ESTRO 2022 - Abstract Book

S144

Abstract book

ESTRO 2022

was seen in 2 patients (1 RMS and 1 ES) and 1 (RMS) experienced a combined local and distant failure. A total of 5 patients had died and all of them due to their disease. For the NPC cohort the actuarial 1-year overall survival, local control, and distant control rates were 100%, 100%, and 100%. Grade 2 or worse acute skin and mucosal toxicities were seen in 81% (grade 3- 6%) and 60% (Grade 3- 17%) patients respectively. Acute grade 2 or worse dysphagia rates were 50% (Grade 3 - 10%). Weight loss >5% was seen in 17% of patients. Approximately half of the patients (54%) had a prophylactic feeding tube put in prior to PBT and 6% required reactive tube placement due to weight loss. Weight loss did not correlate with prophylactic tube placement in this cohort (p=0.22). None of the patients experienced any grade 2 or worse late skin toxicity. Grade 2 or worse late xerostomia rates were 10% and Grade 3 dysphagia rates were 2% (feeding tube dependence). Other late toxicities (Grade 3) included hypothyroidism (6%), pituitary insufficiency (4%), neurocognitive deficits (2%), vision loss (2%), and hearing loss (6%). Acute and late toxicities are highlighted in table 2. Conclusion Pencil beam scanning PBT with daily CBCT is associated with excellent local control rates and low rates of acute and early late toxicities similar to historical controls. Longer follow-up is required to determine ongoing disease response and evolving late toxicities.

PD-0168 Early outcomes after proton therapy for paediatric and TYA pelvic sarcomas

M. Li 1 , S. Sashidharan 1 , A. France 1 , M. Clarke 1 , N. Thorp 1,2

1 The Christie NHS Foundation Trust, The Christie Proton Beam Therapy Centre, Manchester, United Kingdom; 2 The Clatterbridge Cancer Centre, Department of Oncology, Liverpool, United Kingdom Purpose or Objective Pelvic sarcomas are challenging to treat due to growth extent and location. Proton beam therapy (PBT) is increasingly used for their management, especially in the paediatric/TYA group to reduce late toxicity, but there is a dearth of published data. This study aimed to evaluate the acute toxicity and early outcomes of paediatric and TYA patients with pelvic Ewing sarcoma (ES) and rhabdomyosarcoma (RMS) treated with PBT in a national proton treatment centre. Materials and Methods We retrospectively reviewed the records of 20 patients aged ≤ 25 years old with pelvic ES and RMS treated with PBT and systemic anti-cancer therapy (SACT) according to national protocols between April 2019 and December 2020. The staging,