MARS 2
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.
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.
Setting
Resectable pleural mesothelioma: extended pleurectomy/decortication + chemotherapy vs chemotherapy alone
Phase
Phase 3
Sponsor
Royal Brompton / NIHR (UK)
Registry
Headline result
OS HR 1.28 favouring no surgery; median 19.3 vs 24.8 months.
Reported
2024
Enrolled
335
Replication
Consistent with MARS 1 feasibility results; no trial has shown a survival benefit for radical mesothelioma surgery.
In plain words
What these results mean for people, not percentages
Overall survivalprimarysurvival endpoint
- Median 19.3 vs 24.8 months with Surgery + chemotherapy compared with Chemotherapy alone; about 5.5 months shorter for half the group.
- A median is a midpoint: half the people did better than this and half did worse, so it is not a prediction for any one person.
- Put another way, the treated group had about 28 percent higher chance of the event at any given time (hazard ratio 1.28, likely range 1.02 to 1.6).
- Overall survival counts deaths from any cause, so it is the most direct measure of whether a treatment helps people live longer.
- These results apply to the people the trial enrolled: Resectable pleural mesothelioma: extended pleurectomy/decortication + chemotherapy vs chemotherapy alone. People in a different situation may not see the same effect.
Numbers are from the trial as recorded here; see the source links in the table below. This is orientation, not medical advice: ask your team how closely the trial population matches you.
335 participants enrolled.
Overall survivalprimary
HR 1.28 (1.02–1.6)
Surgery + chemotherapy
19.3 mo
Chemotherapy alone
24.8 mo
| Endpoint | Arm | n | Value | HR (95% CI) | p | Source |
|---|---|---|---|---|---|---|
| Overall survivalprimary | Surgery + chemotherapy | 169 | 19.3 months | 1.28 (1.02–1.6) | — | link |
| Chemotherapy alone | 166 | 24.8 months |
Replication
Consistent with MARS 1 feasibility results; no trial has shown a survival benefit for radical mesothelioma surgery.