Radiation Oncology: A Question-Based Review

Choroid Plexus Carcinoma and Papilloma

Boris Hristov and Timothy A. Chan

image Background

What are the most common locations of choroid plexus (CP) tumors in children vs. adults?

1.     Children: Lat ventricles

2.     Adults: 4th ventricle

What is the name for the benign CP variant, and how frequent is it? How about the malignant variant?

1.     Benign variant: choroid plexus papilloma (CPP)/WHO I (60%−80% of cases)

2.     Malignant variant: choroid plexus carcinoma (CPC)/WHO III (20%−40% of cases)

What proportion of children present with metastatic Dz at Dx?

One third of children present with metastatic Dz, all typically with CPC.

What is the most common age of presentation for these tumors?

70% of pts are <2 yo.

What % of CPCs can have CSF seeding? How about CPPs?

Up to 40% of CPCs have CSF seeding, but such seeding is very rare for papillomas.

What are the 2 most important prognostic/predictive factors for CP tumors?

Histology (papillomas do better) and extent of resection

What is the 5-yr survival of pts with CPCs and CPPs?

20%–30% for carcinomas and 90%–100% for papillomas

What markers do CPCs often express?

CPCs often express CEA and CD44.

What markers do CPPs often express?

CPPs often express prealbumin and S100.

image Workup/Staging

What are the 2 most common Sx at presentation in pts with CP tumors?

Hydrocephalus and HA

What studies need to be performed during the workup for CP tumors?

Craniospinal MRI and CSF cytology

image Treatment/Prognosis

What is the general Tx paradigm for CP tumors?

CP tumor Tx paradigm: max safe resection (after embolization/chemo, if necessary) +/− chemo (younger pts) and/or RT (if age >3 yrs)

What are the indications for RT in pts with CP tumors?

Age >3 yrs and 1 of the following: carcinoma histology, STR, +CSF/spine Dz (CSI), or recurrent tumors

What is the role of RT in CPPs after STR?

No RT is necessary upfront, as only 50% of STR pts require reoperation, surgical salvage is good, and reoperation may not be needed until yrs later. Consider RT if there is a STR after recurrence. (Mayo data: Krishnan S et al., J Neurooncol 2004)

What is the recommended EB dose for CPPs?

1.     Conventional RT>50 Gy to localized field

2.     Stereotactic RT12 Gy to 50% IDL (Pittsburgh data: Kim IY et al., J Neurosurg 2008)

What makes the resection of CPCs especially challenging?

CPCs are very friable and extremely vascular.

What can be attempted preoperatively to make resection easier?

Embolization (reduces intraoperative bleeding risk) or neoadj chemo

What agents may be used neoadjuvantly (after Bx and before 2nd-look surgery) for CPC?

Ifosfamide, carboplatin, and etoposide (Toronto data: Wrede B et al., Anticancer Res 2005)

What recent data supports the use of adj chemo and/or RT in CPCs?

Johns Hopkins Hospital data (Fitzpatrick LK et al., J Neurooncol 2002): 75 pts. GTR was better than STR (84% survival if GTR vs. 18% if STR). Adj RT offered a survival advantage after STR (p = 0.004) but not after GTR.

What study supports delaying RT in very young children with CPC?

“Baby” Pediatric Oncology Group study (Duffner PK et al., Pediatr Neurosurg 1995): 8 CPC pts treated with surgery, chemo, and delayed RT without any adverse sequelae

What does the data show with regard to RT after GTR for CPC?

1.     The data is controversial, but some studies show OS benefit with RT for older children.

2.     Canadian data (Wolff JE et al., Lancet 1999): 5-yr OS was 70% with RT and 20% without RT.

image Toxicity

After what age are the side effects from RT minimized in children?

After 3 yrs of age, the side effects from RT are minimized.

What are some prominent side effects from RT in the pediatric population with CP tumors?

Skull hypoplasia and neurocognitive/endocrine deficits