Endocrine Abstracts

Contemporary management of pituitary tumours is based on a multidisciplinary approach involving surgery, radiotherapy (RT) and medical therapy. External beam RT significantly reduces the likelihood of tumour re-growth following surgery for non-functioning pituitary adenomas and suppresses hypersecretion in hormonally-active tumours. However, over the years, a number of potentially significant complications of pituitary RT have been described.

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 RT for pituitary and other central nervous system tumours. It is also possible that pituitary RT increases the risk of cerebrovascular disease by causing hypopituitarism, which is itself associated with an increase in vascular mortality. However, questions remain with regards to causation.

Patients with pituitary tumours frequently report problems with memory and sustained attention that impact upon normal daily activities. During conventional pituitary RT, the limbic system, the hippocampus, the mammillary bodies and the pre-frontal cortex all receive a significant amount of radiation. It has been suggested that pituitary RT may be associated with cognitive impairment, but at present it is unclear whether any causal link exists between pituitary RT and abnormalities of memory and higher mental function.

Stereotactic radiosurgery delivers multiple low-energy beams toward a target with improved stereotactic accuracy. The principal advantage is that it reduces the dose of radiation received by transirradiated tissue close to the target. It 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, further data are required to fully assess the long-term adverse profile of stereotactic radiosurgery.