Radiation Oncology/CNS/Choroid Plexus

Epidemiology

• 0.5% intracranial neoplasms
• 10-20% intracranial neoplasms in <1 y/o
• 70% of choroid plexus tumors occur in pts <2 y/o

Histology

• Choroid plexus papillomas are WHO grade I.
• Choroid plexus carcinomas are WHO grade III.
• 80% of choroid plexus tumrs are papillomas.

Patterns of Spread

• Most common site is 4th ventricle.
• As high as 44% of choroid plexus carcinomas can have CSF seeding.
• CSF seeding rare for choroid plexus papilloma.

Treatment

Surgical Excision

• Johns Hopkins, 2002 (1985-2000) PMID 12125972 -- "Is there a requirement for adjuvant therapy for choroid plexus carcinoma that has been completely resected?" (Fitzpatrick et al., J Neurooncol. 2002; 57(2):123-6.)
  • 75 cases of choroid plexus carcinoma described in literature. 37 had GTR, 38 had STR
  • 84% survival if GTR vs 18% if STR
  • Long term survival was seen in pts who received GTR and no further tx; numbers were small.

Adjuvant Radiotherapy

• Indications for adjuvant RT
  • positive margins
  • positive neuraxis staging
  • WHO grade III

• Indications for CSI
  • positive margins
  • positive neuraxis staging

Deferred Radiation in Young Children

• Baby POG I (1986-90)
  • Prospective. 198 children < 3 yrs (132 < 2 yrs, 66 age 2-3 yrs), bx proven malignant brain tumors (low-grade astro excluded), treated with maximal surgery, postop chemo (CTX/VCR followed by cis/etopo) for 2 yrs (if age < 2 at dx) or 1 yr (age 2-3) or until disease progression, followed by RT.
  • Histologies: 8 pts w/ choroid plexus tumors included in Baby POG I
  • 1993 PMID 8388548 -- "Postoperative chemotherapy and delayed radiation in children less than three years of age with malignant brain tumors." (Duffner et al., N Engl J Med. 1993; 328(24):1725-31)
    • CR to chemo PFS comparable those with GTR PFS
  • 1995 PMID 7619719 -- "Postoperative chemotherapy and delayed radiation in infants and very young children with choroid plexus carcinomas. The Pediatric Oncology Group." (Duffner et al., Pediatr Neurosurg. 1995; 22(4):189-96.)
    • 8 pts w/ choroid plexus carcinoma tx'd w/ surg, prolonged chemo, delayed RT.
    • Results suggest this approach may allow prolonged DFS in young pts.