Psychology & Health

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Trait mindfulness and depressive symptoms in non-small cell lung cancer patients: the mediating roles of quality of life and meaning in life Chia-Chen Hsieh , Chao-Chi Ho , Zhong-Zhe Lin , Chong-Jen Yu , Guey-Mei Jow , Feng-Ying Huang , Jin-Yuan Shih & Fei-Hsiu Hsiao To cite this article: Chia-Chen Hsieh , Chao-Chi Ho , Zhong-Zhe Lin , Chong-Jen Yu , Guey-Mei Jow , Feng-Ying Huang , Jin-Yuan Shih & Fei-Hsiu Hsiao (2020): Trait mindfulness and depressive symptoms in non-small cell lung cancer patients: the mediating roles of quality of life and meaning in life, Psychology & Health, DOI: 10.1080/08870446.2020.1825713 To link to this article: https://doi.org/10.1080/08870446.2020.1825713

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PSYCHOLOGY & HEALTH https://doi.org/10.1080/08870446.2020.1825713

Trait mindfulness and depressive symptoms in non-small cell lung cancer patients: the mediating roles of quality of life and meaning in life Chia-Chen Hsieha , Chao-Chi Hob, Zhong-Zhe Linc, Chong-Jen Yud,e, Guey-Mei Jowf, Feng-Ying Huangg, Jin-Yuan Shihb and Fei-Hsiu Hsiaoa,h a School of Nursing, College of Medicine, National Taiwan University, Taipei, Taiwan; bDepartment of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan; cDepartment of Medical Oncology, National Taiwan University Cancer Center, Taipei, Taiwan; dCollege of Medicine, National Taiwan University, Taipei, Taiwan; eBioMedical Park Branch, National Taiwan University Hospital, , Hsinchu, Taiwan; fSchool of Medicine, Fu-Jen Catholic University, Taipei, Taiwan; gDepartment of Education, National Taipei University of Education, Taipei, Taiwan; hDepartment of Nursing, National Taiwan University Hospital, Taipei, Taiwan

ABSTRACT

ARTICLE HISTORY

Objective: The present study examined the potential mediating influences of meaning in life and quality of life in the relationship of trait mindfulness and depressive symptoms in lung cancer patients. Design: We adopted a cross-sectional design studying a sample of patients with non-small cell lung cancer, aged 20–65 years, and receiving cancer treatments or follow-up care. Main Outcome Measures: The outcome measures included Beck Depression Inventory-II, European Organisation for Research and Treatment of Cancer Core Cancer Quality of Life Questionnaire (EORTC QLQ-C30) and lung cancer specific complementary measure (EORTC QLQLC13), Five Facet Mindfulness Questionnaire, and the meaning in life questionnaire. Results: Among 116 lung cancer patients, 26.72% of them had clinically significant depressive symptoms. The presence of meaning, quality of life (QOL) functioning and symptom distress mediated the relationship of trait mindfulness and depressive symptoms. Multiple mediation analyses found that the presence of meaning in life was the main mediator. Conclusion: The reductions of depressive symptoms might be related to trait mindfulness enhancing lung cancer patients’ perceptions of meaning in life. A mindfulness program has the potential to improve depressive symptoms in people with lung cancer.

Received 17 March 2020 Accepted 10 September 2020 KEYWORDS

trait mindfulness; depressive symptoms; function; symptom distress; meaning in illness

Introduction Lung cancer is the leading cause of cancer-related death globally (Vijayvergia et al., 2015). In addition to high mortality rates, disease burden includes high recurrence rates and second primary cancers (Huang et al., 2014). Lung cancer patients commonly experience CONTACT Fei-Hsiu Hsiao [email protected] Professor, School of Nursing, College of Medicine, National Taiwan University, Taipei, Taiwan; Vice Director, Department of Nursing, National Taiwan University Hospital, No.1, Jen-Ai Rd. Sec. 1, Taipei, Taiwan. ß 2020 Informa UK Limited, trading as Taylor & Francis Group

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physical distress (respiratory problems, peripheral neuropathy, pain, and fatigue), and psychological distress (fear of risk of recurrence, guilt about the failure of performing their roles in the family, and self-blame for their smoking resulting in lung cancer) (Boyes et al., 2013; Huang et al., 2014; Vijayvergia et al., 2015). The poor prognosis and heavy symptom burdens result in increasing rates of depressive symptoms among lung cancer patients (Boyes et al., 2013; Pirl et al., 2012; Sanders et al., 2010; Yun et al., 2013). Compared with other types of cancer survivors, lung cancer survivors identified as the highest risk group of suffering from depression at 12 months post-diagnosis (Boyes et al., 2013). Severe depressive symptoms of lung cancer patients predicted the worst survival rates (Arrieta et al., 2013; Sullivan et al., 2014; Walker et al., 2013). The increasing rates of depressive symptoms among lung cancer survivors are related to the burden of disease, a routine screening for a second cancer and access to effective treatments (Sanders et al., 2010; Yun et al., 2013). Over 10 years, mindful-based therapy (MBT) has been noted for its positive effects in improving depressive symptoms for breast cancer patients (Piet et al., 2012), but its effects for lung cancer patients have not been well examined. Before developing an effective intervention, the association of an individual’s trait mindfulness with depressive symptoms among lung cancer patients needed to be clarified. Trait mindfulness is defined as the tendency to be aware of the present moment, without judgement of an individuals’ own body sensations, thoughts, or feelings (Kabat-Zinn, 1990; Segal et al., 2002). A systematic review found that trait mindfulness was negatively associated with depressive symptoms and positively related to less rumination of negative experiences (Tomlinson et al., 2018). Lung cancer patients often experienced intrusive thoughts about cancer progression (Sanders et al., 2010). Mindfulness towards increasing cancer patients’ attention at the present moment reality helps them to disengage rumination about what causes the cancer or worries about cancer recurrence and death (Speca et al., 2006) and regulates the negative thoughts and feelings about cancer (Segal et al., 2002). Garland et al. (2017) found that the correlations of trait mindfulness with the increased meaning of illness and decreased emotional distress were through a series of positive psychological processes that included attention to positive information, positive reappraisal, and savouring among cancer survivors. Their findings supported the mindfulness to meaning theory (Garland et al., 2015) that demonstrated mindfulness awareness expanded the scope of attention to positive information, enhanced cancer patients’ positive reappraisals of stressful cancer events into positive meaning in life such as new opportunity for healthy lifestyle changes, and appreciation of their life. Self-reports of mindfulness levels that correlated with finding positive meaning in illness were also reported in a recent study on cancer patients (Park & Carney, 2018). The presence of meaning in life over a year predicted more severe depressive symptoms in breast cancer patients (Hsiao et al., 2013). The effect of trait mindfulness on reducing depressive symptoms via its impact on meaning in life is not well examined in lung cancer patients. A review study (Vijayvergia et al., 2015) found that after being diagnosed for six months to 2 years, physical distress in lung cancer patients remained higher than other cancer patients. Physical symptoms and side effects of lung cancer treatments were the factors associated with the depressive symptoms (Brintzenhofe-Szoc et al., 2009). The respiratory symptoms were the most common physical distress that increased

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depressive symptoms in lung cancer patients (Molassiotis et al., 2011). Patients’ experiences of breathlessness inducing hyper-vigilance of respiratory symptoms were related to the increases of anxiety and depression (Harrison et al., 2016). Sleep disturbance and fatigue were identified as the independent risk factors associated with depression in lung cancer survivors (Irwin et al., 2013). In addition to symptoms, lower performance status levels were associated with prolonged and intensive psychological distress (Kaasa et al., 1993). A review article by Mehta et al. (2019) reported that mindfulness intervention could effectively improve quality of life and symptom distress including pain, fatigue, and sleep disturbance in cancer patients. The previous studies of the effects of mindfulness practice mainly focused on breast cancer patients. It was not clear whether the correlations of trait mindfulness with symptom distress and functioning could therefore reduce depressive symptoms. In summary, the previous studies have persistently found that mindfulness was negatively associated with depressive symptoms (Piet et al., 2012; Tomlinson et al., 2018), but the potential pathway that might account for this association is not well understood in the lung cancer patients. The mindfulness to meaning theory (Garland et al., 2017) and the previous studies (Brintzenhofe-Szoc et al., 2009; Hsiao et al., 2013; Mehta et al., 2019) suggests that the pathway of mindfulness reducing depressive symptoms was through mindfulness enhancing positive meaning in life and quality of life. Because of the limited studies testing this hypothesis in lung cancer patients, in this pilot study, we adopted a cross-sectional design aiming to examine the potential mediating influence of meaning in life and quality of life in the relationship of trait mindfulness and depressive symptoms in lung cancer patients. We hypothesise that trait mindfulness would be negatively related to depressive symptoms and that this association would be mediated by meaning in life and/or quality of life (functioning and symptom distress).

Methods Participants This study adopted a cross-sectional design and analysed the baseline data from the supportive intervention study for the patients with lung cancer. Participants were recruited from the outpatient departments of surgery and oncology at the general hospital. Eligible participants were those who received a primary diagnosis of nonsmall cell lung cancer, were 20–65 years of age, and received cancer treatments, or follow-up care. Patients with presence of concurrent second cancer were excluded. Informed consent was obtained from all individuals after the researcher assistant explained this study. All participants were then asked to complete the questionnaires. No financial rewards or inducements were offered to participants. All data obtained were treated confidentially. The protocol for this study received approval from the hospital institutional review board.

Measures The outcome measures included Beck Depression Inventory-II (BDI-II), European Organisation for Research and Treatment of Cancer Core Cancer Quality of Life

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Questionnaire (EORTC QLQ-C30) and its lung cancer specific complementary measure (EORTC QLQ-LC13), Five Facet Mindfulness Questionnaire (FFMQ), and the meaning in life questionnaire (MLQ). BDI-II (Beck et al., 1961) consisting of 21 items was used to measure the severity of depressive symptoms over the previous two weeks. The total score ranges from 0 to 63 with higher scores indicating greater depressive symptoms. Cut-off values of 15 on the BDI-II were used to define severity at the level of clinical depression. Internal consistency reliability estimates for the BDI-II in the current sample were good (a ¼ 0.90). European Organisation for Research and Treatment of Cancer Core Cancer Quality of Life Questionnaire (EORTC QLQ-C30) and its lung cancer specific complementary measure (EORTC QLQ-LC13): The EORTC QLQ-C30 was developed by the EORTC QLQ Study Group for the measurement of QOL in cancer patients in clinical trials (Aaronson et al., 1993). It consists of 30 items and combines five functional scales (physical, role, cognitive, emotional, and social); nine symptom scales (fatigue, pain, nausea or vomiting, dyspnoea, insomnia, appetite loss, constipation, diarrhoea, and financial difficulties); and two global health and QOL items. Mean scales and item scores are transformed to a 0–100 scale according to the EORTC scoring manual. The EORTC QLQ-LC13 is a lung cancer-specific questionnaire that compliments the generic EORTC QLQ-C30. It comprises 13 items and combines lung cancer-associated symptoms (cough, haemoptysis, dyspnoea, and site-specific pain), treatment-related side effects (sore mouth, dysphagia, peripheral neuropathy, and alopecia), and pain medication. Internal reliabilities of EORTC QLQ-C30 and QLQ-LC13 in the current sample were adequate (a ¼ 0.53 to 0.91). FFMQ developed by Baer et al. (2006) consists of five dimensions of mindfulness: (1) observing (noticing or attending to internal and external experiences); (2) describing (labelling internal experiences with words); (3) acting with awareness (attending to one’s activities of the moment); (4) non-judging of inner experience (taking a nonevaluative stance toward thoughts and feelings); and (5) non-reactivity to inner experience (allowing thoughts and feelings to come and go, without getting caught up in or carried away by these experiences). The scores for each factor ranges from 8 to 40 (except for the non-reactivity, which ranges from 7 to 35), with higher scores indicating more mindfulness. FFMQ showed acceptable internal consistency reliability in the current sample: a ¼ 0.83, 0.88, 0.85, 0.79, 0.81, and 0.87 for observing, describing, awareness, non-judging, non-reactivity, and total scores, respectively. The MLQ (Steger et al., 2009) measures psychological well-being using two scales: a fiveitem MLQ-Presence scale, measuring the subjective sense that one’s life is meaningful, and a five-item MLQ-Search scale, measuring one’s drive and orientation toward finding meaning in life. Higher scores indicate higher levels of meaning in life. Internal reliability in the current sample was adequate (a ¼ 0.89 for presence scale and a ¼ 0.92 for search scale).

Data analysis strategy Data analysis aimed to test two hypotheses: (1) trait mindfulness was negatively related to depressive symptoms, and (2) QOL (global health, functioning, general symptom distress, and lung cancer specific symptom distress) and meaning in life might mediate the relationship of trait mindfulness and depressive symptoms. For mediation analysis, the

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SPSS macro PROCESS (Hayes, 2018) was utilised to examine the direct and indirect effects of mindfulness on depressive symptoms. We applied 5000 bootstrap samples to generate 95% bias-corrected confidence intervals (CIs) for the indirect effects, which indicated significant if zero did not fall within the CI. Simple mediation models were conducted to examine meaning in life, global health status, QOL functioning, general symptom distress, and lung cancer specific symptom distress as mediators of associations between trait mindfulness and depression. Multiple mediation analyses simultaneously included all hypothesised mediators in the model. We examined all relevant mediators at the same time to determine which was the major mediator.

Results Characteristics of participants As indicated in Table 1, 116 lung cancer patients with 68 females and 48 males participated in this study, with a mean age of 54.85 years (SD ¼ 7.29, range ¼ 26–65). The majority of participants were married (84.48%) and were religious (83.62%). Approximately half of patients were employed at the time of study participation (55.17%). More than half (56.03%) of the patients were at an advanced cancer stage (IIIB or IV). The majority of the patients were receiving lung cancer treatment while they participated in this study. The average duration since diagnosis was 32.91 months, with a range from 0 to 155 months.

Depressive symptoms The mean scores of the BDI-II depressive symptoms were 11.18 (SD ¼ 8.79), with a range from 0 to 42. Total 31 (26.72%) lung cancer patients who scored greater than 15 on the BDI-II scale appeared to have clinically significant depressive symptom. As noted, four (3.45%) of the patients’ score greater than 30 showed had severe depressive symptoms.

The correlations between the main factors and depressive symptoms The sociodemographic and medical variables were examined for associations with depressive symptom. The results found a significant difference in depression mean scores between the patients with and without the previous illness history of depressive disorders (26.50 versus 10.63, respectively, t ¼ 3.74, p < .001). Therefore, the previous illness history of depressive disorders was used as a covariate in all further analysis. Means and standard deviations with bivariate correlations for depression scores and other potential predictors are presented in Table 2. Depression negatively correlated with mindfulness (r ¼ 0.54, p < .001), presence of meaning (r ¼ 0.60, p < .001), search for meaning (r ¼ 0.34, p < .001), global health status (r ¼ 0.50, p < .001), and QOL functioning (r ¼ 0.62, p < .001). Depression positively correlated with QOL symptom distress (r ¼ 0.67, p < .001) and lung cancer specific symptom distress (r ¼ 0.44, p < .001). Mindfulness positively correlated with presence of meaning (r ¼ 0.62, p < .001), search for meaning (r ¼ 0.34, p < .001), global health status

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Table 1. Sociodemographic and clinical characteristics. Characteristic Age (mean ± SD), years Gender (%) Male/ female Education (%) High school and below/ undergraduate and above Working status (%) Employed/ unemployed Religion (%) With/ without Marital status (%) Single/ cohabitation History of smoking (%) Yes/ no Smoking partner (%) Yes/ no History of drinking (%) Yes/ no Cooking (%) Yes/ no Diagnosis of depression (%) Yes/ no Family history of cancer (%) Yes/ no Cancer stage (%) Early (I–IIIA)/ advanced (IIIB–IV) Current treatment (%) No treatment Chemotherapy Target therapy Radiotherapy Immunotherapy Chemotherapy plus immunotherapy Target therapy plus immunotherapy Surgery Time since diagnosis (mean ± SD), months

Lung cancer patients (n ¼ 116) 54.85 ± 7.29 41.38/ 58.62 49.14/ 50.86 55.17/ 44.83 83.62/ 16.38 15.52/ 84.48 26.72/ 73.28 31.03/ 68.97 3.45/ 96.55 63.79/ 36.21 3.45/ 96.55 69.83/ 30.17 43.97/ 56.03 15.52 34.48 41.38 2.59 0.86 2.59 1.72 0.86 32.91 ± 29.28

(r ¼ 0.25, p ¼ .006), and QOL functioning (r ¼ 0.29, p ¼ .002) while mindfulness negatively correlated with QOL symptom distress (r ¼ 0.34, p < .001) and lung cancer specific symptom distress (r ¼ 0.22, p ¼ .02). In the multiple regression model, after controlling for the covariate of previous illness history of depressive disorder, mindfulness, presence of meaning, search for meaning, global health status, QOL functioning, QOL symptom distress, and lung cancer specific symptom distress were related to 66% of the variance in depressive symptoms (F (8, 107) ¼ 26.39, p < .001). Specifically, mindfulness (B ¼ 0.08, SE ¼ 0.04, p ¼ .046), presence of meaning (B ¼ 0.42, SE ¼ 0.12, p < .001), QOL functioning (B ¼ 0.12, SE ¼ 0.05, p ¼ .026), and QOL symptom distress (B ¼ 0.22, SE ¼ 0.05, p < .001) significantly associated with depressive symptoms.

Simple mediation analysis Results of simple mediation analysis (presence of meaning, QOL functioning, and QOL symptom distress) are presented in Figure 1. The association of trait mindfulness with depressive symptoms was mediated by presence of meaning [effect ¼ 0.119, BootSE ¼

1. Depression 2. Mindfulness 3. Observing 4. Describing 5. Awareness 6. Non-judging 7. Non-reactivity 8. MLQ presence 9. MLQ search 10. Global health 11. QOL functioning 12. QOL symptom distress 13. LC symptom distress p < .001. p < .01. p < .05.

Mean/SD 11.18/ 8.79 129.57/ 17.48 27.72/ 6.05 27.28/ 6.39 28.61/ 5.77 23.13/ 5.64 22.83/ 5.37 23.97/ 6.62 24.56/ 6.64 59.91/ 21.34 77.36/ 15.06 22.96/ 15.89 16.88/ 12.12

1 1.00 –0.54 –0.13 –0.39 –0.60 –0.07 –0.42 –0.60 –0.34 –0.50 –0.62 0.67 0.44 0.66 0.84 0.79 –0.07 0.73 0.62 0.34 0.25 0.29 –0.34 –0.22

2

0.63 0.29 –0.52 0.50 0.42 0.37 0.12 –0.03 –0.15 –0.10

3

0.57 –0.37 0.62 0.53 0.32 0.13 0.19 –0.27 –0.23

4

0.08 0.41 0.58 0.23 0.34 0.44 –0.39 –0.26

5

–0.34 –0.18 –0.26 –0.04 0.06 0.01 0.14

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Table 2. Descriptive statistics and correlation matrix among the main study variables (n ¼ 116).

0.50 0.33 0.21 0.21 –0.23 –0.20

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0.58 0.38 0.34 –0.35 –0.36

8

0.38 0.28 –0.30 –0.30

9

0.65 –0.59 –0.45

10

–0.73 –0.55

11

0.64

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Figure 1. Simple mediation analysis for the relationship between mindfulness and depressive symptoms. Prior diagnosis of depression was controlled as a covariate. Unstandardised path coefficients and SE indicated above. Significant indirect pathways were boldfaced.  p < .001,  p < .01, p < .05.

0.031, 95% BootCI ¼ (–0.186, 0.064)], QOL functioning [effect ¼ 0.064, BootSE ¼ 0.027, 95% BootCI ¼ (–0.124, 0.016)], and QOL symptom distress [effect ¼ 0.089, BootSE ¼ 0.030, 95% BootCI ¼ (–0.153, 0.036)], respectively. The results support our hypothesis of the mediating influence of meaning in life, QOL functioning and QOL symptom distress in the relationship of trait mindfulness and depressive symptoms in lung cancer patients.

Multiple mediation analysis Figure 2 presents results of multiple mediation analysis that examined the main mediators among three mediators (presence of meaning, QOL functioning, and QOL symptom distress). The overall indirect effect of mindfulness on depressive symptoms through these three mediators was confirmed [Effect ¼ 0.166, BootSE ¼ 0.041, 95% BootCI ¼ (–0.255, 0.093)]. However, examining the specific indirect effects of each mediator in the multiple mediation models, only presence of meaning significantly mediated the relationship between mindfulness and depressive symptoms [Effect ¼ 0.081, BootSE ¼ 0.027, 95% BootCI ¼ (–0.138, 0.033)] while QOL functioning [Effect ¼ 0.012, BootSE ¼ 0.017, 95% BootCI ¼ (–0.055, 0.013)] and QOL symptom distress [Effect ¼ 0.020, BootSE ¼ 0.018, 95% BootCI ¼ (–0.060, 0.009)] did not significantly show mediating effects. Multiple mediation analyses confirmed the association of trait mindfulness with depressive symptoms was mainly mediated by the presence of meaning in life. Further analysis was conducted to identify what facets of mindfulness (observing, describing, acting with awareness, non-judging, or non-reactivity) were associated with presence of meaning. While one facet was examined, the other facets of mindfulness and previous illness history of depressive disorder were included as covariates in the analysis. The multiple mediation analyses revealed that the indirect effect of acting with awareness on depressive symptoms via presence of meaning in life was significant [Effect ¼ 0.170, BootSE ¼ 0.068, 95% BootCI ¼ (–0.323, 0.060)]. Acting with awareness was positively associated with the presence of meaning in life (B ¼ 0.456, SE ¼ 0.111, p < .001), and the presence of meaning in life was negatively correlated with depressive symptoms (B ¼ 0.373, SE ¼ 0.098, p < .001). The result revealed that

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Figure 2. Multiple mediation models for the relationship between mindfulness and depressive symptoms via presence of meaning, QOL functioning, and QOL symptom distress. Prior diagnosis of depression was controlled as a covariate. Unstandardised path coefficients and SE indicated above. Significant indirect pathways were boldfaced.  p < .001,  p < .01, p < .05.

among five facets of trait mindfulness, acting with awareness was particularly correlated with depressive symptoms and presence of meaning in life.

Discussion This study found that 26.72% of lung cancer patients had clinically significant depressive symptoms. The results indicated that QOL functioning, QOL symptom distress, and the presence of meaning mediated the relationship between trait mindfulness and depressive symptoms. Multiple mediation analysis revealed that among these mediators, presence of meaning in life was the main mediator. The results suggested that trait mindfulness could reduce depressive symptoms because trait mindfulness was helpful in releasing physical distress, functional decline, and enhancing presence of meaning in lung cancer patients. Consistent with the systematic review (Tomlinson et al., 2018), this study found an inverse relationship between trait mindfulness and depressive symptoms in lung cancer patients. This study suggested that association of trait mindfulness with depressive symptoms was likely through trait mindfulness enhancing lung cancer patient sense of meaning in life. Consistent with the recent study on cancer patients (Garland et al., 2017; Park & Carney, 2018), this study found correlations of trait mindfulness with lung cancer patients’ sense of meaning in life. Moreover, this study found that while five facets of trait mindfulness were tested in the model, acting with awareness correlated significantly with meaning in life and this link reduced depressive symptoms. Mindful awareness, which expands the scope of attention and allows accessing a broader information, helps an individual to engender the positive reappraisals of stressful life events (Garland et al., 2015). The path analysis on cancer patients indicated that the correlations of trait mindfulness

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with meaning of illness and emotional distress were through a series of positive psychological processes including attention to positive information, positive reappraisal, and savouring among cancer survivors (Garland et al., 2017). Their results demonstrated that through mindful awareness, cancer patients who paid attention to the positive aspects of cancer and reappraisal cancer as opportunities for personal and relationship growth; found joy in the ordinary life and established new priorities in life. This positive psychological process enhances the positive sense of meaning in life. Our previous study found that the lower presence of meaning in life over one year predicted more severe depressive symptoms in breast cancer patients (Hsiao et al., 2013). This study found an inverse relationship between the presence of meaning in life and depressive symptoms in lung cancer patients. The consistent findings suggest that the positive sense of the presence of meaning in life is the protective factor for cancer patients when they confront the life-threatening illness. Steger (2012) also demonstrated that the positive sense of meaning in life was associated with positive inner strength and effective use of positive coping strategies. This study found that QOL functioning and symptom distress mediated the relationship between trait mindfulness and depressive symptoms. The results suggest that the association of higher trait mindfulness with lower depressive symptoms is likely through trait mindfulness increasing functioning and decreasing symptom distress in lung cancer patients. Mehta et al. (2019) reported that a mindfulness program could improve quality of life and reduce symptoms distress in cancer patients. Lengacher et al. (2012) demonstrated that mindfulness practice that emphasised awareness of the present experiences with non-judgement, acceptance, and letting-go could reduce the impacts of life-threatening illness on interference of quality of life and symptom distress in breast cancer patients. Accordingly, trait mindfulness that might decrease the interference of the stress from cancer could enhance lung cancer patients’ QOL function and decrease their symptom distress. These are the potential explanations of the negative association of trait mindfulness with depressive symptoms. As noted, while general symptoms mediated the relationship between trait mindfulness and depressive symptoms, lung cancer specific symptoms (cough, haemoptysis, dyspnoea, and site specific pain) did not show the mediating effects. Nevertheless, dyspnoea was found to be the mediator of the relationship between acting with awareness and depressive symptoms. Patients’ experiences of breathlessness that induced hyper-vigilance of respiratory symptoms were related to increased depression (Harrison et al., 2016; Yohannes et al., 2010). Our finding may suggest that mindfulness focusing on breathing at the present without over reaction to the situation might decrease levels of dyspnoea and consequently, reduce depressive symptoms in lung cancer patients.

Clinical implications Based on the findings of this study, a mindfulness program, particularly cultivating acting with awareness, has the potential to manage the causes of depressive symptoms: symptom distress, functional impairment, and a lack of meaning for lung cancer patients. Mindfulness can be improved through practice. A mindfulness program can include mindful breathing, body scan and meditation to train mindfulness skills

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including awareness of the present moment, without judgement about individuals’ own body sensations, thoughts, and feelings. The mindfulness program is expected to reduce lung cancer patients’ depressive symptoms because it may help to disengage rumination, accept life-threatening illness, and establish new priorities in life.

Study limitations The main limitation of this pilot study was adopting a cross-sectional design, which provides evidence for association but not causal relationships. However, based on the mindfulness to meaning theory and the previous studies, this pilot study reveals that the potential pathway of mindfulness reducing depressive symptoms is likely through mindfulness enhancing positive meaning in life and quality of life. The associations and indirect effects identified in this study need to be tested in the future study using longitudinal design to form hypotheses of the potential mechanisms in this pathway existing stably during a period of time.

Conclusion This study concludes the mediating influence of meaning in life and quality of life in the relationship of trait mindfulness and depressive symptoms in lung cancer patient. A mindfulness program has the potential to improve depressive symptoms in people with lung cancer.

Funding This study was partially supported by the Ministry of Science and Technology under Grant (MOST 105-2314-B-002  135, MOST 106-2314-B-002  009 -MY2).

Declaration of interest All authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Data availability statement The data that support the findings of this study are available on request from the first or corresponding author.

ORCID Chia-Chen Hsieh

http://orcid.org/0000-0001-9529-6593

References Aaronson, N. K., Ahmedzai, S., Bergman, B., Bullinger, M., Cull, A., Duez, N. J., Filiberti, A., Flechtner, H., Fleishman, S. B., & de Haes, J. C. (1993). The European Organization for Research and Treatment of Cancer QLQ-C30: A quality-of-life instrument for use in international clinical

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