Treatment of Acromegaly aims to reduce excess growth hormone, relieve the pressure that the tumour is exerting on the surrounding structures and thus improve symptoms of the disease. If not treated the condition may worsen and eventually lead to severe symptoms and death.
Treatment can be achieved in two manners – surgery or medications.
In most cases of acromegaly (85%) the cause of the condition is an adenoma in the pituitary gland. This is a non-cancerous and benign tumor but can press upon surrounding vital structures of the brain causing severe symptoms such as vision loss.
Surgery is undertaken to remove this tumor. Sometimes the tumour is too large to be removed completely. Removal of a pituitary adenoma is usually undertaken under general anaesthesia wherein the patient is made unconscious during surgery. The surgeon will make an incision though the nose or inside the upper lip to access the gland. The tumor is then removed and this may cause a dramatic relief of pressure on the surrounding structures and a lowering of growth hormone levels.
Trans-sphenoidal surgery is the treatment of choice in most cases. It has a remission rate or cure rate of 80-85% for microadenomas and 50-65% for macroadenomas. Patients may need drug treatment after surgery in order to reduce growth hormone levels.
In most cases surgery is the successful treatment if the tumor is not too big. After surgery there may be some soft tissue swelling and bruises that may disappear in a few days.
Although successful, pituitary surgery is a complex one and may lead to several complications like damage to the healthy parts of the pituitary gland, leakage of cerebrospinal fluid, bleeding and infection etc.
Radiation therapy for acromegaly
If the pituitary tumor is large and surgery is not possible, the tumor may be shrunk using radiation therapy. Radiation therapy has one disadvantage: reduction in growth hormone levels after radiation is very slow.
In addition, there is a risk of damage to the whole gland which may cause a gradual decline in the production of other hormones from the gland. This necessitates hormone replacement therapy for the rest of the patient’s life. Also, due to effects on the reproductive hormones from the pituitary, radiation may cause infertility.
Radiation may be given as conventional form where the tumour is targeted with external beams. The patient needs to attend the office of the radiologist to receive the radiation from a large X ray like machine in small doses over four to six weeks. Weekends are let off to allow normal tissues to heal. This type of radiation causes damage to the structures surrounding pituitary gland and brain tissues.
Radiation may also be given as stereotactic delivery. In this method high-dose beam of radiation can be precisely aimed at the tumour. The head is kept still by wearing a rigid head frame. The beam kills the tumors cells usually in a single session.
Pharmacotherapy or use of medications for treatment
Medications used in treatment of acromegaly include:-
Bromocriptine or cabergoline suppress growth hormone production. These are however effective in a small number of patients. These are dopamine agonists.
Octreotide or lanreotide control growth hormone release and also lead to shrinkage of the pituitary tumor in one third of the acromegaly patients. These are somatostatin analogues. Somatostain inhibits the release of growth hormone normally in the body. These are given as intramuscular injections once a month. These can be safely used over long term.
Pegvisomant directly blocks the effects of growth hormone and can improve symptoms. It is a genetically modified analogue of human growth hormone and is a selective growth hormone receptor antagonist. It can lower the IGF-1 in 90 to 100% patients. This is given as once daily injections. Growth hormone levels increase during treatment and no decrease in tumour size is seen. Pegvisomant is licensed for the treatment of acromegaly in patients with inadequate response to surgery, radiotherapy or somatostatin analogues.
Reviewed by April Cashin-Garbutt, BA Hons (Cantab)