ESTRO 2024 - Abstract Book

S936

Clinical - CNS

ESTRO 2024

At median follow-up of 18.9 months (5.3-41.6 months) the local failure-free survival was 100%. Five tumors recurred intracranial, resulting in actuarial OS and DSF at 12 months of 100% and 81% (95%CI: 42.8-94.9), at 18 month 87.5% (95% CI: 38.7-98.1) and 67.5% (95%CI: 27.9-88.6), respectively.

No toxicity ≥grade II was observed, specifically no brainstem toxicity. One asymptomatic radiation induced cerebellar brain lesion grade I was observed at 6 months, which resolved after 12 months.

Conclusion:

Early clinical data suggest that PBT can be safely delivered for CNS-Tumor recurrences close to and adjacent to brainstem. Small volumes of high cumulative brainstem doses required to deliver curative target doses resulted in excellent local control without significant toxicity.

Characteristic

n (%) / median (range)

Sex Male

7 (64%) 4 (36%)

Female

Age at ReRT (years) 6.7 (3.1-18.6)

Histology Ependymoma

6 (55%) 3 (27%)

AT/RT

other

2 (18%)

Previous radiation Photon RT

6 (55%) 5 (45%)

Proton RT

ReRT CTV (cm3)

3.2 (1.3 – 146.4)

Table 1 Patient and Tumor characteristics; (n=11)