Introduction: Stereotactic radiosurgery with GammaKnife is the gold standard in radiotherapy for pituitary adenomas, but it is limited to lesions greater than 3 mm from the optic apparatus. Fractionated radiotherapy is typically employed for such perioptic tumors. Hypofractionated Cyberknife (i.e., 3-5 fractions) treatment schemes have been employed with success. The addition of a traditionally fractionated (i.e., 25-30 fractions) scheme to Cyberknife radiotherapy allows for a higher total dose to be delivered to the tumor with preservation of the surrounding critical structures. This series describes the tumor control rates as well as endocrine and vision outcomes for this novel approach.
Methods: Fifty-three patients were treated with traditionally fractionated Cyberknife radiotherapy (Accuray Inc, Sunnyvale, California) for pituitary adenomas within 3 mm of the optic apparatus. The primary end-point was tumor control with secondary end-points of vision and pituitary function preservation, as well as endocrine control in hormone-secreting tumors.
Results: The tumor control rate, as measured on MRI as either stable or decreased in size, was 98.1% (52/53) at a mean follow-up of 32.5 months (range 3 – 77 months). The mean total dose was 46.7 Gy (Range 45-50.4 Gy) delivered in 25 fractions (51 patients) or 28 fractions (2 patients). All patients experienced preservation or improvement of their pre-existing vision status. No change in pituitary function was noted in 98.1% (52/53). One patient experienced worsening of pituitary function secondary to pituitary apoplexy that occurred 4 months after undergoing treatment. The endocrine control rate in hormone-secreting tumors was 75% (6/8).
Conclusions: Fractionated Cyberknife radiotherapy demonstrates local tumor control and endocrine control rates similar to GammaKnife with superior vision and pituitary function preservation. It potentially has the benefit in endocrine control for hormone-secreting tumors over hypofractionated Cyberknife.
Patient Care: Perioptic pituitary adenomas are difficult lesions to treat, and this treatment paradigm has the advantage of excellent tumor control, vision preservation, and endocrine control. It is a potential improvement upon current standard of practice for these lesions.
Learning Objectives: By the conclusion of this session, participants should be able to 1.) Describe the importance of fractionated radiotherapy for preservation of the optic apparatus, 2.) Understand the challenge of treating functional pituitary adenomas with radiotherapy, 3.)Identify a novel treatment paradigm for perioptic lesions.