What if the tumor grows in pregnancy?
During pregnancy, high estrogen levels from the placenta can stimulate prolactinoma growth, and the dopamine agonist’s inhibitory effect is gone once that medication’s been stopped. This means that “We have both a ‘push’ and a decrease in the ‘pull’ here, so you may have tumor enlargement,” said Dr. Molitch.
The risk for tumor enlargement in microadenomas is about 2.4%, and ranges to about 16% for enlargement of macroadenomas during pregnancy. For macroadenomas, “you might consider a prepregnancy debulking of the tumor,” Dr. Molitch said.
It’s reasonable to stop a dopamine agonist once pregnancy’s been established in a patient with a prolactinoma, and “follow the patient symptomatically every few months,” letting suspicious new symptoms like visual changes or headaches be the prompt for visual field exam and magnetic resonance imaging without contrast, said Dr. Molitch.
Though it’s not FDA approved, consideration can be given to continuing a dopamine agonist in a patient with a large prepregnancy adenoma throughout pregnancy – and if the tumor is enlarging significantly, the dopamine agonist should be restarted if it’s been withheld, said Dr. Molitch. Finally, surgery is the option if an enlarging tumor doesn’t respond to a dopamine agonist, unless the pregnancy is far enough along that delivery is a safe option.