Pituitary Tumor: Radiation Therapy

Radiation uses high-energy beams of X-rays or particles to kill tumor cells. The most common way to get radiation for pituitary tumors is from a large machine that focuses beams of radiation at the tumor. This is called external beam radiation . You often get external beam radiation on an outpatient basis in a hospital or clinic. This means you go home the same day.

When might radiation therapy be used?

This treatment might be suggested for pituitary tumors that:

• Come back after surgery

• Are causing problems and surgery can't be done

• Are causing problems and medicines aren't working

• Have been mostly removed with surgery (Radiation can be used to help kill any tumor cells left in the area.)

• Are very large (Surgery may be done first to take out as much of it as is safely possible. Then the rest of the tumor is treated with radiation.)

Radiation works very slowly on some pituitary tumors. Even when the tumor is no longer growing after treatment, it can take years for hormone production to improve.

How is radiation therapy given?

Before radiation starts, imaging scans are done. These are used to clearly outline the size and shape of the tumor. The radiation beams are formed to fit this shape and focus on the tumor.

Types of radiation that may be used include: 

• IMRT (intensity modulated radiation therapy). This is a form of 3-D radiation that's used most often. The radiation comes from a machine outside the body. A computer is used to control the intensity and shape of the beams so they match the shape of the tumor. This helps limit damage to nearby tissues. Treatment may be given 5 times a week for 5 to 6 weeks.

• Stereotactic radiation. This form of radiation precisely targets the tumor with high doses of radiation. It directs beams at the tumor from different angles. It's often used as 1 high-dose treatment, but it can be repeated. It's very precise. It treats the tumor and not the entire brain or the healthy part of the pituitary. This kind of radiation may cause fewer side effects. 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 particle (or energy) beam. It's aimed into the body by a large machine. It can focus right on the pituitary tumor. This helps limit radiation to nearby healthy tissues. Proton radiation is only done in certain medical centers because special equipment must be used. Studies are still looking at if it's safer and if it works better than standard radiation.

A mold, mask, or frame is often made for you before radiation starts. This will hold you in the exact same position for each treatment and help keep you from moving during treatment.

Side effects of radiation for pituitary tumors

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

Most side effects get better over time after treatment ends.

Some common side effects of radiation therapy include:

• Skin in the treated area that's 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. Sometimes the hair doesn't grow back the same.

• Feeling very tired or weak

• Nausea and vomiting

• Swelling in the brain that causes headaches, confusion, seizures, and speech problems

• Damage to the healthy part of the pituitary gland that makes it stop working. This may require careful blood test monitoring and hormone replacement therapy.

• Memory changes

• Vision problems

Talk with 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 for. Know when you should call your healthcare team and how to get help after office hours and on weekends and holidays.

Some long-term side effects of radiation include hormone changes, memory loss, and stroke-like symptoms. These may not show up until many years after you finish treatment. They depend on the dose of the radiation and the area that's treated. They also depend on how many times you have treatment. Ask your doctor what you may expect.