Palliative radiotherapy in symptomatic pelvic soft tissue tumors (PallSoft)- protocol for a national, randomized, non-inferiority study.

backgroundPalliative radiotherapy is essential in the management of patients with symptomatic pelvic soft tissue tumors, often providing rapid and efficient symptom relief. No standard treatment recommendations currently exist, yielding large differences in patient management across cancer types and institutions. PallSoft is a national, phase III, non-inferiority study aiming to compare two short-course radiotherapy approaches for these patients.

methods200 patients will be recruited from 11 institutions over 2-4 years. Patients with either gastrointestinal, urological or gynecological cancers, referred to palliative radiotherapy due to a symptomatic pelvic soft tissue tumor, are eligible for study inclusion. Patients will define their target symptom and be randomly assigned to treatment with either 1 fraction of 8 Gy (Gy) (arm A) or 5 fractions of 5 Gy (arm B). An additional fraction of 8 Gy may be offered to patients in arm A if unsatisfactory symptomatic effect occurs, evaluated according to predefined criteria. The primary objective is to investigate whether the patient-reported target symptom relief in arm A is non-inferior to arm B, assessed on a Numeric Rating Scale (NRS). Secondary objectives are physician-assessed bowel and bladder toxicities and overall survival. Explorative objectives include evaluations of health-related quality of life, general patient satisfaction and health economic aspects. Prognostic models for survival prediction and predictive biomarkers for radiotherapy response will be explored. Statistical analyses using linear regression models and survival analyses will be employed. DISCUSSION: We aim to provide evidence of the most optimal palliative radiotherapy regimen for patients with symptomatic pelvic soft tissue tumors, and thereby contribute to establish a standard-of care for these patients. The participation of all radiotherapy units in Norway may ease national implementation of study results.

trial registrationRegistered at ClinicalTrials.gov (Palliative Radiotherapy in Symptomatic Pelvic Soft Tissue Tumors, NCT06398314) on May 3rd, 2024. First patient enrollment in February 2025. All hospitals are currently recruiting. TRIAL SPONSOR: Telemark Hospital Trust.