Delivery of Re-irradiation and Complex Palliative Radiotherapy Using
Proton Therapy in Pediatric Cancer Patients
Abstract
Background: Characterize indications for pediatric
palliative-intent proton radiation therapy (PIPRT). Procedure:
We retrospectively reviewed patients ≤21 years who received PIPRT. We
defined PIPRT as radiotherapy (RT) aimed to improve cancer related
symptoms/provide durable local control in the non-curative setting.
Mixed proton/photon plans were included. Adjacent reirradiation (reRT)
was defined as a reRT volume within the incidental dose cloud of a prior
RT target, whereas direct reRT was defined as in-field overlap with
prior RT target. Acute toxicity during RT until first inspection visit
was graded according to the Common Terminology Criteria for Adverse
Events. The Kaplan-Meier method, measured from last PIPRT fraction, was
used to assess progression free survival (PFS) and overall survival
(OS). Results: 18 patients underwent PIPRT between 2014-2020.
Median age at treatment start was 10 years (2-21). Median follow up was
8.2 months (0-48). Treatment sites included: brain/spine (10),
abdomen/pelvis (3), thorax (3) and head/neck (2). Indications for
palliation included: durable tumor control (18), neurologic symptoms
(4), pain (3), airway compromise (2), and great vessel compression (1).
Indications for protons included: reRT (15) (4 adjacent, 11 direct),
craniospinal irradiation (4), reduction of dose to normal tissues (3).
16 experienced grade (G) 1-2 toxicity; 2 G3. There were no reports of
radionecrosis. Median PFS was 5.3 months (95% CI 2.7-16.3). Median OS
was 8.3 months (95% CI 5.5-26.3). Conclusions: The most common
indication for PIPRT was reRT to provide durable tumor control. PIPRT
appears to be safe, with no cases of high grade toxicity.