Psychiatric symptoms, such as those associated with depression and anxiety, are commonplace among cancer patients [1]. Their intensity and duration can vary significantly. They may manifest as temporary emotional responses given the immense stress of a cancer diagnosis and treatment, resulting in patients experiencing intermittent episodes of sadness or worry. Yet, when such symptoms persist, become intense, and continue for an extended period (usually at least two weeks), they may interfere with daily life and well-being, potentially escalating into diagnosable psychiatric disorders like major depressive disorder or generalized anxiety disorder [2,3]. In this study, we will use the terms ‘depression’ and ‘anxiety’ specifically in reference to the associated symptoms as perceived and reported by individuals. These subjective experiences will be gauged via standardized self-report measures, thus ensuring an accurate representation of these emotions.

Regardless of the stage in a patient's cancer journey, approximately 10% of cancer patients experience anxiety, while about 20% grapple with depression [4]. These mood disturbances pose an additional layer of hardship for cancer patients already burdened by physical and psychological distress. The presence of such added burdens has deleterious implications for the overall treatment experience, making the management and control of the condition more challenging [5]. Furthermore, the impact of anxiety and depressive symptoms extends beyond the individual's emotional well-being, affecting various facets of the care process. This includes compliance with treatment protocols [6], the duration of hospital stays [7], and, subsequently, their overall survival rate [8,9]. Given the high prevalence and detrimental effects of depression and anxiety in people with cancer, establishing evidence-based interventions for the provision of psychological support in cancer care becomes a matter of substantial clinical urgency.

Emerging evidence from trials of mind-body therapies (MBT), including relaxation/imagery [10], yoga [11,12], hypnosis [13], and creative therapies [14,15], suggests their potential as valuable adjuncts to the treatment of depression and anxiety in cancer patients. A growing body of research points to comparable psychological benefits from the use of Chinese Tai chi and Qigong [16,17], but, the magnitude of those effects and whether they differ based on patient characteristics, Tai chi/Qigong intervention properties in the context of clinical care, and the features associated with research design remain uncertain.

Tai chi, an ancient Chinese martial art, involves a continuous interplay of slow or sudden movements marked by dynamic patterns of motion. Implementing these motions demands Tai chi practitioners skillfully regulate their center of gravity, ensuring extreme body stability [18,19]. In comparison, Qigong boasts a longer historical lineage than Tai chi. This practice encapsulates diverse techniques aimed at fostering functional integrity and enhancing Qi, acknowledged as the vital life force in Chinese culture [20]. In typical Qigong practice, body motions exhibit a slower and less forceful nature than Tai chi. Yet, akin to Tai chi, Qigong involves flowing movements seamlessly synchronized with deep regulated breathing and meditative focus during motion. Despite differences in their gestural practices, both Tai chi and Qigong entail a foundational principle emphasizing mind-body unity, drawn from Chinese Traditional Medicine (CTM) [21]. Therapeutic Tai chi and Qigong practices, in this context, are firmly grounded in the synergy of body movement, spatial orientation, breathing regulation, and inner tranquility [22,23]. This unity represents a shared ethos that transcends their stylistic discrepancies, contributing to the holistic well-being of practitioners. For these reasons, Tai Chi and Qigong are viewed as equivalent mind-body interventions in this study, categorized together as TCQ, aligning with previous reviews [16,24,25].

TCQ has evolved as a form of MBT that finds utility in addressing cancer-related symptoms, such as fatigue [26,27], sleep quality [28,29], and overall quality of life [30,31]. Accumulated evidence from systematic review and meta-analysis examines its potential effects on the psychological well-being of cancer patients and survivors, particularly in symptoms of depression and anxiety [16,28,29,[32], [33], [34], [35], [36]]. However, despite rigorous review of existing meta-analytic studies, a definite understanding of TCQ's effects remains obscure. Certain inconsistencies and limitations in prior research motivate our study. Some meta-analyses were contradictory, showing significant improvements in depression [16,33,34] and anxiety [[32], [33], [34], [35]] in participants practicing TCQ, while others found no significant improvements [28,29,32,36]. The previous reviews lacked thorough exploration of how modifying variables such as patient characteristics, research design, or TCQ features influenced anxiety or depression outcomes. Lastly, conventional meta-analyses, due to their inherent assumption of independence, typically aggregate effect sizes from a single effect in each study. This approach can potentially cause an unnecessary exclusion of relevant data and loss of valuable information, particularly as TCQ intervention studies typically generate multiple effect sizes within each study due to elements such as a variety of comparisons, differing measurement scales, and distinct assessment timings.

To advance knowledge, we conducted a comprehensive review and meta-regression analysis, expanding on previous systematic reviews and meta-analyses. Using a multi-level meta-analysis technique to address multiple effects nested within studies, we focused on randomized controlled trials. The primary goal of this meta-analysis was to evaluate the effect of TCQ intervention on symptoms of depression and anxiety among adult cancer patients or survivors. Additionally, we explored whether patient characteristics, TCQ exposure, and study design features moderated these effects.