MARS 2 Trial

The MARS 2 Trial (Mesothelioma and Radical Surgery 2) was a UK-based randomized clinical trial that compared extended pleurectomy decortication (a lung-sparing cancer surgery) plus chemotherapy against chemotherapy alone in patients with pleural mesothelioma. Results published in 2024 found that adding this major surgery did not improve survival and was associated with more serious complications and worse quality of life. The findings have significantly changed how surgeons and oncologists discuss surgery for pleural mesothelioma.

Origin

MARS 2 was led by Professor Eric Lim at the Royal Brompton Hospital in London and funded by the UK National Institute for Health Research. It followed the earlier MARS 1 feasibility trial (published 2011), which had cast doubt on the more aggressive extrapleural pneumonectomy. MARS 2 recruited patients from 2015 to 2023 and reported results at the 2024 American Society of Clinical Oncology meeting and in The Lancet Respiratory Medicine.

Significance in Asbestos Context

For patients newly diagnosed with pleural mesothelioma, MARS 2 is one of the most consequential studies of the last decade because it directly addresses whether to undergo major chest surgery. Before MARS 2, extended pleurectomy decortication (P/D) was offered at many specialist centers as a potentially curative option; after MARS 2, many centers now consider it less favorably outside of clinical trials. The trial doesn't say surgery is wrong for every patient (some surgeons argue specific subgroups still benefit), but it shifts the default conversation toward chemotherapy and immunotherapy as primary treatment. In a legal claim, the treatment decisions a patient makes (and the medical reasoning behind them) can affect damages calculations for medical expenses, pain and suffering, and loss of quality of life.

Example Sentence

After reviewing the MARS 2 Trial results with her thoracic surgeon, she decided to proceed with chemotherapy and immunotherapy rather than undergo extended pleurectomy decortication.

Related Terms

Pleurectomy Decortication, Extrapleural Pneumonectomy, MARS 1 Trial, Pleural Mesothelioma, Trimodality Therapy, Immunotherapy

Notes

• If surgery has been recommended for your pleural mesothelioma, ask your surgeon specifically how they interpret MARS 2 and why they believe surgery is appropriate in your case.
• Request a second opinion at a high-volume mesothelioma center before agreeing to extended pleurectomy decortication; centers vary significantly in how they have changed practice after MARS 2.
• Keep copies of all treatment decision discussions, second opinions, and the rationale for your chosen treatment. These records matter both for your medical care and for documenting damages in a legal claim.
• MARS 2 applies to pleural mesothelioma; it does not address surgery for peritoneal mesothelioma (HIPEC/cytoreductive surgery), which has different evidence supporting it.
• Ask whether you are eligible for clinical trials combining surgery with newer immunotherapy regimens, as the post-MARS 2 research landscape is actively evolving.