Medical therapy for clinically non-functioning pituitary adenomas.

Surgery is the first-line treatment of patients with clinically non-functioning pituitary adenomas (NFAs). Because of lack of clinical syndrome these tumours are diagnosed with a variable delay, when patients suffer from compression symptoms (hypopituitarism, headache and visual field defects) due to the extension of the tumour outside the pituitary fossa. Surgery is followed by residual tumour tissue in most patients. In these cases, radiotherapy is generally used to prevent tumour regrowth. However, NFA cell membranes, in analogy with GH- and PRL-secreting adenomas, express somatostatin and dopamine receptors. Treatment with somatostatin analogues (SSA) and dopamine agonists (DA) induced some beneficial effects on visual field defects and was also followed by tumour shrinkage in a minority of cases. DA seem to be more effective on tumour shrinkage than SSA. More recently, a combination treatment with both SSA and DA have been tested in a few patients with interesting results. Lack of randomized, placebo-controlled trials prevents any conclusion on the efficacy of these drugs. By contrast, use of gonatotrophin-releasing hormone analogues has been abandoned.