Lung cancer is the leading cause of cancer mortality, posing a critical public health challenge in both Hong Kong and global populations. Patients with lung cancer frequently experience a distressing symptom cluster characterized by breathlessness-driven respiratory distress, accompanied by persistent cough and fatigue, which collectively impose a substantial disease burden. While our research team leader previously developed and validated a multi-component Respiratory Distress Symptom Intervention (RDSI) in England, demonstrating clinical efficacy for lung cancer management, its impact on psychological distress (anxiety and depression) proved limited. This limitation may reflect insufficient integration of psychological components, a crucial consideration given the well-established bidirectional relationship between respiratory symptoms and psychological distress. Emerging evidence indicates that mindfulness interventions provide dual therapeutic benefits by improving patient adherence and effectively addressing both physical symptoms, such as breathlessness and fatigue, as well as psychological distress, including anxiety and depression. Meanwhile, current evaluation methodologies have mainly focused on behavioral data collection, such as self-reported questionnaires, to reflect the effect before and after the intervention. Neuroimaging data can help understand the brain mechanisms underlying breathlessness and elucidate the effectiveness of interventions, thereby improving intervention strategies.

This study aims to develop and evaluate a mindfulness-oriented respiratory distress symptom intervention (M-RDSI) for patients with lung cancer. This study uses a two-phase experimental design to develop the M-RDSI and to evaluate the M-RDSI intervention's clinical and neurophysiological effects. In Phase I, the aim is to develop and content-validate the M-RDSI, including cultural adaptation adjustment and co-design of the M-RDSI intervention, including intervention teaching materials, through an expert panel consisting of patients with lung cancer and healthcare professionals. In Phase II, sixty-four participants will be randomized into the intervention group, receiving a 6-week M-RDSI intervention in addition to usual care followed by a 12-week follow-up, or the control group, which will receive usual care during the same period. During Phase IIa, the feasibility, acceptability, and preliminary clinical outcomes will be evaluated. Feasibility will be assessed through recruitment, dropout, and retention rates. Acceptability will be measured by treatment adherence rates and participant satisfaction, gathered through qualitative interviews. Preliminary clinical effectiveness will include self-reported outcomes such as breathlessness, cough, fatigue, mindfulness, anxiety, depression, and quality of life. The generalized estimating equation will be employed to analyze the intervention effects. Additionally, one-on-one qualitative interviews will be conducted post-intervention to gather participants' feedback on the perceived effectiveness, acceptability, strengths, limitations, and suggestions for improving the M-RDSI program. In Phase IIb, a task-based fMRI will be conducted at baseline and post-intervention, using a set of breathlessness-related word cues as stimuli to assess changes in brain activity. Analysis will be corrected for multiple comparisons. A general linear model will be constructed for the first-level fMRI analysis. A 2-by-2 factorial ANOVA will assess the group-by-time interaction of brain activity, and a paired t-test will evaluate pre- and post-treatment changes within the intervention group for the group analysis.

Inclusion Criteria:

• HK patients who can understand Cantonese, aged 18 years or older;
• A confirmed diagnosis of an intrathoracic malignancy, including small cell lung cancer, non-small cell lung cancer, or mesothelioma; at any stage of cancer treatment or palliative care;
• Self-reported impact on daily life from at least two of the three symptoms, where one symptom is breathlessness;
• Stability of COPD, if present;
• WHO Performance Status of 0-2;
• fMRI can be conducted;
• Expected lifespan of more than six months.

Exclusion Criteria:

• Cognitive impairments, severe psychotic symptoms, or other medical conditions that might hinder participation;
• Participating in mindfulness or other psychological support interventions or symptom management interventions.

Participants cannot be blinded due to the nature of the intervention. However, they will be instructed to maintain confidentiality and avoid discussing intervention details with other participants to minimize potential biases. The outcomes assessor who collects the participant's information will be blinded to the group allocation. However, the statistician responsible for quantitative data analysis will work with de-identified and de-grouped datasets to ensure blinding during the analysis phase.