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)

Anatomy

 * 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

Histology

 * 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

Diagnosis

 * 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

Treatment

 * 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.

Combined Modality Therapy

 * 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 Techniques

 * 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.

Proton Therapy

 * 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