ESTRO 2024 - Abstract Book

S823

Clinical - CNS

ESTRO 2024

Jonas Willmann 1,2 , Dominic Leiser 3 , Damien Charles Weber 1,2,4

1 Paul Scherrer Institute, Center for Proton Therapy, Villigen, Switzerland. 2 University Hospital Zurich, Department of Radiation Oncology, Zurich, Switzerland. 3 Paul Scherrer Institute, Center for Proton Therapy, Villingen, Switzerland. 4 Inselspital, Bern University Hospital, Department of Radiation Oncology, Bern, Switzerland

Purpose/Objective:

To assess oncological outcomes, long-term toxicities, quality of life (QoL) and sexual health (SH) of low-grade glioma (LGG) patients treated with pencil beam scanning proton therapy (PBS-PT).

Material/Methods:

We retrospectively analyzed 89 patients with LGG treated with PBS-PT from 1999 to 2022 at the Center for Proton Therapy at Paul Scherrer Institute. QoL was prospectively assessed during PBS-PT and yearly during follow-up from 2015 to 2023, while a cross-sectional exploration of SH was conducted in 2023. The EORTC QLQ-C30 questionnaire, which includes 30 items to cover different aspects of QoL in cancer patients, and the EORTC QLQ-BN20 module, which includes 20 brain tumor-specific items, were employed to assess QoL before, during and at the end of PBS-PT, and yearly thereafter, as reported by the patient.

For the assessment of SH, the EORTC QLQ-SH22 questionnaire was applied, using the patient's self-assessment.

Results:

The most commonly treated LGG subtypes were astrocytoma (30.3%, n=27), pilocytic astrocytoma (23.6%, n=21) and oligodendroglioma (23.6%, n=21). The majority of the tumors, 58 (65.2%), were classified as CNS WHO grade 2, while 17 (19.1%) were WHO CNS grade 1, and 14 (15.7%) were either unknown or diagnosed radiographically. Tumors were found to be distributed across different brain locations, with the largest group, 43 (48.3%) in the visual apparatus or thalamic area, followed by 31 (34.8%) in the frontotemporal region, and 15 (16.9%) in other parts of the brain. Only four patients (4.5%) had neurofibromatosis type 1. Twenty-four (27%) patients received chemotherapy before PBS-PT. Concomitant chemotherapy during PBS-PT was rarely administered (4.5%, n=4); all of these cases received temozolomide. Following PBS-PT, 28 patients (31.5%) received adjuvant chemotherapy. The most common adjuvant chemotherapy regimen was procarbazine, CCNU (lomustine) und vincristine (PCV) (60.7%, n=17/28)

After a median follow-up of 50.2 months, the 4-years rates of overall survival and progression-free survival were 89.1% (95% CI 81.7-97.2) (Figure 1) and 68.7% (95% CI 58.5-80.7) (Figure 2), respectively.

Twenty-four (27%) patients presented with treatment failures and most of these (n=17/24; 70.8%) received salvage treatment The most common approach was salvage surgery, utilized in eight (33.3%) of these cases. Re-irradiation was the treatment of choice in only two (8.3%) of the cases.