Feasibility and outcome of re-irradiation in the treatment of multiply recurrent pituitary adenomas

Purpose: This study evaluates the toxicity and outcomes of re-irradiation to the sella for pituitary adenomas.

Conclusions: Re-irradiation is a feasible treatment option for local control in patients with recalcitrant pituitary adenomas, with acceptable rates of RION and TLN given the lack of options that may be available otherwise. Re-irradiation, however, did not control hormonal hypersecretion.

Methods: Patients diagnosed with a pituitary adenoma and treated with two or more courses of radiation treatment (RT) to the sella were retrospectively analyzed for: initial diagnosis, including histological type and functional status; RT modality, technique, dose, and fractionation; treatment with surgery, endocrine agents, and chemotherapy; toxicity of RT including radiation-induced optic neuropathy, radionecrosis, and radiation-induced neoplasms; and outcomes including local control, distant metastasis, biochemical control of functional tumors, and vital status at last follow-up.

Results: We identified 15 patients with non-functioning pituitary adenoma (n = 6), Cushing’s disease (CD) (n = 5), acromegaly (n = 3), and prolactinoma (n = 1). Initial RT was delivered using opposed lateral fields in 8 (53 %), intensity-modulated radiation therapy (IMRT) in 4 (27 %), fractionated stereotactic radiation therapy (FSRT) in 1 (6.7 %), and stereotactic radiosurgery (SRS) in 2. The median dose was 49.5 Gy for fractionated RT and 15–25 Gy for SRS. Re-irradiation was performed a median of 5.8 years after initial RT, and delivered using lateral opposed beams (n = 1), IMRT (n = 4), linear-accelerator based SRS (n = 3), FSRT (n = 3), gamma knife surgery (n = 2), and yttrium-90 brachytherapy (n = 1). The median dose of re-irradiation was 45 Gy (range 27.9–54 Gy) for fractionated RT and 18 Gy for SRS. Radiation-induced optic neuropathy (RION) was observed in 2 (13.3 %) patients, 6 months and 14 years after re-irradiation; the 5-year rate of RION was 9 %. Temporal lobe necrosis (TLN) occurred in two patients (13.3 %), both of whom had received SRS. The 2- and 5-year rates of TLN were 10 and 28 %. Actuarial local control rates at 2 and 5 years were 80 and 58 %, respectively. Biochemical remission occurred in one of three patients with CD. Four patients (27 %) ultimately developed pituitary carcinoma.