancer: A Secondary Analysis of a Randomized Trial

Background: Exercise can reduce symptom burden during colorectal cancer treatment, but the patient-reported effects of multicomponent programs that combine behavioral theory, individualized exercise prescription, and low-burden nudge strategies remain uncertain. Methods: This secondary patient-reported outcome analysis used the completed Shanghai single-center cohort of an open-label, parallel-group randomized trial. Fifty-six adults with stage II–IV colorectal cancer were assigned 1:1 to a 12-week theory-of-planned-behavior-informed multicomponent exercise intervention or an active comparator comprising usual care plus exercise guidance. Participants and interventionists were not blinded; scheduled outcome assessments were completed by nurses unaware of allocation. EORTC QLQ-C30 global health/quality of life and Cancer Fatigue Scale total score were designated as the two primary outcomes of this secondary analysis; they were not prespecified as co-primary outcomes of the parent trial. Baseline-adjusted mixed models for repeated measures estimated week12 effects, with Holm adjustment within this two-outcome family. Results: All 56 randomized participants contributed to longitudinal analyses; week 12 core outcomes were observed for 28 intervention and 27 control participants. The adjusted intervention-control difference was 22.75 points for global health/quality of life (95% CI 14.66–30.84; adjusted p < 0.001) and −14.74 points for Cancer Fatigue Scale total score (95% CI −18.48 to −10.99; adjusted p < 0.001). QLQ-C30 fatigue was 30.53 points lower, self-efficacy was 3.66 points higher, and adjusted physical activity was approximately doubled (ratio 2.03). No serious exercise-related adverse event was recorded; descriptive muscle-soreness counts were 7/28 versus 16/28 participants. Conclusions: The intervention group showed favorable adjusted 12-week differences in quality of life and fatigue, accompanied by coherent changes in self-efficacy and physical activity. Because delivery was open label and intervention contact exceeded comparator contact, the estimates represent the complete supported program and may include attention and expectation effects. These single-center secondary-analysis estimates support prospective confirmation in a fully enrolled multicenter trial. Trial registration: ChiCTR2400087302, retrospectively registered 24 July 2024. Funding: Shanghai institutional research programs.