Effects of Exercise-Based Interventions on Depressive Symptoms in Adults with Lung Cancer: A Systematic Review and...

Background and Objectives: Exercise is increasingly used in supportive care for lung cancer, but its effects on depressive symptoms remain uncertain. This systematic review and meta-analysis synthesized randomized evidence. Materials and Methods: Four electronic databases were searched for reports published from January 2000 to July 2026. Eligible studies enrolled adults with lung cancer and compared a structured exercise-based intervention with usual care or an eligible active rehabilitation comparator. One depression result per independent trial was selected using documented rules for assessment time, outcome format, and multiple intervention arms. A random-effects model used REML with Hartung-Knapp inference. Results: Seventeen studies met the eligibility criteria; 15 independent trials (1041 participants) contributed to the primary synthesis. The pooled effect favored exercise (Hedges' g = -0.75, 95% CI -1.18 to -0.32; p = 0.002), but heterogeneity was considerable (τ² = 0.4582; τ = 0.6769; I² = 87.1%; H² = 7.76; Q(14) = 74.11, p < 0.001) and the 95% prediction interval crossed the null (-2.27 to 0.76). The direction remained favorable in all sensitivity analyses, although exclusion of two influential studies attenuated the pooled effect to -0.49 and reduced I² to approximately 0%. Exploratory subgroup and study-level moderator analyses did not identify a stable explanation for heterogeneity. Certainty was very low after downgrading for risk of bias, inconsistency, and indirectness. Conclusions: Exercise-based interventions may reduce depressive symptom scores in some adults with lung cancer, but confidence in the magnitude and transferability of the average effect is limited. The evidence does not establish efficacy for major depressive disorder or identify an optimal modality, dose, or delivery format.