MARS 2
Does extended pleurectomy/decortication add benefit to chemotherapy in pleural mesothelioma?
One underlying study; aliases and follow-up reports consolidated. Primary discipline: Surgical.
335 patients with pleural mesothelioma eligible after two cycles of chemotherapy.
Selected patients considered for surgery-based management after induction chemotherapy.
335 randomised/evaluable as reported.
Extended pleurectomy/decortication plus chemotherapy.
Chemotherapy alone.
Endpoints and results
Overall survival, quality-adjusted survival and serious adverse events.
- Median survival 19.3 months with surgery+chemotherapy vs 24.8 months with chemotherapy alone.
- Difference in 2-year restricted mean survival time −1.9 months (95% CI −3.4 to −0.3; p=0.019), favouring chemotherapy alone.
- Serious adverse-event incidence-rate ratio 3.6 (95% CI 2.3–5.5; p<0.0001).
Absolute Effect and outcome visualisation
Median OS
months (median, not fixed-time rate) · Primary analysis. Bars compare reported medians only and are not fixed-time survival probabilities.
Interpretation: No NNT from median survival. Restricted mean survival and excess serious adverse events communicate the balance more appropriately.
Toxicity, discontinuation and quality of life
Trial-specific harms: Surgery increased serious adverse events substantially; perioperative complications and recovery burden are central.
Treatment burden/discontinuation: Major operation, hospitalisation and recovery added to chemotherapy.
Quality of life: Quality-adjusted survival was assessed; surgery did not provide an advantage sufficient to offset its burden in the reported analysis.
Subgroups, maturity and limitations
Subgroups: No subgroup benefit claim without prespecified and adequately powered interaction evidence.
Maturity: Phase III pragmatic randomised trial, 2024.
Limitations: Open-label; surgical expertise and selection matter, but randomised data do not support routine extended surgery as survival-improving.
MARS 2 challenges routine radical surgery for pleural mesothelioma: no survival improvement and substantially more serious harms.
Current-practice context must be checked against regional guidelines, patient fitness, biomarkers, alternatives and regulatory status before clinical application. Clinical freshness review and browser-rendered QA remain pending.
Primary sources and registry
Registry: ISRCTN95595114
The Absolute Effect · Updated 26 October 2026 · Never derive NNT from median survival.