ESTRO meets Asia 2024 - Abstract Book

S216

Interdisciplinary – Lung

ESTRO meets Asia 2024

Results:

Mandatory OAR constraints were met in all cases. 73.1% were central and 26.9% were ultracentral. The location of the tumours can be seen in Fig 1. The proportion of the PTV receiving 100% of the prescription dose ranged from 28%-94% (median 89%). Median follow-up was 7 months (1 – 47 months). Local control was achieved in 92%. 17% developed metastatic recurrence. No G3+ acute or late toxicities were observed. G2 fatigue and pneumonitis was seen in 15% and 4% (n=1) respectively. The 5 patients with most PTV compromise received 100% of the dose to 28 53% of the volume. While PBT could reduce the low doses received by OARs, target volume coverage was not improved with PBT because of the necessity to meet Dmax constraints in crucial, serial OARs (see Figure 2).

Conclusion: Compromising PTV coverage to meet OAR constraints still offers high rates of local control by SABR for central/ultracentral primary lung cancers without excess toxicity. PBT does not appear to improve target volume coverage compared to photon SABR.

Keywords: SBRT; lung cancer; proton beam therapy