Proton Therapy

What is proton therapy?

Proton therapy — also called proton beam therapy — is a form of radiation therapy and a type of cancer treatment. During treatment, a machine directs concentrated streams of positively charged, high-energy particles (protons) toward tumors. The protons destroy tumor cells while sparing nearby healthy tissue. This is because protons don’t damage tissue until they’re moving slowly enough. Your doctor (radiation oncologist) can aim and focus the beams so the protons slow down and stop near the tumor.

Proton beam therapy isn’t as common as traditional radiation therapy. Traditional radiation delivers high-energy X-rays or electrons instead of protons.

What does proton therapy treat?

In general, radiation oncologists use proton therapy for tumors that are near very sensitive parts of your body, like areas in your brain or spinal cord. Radiation oncologists also frequently use proton therapy to treat childhood cancers.

How should I prepare for proton therapy?

Proton therapy treatment begins with a planning session to design the treatment. Your care team will also decide how to position you for your daily treatment. This planning session may take some time, so it’s a good idea to ask your team how long the process could take. Ask if you should wear specific kinds of clothes or if you can plan on bathroom breaks during the planning session.

Getting in position

Your radiation oncology team will help you lie down comfortably on a treatment table, just as you will during treatment. You’ll need to stay still during treatment, so your team may fit you with an immobilizing device to help you stay in place. The type of device depends on the tumor’s location. For example, if you’re receiving proton therapy for a tumor in your eye, you may need to wear a tight-fitting mask.

Getting imaging scans

Once you’re situated and comfortable, your team will begin doing scans to determine the tumor(s) size, dimensions and locations. This is usually a CT scan. Your team may make tiny marks on your body or on the immobilizing device. This helps ensure you’re in the correct position every day of your treatment.

What happens during this procedure?

You’ll receive proton therapy in a special treatment room. Here’s what you may expect:

1. The team will get you into position. You’ll be positioned as you were during your planning session. Your team will help you with any immobilizing devices.
2. You’ll get imaging scans done. Your team will go to another room with delivery controls to operate the machine. Before every treatment, the team will take images of you in position to ensure that everything is lined up.
3. The team will deliver treatment. A device attached to a mechanical arm called a gantry delivers the protons. The gantry will rotate around the table or chair to deliver treatment from the best possible angles.

Although your team won’t be in the same room as you, there will be a video screen so they can always hear and see you.

How long does proton beam therapy take?

Proton therapy only takes a few minutes to complete. But the imaging scans and setup time may take closer to 20 to 30 minutes or more.

Many people get proton beam therapy for five days a week for several weeks. But treatment schedules vary. Ask your radiation oncologist what your schedule will be.

What happens after proton therapy?

Your radiation oncology team will let you know when treatment is complete. They’ll come back into the treatment room and help you out of the immobilizing device. They’ll assist you off the treatment table.

Most people get to go home the same day. It’s perfectly safe to be around others. You won’t give off radiation.

What are the benefits of proton therapy?

Proton therapy is relatively new compared to traditional radiation. So, there’s still a lot of research needed to fully understand its benefits. But medical experts do know that proton therapy leaves almost no “exit dose.” The exit dose is the amount of radiation that passes through the healthy normal tissue near a tumor. Less of an exit dose means less damage to healthy tissue.

Potential benefits include:

• Fewer (or milder) side effects. People experience side effects when healthy tissue is exposed to radiation. Less exposure may mean fewer side effects.
• Reduced risk of developing a secondary cancer. Sometimes, people develop cancer after getting radiation treatment for a different type of cancer. This can happen when healthy cells are exposed to the radiation. Less radiation exposure during proton therapy may reduce this risk.
• Having a new treatment option for recurrent cancer. Sometimes, cancer goes away but then comes back after treatment (recurs). Proton beam therapy may be a good follow-up treatment for people who are unable to tolerate more aggressive treatments.

What is the success rate of this procedure?

Proton therapy and traditional radiation therapy have about the same success rate. Research shows that in certain situations, such as cancer in children with brain/spinal cord cancers, proton therapy may be better than traditional radiation. Research comparing the two types of radiation therapy is ongoing.

Your radiation oncologist will review which technique is best given your specific situation.

What are the risks of proton therapy?

As with any cancer treatment, proton beam therapy can cause side effects. For some people, they show up right away. But for most people, they tend to develop gradually, over many treatment sessions. Side effects depend on what location is being treated.

For example, radiation directed at your brain can cause headaches or memory loss. Radiation directed at your gut can cause diarrhea or digestion issues.

Ask your healthcare provider what side effects to watch out for based on your diagnosis.

How long does it take to recover from proton therapy?

Depending on your situation, it may be a few weeks after finishing treatment before you feel completely recovered. Your healthcare provider will review your recovery timeline with you.

When should I call my healthcare provider?

Contact your healthcare provider if you have side effects that are more severe than you expected. Before leaving your treatment session, ask your radiation oncology team to explain which side effects are a sign of a major issue.