INTRODUCTION
Patients diagnosed with cancer often report experiencing internal struggles, feeling that their sense of self, social relationships and roles, and life’s purpose are threatened [1]. A life crisis can threaten the world that provides control and predictability to the individual who is under threat, impacting their safety and future [2]. Theorists who liken life crises to earthquakes [3] emphasized the importance of cognitive processes in adapting to stressful events by understanding and integrating the event into one’s life [4]. When an individual’s global meaning system is shattered, they often initiate a “meaning-making” process to construct a new meaning system. Subsequently, finding or creating appropriate meaning can lead to better adaptation [5].
Failure to discover meaning in life is associated with psychological distress, and a lack of meaning in life has been linked to higher levels of depression, anxiety, and suicidal ideation. Conversely, a greater sense of meaning in life has been associated with positive outcomes, including higher life satisfaction, happiness, and various other measures of psychological well-being [6]. In studies conducted with patients with cancer, those who reported a greater sense of meaning in life also exhibited lower levels of depression and anxiety while demonstrating a higher quality of life [5,7]. Given the crucial role that meaning in life appears to play in the adaptation process of individuals experiencing highly stressful events, such as cancer diagnosis [5], the assessment and intervention of meaning in life for cancer patients seems significant.
Over the past 20 years, the topic of life’s meaning has attracted considerable research interest, resulting in the development of several measurement tools [6,8-11]. Measurement tools examining the meaning of life predominantly focused on various aspects such as the presence of meaning, exploration of meaning [6], sources of meaning [12], and meaning crisis [11]. Tools have been developed to measure the meaning of illness among patients; however, assessment instruments specifically designed for particular patient groups, such as patients with cancer, are rare [13]. The majority of tools developed to measure the meaning of life were developed in North America, raising the need for validation of these scales in regions with different cultural backgrounds [13].
Reker proposed an integrative and multidimensional structure for the meaning of life, encompassing not only cognitive but also emotional and motivational aspects [14]. The Meaning in Life Scale (MiLS) integrates validated measures of meaning in life among patients with cancer, constructing multidimensional components incorporating cognitive, affective, and spiritual dimensions [15].
This study aimed to examine the structure of meaning in life among patients with cancer through the validation of MiLS. Additionally, this study explored the implications for clinical interventions applicable to patients with cancer by examining the structure of meaning in life and its correlates among patients with cancer.
METHODS
Participants
Participants were recruited from August 2021 to November 2022 from various locations in South Korea, including regional cancer centers, national cancer centers serving regional areas, university hospitals, and local communities. The inclusion criteria were as follows: 1) aged between 20 and 75 years, 2) within five years of cancer treatment, and 3) having no evidence of disease state. The exclusion criteria were: 1) diagnosis of metastatic cancer, 2) severe physical or mental symptoms, and 3) difficulty in responding to self-report questionnaires owing to visual or cognitive impairments. Patients were recruited in two stages: the first for exploratory factor analysis (EFA) and the second for confirmatory factor analysis (CFA). The MiLS has been validated only for cancer patients in the Americas [15,16], and given the lack of research in Asian cultural contexts, the present study followed a procedure of conducting EFA followed by CFA [17,18]. Without a solid theoretical foundation, it is recommended to begin with EFA; subsequently, CFA should be conducted on a separate sample to confirm whether the identified structure is consistent across various population groups [19].
Based on the recommendation that the variable-to-sample ratio should be at least 1:5 [20] and the sample size should exceed 100 [21] for EFA and that a minimum ratio of 1:10 and a typical sample size of 200 is for CFA [22], the target sample size was set at a minimum of 105 participants for EFA and 210 participants for CFA.
This study used data from a Ministry of Health and Welfare project (grant number HA21C0100).
This study was approved by the Ethics Committee at Seoul National University (H-2109-139-1258), National Cancer Center (NCC2021-0280), and The Cyber University of Korea (CUKRIB-202108-HR-002-01), South Korea. All participants were informed of the purpose of the study, the procedures and content of the assessments, and the confidentiality prior to signing the consent form. This study was conducted in accordance with the revised Helsinki Declaration of 2013 and ICH-GCP guidelines. All participants consented to the publication of research findings in academic journals or conferences under the condition of non-disclosure of personal information.
Measures
MiLS was used to measure the meaning of life in cancer patients. MiLS [15] is a 21-item scale comprising four dimensions. The original developer permitted us to develop the Korean version of the MiLS (K-MiLS). We adapted the scale in compliance with the guidelines of the International Society for Pharmacoeconomics and Outcomes Research [23]. Two bilingual individuals participated in the translation and back-translation processes, and the final items were confirmed through discussions with the authors. The K-MiLS items and scoring instructions used in this study are provided in the Supplementary Materials.
Depression was measured using the Patient Health Questionnaire-9 (PHQ-9). The PHQ-9 [24] comprises a total of nine items reflecting the diagnostic criteria for major depressive episodes outlined in the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition. The total score ranged from 0 to 27, with higher scores indicating a greater severity of depressive symptoms. Cronbach’s α for the PHQ-9 was 0.858 in this study.
The fear of cancer recurrence was assessed using the Fear of Cancer Recurrence Inventory (FCRI) [25], a multidimensional self-report scale comprising 42 items divided into seven subscales. A higher total FCRI score indicated a higher level of fear of cancer recurrence. Cronbach’s α for the FCRI was 0.943 in this study.
Anxiety was assessed using the Generalized Anxiety Disorder-7 (GAD-7). The GAD-7 [26] is a self-report scale consisting of seven items designed to screen for GAD-7 and to assess the intensity of symptoms. Higher scores indicate greater severity of anxiety symptoms. Cronbach’s α for the GAD-7 was 0.932 in this study.
The quality of life of patients with cancer was assessed using the Functional Assessment of Cancer Therapy-General (FACT-G, version 4). The FACT-G 27 comprises a total of 27 items grouped into four domains. Each item is scored on a scale of 0 to 4, with higher scores indicating a higher quality of life. In this study, we excluding two items (social/family well-being items 1 and 3) which had low correlations in the Korean version of the FACT-G [28] factor analysis, and utilized 25 items. Cronbach’s α for the FACT-G was 0.895 in this study.
The Posttraumatic Growth Inventory (PTGI) [29] was used to assess post-traumatic growth. It consists of 21 items measuring posttraumatic growth. Each item is rated on a 6-point scale, with higher scores indicating a greater experience of posttraumatic positive changes. In the validation study of the Korean version of PTGI, after excluding the five items (2, 4, 9, 14, and 20) with low factor loadings, the Cronbach’s α was 0.940.
Self-compassion was measured using the Self-Compassion Scale (SCS) [30], a self-report scale comprising 26 items organized into six subscales rated on a 5-point Likert scale. Cronbach’s α for the SCS was 0.925 in this study.
Social support was measured using the Functional Social Support Questionnaire (FSSQ) [31]. The FSSQ consists of eight items organized into two subscales on a 5-point Likert scale. Cronbach’s α for the FSSQ was 0.921 in this study.
Statistical analysis
To examine the construct validity, we divided the data into two groups (group 1 [n=123], group 2 [n=222]). We performed an EFA using a common factor analysis method with oblimin rotation in group 1. The number of factors was considered based on eigenvalues greater than one and loading values greater than 0.4. To clarify the factor structure further, an additional factor analysis was conducted on the entire participant group (n=345).
CFA was performed for group 2 using maximum likelihood to test whether our factor structure provided a good fit to the data. We assessed the model’s goodness-of-fit using the Goodness-of-Fit Index (GFI), Comparative Fit Index (CFI), Normed Fit Index (NFI), root-mean-square error of approximation (RMSEA), and Standardized Root Mean Square Residual (SRMR). GFI, CFI, and NFI values greater than 0.90, RMSEA values less than 0.08, and SRMR less than 0.1 are all acceptable for a good model fit [32,33].
To examine convergent and discriminant validity, we calculated Pearson’s correlation coefficients between the MiLS among Korean patients and other scales. We conducted correlation analyses between the PHQ-9, GAD-7, FCRI, and K-MiLS. We also conducted correlation analyses between the FACT-G, SCS, posttraumatic growth, FSSQ, and K-MiLS.
Regarding concurrent validity, hierarchical multiple regression analyses were conducted to validate the K-MiLS as a “predictor” of depression, anxiety, post-traumatic growth, and quality of life. Multiple regression analysis was conducted with controlled demographic and disease-related variables significantly correlated with the PHQ-9, GAD-7, PTG, and FACT-G. Correlation analysis, independent samples t-tests, and one-way analysis of variance were conducted to identify controlled variables associated with socio-demographic factors and the PHQ-9, GAD-7, PTG, and FACT-G.
Test-retest reliability was also assessed using Cronbach’s alpha values at two to four weeks intervals.
RESULTS
The demographic characteristics of patients are presented in Table 1.
The two samples did not differ in gender, marital status, religion, education, stage of cancer progression, or recurrence; age, type of cancer, and time since diagnosis differed among the patients. An independent samples t-test was conducted to examine whether the groups had differences in MiLS. The results showed no significant differences between the two groups.
EFA
To examine the factor structure of the K-MiLS, EFA was conducted on 21 items from 123 patients with cancer. The Kaiser-Meyer-Olkin measure of sampling adequacy (KMO=0.884) exceeded the recommended value of 0.6 [34], indicating that the 21 items formed a homogeneous collection of variables suitable for factor analysis. Bartlett’s test of sphericity (χ2=2248.973, p<0.001) also suggests that the correlations among the items are significantly different.
The factor analysis results indicated, consistent with a prior study [15] that the K-MiLS consists of a four-factor structure (Table 2). Four factors with eigenvalues greater than one emerged from the MiLS analyses. The eigenvalues for the first factor were 9.524 (45.351%), for the second factor 2.526 (12.027%), for the third factor 1.814 (8.640%), and fourth factor 1.023 (4.869%), respectively. The cumulative total variance of the four factors is 70.887%.
The factor analysis conducted on the entire participant group (n=345) revealed that while the factor structure and the included items were consistent with the results of the EFA, the loading values for each factor differed: Factor 1 was “Benefits of Spirituality,” Factor 2 was “Confusion and Lessened Meaning,” Factor 3 was “Harmony and Peace,” and Factor 4 was “Life Perspective, Purpose, and Goals.”
CFA
In the CFA, the goodness-of-fit indices for the K-MiLS with the four-factor model were high (GFI=0.884; CFI=0.952; NFI=0.907; RMSEA=0.065; SRMR=0.057).
Reliability for the MiLS
Cronbach’s α for the K-MiLS was 0.703 (ranged from 0.660 to 0.730). The “Confusion and Lessened Meaning” subscale indicated negative correlations with the other three subscales (Table 3). A 2-4-week test-retest reliability (n=219) was 0.925 (p<0.001).
Convergent and discriminant validity for the K-MiLS
The correlation between K-MiLS and negative emotions was for depression (r=-0.500), generalized anxiety (r=-0.413), and fear of cancer recurrence (r=-0.353) (Table 3). The K-MiLS showed positive correlations with quality of life (r=0.566), social support (r=0.450), and self-compassion (r=0.590). The correlation with post-traumatic growth (r=0.740) was strong. Given that the K-MiLS total score with other variables exhibited correlations of 0.3 or higher, the convergent and discriminant validity were confirmed to be at an above-moderate level [35]. Regarding concurrent validity, hierarchical regression analyses controlled for sociodemographic and disease-related variables associated with the K-MiLS explained 28.1% of the total variance for depression, 22.4% for anxiety, 55.1% for post-traumatic growth, and 34.3% for quality of life. All the regression models were statistically significant (Table 4).
Among demographic and disease-related variables, the variables correlated with K-MiLS were age (r=0.161, p<0.01), parental status (t=-2.907, p=0.004), marital status (t=-3.251, p=0.001), religion (t=-7.838, p<0.001) and time after cancer treatment (F=2.607, p=0.025). However, multiple regression analysis revealed that only religious affiliation (β=0.360, p<0.001) was significantly associated with K-MiLS.
DISCUSSION
This study aimed to explore the structure of meaning in the lives of patients with cancer through scale validation. This study demonstrates that the four subscales of the K-MiLS represent reliable and structurally sound measures. The four-factor structure, including “Harmony and Peace,” “Life Perspective, Purpose, and Goals,” “Benefits of Spirituality,” and “Confusion and Lessened Meaning,” is consistent with the results of a previous study [15]. The overall reliability was 0.703, with a retest reliability of 0.928. The CFI, NFI, RMSEA, and SRMR measurements met the criteria for a good model fit, suggesting that K-MiLS has an acceptable model fit. However, only the GFI did not surpass the acceptable threshold of 0.90, likely due to this study’s sample size. The GFI is known to be sensitive to sample size, and the sample size in this study was smaller than the typical sample size (n=250) for GFI [36]. In the case of reverse-scored item 15, it loaded redundantly on both the “Harmony and Peace” and “Life Perspective, Purpose, and Goals” domains. If duplicate loading occurs in scale items, the item can be included in a specific factor if there is a clear theoretical rationale [37]. In the case of the duplicated loading of item 15, the authors reached a consensus to include item 15 within the “Harmony and Peace” factor.
The intriguing aspect of the structure of meaning in the lives of patients with cancer was that they possessed perspectives and purposes in life while simultaneously experiencing confusion and a diminished sense of meaning. These results suggest that even if patients with cancer, who undergo surgery, radiation therapy, take medication, and experience side effects, discover the meaning of their lives, they may often experience confusion and a decrease in the sense of life’s meaning. The confusion and lessened meaning experienced by patients with cancer may also be part of the process of meaning-making [38] or searching for meaning [6].
“Harmony and Peace” appear to be related to the affective component among the meaning structures proposed by Reker and Wong [12]. In some previous studies, the emotional aspect that manifested in the meaning of life for patients with cancer was suggested to be “satisfaction” [39]; however, this remains unclear. This study suggests that the affective component in the meaning of life for patients with cancer is associated with harmony or peace.
Finally, the benefits of spirituality are associated with religious faith and spirituality [15]. Religion often provides a belief system necessary for understanding and enduring suffering and loss and is central to life’s purpose [40]. In modern times, while the term “religion” denotes organized, social, and traditional beliefs and practices, “spirituality” is often relevant to individualistic, transcendent, and relatedness concepts [41]. These findings suggest that spirituality and religion are important components of meaning in the lives of patients with cancer, not only in North America, where the scale was developed but also in areas with different religious and cultural backgrounds.
The factor analysis results compared with those from the original author’s study reveal that the four-factor structure and the included items were consistent. However, the original research showed the first two factors as “Harmony and Peace” and “Life Perspective, Purpose, and Goals.” In contrast, the factor analysis performed on the entire participant group in the present study (n=345) indicated that the first two factors were “Benefits of Spirituality” and “Confusion and Lessened Meaning.” Based on prior research indicating that sufficient time is necessary to discover the meaning of life, the original author conducted an EFA on cancer patients who had completed treatment, had no recurrence, and had been diagnosed for 2 years. Considering that approximately 45% of the participants in this study were diagnosed within 2 years, cancer patients may experience confusion regarding the meaning of life during the initial stages of diagnosis, where spiritual aspects may be particularly significant.
In the factor analysis conducted on the entire participant group (n=345), item 15, “I have trouble feeling peace of mind,” loaded above 0.4 on both the “Harmony and Peace” and “Life Perspective, Purpose, and Goals” factors. These results suggest that Korean cancer patients tend to associate their life perspective with a sense of inner peace.
To assess the convergent validity of the MiLS, the negative correlation observed between anxiety, depression, and meaning in life was aligned with previous research. These results suggest that individuals who lead meaningful lives may reduce depressive affect by living purposefully and proactively [42]. The benefits of finding meaning in life may also be associated with anxiety [43]. The convergent validity results also exhibit a sense of meaning in life, which is positively correlated with life satisfaction and social support, as supported by prior research [44]. Furthermore, consistent with a previous study [45], post-traumatic growth had a strong positive correlation, with correlations exceeding 0.7 [35].
Notably, the correlation between meaning in life and self-compassion was the second strongest correlation, following the correlation with post-traumatic growth. The measure of self-compassion was composed of three components: treating oneself with care during distressing situations (self-kindness vs. self-judgment), recognizing that suffering is a normal part of life (common humanity vs. isolation), and not downplaying or over-identifying negative thoughts but experiencing them in a balanced manner (mindfulness vs. overidentification) [30,46]. Therefore, individuals with high self-compassion are likely to observe experienced adverse events from a balanced perspective, accept themselves experiencing such events, and potentially modify past life goals to find realistic goals and meaning [47]. While several studies examined the relationship between self-compassion and meaning in life [47-50], to our knowledge, only one study involved patients with cancer [51].
In a controlled model with demographic and disease-related variables, the K-MiLS demonstrated statistically significant variations ranging from 22.4% to 55.1% in depression, anxiety, quality of life, and post-traumatic growth. Among the sociodemographic variables, the K-MiLS correlated with age, marital status, parental status, time after treatment, and religious affiliation. In the multiple regression analysis, no disease-related variables significantly correlated with the K-MiLS except religious affiliation. Religious affiliation was a significant predictor in the multiple regression analysis. This finding suggests that religious affiliation is an important aspect in the lives of patients with cancer that contributes to meaning in their lives.
Study limitations and future directions
This study has several limitations. First, in the CFA, the GFI did not exceed 0.90. This may be attributed to the relatively small sample size. Therefore, future studies should reconfirm the model fit using a larger sample size. Second, this study predominantly comprised female cancer patients in South Korea, with a relatively small representation of individuals aged 60 years and above. This limitation raises concerns about the generalizability of our results to a broader population of patients with cancer. Finally, this study presented a multidimensional structure of meaning in the lives of cancer patients but did not propose a specific model for how cognitive, emotional, and spiritual aspects interact with each other. Future research appears necessary to conduct integrated studies on the mechanisms of cognitive and emotional spiritual factors in the aspect of meaning in life among cancer patients, including each protective and risk factor.
Conclusion
The K-MiLS exhibited a multidimensional four-factor structure similar to its original version, establishing its reliability and validity in evaluating the meaning of life among cancer survivors. It may serve as a valuable tool for assessing the meaning of life for cancer survivors and implementing meaning-centered interventions.
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