Hypopituitarism following radiation therapy of pituitary adenomas

Pituitary function was evaluated before and after supervoltage radiotherapy for a pituitary adenoma in 35 patients; 22 had had prior surgical treatment, and 13 had not. For comparison, pituitary function was also followed concurrently in another 10 patients whose pituitary adenomas were treated surgically, but who did not receive subsequent radiotherapy. Following radiotherapy, deficiencies of adrenal, thyroid, and gonadal function developed in 67, 55, and 67 percent of the patients who had previously been treated surgically during a mean of 4.2 years of observation, and in 55, 15, and 50 percent of the patients who did not have prior surgery during the subsequent five years. In contrast, in patients who had previously been treated surgically and who did not receive radiation, deficiencies of these hormones developed in only 13, 13, and 0 percent during four years of observation. It is concluded that supervoltage radiotherapy for pituitary adenoma, especially when preceded by surgical treatment, frequently produces, during the ensuing four to five years, deficiencies of pituitary hormones that had been secreted normally prior to irradiation.