Long-term results of radiation therapy for pituitary adenoma

Purpose. Local control for pituitary adenomas treated with external beam radiation therapy was retrospectively analyzed to evaluate the efficacy of radiation. Materials and methods. Thirty-eight patients treated with radiation therapy between 1979 and 1994 were analyzed. The median age was 46. Nineteen newly diagnosed tumors were treated with surgery and radiation therapy, while the others were recurrent cases. Twenty-two tumors were non-functioning, while 10 produced growth hormone (GH) and three each were prolactin-, and adrenocorticotropic hormone (ACTH)-producing tumors. The median radiation dose was 50 Gy in 25 fractions. Results. Non-functioning adenomas and prolactin-producing adenomas were completely controlled, judging from the absence of tumor progression on neuroimaging studies and clinical symptoms, and normalization of the serum prolactin level (< 25 ng/ml). On the other hand, local control was obtained in only one of the 3 patients with ACTH-producing adenomas, and the control rate at 10 years was only 46% for GH-producing adenomas. Panhypopituitarism developed in 35% of the patients after radiation therapy. No other serious complications were noted. Conclusion. Non-functioning pituitary adenomas and prolactin-producing adenomas were well controlled with external radiation therapy combined with surgery. However, dose escalation might be necessary to control GH- or ACTH-producing tumors. It is important to replace corticosteroid hormone and thyroid hormone in many patients.