Mediating effects of fatigue and health promotion behaviors on cognition and quality of life among patients with gastrointestinal cancer undergoing chemotherapy: a cross-sectional study

Purpose Cognitive disability, a common symptom among patients with gastrointestinal cancer undergoing chemotherapy, is frequently accompanied by fatigue and poor health promotion behaviors. These symptoms impair quality of life; however, their interrelationships remain unclear. This study aimed to determine whether fatigue and health promotion behaviors mediate the relationship between cognition and quality of life in patients with gastrointestinal cancer undergoing chemotherapy. Methods In this cross-sectional study, 127 patients were recruited from a university hospital in South Korea. A quantitative mediation analysis was conducted. The participants completed validated self-report measures assessing cognition, fatigue, behaviors, and quality of life. Data were analyzed using Hayes’ Process Macro with 50,000 bootstrap replicates. Results Our findings revealed that cognition influenced fatigue (B = 0.47, p  = 0.003), health promotion behaviors (B = − .35, p  < 0.001), and quality of life (B = -0.51, p  < 0.001), and fatigue and health-promoting behaviors mediated the relationship between cognition and quality of life (B = − .26, (95% CI, -0.345, -0.171), p  < 0.001; B = 0.61, (95%CI, 0.453, 0.779), p  < 0.001). Conclusion Cognition influences fatigue and health promotion behaviors, thereby directly impacting quality of life. Our findings support the need for integrated symptom management approaches in patient care. Interventions targeting fatigue and health promotion behaviors may be effective in reducing cognitive disability and improving the quality of life in patients with gastrointestinal cancer undergoing chemotherapy.