Frequently Asked Questions about Proton Therapy

Following are the most frequently asked questions by men who are researching their prostate cancer treatment options. We have done our best to answer these questions based on the patient's perspective and our own personal experience. If you have a question that you do not see covered here, please contact us.

Protons have been used to treat cancer since the 1950s. Since a particle accelerator is required to bring proton particles to the necessary energy level, early patients had to be treated in physics laboratories.

In 1990, Loma Linda University Cancer Center (LLUCC) in Loma Linda, California opened the first hospital-based proton treatment center. To date, LLUCC has treated more than 17,000 patients with protons. Roughly 11,000 of these patients have been treated for prostate cancer.

Since 1990, 14 more proton treatment centers have opened in the U.S. and others are now treating in Europe and Asia. Many more proton treatment centers are in the planning stages; in fact one recent study reports that the number of proton centers in the U.S. will reach 29 by 2018.

The average person probably knows something about the use of X-rays for the treatment of cancer but is probably unaware of the existence and use of proton radiation therapy for this purpose. How do the two types of radiation compare?

In medical terms, there is an important distinction between the two radiation forms. The nature of X-rays makes it difficult for the physician to effectively direct the radiation dose to the tumor without delivering a similar dose to surrounding healthy tissue, thereby, resulting in possible collateral damage and increasing the risk of secondary cancers later in life.

The nature of the proton particle, on the other hand, allows the physician to direct the proton radiation to a well-defined volume while largely avoiding damage to surrounding healthy tissue. This characteristic of the proton means that the physician can increase the dose to the tumor, thereby increasing the chances of destroying the cancer. Also, because almost all of the radiation is delivered to the targeted tumor volume, the possibility of causing harmful side effects and secondary cancers is considerably lower with proton therapy.

As mentioned in FAQ 1, the accurate 3-D delivery of proton radiation largely spares surrounding healthy tissue from potentially damaging effects. Most of our members report minimal or no side effects. Short term, temporary side effects might include some urinary urgency or slight “burning” on urination. Incontinence is extremely rare. Some report changes in potency, which is often aided by medication. Some rectal bleeding may be expected, and this usually resolves itself. Side effects that may be experienced are usually minor and rarely require medical intervention. In very rare cases there can be more significant side effects.

Click here for more information on side effects.

Studies have shown that proton treatment cure rates, both clinical and biochemical, to be comparable with other major treatment options.

Even Johns Hopkins—“the prostate cancer surgery capital of the world”—in their April 2005 Health Letter, admits that,

“…recent studies demonstrate that newer types of radiation are as effective as surgery, which was once thought to be the surest way to a cure. And as radiation techniques grow ever more precise, side effects may be more limited and treatment and recovery made easier.”

The following proton centers have been established in the U.S.:

  • James M. Slater, M.D. Proton Treatment and Research Center at Loma Linda University Medical Center, Loma Linda, CA (1990)
  • Francis H. Burr Proton Therapy Center at Massachusetts General Hospital, Boston, MA (2003)
  • M.D. Anderson Cancer Center’s Proton Center, Houston, TX (2006)
  • University of Florida Proton Therapy Institute, Jacksonville, FL (2006)
  • ProCure Proton Therapy Center, Oklahoma City, OK (2009)
  • Northwestern Medicine Chicago Proton Center, Chicago, IL (2010)
  • Hampton University Proton Therapy Institute, Hampton, VA (2010)
  • Roberts Proton Therapy Center at UPENN, Philadelphia, PA (2010)
  • ProCure Proton Therapy Center, NJ/MetroNY, Somerset, NJ (2012)
  • SCCA Proton Therapy Center, Seattle, WA (2013)
  • S. Lee Kling Proton Therapy Center at Barnes-Jewish Hospital, St. Louis, MO (2013)
  • Provision Center for Proton Therapy, Knoxville, TN (2014)
  • Willis-Knighton Health System, Sheveport, LA (2014)
  • Ackerman Cancer Center, Jacksonville, FL (2015)
  • Robert Wood Johnson University Hospital, New Brunswick, NJ (2015)
  • Texas Center for Proton Therapy, Irving, TX (2015)
  • Mayo Clinic Proton Beam Therapy Center, Rochester, MN ()
  • Mayo Clinic Proton Beam Therapy Center, Phoenix, AZ (2016)
  • Maryland Proton Treatment Center, Baltimore, MD (Univ. of MD) (2016)
  • University of Florida Health Center at Orlando Health, Orlando, FL (2016)
  • University Hospital Seidman Cancer Center, Cleveland OH (2016)
  • Proton Therapy Center at Beaumont Hospital Cancer Institute, Royal Oak, MI (2017)
  • California Protons Cancer Therapy Center, San Diego, CA (2017)
  • Miami Cancer Institute Baptist Health South Florida, Miami, FL (2017)
  • MedStar Georgetown University Hospital, Washington, DC (2018)

Proton therapy is also practiced in Europe and Asia. 

Robert Wilson first proposed the use of proton radiation for medical purposes in 1946. In 1954 proton treatment was introduced at the Berkeley Radiation Laboratory. Harvard University and the Massachusetts General Hospital began using protons for cancer treatment in 1961 at the Harvard Cyclotron Laboratory. In 1990, Loma Linda University Cancer Center (LLUCC) opened their new, state-of-the-art, Conformal Proton Beam Treatment Center and began treating patients in a hospital setting. More than 17,000 patients have been treated at LLUCC, and while most have been prostate cancer patients, a wide range of other diseases has been treated there as well. More than 100,000 patients have been treated with proton therapy worldwide.

Essentially all localized (non-metastatic) prostate cancers are treatable by proton therapy. Patients with extremely high PSAs and Gleason scores up to 10 have been successfully treated with protons.

Contact a medical center that practices proton therapy. Specialists there can answer your questions and can arrange for a consult.

Most urologists will not perform surgery on a patient who has received any form of radiation for prostate cancer, but there are specialists who do perform a salvage radical prostatectomy. However, removal of the prostate by surgery following failed radiation treatment may be inappropriate, as the reason for the failure is most likely because the cancer had previously traveled outside the prostate bed. There are salvage options available to patients where radiation treatment has failed. Depending on the cancer location, patient age, and progression rate, these options may include cryosurgery, brachytherapy, high intensity focused ultrasound, hormonal therapy, and chemotherapy, among others.

Medicare and some private insurance companies reimburse for proton treatment. The Brotherhood of the Balloon can assist individuals with appeals if their claim is denied. If you have received an insurance denial or have questions about obtaining coverage for your proton therapy, send an email to

Yes. One of the best ways to learn the truth about any treatment option is to speak with former patients. In fact, we recommend you speak with AT LEAST 10 former patients representing each treatment option you are considering. You will learn much more about any option by talking with someone who has been through it, than from any other source.

If you'd like to contact former proton patients by email or phone, send an email to and we will email you a list.

Do you have a specific question(s) about proton therapy or the BOB? Just ask.