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Dopamine agonists and pituitary tumor shrinkage
J S Bevan1, J Webster, C W Burke
1Division of Endocrinology, Diabetes and Metabolism, University of Wales College of Medicine, Heath Park, Cardiff, UK.
Endocrine Reviews
|May 1, 1992
Summary
Dopamine agonists effectively shrink most prolactinomas by reducing cell size, with significant tumor reduction observed in most patients. However, nonfunctioning and other hormone-secreting pituitary tumors rarely respond to this treatment.
Area of Science:
- Endocrinology
- Oncology
Background:
- Pituitary macroadenomas are tumors of the pituitary gland that can cause hormonal imbalances and mass effects.
- Dopamine agonists are a class of drugs used to treat certain pituitary tumors, particularly prolactinomas.
Purpose of the Study:
- To review and clarify the tumor-shrinking effects of dopamine agonists on various types of pituitary macroadenomas.
- To assess the efficacy of dopamine agonists in relation to different cell types and patient outcomes.
Main Methods:
- Systematic review of existing literature on dopamine agonist treatment for pituitary macroadenomas.
- Analysis of tumor shrinkage rates, response variability, and resistance mechanisms across different tumor subtypes.
Main Results:
- Dopamine agonists, particularly bromocriptine (BC) and cabergoline, significantly reduce the size of macroprolactinomas, with 89% showing some shrinkage due to cell size reduction.
- Shrinkage primarily occurs within the first three months; resistance is rare, and drug withdrawal usually leads to hyperprolactinemia.
- Nonfunctioning and other functioning pituitary tumors (GH-, TSH-, ACTH-secreting) rarely shrink with dopamine agonists, though some growth restraint may occur.
Conclusions:
- Dopamine agonists are highly effective for macroprolactinomas, often obviating the need for surgery.
- Treatment resistance in macroprolactinomas is uncommon, but molecular mechanisms require further investigation.
- Dopamine agonists have limited efficacy for nonfunctioning and other functioning pituitary tumors, for which surgery remains a primary treatment option.