Meta-analysis on the Impact of Positive Psychological Resources on Quality of Life in Cancer Patients

Purpose: The main purpose of this study was to assess the evidence of the association between positive psychological resources and quality of life among cancer patients. Methods: Electronic search was performed to retrieve articles from PubMed, Web of Science, CNKI and CBM (from inception to November 10, 2020). Summary correlation coecient (r) values were extracted from each study, and 95% condence intervals (95%CIs) were calculated by random-effect model. Subgroup and sensitivity analyses were performed to investigate potential heterogeneity. Results: Forty-three articles were included in the present study. The pooled r for resilience was 0.52 (95%CI: 0.43, 0.62), hope 0.50 (95%CI: 0.44, 0.56), self-ecacy 0.54 (95%CI: 0.41, 0.63), self-esteem 0.45 (95%CI: 0.26, 0.64) and optimism 0.32 (95%CI: 0.17, 0.46). For subgroup analysis, the effects of hope and resilience varied with patients’ age. Conclusion: Our study indicated that cancer patients with high level of positive psychological resources tend to live a better quality of life. Therefore, interventions programs based on difference in age for cancer patients could be developed by increasing positive psychological resources in the future research. GCGM Generic and Treatment of cancer quality of life, Questionnaire. EQ-5D European Quality of Life-5 Dimensions. FACT-B = Functional Assessment of Cancer Therapy Breast cancer. FACT-BL = Functional Assessment of Cancer Therapy-Bladder. FACT-C = Functional Assessment of Cancer Therapy-Colorectal cancer. FACT-G = Functional Assessment of Cancer Therapy-General. FACT-H&N = Functional Assessment of Cancer Therapy-Head and Neck. FACT-Hep = Functional Assessment of Cancer Therapy-Hepatobiliary. FACT-L = Functional Assessment of Cancer Therapy-Lung. FLIC = Functional Living Index-Cancer. LASA = Linear Analogue Scale Assessment. MMQL-AF = Minneapolis-Manchester Quality of Life Instrument-Adolescent Form. MQOL = McGill Quality of Life Questionnaire. MQOL-C = Multidimensional Quality of Life Scale-Cancer. PedsQL = Pediatric Quality-of ‐ Life. QLACS Quality of Life in Adult Cancer Survivors. QLI Quality-of-Life Index. QOL-CS Quality of Life-Cancer Survivors. SF Short Form. UW-QoL University Washington quality of life. WHOQOL-BREF World Health Organization' s Quality of Life Questionnaire-Brief. Sensitivity analysis showed that all the pooled r for quality of life in cancer patients were stable, which indicated that our results were reliable. The result of the Egger test indicated that there was publication bias in this meta-analysis (hope: P = 0.733; resilience: P = 0.246; self-ecacy: P = 0.626; self-esteem: P = 0.545; optimism: P = 0.078).


Introduction
Cancer has been ranked as the major cause of death in developed or less developed countries, which is known as the most important barrier of enhancing life expectancy. Although medical anti-cancer therapies, radio and surgical-oncology have improved, these in turn threaten both patients' mental health and quality of life. Previous studies indicate that patients suffering cancer feel more di cult in handling with the negative emotion and experienced a poorer quality of life during the disease-free survivor stage [1][2][3]. A number of side effects like aggressive cancer therapy, medical nancial hardship, di culties in accessing affordable medical health insurance and limited employment opportunities [4][5][6][7] are thought to be the main reason.
Ultimately, cancer patients are vulnerable to threaten their physical and psychological well-being. However, a longitudinal study [8] reported that cancer survivors with high level psychological adaptation could better deal with the adversity in the course of disease, and had less psychiatric disorders, as well as better quality of life. Therefore, increasingly studies thought that positive psychological resources could help explain individual variation in quality of life in cancer survivors.
Positive psychological resources have been attached increasing attention to oncology eld in the past 30 years. According to the literature review, resilience, hope, optimize, self-esteem and self-e cacy are de ned as the important positive psychological variables in this eld. Several studies showed that cancer patients with high level of resilience were more able to cope with disease adjustment and maintain mental health [5,6,8]. Resilience is considered as a developable capability characterized by a relatively stable psychological trait that reduces, adapts to and even overcomes the destructive impacts caused by adverse factors in the face of disasters or stressors. It is thought to be a certain promoting role in alleviating the negative impact of traumatic pressure on individuals and maintaining the normal psychological state of the body [9]. Snyder [10,11] conceptualized hope as a positive motivational state based on inactively deprived sense of successful agency (achieving goals by available willpower and determination) and pathways (pursuing goals by creating alternative routines). Self-e cacy is de ned as positive belief of individual competence to deal with adversities or achieve desired goals in the face of various stressful situations [12]. Furthermore, several studies have been con rmed that general self-e cacy has a bearing on cancer patients' adjustment and management [13,14]. Optimism is a psychological trait that is considered as the degree of general expectation that positive outcomes will happen rather than bad things [15,16]. Compared with pessimists, research in optimism stated that optimists are capable to adapt to and deal with the negative impacts of cancer by accepting the reality, placing the light and humors among cancer patients [17].
At present, an extensive body of research has found that positive psychological resources are associated with cancer survivors' quality of life and well-being. For instance, Li et al [18] found that hope and resilience were positively associated with quality of life in adult patients with bladder cancer. Besides, Chung et al [19] suggested that greater resilience was associated with better quality of life and lower depressive symptoms, and self-esteem was also signi cantly related to physical and psychological well-being in children with cancer. However, a small number of studies thought positive self-esteem and self-e cacy were not associated with quality of life [20,21], or the association between them were pretty weak [22,23].
Differences in demographic variables of participants, disease characteristics, measuring method and study quality have been considered to induce the variability in referred study.
In sum, the present study aims to conduct a meta-analytic review containing all studies with cancer patients, which would investigate associations between positive psychological resources and quality of life. A broad review of literatures has been reviewed and ve positive psychological resources identi ed. Meta-analysis is adopted to identify which resources are associated with quality of life among cancer patients.

Study selection and procedures
According to the PRISM statement [24], the present meta-analysis was performed and was registered with PROSPERO (CRD42021228033). An electronic search was conducted to retrieve articles from PubMed, Web of Science, CNKI and CBM (from inception to November 10, 2020 The primary data of eligible articles were extracted by three authors independently. The primary data included the name of rst author, the year of publication, study location, sample size, the mean age of participants, cancer types, and the measuring methods of quality of life, and Spearman and Pearson correlation coe cient (r). Study quality was assessed by Joanna Briggs Institute (JBI) guidelines [25]. The JBI guidelines contain 10 items: purpose of the study, sampling method, characteristic description, reliability and validity of tool, authenticity of information, ethical issues, statistical analysis, statement of results and research value. It is scored from 0 to 2 (0 = "not meeting the requirements", 1= "mentioned but not described in detail", 2= "detailed and comprehensive description"), and the total score ranges from 0 to 20. When literature score > of the maximum total score 70%, it can be considered that the study quality is in a relatively high level. Two authors evaluated the study quality of included articles, and the third author solved disagreements in this meta-analysis.

Statistical analysis
Heterogeneity was tested by Q statistic (P < 0.05 = heterogeneity) and inconsistency index (I 2 > 50%=heterogeneity) [26][27][28], and publication was tested by Egger method [29] (P < 0.05 = publication bias). Random-effect model was used rather than xed-effect model due to high heterogeneity [30]. Subgroup analysis was used to nd whether effects were related to the factors like participants group. In addition, sensitivity analysis was used to adjust for one possible atypical study. R V4.0.2 was used to perform meta-analysis in this study.

Results
Our meta-analysis retrieved 6205 results. A total of 6162 studies were excluded due to duplicate, review and meta-analysis, meeting, clinical trial, book and document, and based on title and abstract and full-text. Finally, there were 43 [1,2,[18][19][20][21][22][23] articles in our study (Fig. 1). All articles presented clear research purpose, su cient research basis, authentic information, correct statistical analysis method, appropriate and correct statement of analysis result and research value. Only two articles adopted random sampling, and others used convenient sampling; 39 articles had clear inclusion and exclusion criteria; 41 articles clearly descripted characteristic of participants; 37 articles used measurement tools that were good reliability and validity; 19 articles indicated ethical issues (Table 1).        The meta-analysis of these studies found a large and signi cant overall effect size of r = 0.52 with con dence intervals excluding zero (95%CI: 0.43, 0.62) (Fig. 2). In addition, the results of subgroup analysis indicated that the impact of resilience on quality of life was larger for studies based in children and adolescent with cancer (k = 2, r = 0.68, 95%CI: 0.53, 0.83) than adult with cancer (k = 9, r = 0.49, 95%CI: 0.44, 0.54) ( Table 2).

Hope and quality of life
The meta-analysis of twelve studies involving 2853 patients with cancer, revealed a large and signi cant overall effect size of r = 0.50 with con dence intervals excluding zero (95%CI: 0.44, 0.56) (Fig. 2). In subgroup analysis, differences were found between the effects of hope for studies based in in children and adolescent group (k = 4, r = 0.57, 95%CI: 0.49, 0.64) as compared to adult group (k = 7, r = 0.48, 95%CI: 0.44, 0.52) ( Table 2).

Self-esteem and quality of life
Nine studies, involving 2211 cancer patients, examined the relation between self-esteem and quality of life, and yielded a signi cant and medium overall effect size of r = 0.45 with con dence intervals excluding zero (95%CI: 0.26, 0.64) (Fig. 2). Differences were not found between the effects of self-esteem on quality of life in subgroup analysis ( Table 2).

Self-e cacy and quality of life
Eleven studies involving 2265 patients with cancer examined the association of self-e cacy with quality of life. The current meta-analysis of these studies yielded a signi cant and large effect size of r = 0.54 with con dence intervals excluding zero (95%CI: 0.41, 0.68) (Fig. 2).

Optimism and quality of life
Five studies, involving 997 cancer patients, examined the relation between self-esteem and quality of life, and yielded a signi cant and medium overall effect size of r = 0.32 with all con dence intervals excluding zero (95%CI: 0.17, 0.46) (Fig. 2) and thus statistically signi cant.

Sensitivity analysis and publication bias
Sensitivity analysis showed that all the pooled r for quality of life in cancer patients were stable, which indicated that our results were reliable. The result of the Egger test indicated that there was publication bias in this meta-analysis (hope: P = 0.733; resilience: P = 0.246; self-e cacy: P = 0.626; self-esteem: P = 0.545; optimism: P = 0.078).

Discussion
The purpose of the present study was to conduct a meta-analysis

Self-e cacy and quality of life among cancer patients
The meta-analysis presented that highly e cacious cancer patients tended to live a better quality of life throughout the course of suffering cancer. The result was consistent with previous study, for instance in a recent meta-analytic review by Andrea et al involving 3162 cancer patients, there was a large signi cant overall effect size of r = 0.73 for the association of self-e cacy with quality of life [70]. The reason could be highly e cacious cancer patients characterized by sense of agency or control may perceive some causal relationship between coping behaviors executed and certain desired outcomes, including level of type of quality of life [71]. Future research may bene t from addressing the question of how self-e cacy interacts with other factors to affect quality of life in cancer patients. For example, a study found that self-e cacy for coping moderated the effect of distress on quality of life among breast cancer patients [72].

Resilience and quality of life in patients with cancer
Results from the meta-analysis indicated that highly resilient cancer patients could remain the better life quality, compared to low resilient individuals. Evidence suggests that high-resilient people strategically elicit positive emotions through the use of humor, relaxation techniques, and optimistic thinking in order to proactively cultivate their positive emotionality [68]. Then, positive emotionality emerges as the crucial element of resilience. It was found that resilience had indirect impact on cancer patients' quality of life by in uencing social support, in addition to direct impact [45]. Besides, resilience was found to be associated with lower psychological distress and fatigue among patients and survivors with cancer [73].
Subgroup analysis indicated that the relationship between resilience and quality of life among cancer patients was affected by age. Correlation of adolescent or children sample was signi cantly larger compared to adult sample, and the correlation of both groups was signi cant. Risks of loneliness and psychological distress rise with age for the elderly owing to the self-neglect and physical degradation, while resilience can effectively cope with these symptoms and enhance the quality of life, which was a crucial factor for successful aging [74,75]. However, it was inconsistent with previous study [76]. The result of adolescent or children sample might be overweight or inaccurate due to the small number of this group (k = 2). Thereby, future research may bene t from examining the effect of age on the association of resilience with quality of life.

Hope and quality of life in patients with cancer
The present meta-analysis indicated that cancer patients high in hope tended to show better health outcomes, such as quality of life. According to the theory of Snyder, hope is conceptualized as a positive motivational state based on interactively derived sense of successful agency (goal-directed energy) and pathways (planning to meet goals) [10,11]. Rousseau [77] found that hope could be developed by learning to control one's symptoms, exploring one's faith, and strengthening interpersonal relationships. It was also found in another study that individuals full of hope reported signi cantly higher levels of personal adjustment and global life satisfaction, and less psychological distress [78]. Subgroup analysis indicated that the effect of hope varied with the change of patients' age. The impact of hope on quality of life was more signi cant on studies based in children and adolescent with cancer than adult suffering cancer.
Furthermore, few studies aimed to explore the effect of hope on quality of life in children and adolescent with cancer. Therefore, future studies may bene t from efforts to increase or develop patients' levels of hope through psychological treatment, and focus on investigating the impact on children and adolescent with cancer.

Optimism and quality of life in patients with cancer
The meta-analysis reported that optimistic patients lived a better quality of life among cancer patients. The optimistic attitude plays a crucial role in effectively coping with disease diagnosis, treatment and prognosis, as well as in enhancing quality of life [77]. Furthermore, comparing with pessimists, optimistic cancer patients reported greater survival rates a year after diagnosis [79]. Most of studies investigated the effect of optimism on quality of life in adult patients with cancer, but few studies examined the association among children and adolescent patients. Hence, future studies can bene t from examining the impact of optimism on quality of life in children and adolescent.

Self-esteem and quality of life in cancer patients
Results of the current meta-analysis showed that the more self-esteem experience by cancer patients, the higher quality of life. many studies have indicated that patients with cancer had the low to moderate level of self-esteem [80-82]. Low self-esteem patients mean self-contempt, self-disappointment, self-rejection and lack self-respect for themselves. Based on the theory of Rosenberg [83], high level of self-esteem implies that they have high self-respect for who they are within limits, and do not assume that they are more superior in any way than anyone else. Cancer diagnosis has the tendency of affecting the patients' body image, which negatively results in changes in self-esteem. Even the easiest daily routine may be disrupted and patients need to be aware of these long-term consequences negatively in uencing their level of self-esteem. The results of subgroup analysis reported that the differences of age in the relationship between self-esteem and quality of life among cancer patients was non-existent, which was not similar to prior study [23].

Conclusions
The current meta-analysis provided a comprehensive summary of the current literature on positive psychological resources and quality of life among cancer patients. Results of our study indicated that cancer patients with high level of positive psychological resources tend to live a better quality of life. The effects of resilience and hope on quality of life varied with patients' age. Finally, interventions programs for cancer patients could be developed by increasing positive psychological resources in the future research.

Declarations
Competing interests The authors declare that there are no competing interests.

Funding
There was no funding support.  Figure 1 Study ow diagram Figure 2 Effect sizes of the correlation between ve positive psychological resources and quality of life