Radiotherapy of nonfunctional adenomas of the pituitary gland. Results with long-term follow-up.

A total of 112 patients with the diagnosis of nonfunctional pituitary adenoma received radiation therapy at the University of Pittsburgh between 1964 and 1987. Postoperative radiation therapy was administered in 87 patients. Actuarial progression-free survival (tumor control) at 5, 10, 15, and 20 years was 97%, 89%, 87%, and 76%, respectively. Radiation prescribed to the 95% isodose ranged from 35.72 Gy to 62.32 Gy. Multivariate analysis showed decreased tumor control to be significantly associated with increasing field size (P = .036). No improvement in tumor control could be detected with increasing total radiation dose or nominal standard dose (NSD). One patient developed optic neuropathy and another developed a glioblastoma after doses in both patients of 4750 cGy in 25 fractions. External beam radiotherapy for nonfunctional pituitary adenomas was found to be effective and safe when doses less than 4750 cGy in 25 fractions were used.