Hypofractionated CyberKnife radiosurgery for perichiasmatic pituitary adenomas: early results.

Document Type

Article

Abstract

OBJECTIVE: Radiation therapy is recommended for pituitary tumors that are refractory to surgical and medical therapies. The efficacy of single-fraction radiosurgery is established for these lesions, but lesions within 3 mm of the optic pathway cannot be safely treated with doses higher than 8 to 10 Gy. We hypothesized that the optic nerve will tolerate 5 consecutive daily radiosurgery fractions of 500 cGy with effective tumor control.

METHODS: We reviewed our first 20 patients with recurrent or residual pituitary adenomas within 3 mm of the optic chiasm treated with the CyberKnife radiosurgery system (Accuray, Inc., Sunnyvale, CA). Tumors were treated with a mean coverage of 97 +/- 2.2% (range, 89.8-99.7%), a mean conformity index of 1.3 +/- 0.2 (range, 1.1-1.6), and a mean treatment isodose line of 74.5 +/- 6.6% (range, 60-86%). The primary end point was an interim analysis of visual preservation, and secondary end points were radiographic and endocrinological tumor control.

RESULTS: The mean follow-up period for visual field testing was 26.6 +/- 10.5 months (range, 10.6-41 months). The vision of all 14 patients with intact preoperative vision remained intact. Of the 5 patients with impaired vision, 2 remained stable, and 3 improved. No patient's vision deteriorated. The mean radiographic follow-up was 29.3 +/- 8.6 months (range, 10.2-40.5 months). On magnetic resonance imaging, 12 tumors were stable, 8 were smaller, and none enlarged.

CONCLUSION: This preliminary study establishes that the optic nerve and chiasm tolerate CyberKnife hypofractionated radiosurgery of 5 x 500 cGy to perichiasmatic pituitary adenomas. Early data suggest that this dosing paradigm may achieve satisfactory radiographic and endocrinological tumor control for these challenging lesions, but longer follow-up is necessary to confirm these results.

Medical Subject Headings

Adolescent; Adult; Aged; Female; Humans; Magnetic Resonance Imaging; Male; Middle Aged; Neoplasm Recurrence, Local; Neoplasm, Residual; Optic Chiasm; Pituitary Gland; Pituitary Neoplasms; Radiosurgery; Retrospective Studies; Vision Tests; Vision, Ocular

Publication Date

2-1-2009

Publication Title

Neurosurgery

ISSN

1524-4040

Volume

64

Issue

2 Suppl

First Page

19

Last Page

25

PubMed ID

19165069

Digital Object Identifier (DOI)

10.1227/01.NEU.0000341630.42160.18

This document is currently not available here.

Share

COinS