Pheochromocytoma medical therapy
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Ahmad Al Maradni, M.D. [2]
Overview
Treatment with alpha blockers (example: phenoxybenzamine) followed by beta blockers (example: atenolol) is required before surgery. Adjunctive chemotherapy and radiation are used in metastatic disease.
Medical Therapy
Preoperative medical therapy:
All patients doing surgery need preoperative treatment to control hypertension during surgery and hypotension after it. There are three medical regimens for treatment; Combined alpha and beta-adrenergic blockade, calcium channel blockers, and metyrosine.[1]
Any surgical option requires prior treatment with both the non-selective alpha adrenoceptor blocker (phenoxybenzamine) to counteract hypertension and the beta-1 adrenoceptor antagonist atenolol to reduce cardiac output. Given before surgery, these can also block the effect of a sudden release of adrenaline during tumour resection, which would otherwise endanger the anaesthetised patient.
Medical preparation for surgery — No universally accepted method of preparation for surgery in children with pheochromocytomas has been established. In our practice we generally use alpha-adrenergic blockade with phenoxybenzamine(Dibenzyline) [10]. some clinicians may choose to a selective alpha-1 antagonist (eg, doxazosin, terazosin, prazosin).
On the second or third day of alpha-adrenergic blockade, patients are encouraged to start a diet high in sodium content because of the catecholamine-induced volume contraction and the orthostasis associated with alpha-adrenergic blockade.
After adequate alpha-adrenergic blockade has been achieved, beta-adrenergic blockade is initiated, which typically occurs two to three days preoperatively. The beta-adrenergic blocker should never be started first, because blockade of vasodilatory peripheral beta-adrenergic receptors with unopposed alpha-adrenergic receptor stimulation can lead to a further elevation in blood pressure. The clinician should exercise caution if the patient is asthmatic or has heart failure. Chronic catecholamine excess can produce a cardiomyopathy that may become evident with the initiation of beta-adrenergic blockade, resulting in acute pulmonary edema. Therefore, when the beta-adrenergic blocker is administered, it should be used cautiously and at a low dose. The dose is then increased as necessary to control the tachycardia. the patient is ready for surgery in 10 to 14 days after starting the alpha-adrenergic blockade.
administration of a calcium channel blocker for blood pressure control 64,65
most clinicians reserve metyrosine primarily for patients who cannot be treated with the combined alpha and beta-adrenergic blockade protocol because of intolerance or cardiopulmonary concerns. The use of metyrosine has also become more problematic because of increases in cost.
Chemotherapy
Metastatic pheochromocytoma is treated with Averbuc protocol which is a combination of cyclophosphamide, vincristine, and dacarbazine.[2]
Radiation
131I-MIBG radiation therapy has been used for the treatment of MIBG-avid metastases.[2]
Contraindicated medications
Pheochromocytoma is considered an absolute contraindication to the use of the following medications:
References
- ↑ Tauzin-Fin P, Sesay M, Gosse P, Ballanger P (2004). "Effects of perioperative alpha1 block on haemodynamic control during laparoscopic surgery for phaeochromocytoma". Br J Anaesth. 92 (4): 512–7. doi:10.1093/bja/aeh083. PMID 14766711.
- ↑ 2.0 2.1 National Cancer Institute. Physician Data Query Database 2015. http://www.cancer.gov/types/pheochromocytoma/hp/pheochromocytoma-treatment-pdq#link/_179_toc