Endocrine Abstracts

Pituitary radiotherapy (RT) causes hypopituitarism that is associated with a doubling in standardised mortality ratio. Other potential complications of pituitary RT are less clearly defined. Retrospective observational studies have estimated the risks of secondary intracranial tumour formation to be as high as 1-2% following conventional pituitary RT but these figures have been calculated against background normal population data. The majority of cases of intracranial tumors following pituitary RT have been published as case reports, thus making it impossible to know the denominator upon which to calculate the true incidence of this potential complication. Moreover, published reports are weighted towards describing the unusual, and an association may be one of ascertainment rather than causation. Currently, there exists no direct causal link between pituitary RT and secondary intracranial tumours. We present four cases detailing dual intracranial pathology in the absence of preceding pituitary RT.

Age Sex Pituitary tumour Extent Other tumour

66 F NFT Suprasellar Sphenoid wing meningioma

45 F NFT Suprasellar Parafalcine meningioma

40 F MicroPRL Intrasellar Frontal low grade astrocytoma

62 F NFT Intrasellar Cerebellopontine angle meningioma

F - female; NFT - clinically non-functioning tumour; MicroPRL - microprolactinoma

Such cases serve to highlight the observation that coexisting intracranial tumours occur not infrequently in association with pituitary adenomas. It is intriguing to postulate that such tumours may even share a common aetiological basis. In summary, the true excess risk of secondary tumours following pituitary RT is unknown. There may be a predilection of association between pituitary adenomas and other intracranial tumours. Further studies are required to determine the relative risk of intracranial tumours in pituitary patients who have received RT compared with those who have not.