PRolaCT - Three Prolactinoma RCTs

Inclusion Criteria:

* At least 18 years of age.
* A history of signs and symptoms compatible with the diagnosis prolactinoma.
* New, recent (PRolaCT-1) or known diagnosis of hyperprolactinaemia, defined as a prolactin level 2 times the local laboratory maximum. At the time of randomization hyperprolactinaemia is still present, or was present \< 12 months before inclusion (PRolaCT-2 and PRolaCT-3).
* No clear alternative explanation for hyperprolactinaemia, e.g. medication use.
* Presence of a clearly identifiable (persisting) pituitary mass on MRI not invading the cavernous sinus and having an optimal chance to be completely resected (generally adenomas with a maximum diameter nog exceeding 25mm). A representative MRI at the time of randomization is required, this MRI should generally not be older than 12 months in PRolaCT-3 and 2 months in PRolaCT-1 and PRolaCT-2.
* Competent and able to fill in questionnaires.
* One of the following, dividing patients in to our three RCTs:

  * PRolaCT-1: no prior treatment for prolactinoma;
  * PRolaCT-2: treatment with a dopamine agonist for 4-6 months; or
  * PRolaCT-3: treatment with a dopamine agonist for at least 2 years.

Exclusion Criteria:

* Contraindication for one of the treatment modalities, e.g. severe side effect of cabergoline, contraindications to surgery, or a clear indication for surgical resection.
* Pregnancy at the time of randomization.
* Clinical acromegaly.
* Prior pituitary gland surgery or radiotherapy to the pituitary gland area.
* Severe renal failure (eGFR \<30 ml/min).
* Insufficient understanding of the Dutch or English language.
* Other medical conditions that to the opinion of the physician are not compatible with inclusion in a trial.

Patients eligible for participation in one of the RCTs, but do not consent to randomisation or in whom there is a clear patient or physician preference for either DA treatment or surgery, are considered for participation in PRolaCT-O.