Oligometastatic Mesothelioma Treated with Ablative Radiotherapy (OMAR): A Multicenter Study

Area of Science:

• Oncology
• Radiation Oncology
• Thoracic Oncology

Background:

• Pleural mesothelioma (PM) is a rare cancer.
• Unresectable PM progression after chemotherapy presents treatment challenges.
• Oligoprogression or oligorecurrence in PM requires effective local therapies.

Purpose of the Study:

• To evaluate the efficacy and safety of ablative radiotherapy (RT) for unresectable pleural mesothelioma.
• To assess the role of stereotactic ablative radiotherapy (SABR) in patients with limited disease progression after chemotherapy.
• To determine outcomes including time to further systemic therapy, local control, survival, and toxicity.

Main Methods:

• Multicenter retrospective study of 56 adult patients with unresectable PM.
• Patients received SABR with radical intent for up to three pleural or extrapleural sites.
• Endpoints included time to further systemic therapy (TFST), local control (LC), progression-free survival (PFS), overall survival (OS), and toxicity.

Main Results:

• SABR was well-tolerated with manageable acute and late toxicities.
• Median TFST was 18.6 months; 1-year OS rate was 85.2%, 2-year OS rate was 65.6%.
• Favorable 1-year local control (79%), but most recurrences were outside the SABR volume. Median PFS was 8.17 months.

Conclusions:

• SABR is a safe and effective treatment for oligorecurrent/oligoprogressive PM.
• SABR significantly extends time to further systemic therapy.
• Results suggest potentially indolent behavior in oligometastatic PM, warranting further investigation.