{"entity":{"id":"mars-2","kind":"trial","name":"MARS 2","aka":[],"tldr":"MARS 2 is the trial that overturned decades of surgical practice: removing the lining of the lung did not help patients live longer and left them worse off.","summary":"Survival was worse with surgery (HR 1.28, 95% CI 1.02-1.60; median 19.3 vs 24.8 months), with more serious adverse events and poorer quality of life. Extended pleurectomy/decortication is no longer recommended outside trials in most guidelines; MARS 1 had earlier cast doubt on extrapleural pneumonectomy.","status":"negative","asOf":"2026-09-07","links":[{"label":"ClinicalTrials.gov NCT02040272","url":"https://clinicaltrials.gov/study/NCT02040272"}],"tags":["lesson:surgery-without-evidence"],"related":[],"cancers":["mesothelioma","pleural-mesothelioma"],"sections":[],"technologies":["pleurectomy-decortication"],"targets":[],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":["dean-fennell"],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"nct":"NCT02040272","phase":"3","setting":"Resectable pleural mesothelioma: extended pleurectomy/decortication + chemotherapy vs chemotherapy alone","sponsor":"Royal Brompton / NIHR (UK)","result":"OS HR 1.28 favouring no surgery; median 19.3 vs 24.8 months.","started":"2015-05","yearReported":2024,"enrolled":335,"enrolledBasis":"registry","outcomes":[{"endpoint":"Overall survival","primary":true,"unit":"months","arms":[{"name":"Surgery + chemotherapy","n":169,"value":19.3},{"name":"Chemotherapy alone","n":166,"value":24.8}],"hr":1.28,"ci":[1.02,1.6],"source":"https://www.thelancet.com/journals/lanres/article/PIIS2213-2600(24)00119-X/fulltext"}],"replication":"Consistent with MARS 1 feasibility results; no trial has shown a survival benefit for radical mesothelioma surgery."},"route":"/trials/mars-2/","neighbours":{"cancer":[{"id":"mesothelioma","kind":"cancer","name":"Mesothelioma","route":"/cancers/mesothelioma/"},{"id":"pleural-mesothelioma","kind":"cancer","name":"Pleural mesothelioma","route":"/cancers/pleural-mesothelioma/"}],"technology":[{"id":"pleurectomy-decortication","kind":"technology","name":"Extended pleurectomy/decortication & radical mesothelioma surgery","route":"/technologies/pleurectomy-decortication/"}],"person":[{"id":"dean-fennell","kind":"person","name":"Dean A. Fennell","route":"/people/dean-fennell/"}],"bottleneck":[{"id":"b-surgery-radiation-innovation","kind":"bottleneck","name":"Surgery and radiotherapy cure most, get least","route":"/bottlenecks/b-surgery-radiation-innovation/"}],"paper":[{"id":"paper-mars-2-lancet-respir-med-2024","kind":"paper","name":"MARS 2: extended pleurectomy decortication plus chemotherapy versus chemotherapy alone for pleural mesothelioma","route":"/key-papers/paper-mars-2-lancet-respir-med-2024/"}],"term":[{"id":"clinical-equipoise","kind":"term","name":"Clinical equipoise","route":"/terms/clinical-equipoise/"},{"id":"pleura","kind":"term","name":"Pleura","route":"/terms/pleura/"},{"id":"pneumonectomy","kind":"term","name":"Pneumonectomy","route":"/terms/pneumonectomy/"},{"id":"qol-pro","kind":"term","name":"Quality of life and patient-reported outcomes (QoL, PRO)","route":"/terms/qol-pro/"},{"id":"quality-adjusted-survival","kind":"term","name":"Quality-adjusted survival (QALYs and Q-TWiST)","route":"/terms/quality-adjusted-survival/"}],"roadmap":[{"id":"surgery-roadmap","kind":"roadmap","name":"Surgery roadmap: radical operations → less surgery → no surgery when a drug has done the work","route":"/roadmaps/surgery-roadmap/"}]}}