ESTRO 2024 - Abstract Book

S1788

Clinical - Lung

ESTRO 2024

response rates in the dose escalated and standard arms were 42.6% and 35.7% respectively. The difference of 6.9% was not statistically significant (80% confidence interval (CI) -6.8 – 20.6%). Regarding secondary endpoints, toxicities were generally mild with modest increases in the dose escalated arm in the incidence of nausea (G1-2), pain (G2-3) and vomiting (G1) during treatment, and the incidence of radiation dermatitis (G1-2) during follow-up. Pain (G1-2) was reported more frequently during follow-up in the standard arm. Median OS was 5.8 months (80% CI 4.7 – 7.4) in the dose escalated arm and 4.7 months (4.1 – 5.9) in the standard arm. Six-month OS rates were 49.5% (40.2 – 58.1) and 39.9% (31.3 – 48.4) in dose escalated and standard arms respectively while 12-month OS rates were 32.3% (22.3 – 42.7) and 8.9% (3.4 – 17.8). By Kaplan-Meier analysis the hazard ratio for death was 1.59 (95% CI 1.00 – 2.53, p=0.052) in the standard arm (Figure 1).

With approximately 10% of patients still alive and on follow-up, final OS data will be presented at the conference. Radiological response data are currently being analysed and will also be presented at the conference.

Conclusion:

Preliminary results of this randomised trial examining radiotherapy dose escalation in MPM show that both radiotherapy schedules were well tolerated with low rates and severities of toxicity in both arms. The study did not demonstrate a significant improvement in the primary endpoint (worst pain score at 5 weeks) but early survival data indicate a potential reduction in risk of death in patients treated with dose escalated radiotherapy. This effect is currently of borderline significance and the survival analysis will be repeated in April 2024, by which time radiological response analysis will also be complete. Molecular and radiomic translational studies are underway with the aim of identifying biomarkers that predict benefit from dose escalated radiotherapy.