Abstract
BackgroundSurgical resection of prolactinomas resistant to dopamine agonists is frequently incomplete due to fibrotic changes of the tumour under pharmacological therapy. In order to identify a subgroup of patients who may benefit from early surgery, we thought to investigate possible predictive factors of pharmacological resistance of prolactinomas to dopamine agonists.MethodsWe retrospectively analyzed a database of a Belgian tertiary reference center for patients with pituitary tumours from 2014 to 2016. The groups of interest were patients with dopamine agonist responsive and resistant prolactinomas. The possible predictive factors, including MRI findings, endocrinological parameters, response of tumour and patient factors for dopamine agonist resistance were investigated.ResultsWe included 69 patients of whom 52 were women (75,4%) and 17 were men (24,6%). Rate of dopamine agonist resistance was 15.9%. We identified four significant predictors of dopamine agonist resistance: male gender, a large tumour volume, prolonged time to prolactin normalization and presence of a cystic, hemorrhagic and/or necrotic component. In addition, symptoms due to mass effect, high baseline prolactin level and a high contrast capture on MRI are factors that can be taken into consideration.ConclusionWe identified predictive factors for pharmacological resistance and developed a scoring system for patient specific prediction of resistance to dopamine agonists. This scoring system may have impact on the timing and decision of surgery in prolactinoma patients after further prospective evaluation.
Highlights
Surgical resection of prolactinomas resistant to dopamine agonists is frequently incomplete due to fibrotic changes of the tumour under pharmacological therapy
We considered the diagnosis of prolactinoma only in the presence of a corresponding MRI image and prolactin levels that were clearly elevated corresponding with levels at least 2 times higher than the upper limit of normal for microadenomas and at least 5 times higher than the upper limit of normal for macroadenomas and established on two separate occasions
There was a higher occurrence of macroprolactinomas in men compared to women (88.2% in men versus 30.8% in women)
Summary
Surgical resection of prolactinomas resistant to dopamine agonists is frequently incomplete due to fibrotic changes of the tumour under pharmacological therapy. Prolactin (PRL) secreting adenomas are particular in the responsiveness to a pharmacological therapy in contrast to other pituitary tumours [1]. Dopamine reduces the secretion of prolactin and tumour volume by its suppressive effect on lactotrophic cells in the pituitary and by lowering the angiogenesesis in the surrounding tissue [1, 4]. A minority (5–18%) of patients treated with dopamine agonists, nowadays mainly using cabergoline (CAB) instead of the older variant bromocriptine (BRC), do not achieve sufficient response. This is most commonly owed to resistance or intolerance [2]
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