EXTERNAL RADIOTHERAPY OF PITUITARY-ADENOMAS

Purpose: To evaluate therapeutic outcome and side effects of radiother apy in pituitary adenomas as sole or combined treatment. Methods and M aterials: Retrospective analysis of 138 patients (74 male, 64 female) irradiated for pituitary adenoma from 1972 to 1991 was performed. Mean age was 49.7 years (15-80 years). Regular follow-up (in the mean 6.53 +/- 3.99 years) included radiodiagnostical [computed tomography (CT), magnetic resonance imaging (MRI), x-ray], endocrinological, and ophth almological examinations. Seventy patients suffered from nonfunctional pituitary adenoma, 50 patients suffered from growth-hormone producing adenomas, 11 had prolactinomas, and 7 patients had adrenocorticotropi c hormone (ACTH) producing pituitary adenomas. In 99 patients surgery was followed by radiotherapy in case of suspected remaining tumor (inv asive growth of the adenoma, assessment of the surgeon, pathologic CT after surgery, persisting hormonal overproduction). Twenty-three patie nts were treated for recurrence of disease after surgery and 16 patien ts received radiation as primary treatment. Total doses from 40-60 Gy (mean: 45.5 Gy) were given with single doses of 2 Gy 4 to five times a week. Results: Tumor control was achieved in 131 patients (94.9%). In seven patients, recurrence of disease was diagnosed in the mean 2.9 y ears (9-98 months) after radiotherapy and salvaged by surgery. A stati stically significant dose-response relationship was found in favor of doses greater than or equal to 45 Gy. Ninety percent of the patients w ith hormonally active pituitary adenomas had a benefit from radiothera py in means of complete termination (38%) or at least reduction (52%) of hormonal overproduction. Partial or complete hypopituitarism after radiotherapy developed, depending on hormonal axis, in 12 (prolactin) to 27% (follicle-stimulating hormone FSH) of patients who had not alre ady had hypopituitarism prior to radiation. Two out of 138 patients su ffered reduction of visual acuity, which was, in part, related to radi otherapy. Both therapeutic effects and side effects occurred after a l atency period of 3 months up to 9 years. Conclusion: We conclude that radiotherapy of pituitary adenomas, using modern treatment planning te chniques, is effective and safe. To achieve optimal tumor control, dos es of 45-48 Gy (conventionally fractionated) should be applied.