What is a pituitary tumor?
The pituitary gland is a gland at the base of the brain that produces the hormones that regulate growth and other important functions in the body. In some patients, abnormal cells grow to form a tumor in the pituitary gland.
Although most pituitary tumors are harmless and do not need treatment, approximately one out of every 1,000 will need more advanced treatment such as surgery, medication, radiation therapy or chemotherapy.
Most pituitary tumors are curable, but if left untreated, they can lead to serious complications such as complete vision loss.
Causes of pituitary tumors
The cause of a pituitary tumor is unknown. Research is being done to evaluate how changes in a person’s DNA can cause abnormal cell growth in the pituitary gland. Some people inherit gene mutations and are more likely to develop a pituitary tumor.
Risk factors for pituitary tumors
If you have a family history of hereditary conditions such as multiple endocrine neoplasia, type I (MEN I) you are more likely to develop a pituitary tumor. People with family history of (MEN I) can get genetic testing to determine if they inherited this condition.
Although rare, patients with a family history of pituitary tumors are at higher risk of developing a pituitary tumor as well.
Symptoms of pituitary tumors
Many pituitary tumors do not cause symptoms. The most common symptoms of pituitary tumors are:
- Problems with vision
Other symptoms of pituitary tumors include:
- Mood changes
- Unexplained breast growth or milk production
If the pituitary tumor produces hormones, symptoms vary depending on the hormone they are producing.
Diagnosis of pituitary tumors
Because symptoms of pituitary tumors are similar to other conditions, they often go undiagnosed. In many cases, pituitary tumors are diagnosed during diagnostic testing for other medical conditions. If your doctor suspects you have a pituitary tumor, he or she will take a full medical history, including your family history, perform a physical exam and order diagnostic testing such as:
- Blood tests — a blood test may be used to determine the number of certain hormones in the blood.
- Urine tests — a urine test can determine if you have excess cortisol in the body; Cushing’s disease is a rare pituitary condition that results when the body has too much cortisol.
- CT scan (computed tomography scan) — a CT scan produces 3D images of the brain using x-ray images from different angles to show the size of a pituitary tumor.
- MRI (magnetic resonance imaging scan) — a MRI uses magnetic fields to produce detailed images that can show the location and severity of a pituitary tumor.
- Vision testing — if a pituitary tumor is putting pressure on the optic nerve, a vision test is used to evaluate vision, if you have impaired vision, you may have a pituitary tumor.
Treatment of pituitary tumors
Most pituitary tumors are benign, and some do not require treatment. Treatment will depend on the size and location of the tumor and whether the tumor produces hormones and if so, what hormone it is producing. Treating a pituitary tumor requires a team of specialists including a neurologist, neurosurgeon, endocrinologist, radiation oncologist and medical oncologist. Treatment options may include a combination of observation, medication, surgery and radiation therapy.
Observation is always the first step of treatment for a pituitary tumor. If your tumor is not causing any problems, you may not need treatment right away. In these cases, your doctor may recommend regular monitoring to see if your tumor is growing. Your doctor will go over the benefits and risks of living with a tumor versus treatment and work with you to develop the most appropriate treatment protocol.
Pituitary tumor medications
Medication can also be an effective treatment option for patients with pituitary tumors that are producing hormones. There are a variety of medications that can shrink the pituitary tumor or stop the excessive production of hormones.
Dopamine agonists are medications that can shrink and/or stop prolactinomas from producing an excessive amount of the hormone prolactin. In many patients with a prolactinoma, medications alone are an effective treatment option. If drug treatment is successful, medications may be required for life to manage the condition.
Somatostatin analog medications are used in combination with surgery for patients with somatotroph adenomas or growth hormone-secreting tumors. These medications can help normalize growth hormone levels in most patients.
Pegvisomant is a newer medication that is used in combination with surgery for patients with growth hormone-secreting tumors. This category of drugs can block the overproduction of growth hormones in the body.
Pituitary tumor surgery
Surgery is the most common treatment to remove pituitary tumors. If the entire tumor can be removed surgically, this may be the only treatment necessary. Patients who can’t be controlled with medical management, those who have tumors that are growing despite previous treatment and those who are experiencing symptoms because of the tumor are candidates for surgery.
Types of surgery to treat pituitary tumors include:
Craniotomy (transcranial approach)
Large pituitary tumors can be removed with a craniotomy. During a craniotomy, the tumor is surgically removed via an incision in the upper part of the skull.
A neuroendoscopy is a minimally invasive procedure used to remove smaller pituitary tumors. During the procedure, the tumor is removed via a small hole in the skull or through the nose or mouth. Neuroendoscopy allows surgeons to reach areas of the brain that can’t be reached with a craniotomy.
Endoscopic transnasal transsphenoidal approach
The transnasal transsphenoidal approach is the most commonly used technique to remove pituitary tumors. During this procedure, the pituitary tumor is removed via the sphenoid sinus (empty space in the skull that is below the brain and behind the nasal passages). The brain is not touched during this procedure, so the risk of damage is minimal and there are fewer side effects and no scar. But, this surgery is more complex and longer. Success rates from this procedure are greater than 80 percent.
Radiation therapy for pituitary tumors
Radiation therapy for pituitary tumors uses high-energy x-rays to eliminate tumors. Radiation therapy is often used in combination with surgery or alone if surgical removal of the tumor is not an option. Radiation therapy is also often used if the tumor returns after surgery. Radiation therapy options include:
Gamma Knife is a type of stereotactic radiosurgery that delivers a single, high dose radiation beam directly to the tumor. Treatment is typically completed in one session, but in some cases, you may need multiple treatments. Although the name Gamma Knife might indicate surgery or usage of knives, this technology does not involve incisions. Because of the precise targeting, this technology limits the brain’s exposure to radiation and lessens damage to the pituitary gland.
External beam radiation
During external beam radiation, radiation is delivered in small doses over a series of treatments over four to six weeks. Although effective in many cases, external beam radiation may damage normal pituitary cells and/or brain tissue.