According to the National Comprehensive Cancer Network (NCCN) guideline, psychological distress is a multifactorial and unpleasant emotional experience, involving changes in psychological, social, spiritual, and physical aspects (Riba et al., 2019). Psychological distress can be detected at any stage in patients with cancer and even remain throughout the cancer trajectory (Gao et al., 2010). Overall, studies reported a prevalence of 20–52% for psychological distress [distress thermometer (DT) > 4] among patients with cancer (Funk et al., 2016; Mehnert et al., 2018). However, compared to patients with other types of cancers, patients with lung cancer reported the highest incidence of psychological distress (Zabora et al., 2001), with a detection rate of 17.0–73.0% (Lynch et al., 2010; Chambers et al., 2015; Tian et al., 2021a). It is noted that approximately 220 million new lung cancer cases were estimated in 2020, ranking second place among all the cancers (Sung et al., 2021). Therefore, the anticipated prevalence of psychological distress among patients with lung cancer should be especially emphasized.

Psychological distress has become a major psychological problem faced by patients with cancer because it has been demonstrated to be associated with the occurrence of several adverse consequences (Riba et al., 2019). As an example, psychological distress was found to be the contributor to the interruption of anticancer treatment (Mausbach et al., 2015; Lin et al., 2017; Yee et al., 2017). Meanwhile, psychological distress has also been found to be associated with longer hospital stays (Nipp et al., 2017), poor quality of life (Chambers et al., 2015), and increased risk of mortality (Batty et al., 2017; Hamer et al., 2009). Moreover, psychological distress was evidenced to accelerate the growth of tumor cells (Zhang et al., 2020a). Therefore, to develop effective intervention protocols to address psychological distress among patients with lung cancer, it is critically important to clarify the potential mechanisms involved in the development and progress of psychological distress (Riba et al., 2019).

Mindfulness refers to an individual’s focused attention on the present moment and non-judgmental awareness (Kabat-Zinn, 2003). As a protective source of negative psychological outcomes, several studies have suggested the positive effects of mindfulness among different populations (Kashiwazaki et al., 2020), even in the general population (Freudenthaler et al., 2017). At present, several meta-analyses have demonstrated that interventions involving mindfulness elements (Cillessen et al., 2019; Zhang et al., 2019; Nnate et al., 2021; Rieger et al., 2021), such as mindfulness-based cognitive therapy (MCT), mindfulness-based art intervention, and mindfulness-based stress reduction (MBSR), significantly improved the psychological wellbeing of patients with cancer. It should be noted that, moreover, our previous study consistently determined the negative association between mindfulness and psychological distress among patients with lung cancer and further clarified the influence of mindfulness on psychological distress through the mediating role of social support and perceived stigma, with a slight total effect of 0.048 (Lei et al., 2021). However, are there other potential mechanisms else in the association between mindfulness and psychological distress among patients with lung cancer to be discovered and elucidated?

Illness perception refers to an individual’s reflection in both the cognitive and emotional aspects and coping styles through personal knowledge and experiences when one confronts symptoms or illness threats, which have been revealed to have an impact on health outcomes (Leventhal et al., 2016). In a prospective, longitudinal, and observational study, illness perceptions were demonstrated as a potential predictor of psychological distress in patients with non-muscle-invasive bladder cancer (Zhang et al., 2020b). Meanwhile, illness perception has been found to predict psychological distress in head and neck cancer survivors (Zhang et al., 2018), esophageal cancer survivors (Dempster et al., 2011), and breast cancer survivors (Zhang et al., 2017). However, it is not yet known whether the same association holds for patients with lung cancer. Moreover, no study has investigated the association between mindfulness and illness perception; however, mindfulness-based interventions have been found to reduce the level of negative illness perceptions in patients with rheumatoid arthritis (Dalili and Bayazi, 2019) or acute coronary syndrome (Nasiri et al., 2020). We, therefore, assume that the association between mindfulness and illness perception also holds among patients with lung cancer.

Perceived stress refers to an individual’s subjective perception of stress and assessment of the ability of processing stress (Kim and Jang, 2020), which was positively related to psychological distress among patients with lung cancer in our previous study (Tian et al., 2021a). Meanwhile, perceived stress was also speculated to be associated with mindfulness because mindfulness-based intervention protocols had generally been shown to reduce stress (Lengacher et al., 2021). Interestingly, the negative association between mindfulness and perceived stress has been detected in patients with digestive tract cancer (Zhong et al., 2019). Moreover, some studies have also investigated the relationship between illness perception and perceived stress and found that individuals will experience greater levels of perceived stress if they negatively perceived their illness (Miceli et al., 2019). Unfortunately, these relationships of variables introduced above have not yet been determined in patients with lung cancer.

In the light of the above, we performed this study to examine three hypotheses as follow: (a) illness perception is positively associated with perceived stress and psychological distress, (b) mindfulness can influence psychological distress through illness perception, and (c) mindfulness has an impact on psychological distress through simultaneously influencing illness perception and perceived stress among patients with lung cancer.

Psychological distress has been demonstrated to be associated with several negative clinical outcomes such as interruption of anticancer treatment, poor quality of life, and higher morbidity and mortality (Riba et al., 2019). It is imperative to clarify the potential mechanisms of the development and progress of psychological distress among patients with lung cancer to develop a more effective intervention protocol (Lei et al., 2021; Riba et al., 2019). The major aim of this study is to determine whether negative illness perception is positively related to be psychological distress and whether mindfulness may have a protective effect on psychological distress through negatively influencing illness perception and perceived stress among patients with lung cancer.

After completing this study, we found that 24.4% of patients experienced clinically significant psychological distress, which was consistent with previous findings (Tian et al., 2021a) although there also are some studies that reported a higher detection rate (Hong et al., 2015; Carlson et al., 2004). It is possible that the relatively lower detection rate of psychological distress in our study can be explained by the fact that patients experience significantly serious stigma after confirming the diagnosis of advanced lung cancer (Maguire et al., 2019), which has an impact on the tendency of patients to deliberately conceal their psychological distress. Moreover, as stated in our previous study (Lei et al., 2021), DT is not specific to patients with cancer (Hong et al., 2015) and cannot differentiate the risk of initial psychological distress from the accumulated risk of psychological distress, which may be an explanation for our findings.

Leventhal’s commonsense model of illness representations proposes that individuals’ illness perceptions are the major determinants of their health outcomes (Diefenbach and Leventhal, 1996). The individual will concurrently construct or elaborate both cognitive and emotional representations of their symptoms and illness to relieve the adverse impacts resulting from the symptom or an illness (Dempster et al., 2011). Some studies have revealed the association between illness perception and psychological distress among different populations (Zhang et al., 2017, 2018, 2020b). In this study, we first investigated the association between illness perception and psychological distress among patients with lung cancer and determined that illness perception was positively related to psychological distress.

As a positive psychological trait, mindfulness was found to be beneficial for improving adverse psychological outcomes through effective self-designed regulation and keeping positive emotional status (Ludwig and Kabat-Zinn, 2008). We have previously determined the direct association between mindfulness and psychological distress in patients with lung cancer; however, this specific association was not held in this study, which may be explained by the relatively mild severity of psychological distress compared with our finding (Lei et al., 2021). Moreover, we did not separately investigate the relationships of facets in mindfulness scale and psychological distress (Burger et al., 2021). Interestingly, we first determined the negative association between mindfulness and illness perception and revealed that mindfulness has an indirect impact on psychological distress through correcting negative illness perception. Illness perceptions refer to the attitudes, beliefs, and expectations of patients about symptoms or illnesses (Dalili and Bayazi, 2019), which are related to health information behavior practices and coping strategies (Katavic et al., 2016). Several studies have established that mindfulness-based interventions were associated with increased positive health perceptions and health behaviors (Roberts and Danoff-Burg, 2010), which provide theoretical support for our findings.

This study also revealed another novel finding that mindfulness indirectly influenced psychological distress among patients with lung cancer through the mediating effect of illness perception and perceived stress. As we introduced earlier, a higher negative perception of symptoms or illness represented worse psychological outcomes (Weinman et al., 1996). As one of the most common psychosocial risk factors, perceived stress has been suggested as a precursor state of adverse psychological outcomes because it has a negative impact on individual psychological adjustment (Kim and Jang, 2020). Previous studies also revealed the predictive effect of illness perception on perceived stress (Miceli et al., 2019; Sadeghi et al., 2019), which was further demonstrated in this study.

This study has some potential limitations that should be further interpreted. First, we used a convenience sample to investigate the associations between variables, which may introduce bias. Second, we calculated the theoretical sample size according to the number of variables, rather than performing an estimation based on acceptable statistical power. Third, all the patients were recruited from a single hospital in a single city and the sample size was relatively small; therefore, the generalizability of the study is questionable. Fourth, the level of mindfulness, illness perception, perceived street, and psychological distress were measured by using the self-report instruments, which may introduce subjective bias from patients. Definitively speaking, the prevalence of psychological distress and the type of scale could have some effects on the results.

This study first shows that illness perception is positively related to the perceived stress and psychological distress in patients with lung cancer and negatively related to mindfulness. This study provided some evidence for the hypothesis that mindfulness can relieve the severity of psychological distress by decreasing the level of negative illness perception alone or decreasing the level of negative illness perception and perceived stress simultaneously. Based on these findings, illness perception and perceived stress screening should be enrolled in mindfulness-based intervention strategies for patients with lung cancer. Certainly, the total effect of mindfulness on psychological distress through the two targeted pathways in this study was very low; we, therefore, suggest continuing to explore other potential mechanisms.

This study further clarified the potential mechanism of mindfulness on psychological distress through influencing illness perception and perceived stress in patients with lung cancer. From our current findings, mindfulness-based intervention protocol focusing on the correction of illness perception and reduction of perceived stress may be feasible and effective in improving psychological distress among patients with lung cancer.

The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.

The studies involving human participants were reviewed and approved by the Institutional Review Board of Chongqing University Cancer Hospital. Written informed consent to participate in this study was provided by the participants’ legal guardian/next of kin.

LT and XT: had full access to all of the data in the study and are held responsible for the integrity of the data and accuracy of the data analysis. X-PQ, LT, XT, and MJ-H: concept and design. X-PQ, LT, XT, and L-JY: acquisition, analysis, or interpretation of data. X-PQ, XT, and MJ-H: drafting of the manuscript. XT, G-HC, and MJ-H: critical revision of the manuscript for important intellectual content. X-PQ and XT: statistical analysis. XT: obtaining funding, administrative, technical, or material support. MJ-H: supervision. All authors contributed to the article and approved the submitted version.

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

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