Encouraging Experience with Image-Guided Pencil Beam Scanning Proton Therapy in Craniopharyngioma—First Case Series From India

We report our early clinical experience with image-guided, pencil beam scanning proton beam therapy (PBS-PBT) for residual and recurrent craniopharyngioma. Between September 2019 and January 2023, 19 consecutive patients with residual or recurrent craniopharyngioma, suitable for radiotherapy and treated with image-guided PBS-PBT were analyzed. We documented detailed dosimetric data, acute toxicities, early outcomes, and imaging response on follow-up magnetic resonance imaging scans. A total of 19 patients (11 males and 8 females) with residual or recurrent craniopharyngioma were treated during the study period. The median age of the cohort was 14 years (range, 3–33 years). The histology of most lesions was the adamantinomatous subtype (95%). The most common clinical presentation (before PBT) and most common endocrine deficit was visual disturbance (79%) and hypocortisolism (74%), respectively. Of the 19 patients, 13 had recurrent craniopharyngioma, and 5 had undergone radiotherapy previously. Five patients (26%) had undergone surgery ≥3 times before proton therapy. The median dose delivered was 54 GyE. The most common acute toxicity was grade 1 alopecia (63%). No patient experienced grade ≥3 acute toxicity. With a median follow-up of 18 months (range, 3–40 months), 12 patients showed shrinkage of the residual tumor and/or cyst, and 4 showed a dramatic cyst reduction at 3–9 months of follow-up. Two patients experienced a reduction in both solid and cystic components, with the remaining experiencing a reduction in the cystic component only. The remaining 8 patients had stable disease on magnetic resonance imaging, with 100% disease control and overall survival. Visual function remained stable after treatment. Our preliminary experience with modern PBS-PBT and image guidance for craniopharyngioma is encouraging. Proton therapy in our cohort was well tolerated, resulting in limited toxicity and promising early outcomes.