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

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 wellbeing (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 cancerspecific 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 TherapySpirituality [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].