What is Proton therapy?

The newest weapon in
the fight against cancer.

Proton therapy works much like traditional X-ray radiation therapy only it uses a proton beam instead of photons. While both are extremely effective resources for attacking cancer cells, protons can deliver a greater dosage of radiation with far less impact on surrounding healthy tissue and organs. With greater precision, the proton beam is also able to target and treat some tumors more effectively.

It is an undisputed paradigm that radiation damages normal tissue and should be avoided in normal tissue. Proton therapy has been shown to increase survivability rates and tumor control in some diagnoses, and has improved overall quality of life for patients. It has also demonstrated an ability to reduce the risk and severity of side effects, including the development of secondary cancers.

The big questions.

What is proton therapy?

Proton therapy is a form of radiation therapy that destroys cancer cells by preventing them from dividing and growing - the same as with standard X-ray radiation. Proton therapy uses protons - heavy, positively charged atomic particles - instead of the photons used in standard X-ray radiation therapy. Protons can be precisely conformed to release most of their energy directly in the tumor, greatly reducing damage to nearby healthy tissue. As a result, patients often can receive higher, more effective doses and generally have far fewer side effects from treatment.

How do proton beams destroy cancer cells?

When protons reach the nucleus (or center) of cancer cells, they transfer energy to the cells' electrons causing a series of interactions, or ionizing events, that damage the DNA of the cancer cells. The damaged cells are permanently injured, can no longer divide, and die.

When was proton therapy first used for medical purposes?

Proton therapy was first used to treat patients in Berkeley, California, in 1955 in a research setting. While promising, it wasn't until advances in imaging technology, such as CT, MRI and PET scans, allowed doctors to accurately "see" the location, size and shape of cancer tumors. Accurately locating tumors made it possible to leverage the precision of protons. The first U.S. center opened at Loma Linda University Medical Center in 1990. More than 20 centers have opened in the past 20 years, and by 2008, there were 29 centers worldwide.

How many patients have received proton therapy?

Since the first hospital-based proton treatment center opened in California in 1990, nearly 30,000 people have received proton therapy in the United States, and more than 60,000 people worldwide. Experts conservatively estimate that about 250,000 cancer patients in the U.S. could benefit from proton therapy.

What kinds of studies have been/are being done to prove effectiveness?

The effectiveness of proton therapy has been studied by researchers around the world. There is a growing number of studies that report on the effectiveness of proton therapy and its benefits compared to alternative treatments. The amount of research being conducted on proton therapy is rapidly increasing as more centers open and more patient experiences become available.

What are the potential side effects of proton therapy?

Patients should not feel pain or discomfort during treatment sessions. There may be side effects during or after treatment, but they are generally minor, less frequent and less severe than the side effects that can result from standard X-ray radiation therapy, primarily because less healthy tissue is exposed to radiation in proton therapy. Potential side effects may include skin reactions in the direct path of the proton radiation, fatigue and temporary hair loss. Depending on the tumor site treated, different side effects may be experienced. Your doctor will discuss with you the specific side effects that you may experience based on your treatment plan.

How does proton therapy work?

Protons can be manipulated to release their energy at precise depths so they can target tumors near the skin surface or deep inside the body, depositing most of their radiation exactly at the tumor site. The peak of this proton radiation dose (called the bragg peak) is set so it releases the radiation when it hits the tumor; immediately after that point, the radiation dose falls to almost zero. Less radiation reaches the healthy tissue in front of the tumor, and almost none reaches the healthy tissue behind the tumor, resulting in much less damage to healthy tissue. Patients often experience fewer short-term and long-term side effects that typically accompany standard X-ray radiation. In addition, because more radiation can be deposited directly in the tumor, a higher dose often can be delivered, leading to more effective treatment.

What is the history of proton therapy?

Advances in imaging, including computed tomography (CT), magnetic resonance imaging (MRI) and positron emission tomography (PET), now allow physicians to "see" deep inside the body and precisely define the location, size and shape of tumors. This capability, coupled with improvements in proton technology, brought about today's growing interest in proton therapy as an important treatment option for cancer. The first hospital-based proton treatment center in the United States was built in 1990 at Loma Linda University Medical Center (LLUMC) in Loma Linda, California. As of February 2010, seven facilities were operating in the United States: ProCure Proton Therapy Center, Oklahoma; Francis H. Burr Proton Therapy Center at Massachusetts General Hospital; the Midwest Proton Radiotherapy Institute at Indiana University; the Proton Therapy Center at the M.D. Anderson Cancer Treatment Center; The Roberts Proton Therapy Center at the University of Pennsylvania; the Florida Proton Therapy Institute at the University of Florida Shands Medical Center; and LLUMC. In addition, there is a specialty proton center that treats only cancers of the eye at the University of California, Davis.

Can proton therapy be used in combination with other cancer treatments?

In many cases, yes. Proton therapy can be used in combination with chemotherapy, as a follow-up treatment to surgery and in combination with standard X-ray radiation treatment.

The Benefits

We provide proton radiation therapy to those who need it most.

The effectiveness of proton therapy has been studied by researchers around the world. There is a growing number of studies that report on the effectiveness of proton therapy and its benefits compared to alternative treatments. The amount of research being conducted on proton therapy is rapidly increasing as more centers open and more patient experiences become available.

Causes little damage to surrounding healthy tissue and organs.
Able to deliver more radiation to a tumor while reducing side effects.
Minimizes the risk of forming
Treatment doses are delivered using
Can typically be used with other therapies