Question: What are the treatments for Acromegaly ?
Answer: Currently, treatment options include surgical removal of the tumor, medical therapy, and radiation therapy of the pituitary.
Goals of treatment are to
- reduce excess hormone production to normal levels - relieve the pressure that the growing pituitary tumor may be exerting on the surrounding brain areas - preserve normal pituitary function or treat hormone deficiencies - improve the symptoms of acromegaly
Surgery
Surgery is the first option recommended for most people with acromegaly, as it is often a rapid and effective treatment. The surgeon reaches the pituitary via an incision through the nose or inside the upper lip and, with special tools, removes the tumor tissue in a procedure called transsphenoidal surgery. This procedure promptly relieves the pressure on the surrounding brain regions and leads to a rapid lowering of GH levels. If the surgery is successful, facial appearance and soft tissue swelling improve within a few days.
Surgery is most successful in patients with blood GH levels below 45 ng/ml before the operation and with pituitary tumors no larger than 10 millimeters (mm) in diameter. Success depends in large part on the skill and experience of the surgeon, as well as the location of the tumor. Even with the most experienced neurosurgeon, the chance of a cure is small if the tumor has extended into critical brain structures or into the cavernous sinus where surgery could be risky.
The success rate also depends on what level of GH is defined as a cure. The best measure of surgical success is normalization of GH and IGF-I levels. The overall rate of remission-control of the disease-after surgery ranges from 55 to 80 percent. (See For More Information to locate a board-certified neurosurgeon.)
A possible complication of surgery is damage to the surrounding normal pituitary tissue, which requires lifelong use of pituitary hormone replacement. The part of the pituitary that stores antidiuretic hormonea hormone important in water balancemay be temporarily or, rarely, permanently damaged and the patient may require medical therapy. Other potential problems include cerebrospinal fluid leaks and, rarely, meningitis. Cerebrospinal fluid bathes the brain and can leak from the nose if the incision area doesnt heal well. Meningitis is a bacterial or viral infection of the meninges, the outer covering of the brain.
Even when surgery is successful and hormone levels return to normal, people with acromegaly must be carefully monitored for years for possible recurrence of the disease. More commonly, hormone levels improve, but do not return to normal. Additional treatment, usually medications, may be required.
Medical Therapy
Medical therapy is most often used if surgery does not result in a cure and sometimes to shrink large tumors before surgery. Three medication groups are used to treat acromegaly.
Somatostatin analogs (SSAs) are the first medication group used to treat acromegaly. They shut off GH production and are effective in lowering GH and IGF-I levels in 50 to 70 percent of patients. SSAs also reduce tumor size in around 0 to 50 percent of patients but only to a modest degree. Several studies have shown that SSAs are safe and effective for long-term treatment and in treating patients with acromegaly caused by nonpituitary tumors. Long-acting SSAs are given by intramuscular injection once a month.
Digestive problems-such as loose stools, nausea, and gas-are a side effect in about half of people taking SSAs. However, the effects are usually temporary and rarely severe. About 10 to 20 percent of patients develop gallstones, but the gallstones do not usually cause symptoms. In rare cases, treatment can result in elevated blood glucose levels. More commonly, SSAs reduce the need for insulin and improve blood glucose control in some people with acromegaly who already have diabetes.
The second medication group is the GH receptor antagonists (GHRAs), which interfere with the action of GH. They normalize IGF-I levels in more than 90 percent of patients. They do not, however, lower GH levels. Given once a day through injection, GHRAs are usually well-tolerated by patients. The long-term effects of these drugs on tumor growth are still under study. Side effects can include headaches, fatigue, and abnormal liver function.
Dopamine agonists make up the third medication group. These drugs are not as effective as the other medications at lowering GH or IGF-I levels, and they normalize IGF-I levels in only a minority of patients. Dopamine agonists are sometimes effective in patients who have mild degrees of excess GH and have both acromegaly and hyperprolactinemiatoo much of the hormone prolactin. Dopamine agonists can be used in combination with SSAs. Side effects can include nausea, headache, and lightheadedness.
Agonist: A drug that binds to a receptor of a cell and triggers a response by the cell, mimicking the action of a naturally occurring substance. Antagonist: A chemical that acts within the body to reduce the physiological activity of another chemical substance or hormone.
Radiation Therapy
Radiation therapy is usually reserved for people who have some tumor remaining after surgery and do not respond to medications. Because radiation leads to a slow lowering of GH and IGF-I levels, these patients often also receive medication to lower hormone levels. The full effect of this therapy may not occur for many years.
The two types of radiation delivery are conventional and stereotactic. Conventional radiation delivery targets the tumor with external beams but can damage surrounding tissue. The treatment delivers small doses of radiation multiple times over 4 to 6 weeks, giving normal tissue time to heal between treatments.
Stereotactic delivery allows precise targeting of a high-dose beam of radiation at the tumor from varying angles. The patient must wear a rigid head frame to keep the head still. The types of stereotactic radiation delivery currently available are proton beam, linear accelerator (LINAC), and gamma knife. With stereotactic delivery, the tumor must be at least 5 mm from the optic chiasm to prevent radiation damage. This treatment can sometimes be done in a single session, reducing the risk of damage to surrounding tissue.
All forms of radiation therapy cause a gradual decline in production of other pituitary hormones over time, resulting in the need for hormone replacement in most patients. Radiation also can impair a patients fertility. Vision loss and brain injury are rare complications. Rarely, secondary tumors can develop many years later in areas that were in the path of the radiation beam.