The efficacy of cognitive behavioral therapy for mental health and quality of life among individuals diagnosed with cancer: A systematic review and meta-analysis

It has long been documented that cognitive behavioral therapy (CBT) has positive impacts on improving mental health (MH) and quality of life (QoL) in the general population, but investigations on its effect on cancer survivors remain limited, especially for QoL outcomes. The purpose of this meta-analysis is to investigate the effects of CBT as compared to control on cancer patients' MH and QoL outcomes. Control is defined in this study as standard therapy, waitlist control, and active/alternative therapy.

Cancer is a debilitating disease that affects millions of individuals each year around the globe. While treatments have advanced in recent decades improving longevity and survival rates, treatment regimens have serious impacts on the physical, psychological, and social well-being of oncology patients.These patients are prone to many psychological and mental health (MH) disturbances, including depression, anxiety, and decreased general wellness, due to these psychosocial burdens associated with cancer treatment. This effect can persist after treatment has ended, and cohort studies report higher incidences of anxiety and depression in long-term cancer survivors, with symptoms lasting for roughly 2 years or more after diagnosis. Addressing the issues that pertain to MH and general wellness is imperative for the long-term wellbeing of these patients. One common and effective intervention utilized in the treatment of MH and general wellness is cognitive behavioral therapy (CBT).

CBT has classically been utilized for the treatment of many MH disorders. Literature has shown that CBT in the general population is effective in the treatment of MH disorders, among them depression and anxiety, as well as improvements in quality of life (QoL).In a most recent meta-review of systematic reviews and panoramic meta-analysis by Fordham et al. a total of 494 systematic reviews and meta-analyses were identified, reporting an overall statistically significant and moderate treatment effect of CBT for QoL outcomes as well as for MH outcomes such as depression and/or anxiety. In addition, CBT has been shown to not only adequately treat MH disorders, but to reduce relapse and recurrence as well, a feature that is particularly noteworthy when treating chronic conditions such as those oncology patients face. In fact, studies have shown that CBT use is effective in cancer patients when treating distress and pain. Besides, CBT has also been shown to be effective in the context of insomnia, PTSD, fatigue, fear, anxiety and depression14 in cancer patients. However, whether CBT is more effective than standard care in the treatment of combined MH and general wellness in cancer patients remains unanswered and is an investigation point of this project. While these studies have shown CBT is effective in treating MH and general wellness in cancer patients, they do not address which outcome is better benefitted in response to CBT and little is known about other factors that may influence the efficacy of CBT.

Recent work has illustrated the efficacy of CBT on MH in breast cancer patients.15, 16 While these studies have shed light on the importance of CBT in treating cancer patients with MH disorders, they leave gaps in our understanding of CBT as an adjunct to treatment. Furthermore, there are a limited number of trials included in these recent works, and most were limited to nonmetastatic Stage 3 breast cancer patients, excluding cases with more widespread aggressive disease.17 Given all that is left to explore, we believe an updated analysis is warranted.

Herein, we discuss the effect of CBT on MH and QoL and analyze two potential moderators of the efficacy of CBT in patients in these two aspects of care: age of patients and the treatment delivery of CBT. We focused on age and treatment delivery of CBT as potentially significant factors impacting CBT's treatment effect for a couple of reasons. First, studies have reported a differential treatment effect of CBT across the age spectrum. For example, Zhang et al.18 systematically reviewed existing psychosocial, behavioral, and supportive interventions for pediatric, adolescent and young adult cancer survivors. Findings of the study suggested that supportive interventions, including CBT, were only effective for pediatric cancer patients but not for adolescents and young adults with cancer. Similarly, Mirosevic et al.19 found a significant treatment effect of CBT on cancer patients' survival only among middle- to older-adult patients but not among younger (< 40 years old) patients. Second, with recent advancement in technology, the delivery of CBT has become increasingly diverse with CBT delivery formats ranging from in-person to interpersonal CBT via technology (e.g., Zoom), or even a mixture of multiple methods. The efficacy of CBT in oncology patients may vary depending on delivery method and setting.20, 21 Specifically, a systematic review and meta-analysis of internet-delivered CBT for depression and anxiety among patients with chronic health conditions revealed overall significant and moderate treatment effect sizes for depression and anxiety, d = 0.31 and d = 0.45, respectively.22 On one hand, these point estimates seemed smaller than in-person CBT's treatment effect for cancer patients, for example, d = 0.57 for QoL or d = 1.10 for anxiety.23 On the other hand, in a recent meta-analysis, Carlbring et al.24 found that internet-based CBT for psychiatric and somatic disorders is equally effective as in-person CBT, indicating the need to further clarify the possible differential treatment effect of CBT for cancer patients' MH and QoL outcomes across different delivery formats. Performing this analysis is critical for understanding how to further provide all-encompassing, comprehensive treatment of cancer patients by not only addressing the disease, but also the psychosocial complications associated with treatments.

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