Encouraging early outcomes with image guided pencil beam proton therapy
for cranio-spinal irradiation and unique considerations for paediatric
population -- First report from India
Abstract
Background: To report our experience with image guided pencil beam
proton beam therapy (PBT) for craniospinal irradiation (CSI). Materials
and Methods: Between January 2019 to Dec 2021, we carried out a detailed
audit of the first forty patients treated with PBT. We had recorded
acute toxicities, reporting early outcomes and discuss limitations of
current contouring guidelines during CSI PBT planning. Results: Median
age of the patient cohort was 8 years, and histologies include 20
medulloblastoma, 7 recurrent ependymoma, 3 pineoblastoma, 3 were germ
cell tumors and remaining 7 constituted other diagnoses. Forty percent
patients received concurrent chemotherapy. Median CSI dose was 23.4 GyE
(Gray Equivalent; range 21.6 - 35). Thirty-five patients (87.5%)
completed their CSI without interruption, 5 required hospital admission.
No patient had grade 2/> weight loss during the treatment.
Forty-five percent (18) developed grade 1 haematological toxicities and
20% (8) developed grade 2 or 3 toxicities; none had grade 4 toxicities.
At median follow up of 12 months, 90 % patients are alive of whom 88.9
% are having local control. Special consideration with modification in
standard contouring used at our institute helped in limiting acute
toxicities in paediatric CSI patients. Conclusion: Our preliminary
experience with modern contemporary PBT using pencil beam technology and
daily image guidance in a range of tumours suitable for CSI is
encouraging. Patients tolerated the treatment well with acceptable acute
toxicity and expected short-term survival outcome. In paediatric CSI
patients, modification in standard contouring guidelines required to
achieve better results with PBT.