Abstract / Summary
Background/Objectives: Patients undergoing surgery followed by adjuvant chemotherapy for gastrointestinal cancer frequently experience impaired health-related quality of life (HR-QoL). This post hoc analysis of the ProDeCa randomized trial investigated whether psychobiotic treatment was associated with longitudinal changes in HR-QoL. Methods: Participants in the randomized, double-blind, placebo-controlled ProDeCa trial (NCT06496438) received either a four-strain psychobiotic formulation or placebo for four weeks during adjuvant chemotherapy. HR-QoL was assessed using the Short Form-36 (SF-36) questionnaire at baseline (V0), treatment completion (V1), and two months later (V2). Longitudinal changes in the eight SF-36 domains and the Physical (PCS) and Mental (MCS) Component Summary scores were analyzed using mixed models for repeated measures. Results: The present analysis included 266 participants, with HR-QoL data available for 231–232 participants at V2, depending on the SF-36 outcome. Significant group-by-visit interactions were observed across the eight SF-36 domains (all p < 0.001), indicating divergent longitudinal HR-QoL trajectories between treatment groups. Visit-specific adjusted comparisons generally favored psychobiotics; however, between-group differences in Vitality and Mental Health were not statistically significant at V1 and became significant at V2. At V2, the adjusted LS mean between-group differences were 16.79 points for PCS (95% CI, 15.69–17.88) and 9.66 points for MCS (95% CI, 8.49–10.84). Exploratory subgroup analyses did not provide evidence of differential treatment effects based on formal interaction tests. Conclusions: Psychobiotic treatment was associated with more favorable longitudinal HR-QoL outcomes during adjuvant chemotherapy after gastrointestinal cancer surgery. These findings support further investigation of psychobiotics as an adjunctive strategy for HR-QoL support in larger multicenter randomized trials.