Radiation Oncology/Craniopharyngioma

Craniopharyngioma

Overview

Represents 6-9% of pediatric brain tumors (#3 after gliomas and medulloblastoma)
Histoligically benign tumors
Clinically present with headaches (~50%), visual disturbances (40-70%), and pituitary dysfunction (up to 90%)
- Children: hypothyroid and GH deficiency
- Adults: sexual dysfunction (men erectile dysfunction, women amenorrhea)
Due to its locally advancing nature, often gives rise to endocrine deficits chiefly of pituitary origin
Bimodal distribution in incidence: pediatric (infants/children) and adult (55-65 years)

Derived from Rathke's pouch remnant (embryonic precursor of the anterior pituitary)
Most commonly suprasellar location (pituitary stalk) with possible extension into posterior and middle cranial fossae
70% retrochiasmatic, often extending to 3rd ventricle and along hypothalamus
Commonly has both solid and cystic components
Size varies from small well-circumscribed lesions to very large multiple cysts

Benign tumor of squamous cell origin
Histologic subtypes include:
- Adamantinoma: epithelial mass forming a reticulum - most common in children
- Mucoid epithelial cyst
- Squamous papillary
Presumably arise from embryonic remnant and grow slowly since birth; however, de novo case in a 55 year-old has been documented

Classic CT findings are calcified suprasellar mass with cysts
- Mass is usually a mixed cystic and solid lesion
- 75% have at least 1 cyst
- 80% have calcifications
Endocrine work up should be performed prior to initiation of therapy

Total resection may be attempted, but radical surgery can have as high a mortality rate as 10%, and a high severe morbidity rate.
Maximal safe resection followed by irradiation is the currently accepted modality of management. Subtotal resection + RT has nearly equivalent local control and overall survival as gross total resection.
Tumor responds slowly to radiation, and in some patients, radiation induced edema can worsen the symptoms.
Role of chemotherapy in this condition is not documented to date, but intracystic bleomycin has been shown to cause tumor response.

Pittsburgh, 2002 (1971-92) - PMID 12243827 -- "External beam irradiation of craniopharyngiomas: long-term analysis of tumor control and morbidity." Varlotto JM et al. Int J Radiat Oncol Biol Phys. 2002 Oct 1;54(2):492-9.
- 24 pts w/ craniopharyngioma tx'd w/ EBRT as part of treatment course (19 pts w/ subtotal resection, 2 w/ bx alone).
- 10 yr actuarial local control was 89%; 20 yr actual local control 54%
- Multivariate analysis showed dose (>55 Gy) to be significant prognostic factor for control, and tx complication probability was related to hypopituitarism at presentation.

St. Jude's, 2002 (1984-97) - PMID 12062594 -- "Craniopharyngioma: the St. Jude Children's Research Hospital experience 1984-2001." Merchant TE et al. Int J Radiat Oncol Biol Phys. 2002 Jul 1;53(3):533-42.
- 30 pts w/ craniopharyngioma (15 tx'd w/ radical surgery, 15 tx'd w/ limited surgery + upfront RT)
- Surgery group lost avg of 9.8 IQ points, limited surgery + RT group lost avg of 1.25 points.
- Surgery group had more frequent neurologic, ophthalmologic, and endocrine complications.

Joint Center/Children's Hospital, 1994 (1970-1990)
- PMID 7841082 -- "Surgery, radiation, and combination therapy in the treatment of childhood craniopharyngioma--a 20-year experience." Scott RM et al. Pediatr Neurosurg. 1994;21 Suppl 1:75-81.
- 61 pts w/ craniopharyngioma (9 w/ RT alone, 15 w/ surgery alone, 37 w/ surgery + RT)
- 10 yr actuarial survival 91%
- PMID 8407391 -- "20-year experience in childhood craniopharyngioma." Hetelekidis S et al. Int J Radiat Oncol Biol Phys. 1993 Sep 30;27(2):189-95.
- 10 yr PFS in surgery group 31%, in RT alone group 100%, in surgery + RT group 86%.
- Size of tumor (>5cm) correlated w/ risk of recurrence.

Royal Marsden, 1961 - PMID 13753942 -- "Craniopharyngiomas. Treatment by combined surgery and radiation therapy." Kramer S et al. J Neurosurg. 1961 Mar;18:217-26.
- 6 pts w/ craniopharyngioma tx'd w/ limited surgery + RT. All 6 achieved 15 yr PFS.

Radiation therapy is targeted to the tumor volume,encompassing all its components.
A classical coronal arc configuration of treament portal is recommended, or conventional 2- 3 field technique can be used.
Current techniques include 3D conformal RT, IMRT or proton beam.
- CTV expansion on GTV should be at least 1cm (for cyst expansion, not because of microscopic invasion)
- In spite of CTV expansion a significant percentage found to move out to RT field during RT course (35%). Current areas of study include determination of necessity of imaging during RT course.
Dose prescription is 50-60 Gy, and if beyond 60 Gy, optic neuropathy and brain necrosis can be expected.
Cystic lesions can be treated with stereotactically applied intracystic colloidal Yttrium-90.
- Dose prescription is 200-300 Gy to the inner surface of the cyst wall.
- Major toxicity of intracystic beta emitters is visual toxicity.

Harvard; 2009 (2001-2007) PMID 18676089 -- "Surveillance of craniopharyngioma cyst growth in children treated with proton radiotherapy." (Winkfield KM, Int J Radiat Oncol Biol Phys. 2009 Mar 1;73(3):716-21.)
- Retrospective. 17 children with surveillance imaging during RT.
- Outcome: 24% cysts growth beyond original treatment fields. 1 patient field reduction, 1 patient cyst drainage to avoid enlargement of treatment fields
- Conclusion: Routine imaging during treatment is recommended; at least q2 weeks

Loma Linda; 2006 PMID 16630407 -- "Fractionated proton radiation treatment for pediatric craniopharyngioma: preliminary report." (Luu QT, Cancer J. 2006 Mar-Apr;12(2):155-9.)
- Retrospective. 16 patients. Dose 50.4 - 59.4 CGE.
- Outcome: LC in 14/15 (93%). OS 12/15 (80%)
- Toxicity: panhypopituitarism, CVA, and out-of-field meningioma in patient with prior RT
- Conclusion: Fractionated proton therapy effective for craniopharyngeioma