ESTRO 2022 - Abstract Book

S1079

Abstract book

ESTRO 2022

The average MLD decreased from 10.1Gy (SD4.2) with VMAT to 5.4Gy (SD3.8) with IMPT (p<0.0001). The average MHD was 9.1Gy (SD5.8) with VMAT and 6.8Gy (SD5.7) with IMPT (p<0.0001). Finally, the average MED diminished from 8.8Gy (SD6.9) to 2.0Gy (SD4.3) with IMPT (p<0.0001). Average NTCP-values for radiation pneumonitis, cardiac toxicity and dysphagia all decreased with IMPT compared to VMAT from 10.9% to 5.9%, from 16.3% to 11.5% and from 19.4% to 3.6%, respectively. Average difference in NTCP was 5.1% (range 0.6%-15.9%) for radiation pneumonitis, 1.5% (0.5%-2.5%) for cardiac toxicity and 18% (2.2%-43.4%) for dysphagia. Ten patients (77%) had a significantly lower NTCP with IMPT for at least one of the 3 endpoints (Fig.1); 9 of these were treated with IMPT at our centre. Of the remaining 3 patients, one was treated at our centre with VMAT, and this was the only patient developing dysphagia grade 1; all other had no dysphagia. Dermatitis grade 0, 1 and 2 was seen in 2, 5 and 3 patients respectively.

Conclusion IMPT significantly reduced MLD, MHD and MED in all patients compared with VMAT, resulting in a significant reduction of NTCP for at least one endpoint in 77% of patients.

(1) Appelt et al. Acta Oncol 2014;53:605-612. (2) Darby et al. NEJM 2013;14;368:987-998