# MARS 2

Source: https://onco.cc/trials/mars-2/  
OnCo record `mars-2` (Trial). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

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.

## Fields

- Kind: Trial
- Status: negative
- Last checked: 2026-09-07
- Tags: lesson:surgery-without-evidence
- Registry id: NCT02040272
- Phase: 3
- Setting: Resectable pleural mesothelioma: extended pleurectomy/decortication + chemotherapy vs chemotherapy alone
- Sponsor: Royal Brompton / NIHR (UK)
- Enrolled: 335
- Result: OS HR 1.28 favouring no surgery; median 19.3 vs 24.8 months.
- Outcomes: Overall survival: Surgery + chemotherapy 19.3 months vs Chemotherapy alone 24.8 months, HR 1.28
- Replication: Consistent with MARS 1 feasibility results; no trial has shown a survival benefit for radical mesothelioma surgery.

## Sources

- ClinicalTrials.gov NCT02040272: https://clinicaltrials.gov/study/NCT02040272

## Connected records

- cancers: [Mesothelioma](https://onco.cc/cancers/mesothelioma/), [Pleural mesothelioma](https://onco.cc/cancers/pleural-mesothelioma/)
- technologies: [Extended pleurectomy/decortication & radical mesothelioma surgery](https://onco.cc/technologies/pleurectomy-decortication/)
- people: [Dean A. Fennell](https://onco.cc/people/dean-fennell/)
- bottlenecks: [Surgery and radiotherapy cure most, get least](https://onco.cc/bottlenecks/b-surgery-radiation-innovation/)
- key papers: [MARS 2: extended pleurectomy decortication plus chemotherapy versus chemotherapy alone for pleural mesothelioma](https://onco.cc/key-papers/paper-mars-2-lancet-respir-med-2024/)
- terms: [Clinical equipoise](https://onco.cc/terms/clinical-equipoise/), [Pleura](https://onco.cc/terms/pleura/), [Pneumonectomy](https://onco.cc/terms/pneumonectomy/), [Quality of life and patient-reported outcomes (QoL, PRO)](https://onco.cc/terms/qol-pro/), [Quality-adjusted survival (QALYs and Q-TWiST)](https://onco.cc/terms/quality-adjusted-survival/)
- roadmaps: [Surgery roadmap: radical operations → less surgery → no surgery when a drug has done the work](https://onco.cc/roadmaps/surgery-roadmap/)

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JSON: https://onco.cc/api/v1/entities/mars-2.json