Endocrine Abstracts

External beam radiotherapy has been used in the management of hormonally active and non-functioning pituitary adenomas for nearly a century. Administered postoperatively, radiotherapy significantly reduces the likelihood of tumour re-growth following surgery for non-functioning pituitary adenomas. In patients with acromegaly, Cushing’s disease and resistant prolactinomas, conventional fractionated radiotherapy suppresses functional hypersecretion. However, over the years, a number of potentially significant complications of pituitary radiotherapy have been described, including the formation of secondary intracranial tumours, damage to the optic nerves and impaired neurocognitive function. Radiation may cause a variety of vascular injuries and haemodynamic changes to the cerebral vasculature, and several authors have reported cerebrovascular complications and an increase in cerebrovascular mortality in patients receiving radiotherapy for pituitary and other central nervous system tumours.

Another significant problem arising as a consequence of pituitary radiotherapy is the development of hypopituitarism. 10 years following pituitary radiotherapy, over 50 percent of patients develop deficiencies in one or more anterior pituitary hormones. A number of studies have demonstrated increased mortality in patients with hypopituitarism, predominantly due to cerebrovascular and cardiovascular disease. However, questions remain with regards to causation, and pituitary radiotherapy has only been linked directly to mortality in one of these studies.

Stereotactic radiosurgery is a relatively new technique, only recently introduced in the management of pituitary disease. Some authors have suggested the ability to accurately direct high doses of radiation to the pituitary area with relative sparing of the surrounding tissues results in a more beneficial adverse profile. However, there is a lack of long-term data to support this.

Based on current evidence, the use of conventional external beam radiotherapy in the management of pituitary disease must involve a critical risk-benefit analysis in each case. Further data are required to fully assess the long-term adverse profile of stereotactic radiosurgery.