The Long-Term Outcome of Pituitary Irradiation after Unsuccessful Transsphenoidal Surgery in Cushing's Disease

Reviewers: Kenneth Blank, MD and Leonard Farber, MD
Source: pituitary adenoma or, occasionally, hyperplasia. Cushing's disease accounts for approximately 70 percent of the spontaneous adult cases of Cushing's syndrome.

The standard treatment of Cushing's disease is surgical removal of the pituitary adenoma via a transsphenoidal approach. This procedure cures about three-quarters of patients. Those who continue to have symptoms of Cushing's disease - which include centripetal obesity, menstrual changes, hirsutism, cutaneous atrophy, muscle weakness, depression and hypertension- have several options to choose from to cure the disease. Options include a second operation to remove the pituitary adenoma, an operation to remove both adrenal glands, or medical therapy. A fourth option is radiation treatments to the pituitary gland which functions to destroy the disease-causing adenoma.

Radiation therapy after unsuccessfully pituitary surgery in Cushing's disease is often recommended, but its efficacy is unknown. An article in the New England Journal of Medicine from Spain documents 30 patients who underwent radiotherapy of the pituitary gland after unsuccessful microsurgery. Patients received a median dose of 50Gy and were followed every six months with physical exam and laboratory data of pituitary and adrenal function. Remission was defined as the absence of signs and symptoms of Cushing's syndrome, normal urinary cortisol excretion, and low plasma cortisol levels after the administration of dexamethasone. Median follow-up was three and one-half years. 83% of the patients had remissions, most occurring within two years from the radiotherapy. None of the 25 patients who were in remission experienced a relapse. Complications from radiotherapy included low levels of pituitary hormones including growth hormone, gonadotropins, thyrotropin and corticotropin. The authors conclude that irradiation is a safe and effective treatment of Cushing's disease after unsuccessful pituitary surgery.