A clinical trial of group-based body psychotherapy to improve bodily disturbances in post-treatment cancer patients in combination with randomized controlled smartphone-triggered bodily interventions (KPTK): study protocol.

Background: Disturbances in bodily well-being represent one key source of suffering and impairment related to cancer. There is growing evidence that body psychotherapy (BPT) is efficacious for the treatment of various mental disorders. However, with regard to cancer patients, evidence is scarce. The aims of this project are to evaluate whether bodily disturbances in post-treatment cancer patients can be improved by group BPT, and to estimate the efficacy of intermittent smartphone-triggered bodily interventions.

Methods: The project is a bi-center study with two participating centers in Switzerland, applying a pre-post convergent parallel design of a weekly group BPT using a waiting-period comparator, including a nested RCT during the group BPT phase. During the BPT phase, either a smartphone-triggered bodily intervention or a smartphone-triggered control intervention is provided at random over 5 consecutive weeks, on 6 days weekly. Patients who had received curatively intended treatment for any malignant neoplasm (treatment being completed ≥3 months) and are suffering from bodily disturbances are screened to assess eligibility. Sample size estimation is based on an a priori power analysis. We plan to include a total of N = 88 subjects, aiming at at least 52 completers. Patients are surveyed three times (baseline assessment (T0), pre- (T1) and post-intervention assessment (T2)), and on a daily basis along BPT during five consecutive weeks. The primary outcome, bodily disturbances, is assessed using the 'Body Image Scale'(BIS). For the secondary outcomes standardized questionnaires are used to assess changes in experience of presence and vitality, mood, body mindfulness, somatic symptoms and somatic symptom disorder, quality of life, anxiety, and depression including suicidal tendency, vitality and mental health, as well as group cohesion. Using semi standardized interviews (at T0 and T2), we aim to explore the relation of BPT with bodily disturbances and body image in post-treatment cancer patients, as well as the acceptance and burden of the intervention.

Discussion: The proposed study has strong potential benefits for cancer patients, as it may pave the way for new therapeutic approaches to treat bodily disturbances, which persist despite curative tumor therapy. These may considerably improve patients' biopsychosocial well-being and quality of life.

Trial Registration: ClinicalTrials.gov NCT03707548 (registered 9 October 2018; retrospectively registered).