Radiation Oncology/Pilocytic Astrocytoma

Pilocytic Astrocytoma

Juvenile Pilocytic Astrocytoma

• WHO Grade I tumors
• Well-circumscribed, enhancing lesions typically located in the cerebellum; many are Optic Pathway Gliomas
• Surgical resection alone results in favorable outcome, with 10-year OS >80%

Proton Therapy

• Loma Linda; 2002 (1991-1997) PMID 11977386 -- "Conformal proton radiation therapy for pediatric low-grade astrocytomas." (Hug EB, Strahlenther Onkol. 2002 Jan;178(1):10-7.)
  • Retrospective. 27 patients, progressive or recurrent low-grade astrocytoma. Fractionated proton therapy 50.4-63 CGE in 1.8 CGE/fx. Mean F/U 3.3 years
  • Outcome: LC 78%, OS 85%
  • Toxicity: well tolerated; Moyamoya disease in one child with NF1; 6 patients with optic pathway tumors maintained/improved their vision
  • Conclusion: Proton RT is safe and efficacious; longer term follow-up needed

Adult Pilocytic Astrocytoma

• Uncommon
• Clinical presentation includes visual disturbances, seizures, and headaches. Papilledema common
• Favorable prognosis both in terms of survival and neurologic function
• Most remain stable after resection (gross or subtotal) only, and need no adjuvant RT with close follow-up
• It may be reasonable to offer RT in unresectable disease, especially if causing neurologic symptoms
• 10 year OS 95%

• Intergroup NCCTG/RTOG (1986-1994)
  • Prospective. 20 adults with supratentorial pilocytic astrocytoma. If gross total (n=11) or subtotal (n=6) resection, observation. If biopsy only (n=3), RT 50.4 Gy to 2-cm edema margin
  • 10 years; 2004 PMID 15001258 -- "Adult patients with supratentorial pilocytic astrocytomas: a prospective multicenter clinical trial." (Brown PD, Int J Radiat Oncol Biol Phys. 2004 Mar 15;58(4):1153-60.) Median F/U 10 years
    • 10-year outcome: 95% alive. 1 patient died of unknown cause 2.1 years after enrollment; 1 patient progressed 1 month after enrollment and was salvaged with P-32 followed 1.5 years later by RT, now without evidence of progression at 9 years
    • Conclusion: Favorable prognosis; don't need RT after gross total or subtotal resection