Proton therapy is a type of radiation therapy — a treatment that uses high-powered energy to treat cancer and some noncancerous tumors. Radiation therapy using X-rays has long been used to treat these conditions. Proton therapy is a newer type of radiation therapy that uses energy from positively charged particles (protons).

Proton therapy has shown promise in treating several kinds of cancer. Studies have suggested that proton therapy may cause fewer side effects than traditional radiation, since doctors can better control where the proton beams deliver their energy. But few studies have compared proton radiation and X-ray radiation, so it's not clear whether proton therapy is more effective at prolonging lives.

Proton therapy isn't widely available, although new proton therapy centers are being built in the United States and in other countries.

Why it's done

Proton therapy is used as a treatment for cancer and some noncancerous tumors. Proton therapy may be used as the only treatment for your condition. Or it may be used in conjunction with other treatments, such as surgery and chemotherapy.

Proton therapy may also be used if the cancer remains or comes back after traditional X-ray radiation.

Proton therapy is sometimes used to treat:

• Brain tumors
• Breast cancer
• Cancer in children
• Eye melanoma
• Esophageal cancer
• Head and neck cancers
• Liver cancer
• Lung cancer
• Lymphoma
• Pancreatic cancer
• Pituitary gland tumors
• Prostate cancer
• Sarcoma
• Tumors affecting the spine
• Tumors in the base of the skull

Clinical trials are investigating proton therapy as a treatment for several other types of cancer.

Risks

Proton therapy can cause side effects as the cancer cells die or when the energy from the proton beam damages healthy tissue near the tumor.

Because doctors can better control where proton therapy releases its highest concentration of energy, it's believed to affect less healthy tissue and have fewer side effects than traditional radiation therapy. Still, proton therapy does release some of its energy in healthy tissue.

The side effects you experience will depend on which part of your body is being treated and the dose of proton therapy you receive.

In general, common side effects of proton therapy include:

• Fatigue
• Hair loss around the part of your body being treated
• Skin redness around the part of your body being treated
• Soreness around the part of your body being treated

How you prepare

Before you undergo proton therapy, your health care team guides you through a planning process to ensure that the proton beam reaches the precise spot in your body where it's needed.

Planning typically includes:

• Determining the best position for you during treatment. During radiation simulation, your radiation therapy team works to find a comfortable position for you during treatment. It's important that you lie still during treatment, so finding a comfortable position is vital.

  To do this, you'll be positioned on a table that will be used during your treatment. Cushions and restraints are used to place you in the correct position and to help you hold still. Your radiation therapy team will mark the area of your body that will receive the radiation. You may receive a temporary marker or permanent tattoos.

• Planning the path of the protons with imaging tests. You may undergo magnetic resonance imaging (MRI) or computerized tomography (CT) scans to determine the area of your body to be treated and how best to reach it with the proton beams.

Consider the cost

Not all insurance policies cover proton therapy. When considering your treatment options, work with your health insurance provider to understand the costs that are covered by insurance and which costs you'll be expected to pay.

What you can expect

During proton therapy

You typically undergo proton therapy five days a week for several weeks. However, in some situations, you may undergo only one or a few treatments, depending on your condition. The actual proton therapy treatment may take only a few minutes but expect to spend 30 to 45 minutes preparing before each treatment session.

You may also undergo weekly CT scans to see if the dose you receive needs to be recalculated based on changes in weight, or tumor size and shape.

To prepare, you'll be positioned on a table. Cushions and restraints will be used to hold your body still. Then you'll undergo an imaging test, such as an X-ray or CT scan, to make sure your body is in the same precise position before each treatment.

Your radiation therapy team will then leave the room and go to an area where they can monitor you. They can still see and hear you.

Proton therapy is administered with a machine called a gantry that directs the proton beams at precise points on your body. You'll hear the machine when it's turned on and delivering the dose of proton therapy. However, you won't be able to feel the radiation during your treatment.

After proton therapy

Once your treatment session is complete, you can go about your day. You won't be radioactive or give off radiation.

Side effects of proton therapy usually develop over time. You may experience few side effects at first. But after several treatments you may experience fatigue, which can make it feel like your usual activities take more energy or that you have little energy for everyday tasks. You may also notice a sunburn-like skin redness in the area where the proton beams are directed.

Results

Your doctor may recommend periodic imaging tests during and after your proton therapy to determine whether your cancer is responding to the treatments.