What Is Proton Therapy for Breast Cancer?

Medically reviewed by Christina Chun, MPH on April 5, 2017Written by Ann Pietrangelo

Overview

Proton therapy is a type of external beam radiation therapy used to treat cancer. It uses energy from positively charged particles called protons. Proton therapy is more precise than standard radiation therapy. It can deliver radiation to the tumor while sparing more of the surrounding healthy tissue.

Proton therapy is not a new technology. Some U.S. hospitals have used it since 1990. Access to proton therapy continues to expand, but it’s still not available everywhere.

Both standard and proton radiation therapy can be used alone or together with other treatments for breast cancer.

Read on to learn more about how proton therapy compares to standard radiation treatment.

How does proton therapy work?

In standard radiation, photon beams deposit radiation in healthy tissue on their way to the tumor, into the tumor, and beyond the tumor.

A proton beam is more exact. A higher dose of radiation is concentrated on the tumor, while surrounding healthy tissue receives a much smaller amount.

This can be especially important when treating a tumor located near critical organs. An example of this in breast cancer is when a tumor is near the heart and lungs.

What’s the procedure like?

The procedure for proton therapy is similar to that of other types of radiation therapy.

In the planning stage, you may need an MRI or CT scans to help identify the area that needs treatment. Your radiation team will determine the best positioning and mark the area of your body to be treated. The tiny marks may be temporary or permanent.

Your team will place you in the same position for all treatments. Once you’re in position, you have to remain perfectly still. The proton machine will rotate around you and deliver proton beams to the correct spot. There’s another type of proton machine that doesn’t move, but the table does.

You won’t feel anything during treatment. You’ll be able to go home as soon as it’s finished.

You’ll spend the most time getting into the correct position. This can take a half hour or more. The actual treatment takes only a few minutes.

Proton therapy is usually administered five days a week for several weeks. Your doctor will base the schedule on your specific situation.

What are the side effects and complications?

The side effects of proton therapy are similar to those of standard radiation. But because it’s so much more precise, you’ll probably have fewer, milder side effects. Some of the potential side effects are:

  • fatigue
  • headache
  • soreness in the treatment area
  • skin redness and irritation

The risk of serious complications from damage to your heart or lungs is lower than with standard radiation.

Proton therapy vs. standard radiation therapy

Proton therapy and standard radiation therapy are done in the same way. The main difference between the two is that proton therapy is more exact.

Any radiation therapy has risks. One risk is an increased chance of developing a secondary cancer in the future.

When treating a tumor of the breast, the radiation team tries to avoid harming the heart and lungs. This is particularly difficult when the cancer is on the left side, nearer to the heart.

Compared to standard radiation, proton therapy exposes women with left-sided breast cancer to less radiation to the heart, lungs, and other breast.

A study by the Mayo Clinic found that proton therapy may be less toxic and more effective than standard radiation.

Because proton therapy affects a smaller area, it’s more likely that it could be used if cancer should return near the original site. This is usually not possible after an area of your body is treated with standard radiation.

Proton therapy after mastectomy

Radiation therapy can be used to destroy cancer cells that remain in the chest wall or lymph nodes after a mastectomy. Radiation therapy after mastectomy improves survival in locally advanced breast cancer, according to research published by Radiation Oncology. It’s a challenge, but the goal is to do this without harming healthy tissues. Side effects may include:

The heart is especially vulnerable when the cancer is on the left side of the chest.

In the small clinical trial reported in Radiation Oncology, proton therapy after mastectomy had fewer toxic side effects than standard radiation. It may be helpful when treating women with heart or other conditions that make standard radiation difficult.

The process is more complicated if you want breast reconstruction. It’s usually easier to begin the reconstruction process at the same time as your mastectomy. However, if you’re also having standard radiation therapy, your doctor may advise you to postpone the reconstructive surgery until you’ve finished the therapy.

On the other hand, proton therapy can be used if you have immediate reconstruction, even if you have expanders or implants.

Learn more: Mastectomy and reconstructive surgery at the same time »

Proton therapy after lumpectomy

Breast cancer treatment usually involves several therapies. Surgery, either a mastectomy or lumpectomy, is often combined with radiation therapy. Proton therapy after lumpectomy exposes you to less radiation-related toxicity.

How to decide which treatment is right for you

Your oncology team will make recommendations based on the specifics of your breast cancer, such as:

  • type
  • size of the primary tumor
  • stage

If radiation is recommended, ask if proton therapy is a good option for you. Find out how the benefits and risks of each type may affect you.

Proton therapy isn’t available everywhere, so your doctor will let you know if it’s an option where you live. Both standard and proton therapy involve daily sessions for several weeks. If you have to travel a long distance every day, it could become a burden.

Many health insurance plans that cover standard radiation therapy also cover proton therapy. If you have to travel farther from home, the treatment center may not be in your insurance network. Be sure to check these points with your insurer before you start. Your doctor’s office can help you with these details.

The bottom line

Proton therapy is a form of radiation therapy. It gives the radiation team more controlled precision so that healthy tissue surrounding the cancerous area is less affected.

If you’re deciding which type of radiation therapy is best for you, speak with your oncology team. They can help guide you through the decision process.

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