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%

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

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