Side effects of radiation therapy for pituitary tumors

Small pituitary adenomas that are picked up by chance and not causing symptoms may not need immediate treatment. In these cases the pituitary adenoma will be monitored with regular scans.

Table of Contents Show

How is radiation therapy given?
Side effects of radiation for pituitary tumors
What does radiation do to the pituitary gland?
Can radiation shrink a pituitary tumor?
What is the life expectancy of someone with a pituitary tumor?
Is radiotherapy effective for treating pituitary adenoma?

Larger pituitary adenomas and those causing symptoms usually need treatment. The type of treatment recommended depends on the type of adenoma (functioning or non-functioning) and its size. Possible treatment options include medication, surgery and/or radiation therapy.

Medical Therapy

Functioning pituitary adenomas (those producing excess hormones) may be treated with medications that stop the adenoma from producing hormones. The medication also controls the growth of the adenoma. The type of medication recommended is specific for the type of hormone being produced by the adenoma.

Surgery is usually recommended for functioning adenomas that are not responding to medical therapy, or if the adenoma is compressing adjacent structures.

If an adenoma is thought to be surgically resectable this may be done via a small cut made under the upper lip or at the back of the nose (transphenoidal surgery). If the adenoma is not accessible using this route, surgery may be performed via a cut through the skull (craniotomy). If there is residual adenoma left after surgery, post-operative radiation therapy may also be recommended.

Radiation therapy may be used after surgery if there is residual adenoma remaining or if the adenoma recurs following surgery. In some cases radiation therapy may be recommended as primary treatment if the pituitary adenoma is non-functioning and surgery can not be performed.

Radiation therapy may be given as stereotactic radiosurgery (SRS), which involves a single dose of highly focused radiation therapy, or as conventional fractionated (stereotactic) radiation therapy, which involves small doses of radiation, 5 days a week usually for a period of 5-6 weeks. Stereotactic radiosurgery is usually used for small tumours (less than 3cm) that are a safe distance (1-5mm) away from sensitive structures such as the optic nerves and optic chiasm. Larger adenomas or those very close to the optic chiasm are treated with fractionation radiation therapy to reduce the risk of damaging the optic nerve pathways.

Radiation is often used to treat pituitary tumors that come back after surgery. If you are not healthy enough to have surgery, radiation may be used to shrink a tumor that is causing problems. It may also be used to treat pituitary tumors that cause symptoms that medicine can’t help. If a tumor is very large, the surgeon may first remove as much as safely possible. Then the rest of the tumor will be treated with radiation.

Radiation works very slowly on pituitary tumors. It may take up to 10 years to control a tumor's growth and hormone production.

How is radiation therapy given?

Before radiation starts, imaging scans are taken. These are used to clearly outline the size and shape of the tumor. The radiation beams are controlled to fit this shape and kill the tumor. This helps limit damage to nearby healthy tissue.

Radiation for pituitary tumors can be given in different ways. Conventional radiation is given from a machine outside the body. The radiation is directed at the pituitary. Treatment is given 5 times a week for several weeks.

Other types of radiation that may be used include:

Stereotactic radiation. This form of radiation precisely targets the tumor. It directs beams at the tumor from several different angles. Treatment may be given in 1 session. This method can safely give a higher radiation dose. It can also radiate the tumor and not the entire brain. This kind of radiation can prevent a mild decrease in mental sharpness that can happen many years after conventional radiation. But it can’t be used if the tumor is near important nerves, such as the optic nerve.
Proton beam radiation. This type of radiation therapy uses a different type of beam. It can focus right on the pituitary tumor. This may limit radiation to nearby healthy tissues. But it is only done in a few medical centers because special equipment must be used.

It's common to have a mold, mask, or frame made. This will hold you in the exact same position for each radiation treatment.

Side effects of radiation for pituitary tumors

Talk to your doctor about what you might feel like during and after radiation therapy. Side effects may get worse as treatment goes on, but can be treated.

Side effects often get better or go away over time after treatment ends. The side effects of radiation therapy include:

Skin in the treated area that is irritated, dry, red, and blistered like a sunburn
Hair loss on the part of your head that the radiation passes through to reach the tumor
Feeling tired or weak
Swelling in the brain that causes headaches, confusion, seizures, and speech problems
Damage to the pituitary gland that makes it stop working

Talk to your doctor about what side effects you can expect. Also talk about what can be done to prevent or ease them. Ask your doctor what symptoms to watch out for. Know when you should call your healthcare team.

Some long-term side effects of radiation may not show up for many years after you finish treatment. These depend on the dose and location of the radiation. These also depend on how many times you had the treatment. Ask your doctor what you may expect.

What does radiation do to the pituitary gland?

Radiation might damage the remaining normal parts of the pituitary gland. This could result in the loss of pituitary function over time, so treatment with hormones might be needed.

Can radiation shrink a pituitary tumor?

Radiation therapy for pituitary tumors involves sending beams of radiation from an external machine, through the skin and skull toward the tumor. When the beams of radiation reach the tumor, they can destroy the tumor cells by damaging their DNA.

What is the life expectancy of someone with a pituitary tumor?

The 5-year survival rate for people with a pituitary gland tumor is 97%. Survival rates depend on the type of tumor, the person's age, and other factors.

Is radiotherapy effective for treating pituitary adenoma?

While transsphenoidal surgery represents the standard initial approach in the majority of cases, radiotherapy is a valuable and effective treatment option for recurrent adenomas, or lesions not amenable to surgery or medical therapy.