Should I consider the option of surgery to remove mesothelioma? The results of MARS 2

By Professor Eric Lim, Consultant Thoracic Surgeon at the Royal Brompton Hospital and Chief Investigator of the MARS 2 clinical trial

MARS 2, a UK multicentre randomised trial, compared extended pleurectomy decortication and chemotherapy to chemotherapy alone in patients with early-stage resectable mesothelioma. The operation involves removal of the lining of the chest wall, lining of the lung and (where necessary) the diaphragm and/or lining of the heart, but keeping the underlying lung itself intact. The trials initial results were presented on the 10 September 2023 at the World Conference of Lung Cancer in Singapore.

The trial enrolled 335 participants, randomly assigned 169 patients with resectable mesothelioma to extended pleurectomy decortication and 166 patients to chemotherapy (platinum and pemetrexed) or chemotherapy alone. The results were a 28% increase in the risk of death in the surgery group within the first 42 months, with no significant difference in survival after 42 months. Moreover, the surgery group experienced a 3.6-fold higher incidence of serious harmful events and a poorer quality of life and well-being.

Therefore MARS 2 concluded that extended pleurectomy decortication should not be offered to patients with pleural mesothelioma (unless they are participating in a clinical trial).

The MARS 2 investigators expressed their heartfelt gratitude to all the patients who selflessly participated in this trial that helped answer the question to inform us all on treatment choices going forward – we would not have this knowledge to improve care without them.

If you have any questions or concerns about the results of this trial, contact your healthcare team in the first instance or our freephone support line on 0800 169 2409 (Mon to Fri, 9am to 4pm) or email

September 25, 2023

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