Endocrine Abstracts

Beclere first described the use of pituitary radiotherapy in 1909. Despite this long history of use, there is debate surrounding its role in the modern management of patients with pituitary disease. Whilst treatment with conventionally fractionated external beam radiotherapy (RT) is used infrequently as primary therapy in patients with pituitary adenomas, it is commonly administered following non-curative pituitary surgery. In acromegaly, Cushing's disease/Nelson's syndrome, and prolactinoma, RT unequivocally results in a slow but progressive decline in circulating hormone concentrations. However, most controversy surrounds the application of pituitary RT to post-operative remnants of clinically non-functioning pituitary adenomas (NFAs). In the absence of prognostic markers to predict the likelihood of NFA regrowth, some centres adopt a 'blanket' RT approach whilst others adopt a 'wait and see' policy using sequential MRI scanning. Our group has observed a NFA regrowth rate of 7% at 10 years in those treated with RT compared with 53% in those who did not receive RT. Nonetheless, despite these data; case selection for RT remains a contentious issue. With careful modern planning and dosing regimens, many of the historical safety concerns of pituitary RT are unfounded. Radiation damage to the optic chiasm, and brain necrosis are extremely rare. Furthermore, the risks of secondary oncogenesis following pituitary RT are likely to have been exaggerated due to anomalies in case acquisition; any excess risk being small. The relative sensitivities of anterior pituitary cells to RT are well documented, as is the 2-fold excess mortality associated with hypopituitarism. Interestingly, the SMR is significantly higher in RT-induced hypopituitarism. The role of pituitary RT in the management of functioning pituitary adenomas is established but may change with growing confidence in reliable medical therapies. RT also has a role in preventing regrowth of NFAs but careful patient selection is required to avoid unnecessary RT-induced hypopituitarism.