Proton therapy is a type of radiation therapy (also called radiotherapy) that’s being used more frequently to treat certain types of lung cancer. It’s different from traditional radiation therapy in several ways and may not be available in every cancer treatment center.

Here are five facts about proton beam therapy to help you have better conversations with your doctor about lung cancer treatment options.

1. Proton Therapy Is More Precise Than Traditional Radiation

Proton therapy is a form of radiation treatment that can be used to treat certain types of lung cancer. Radiation therapy uses high-energy, charged particles to eliminate lung tumors, a group of cancer cells that multiply quickly. Traditional radiation therapy uses X-ray radiation to target a large amount of tissue in your body. X-ray radiation goes through the entire volume of the body. This depth can’t be changed. Picture a gunshot wound — even though the area the bullet hits is small, it still can get through to the other side. This is similar to how X-ray radiation gets through the full depth of the body.

With proton therapy, on the other hand, the depth of the radiation can be adjusted. Proton therapy uses a different type of charged particles called protons. Pencil beam scanning proton therapy is the most precise type of proton therapy. This type of radiation therapy uses beams of protons to scan through the tumor layer by layer. This process makes proton radiation more targeted than traditional radiation therapy.

2. Proton Therapy Can Be Used for Hard-to-Reach Areas

Because the depth of the radiation is adjustable, proton therapy can reach areas that may be hard for traditional radiation therapy to reach. Importantly, proton therapy can spare healthy tissue and critical organs from radiation toxicity (harm from radiation). The lungs sit right near the heart, spinal cord, and esophagus. These organs are often at risk of radiation toxicity during traditional radiation therapy.

Because there’s less risk of harming the surrounding tissues, proton therapy can also be given in higher doses. High doses may be important for treating a more aggressive tumor, using high power while avoiding healthy tissue.

3. Proton Therapy Works Better on Certain Lung Cancers

Proton therapy has become a more popular treatment option for people with lung cancer.

In 2017, more than 200,000 people were treated with proton therapy across the world. But what type of lung cancers respond well to proton radiation therapy? Who are the best candidates? The physicians that treat and study cancer, or the oncology team, at Johns Hopkins Medicine have created a list of types of lung cancer that could be suitable for proton therapy. They include:

• Small cell lung cancer
• Stage 1 non-small cell lung cancer (NSCLC)
• Stage 2 NSCLC
• Stage 3 NSCLC
• Malignant mesothelioma

Proton therapy may also be useful for cases of inoperable NSCLC or for cases of lung cancer that keep returning after ongoing treatment.

The Johns Hopkins oncology team also mentioned some people who were not good candidates for proton therapy. If the lung cancer has metastasized (spread) to the brain, heart, liver, or bone, proton therapy may not be considered an option. Additionally, if you have trouble breathing from any other lung condition, proton therapy might not be the right fit for you.

Talk to your health care team and radiation oncology specialists to determine if you’re a good candidate for proton therapy.

4. Proton Therapy Requires Short Sessions Over Weeks

What can you expect if your doctor recommends proton therapy? First, you will likely be referred to a cancer center specializing in radiation oncology and proton therapy. Not all medical centers have the equipment needed for proton therapy.

Planning Session

Once you find an appropriate center, your radiation oncologist will hold a planning session. They will use some type of imager to see exactly where your tumor is located. This process will involve using either CT or MRI. Both of these scanners will allow your doctor to see the outer bounds of the tumor.

During the session, you may be asked to breathe in or let out all your air at times, which will help your team get views of the tumor when the lungs are filled with air and empty. This session may take around an hour, and you will need to lie still so the scanner can get a good image.

After the session, your doctor will draw on your body to show where the outer bounds of the tumor are.

Treatments

You may receive one to five proton beam treatments per session depending on your case. When you have fewer treatments, the radiation dose intensity is usually high. If you have more treatments, the radiation in each treatment is less intense.

The entire session usually only lasts between 15 and 30 minutes. There is a specialized room where the beam of protons is delivered. In that room, you will lie on a table.

If you have early-stage cancer, you will likely have four to 10 sessions over two weeks. For more advanced disease, you can expect up to 30 sessions over six weeks.

Because the tumor will hopefully shrink in between sessions, it’s essential to get an accurate view of it. Before and after your session, you will get a CT scan or an X-ray. These images will help your doctor know where to deliver the pulse of protons and track its progress.

5. Proton Therapy Has Limits and Risks

As with any lung cancer treatment, you’ll need to weigh the costs and benefits of proton therapy. When it comes to proton therapy, there are some downsides to consider.

Cost

Proton therapy may cost more than traditional radiation treatments. Your health insurance carrier may not cover it.

Availability

According to the National Association for Proton Therapy, 70 percent of Americans live 100 miles or more from the nearest proton therapy center. As of 2024, there were only 45 proton therapy centers across the U.S. Depending on where you live, this may make it hard to find a treatment facility. Consult with your care team to find out if there are any proton therapy centers near you.

Side Effects

There are potential side effects of proton therapy as there are with traditional radiation therapy for lung cancer. While most people don’t feel the proton beam, fatigue is common after sessions. One MyLungCancerTeam member who underwent proton therapy wrote, “Fatigue was the first symptom that I started dealing with. Other symptoms started surfacing soon after. A loss of appetite was troublesome and difficult to work through.”

The most common side effects are usually seen on the skin where the proton beam is delivered. Dry skin, rash, and burning sensations are common side effects. Blisters, red skin, and swollen skin are also common.

Consult With Your Team

If you’re interested in learning more about proton therapy as part of your treatment plan, consult with your oncology team. Your cancer care team will look at your health history and the kind of cancer you have to decide if proton therapy could work for you. They’ll explain how the treatment is done and what you should expect during your sessions. They will also answer questions about how it works, the benefits, and the possible side effects. This information helps make sure you feel informed and confident about your treatment choices.

Talk With Others Who Understand

MyLungCancerTeam is the social network for people with lung cancer and their loved ones. On MyLungCancerTeam, more than 12,000 members come together to ask questions, give advice, and share their stories with others who understand life with lung cancer.

Have you had proton therapy or discussed it as a treatment option with your lung cancer care team? Share your experience in the comments below, or start a conversation by posting on your Activities page.