Mindfulness-based interventions for cancer survivors: what do we know about the assessment of quality of life outcomes?

KEYWORDS:

• Mindfulness
• meditation
• quality of life
• health-related quality of life
• psycho-oncology
• cancer survivors
• comprehensive care
• integrative health

Mindfulness-based interventions (MBIs) refer to the spectrum of integrative mind–body practices used to support wellness and alleviate suffering, thus enhancing the capacity for quality of life (QOL). Mindfulness practices offer tangible learning opportunities for cancer survivors to disengage from disruptive and worrisome thoughts of the past and the future and instead focus on pleasant, neutral, or uncomfortable experiences arising in the present moment [1]. Present moment awareness allows survivors to differentiate among their thoughts, emotions, and sensations arising from symptom and illness discomfort [1], offering them a greater sense of personal control, acceptance of current life circumstances, and engagement with what is most meaningful in their lives [2]. As a result, survivors often report significantly improved QOL as assessed by subjective questionnaires [3–5], suggesting MBIs as therapeutically valuable. Though the absence of a gold standard measure of QOL may inherently give rise to subjectivity regarding its assessment [6,7], current methods of reporting remain largely variable across trials. As such, disparate conceptualizations and measures of QOL may in fact limit our understanding of MBI impact on survivor health and well-being.

Despite significantly improved QOL, incomplete reporting and the use of different questionnaires across MBI trials are striking limitations. Carlson et al. [3] revealed significantly improved emotional (Cohen’s d = .27) and functional well-being (d = .27) domains, in addition to a ‘total’ QOL score (d = .22) as evaluated by the Functional Assessment of Cancer Therapy-Breast cancer (FACT-B) questionnaire. Physical and social/family well-being were also assessed by this measure, and although statistical significance was not reached, values were reported. Johannsen et al. [5] reported significant improvement in QOL as a single score (d = .42) derived from the World Health Organization Well-Being Index (WHO-5), a psychological well-being measure[8].

Conversely, Schellekens et al. [4] reported significant improvement in QOL as a ‘global health status’ composite score (d = .60) derived from the European Organization for Research and Treatment of Cancer Quality-of-Life questionnaire (EORTC QLQ-C30). Though this measure provided physical, role, emotional, cognitive, and social functioning and cancer-specific symptomology scores, corresponding results were not reported. Incomplete reporting limits our understanding of how various QOL domains are influenced by the experience of cancer[9], whereas the assessment of varying aspects of QOL through use of different questionnaires contributes to inconsistent views of the overall conceptual breadth and operationalization of this outcome.

Though reported as QOL, the questionnaires most often utilized in MBI trials are in fact assessments of ‘health-related quality of life’ (HRQOL) [10], a discrepancy frequent to oncologic literature [6]. HRQOL indicates the subjective perceptions of an individuals’ symptoms, including physical, emotional, social, and cognitive functions, disease symptoms, and side effects of treatment [11], and is considered synonymous with ‘subjective health status’ [7]. The FACT (‘general’ or cancer-specific version), EORTC QLQ-30, and the Medical Outcomes Study Short Form Survey (SF-36) common across cancer trials more adequately reflect this conceptualization [9]. However, the WHO-5 would not be considered a comprehensive assessment of HRQOL.

Accurate conceptualizing and measurement of QOL, however, have been a topic of debate due to it being subject to numerous interpretations [7,11]. QOL is an ‘umbrella term’ covering a variety of concepts including functioning, health status, perceptions, life conditions, behavior, happiness, lifestyle, and symptoms [12], but has been delineated as analogous to ‘satisfaction with life’ [7]. Some of the most widely used QOL measures used in MBIs fall short of reflecting aspects of life that are most important to survivors, spirituality, for example [13–16]. In their MBI trials, Carlson et al. [3] and Henderson et al. [17] assessed HRQOL via the FACT-B with a supplement that measured spirituality (Functional Assessment of Chronic Illness Therapy-Spirituality [FACIT-Sp]). Survivors reported significant improvement in areas of peace, meaning, and faith [3,17]. Because MBIs foster a spiritual sense of connection with self and others [18], including spirituality as a QOL domain is specifically useful in MBI trials. In agreement with Carlson et al. [3] and Henderson et al. [17], we recommend the FACIT-Sp, a psychometrically sound measure of spirituality for people living with cancer [19].

In addition, common questionnaires evaluating QOL mainly evaluate the negative aspects of cancer and do not tap diverse cancer-related experiences that include positive aspects [14,16]. We identify two rigorous multidimensional questionnaires used in cancer research that capture both positive and negative experiences of cancer, in addition to spirituality. We encourage future MBI trials to consider usage of the McGill Quality of Life Questionnaire (MQOL) [14], which assesses both positive and negative aspects of physical, psychological, existential, and support domains of QOL, or the Quality of Life-Cancer Survivors Scale (QOL-CS) [16], which assesses the physical, psychological, social, and spiritual domains specific to survivors.

In summary, we encourage future MBI trials to investigate QOL in cancer survivors but avoid using QOL and HRQOL interchangeably. Survivors with significant health and functional problems do not necessarily have commensurable QOL, deemed a ‘disability paradox’ as discussed by Carr and Higginson [13]. Rather, when reporting subjective health status indicators as assessed by adequate HRQOL questionnaires such as the FACT, EORTC QLQ-30, and SF-36, ‘health-related quality of life’ should be reported, as demonstrated by Monti et al. [20]. Though definitive requirements for QOL is more difficult to establish, trials that intend to investigate satisfaction with life and employ a more comprehensive approach to its assessment, such as including a rigorous spirituality questionnaire (including the FACIT-Sp) and capture both positive and negative aspects of cancer, contribute to a more accurate portrayal of cancer survivor QOL. Such questionnaires include the MQOL and QLQ-CS. Inclusion of these considerations can inform the impact of mindfulness qualities, such as present moment awareness, acceptance of life circumstances, and peace and meaning, on survivors’ QOL. We recommend future trials report all questionnaire domain scores, regardless of statistical significance. Though these recommendations are specific to MBI trials, they can also inform the greater cancer research community. Through succinct terminology, complete reporting, and use of a more comprehensive approach to its assessment, we can refine and strengthen our understanding about the impact of MBIs on HRQOL and QOL in cancer survivors.

Declaration of interest

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties. Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Additional information

Funding

Funding and resource support was received from the National Center for Complementary and Integrative Health (L30AT008380 to D.B.) and the American Mindfulness Research Association.