Does Proton Therapy Have a Future in CNS Tumors?

Area of Science:

• Oncology
• Radiation Oncology
• Medical Physics

Background:

• Proton therapy offers reduced integral dose compared to photon therapy.
• The expanding availability of proton therapy necessitates a clear definition of its clinical indications.
• Current evidence for proton therapy in central nervous system (CNS) tumors is under continuous evaluation against advanced photon treatments.

Purpose of the Study:

• To summarize and discuss current data on proton therapy for CNS tumors.
• To compare the efficacy and safety of proton therapy with modern photon-based treatments.
• To identify specific CNS tumor types where proton therapy may offer a clinical benefit.

Main Methods:

• Review and synthesis of existing clinical data and studies on proton therapy for CNS tumors.
• Comparison of outcomes, including local control, toxicity, and long-term side effects, with photon therapy modalities like Intensity-Modulated Radiation Therapy (IMRT).
• Evaluation of dose escalation possibilities and their associated toxicities.

Main Results:

• No randomized controlled trials confirm a clinical benefit of proton therapy in CNS tumors to date.
• Proton therapy allows for dose escalation in skull base chordomas and chondrosarcomas, warranting referral to proton centers.
• For vestibular schwannoma, proton therapy data is currently inferior to advanced photons; glioma data is comparable for low-grade, but dose escalation in high-grade gliomas led to significant side effects.
• Proton therapy may offer the most significant benefit in pediatric CNS tumors due to reduced long-term side effects, though long-term data is pending.

Conclusions:

• Proton therapy is a viable option for specific skull base tumors (chordomas, chondrosarcomas) and pediatric CNS tumors, potentially offering reduced long-term sequelae.
• Further long-term follow-up studies are required to definitively establish the superiority of proton therapy over advanced photon techniques in CNS tumors.
• While proton therapy shows potential, it should not cause delays or compromise oncological care; its evaluation is recommended when available for specific indications.