Delayed sequelae of pituitary irradiation

Area of Science:

• Neurology
• Endocrinology
• Radiation Oncology

Background:

• Stereotactic radiosurgery using helium particles has been employed since 1958 at Lawrence Berkeley Laboratory.
• A total of 781 patients have undergone this treatment targeting the adenohypophysis.

Purpose of the Study:

• To report autopsy findings in 15 patients treated with helium-particle radiosurgery.
• To evaluate the histopathological effects of radiation on the pituitary gland and surrounding structures.

Main Methods:

• Autopsy examination of pituitary glands from 15 patients who received helium-particle stereotactic radiosurgery.
• Analysis of radiation doses and treatment indications (diabetic retinopathy, eosinophilic adenomas).

Main Results:

• Pituitary radiation for diabetic retinopathy (116 Gy) caused time-dependent progressive fibrosis.
• Treatment for eosinophilic adenomas (56 Gy) resulted in cystic cavitation of adenomas.
• Adenomas were more radiosensitive than normal pituitary tissue, which was more radiosensitive than the neurohypophysis.
• No significant radiation damage was observed in adjacent brain tissue or cranial nerves.
• Endocrine organs under pituitary control showed atrophy and progressive hypofunction.

Conclusions:

• Charged-particle therapy creates a focal radiation lesion confined to the pituitary gland.
• This treatment modality effectively avoids injury to critical surrounding central nervous system structures.
• Long-term effects include pituitary hypofunction and atrophy of dependent endocrine organs.