FRACTIONATED STEREOTACTIC RADIOTHERAPY IN THE TREATMENT OF PITUITARY MACROADENOMAS

Hamdy Sakr Elhateer, Thierry Muanza, David Roberge, Russell Ruo, Eman Eldebawy, Christine Lambert, Horacio Patrocinio, George Shenouda, Luis Souhami

Abstract


Background: The use of fractionated stereotactic radiotherapy (FSRT) has evolved with technical advances in non-invasive immobilization, radiation delivery and image-guidance. The application of FSRT to pituitary tumors is aimed at reducing toxicity through improved dose conformality and reduced treatment margins. The aim of this paper is to review the published data on FSRT for pituitary adenomas and present our own experience.
Methods: Between September 2000 and October 2005, 13 patients with pituitary macroadenomas underwent FSRT in our institution. Twelve patients were treated after prior surgical resection (trans-sphenoidal resection in 8, frontal craniotomy in 3 and multiple trans-sphenoidal resections followed by craniotomy in 1 patient). Four patients had functional tumors (2 ACTH-secreting, 1 prolactinoma and 1 GH-secreting); the remainder had clinically non-secretory tumors. Three patients had panhypopituitarism prior to radiation and 6 patients had pre-treatment visual field defects. All patients were treated with FSRT using non-coplanar micro-MLC portals. A median dose of 50.4 Gy (45-60 Gy) was prescribed to the 76.9-95.2% isodose surface and delivered in 1.8 Gy fractions. The median planning target volume (gross tumor + 3 mm) was 33.5 cm3 (3.2-75 cm3).
Results: After a median follow-up period of 24 months (6-60 months), local control was 100%. One patient had clinical complete response. Treatment was acutely well tolerated for all patients. Radiation induced optic neuropathy was not observed in our patients nor any radiation related endocrine dysfunction.
Conclusion: In accordance with published series, we have found FSRT to be safe and effective in the management of large pituitary macroadenomas.

Key words: Radiotherapy, Fractionated Stereotactic radiotherapy, Macroadenoma, Pituitary adenoma.

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DOI: http://dx.doi.org/10.3747/co.v15i6.293






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