Proton Therapy for Prostate Cancer

When you’ve been diagnosed with prostate cancer, your first instinct may be to get the cancer out as quickly as possible. However, many treatments for prostate cancer can cause long-term side effects and proton therapy may be able to reduce those risks. When patients come for a consultation, our team discusses all treatments for prostate cancer, including surgery, other forms of radiation therapy, hormonal therapy and active surveillance.

Prostate cancer forms in the prostate, the muscular, walnut-sized gland that's located below the bladder and in front of the rectum. The precision of proton therapy can target the tumor and reduce damage to the surrounding tissue, which in turn may reduce side effects such as urinary complications and impotence.

Northwestern Medicine Proton Center is one of the few proton therapy centers throughout the Midwest and the only one in Illinois. Our team is dedicated to explaining all of your treatment options for prostate cancer and facilitating a conversation with you and your physician or oncologist to determine the best treatment option for you.

To learn if you can benefit from proton therapy, call 1.877.887.5807 or fill out our online form.

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Proton Prostate
Cancer Video
Watch a Video: Proton Therapy for Prostate Tumors To learn more about other tumor types, visit our Video Library.

The Advantages of Proton Therapy for Prostate Cancer

When treating cancer with radiation, it’s important to balance the treatment of the tumor and the preservation of healthy tissue. Proton therapy allows this delicate balance to be achieved through precise targeting that conforms to the shape of the tumor, making it an excellent treatment for prostate cancer.1,3,4 The dose of radiation that a patient can receive with standard X-ray radiation is limited because of the risk of damage to the bladder and rectum, which are in close proximity to the prostate. With protons, a higher dose can be delivered to the tumor site, which can result in better tumor control, while largely sparing the bladder and rectum from radiation damage.1,3,4

Proton therapy prostate

Studies and Trials Show Efficacy of Proton Therapy

The greater precision of proton therapy significantly reduces the dose of radiation delivered to nearby organs.1,2 In one study, proton therapy delivered 35 percent less radiation to the bladder and 59 percent less radiation to the rectum compared with X-ray/intensity-modulated radiation therapy (IMRT).1 Delivering less radiation to nearby organs reduces the likelihood of long-term side effects.1,3 The images to the left show the amount and location of radiation that the body receives during treatment with proton therapy and X-rays/IMRT.

Protons significantly reduce excess radiation to non-target areas like the rectum.1 Studies show that less radiation to the rectum reduces the likelihood of gastrointestinal side effects.3

Additionally, a number of researchers have studied the effectiveness of using higher doses of radiation for tumors. The three trials shown in the charts to the left found that patients who were treated with a higher dose of radiation were more likely to have PSA levels within a desirable range over a 5-year period than those treated with a lower dose. The trial that used proton therapy to increase the dose had the best control rate and the lowest rate of severe side effects.5-7

Chicago Proton Center

Comprehensive Treatment Options for Prostate Cancer

As part of the Northwestern Medicine cancer care network, the Proton Center is dedicated to helping you understand your treatment options.

Proton Therapy

A type of external beam radiation therapy that uses proton radiation to kill cancer cells by preventing them from dividing and growing. Proton therapy is a non-invasive treatment that is as effective as X-ray radiation in treating prostate cancer.1,8 The benefit of this type of radiation over standard X-rays is the precision in targeting the tumor. Because of the precision, proton therapy can significantly reduce the dose of radiation to the rectum and bladder.1 As a result, there is a reduced risk of short- and long-term side effects.1,3 Northwestern Medicine uses the SpaceOAR® hydrogel system to further reduce the risk of rectal injury in men receiving prostate cancer radiation therapy acting as a spacer – pushing the rectum away from the prostate and out of the high dose radiation treatment region.

Standard X-ray radiation

This includes IMRT, 3-dimensional conformal radiation therapy (3-D CRT), CyberKnife®, RapidArc™ radiation, IGRT and TomoTherapy®. These common forms of external beam radiation therapy use X-ray radiation to kill cancer cells by preventing them from dividing and growing. Possible side effects include damage to the rectum and bladder9 and the possibility of impotence. Northwestern Medicine uses the SpaceOAR® hydrogel system to further reduce the risk of rectal injury in men receiving prostate cancer radiation therapy acting as a spacer – pushing the rectum away from the prostate and out of the high dose radiation treatment region.


The placement of radioactive seeds in the prostate. The main benefit of this invasive form of radiation therapy is that patients can leave the hospital immediately after the radioactive seeds are implanted. The major disadvantage with brachytherapy is that seeds can move after implantation, resulting in uneven treatment of the cancer cells. Patients become radioactive for a period of months following treatment. Side effects may last as long as the seeds are active (usually a few months), and they may continue and become chronic. In a study, many patients noted a significant decrease in health-related quality of life at one and three months post-treatment.9 Urinary issues are the most common side effect of seed implantations.9


A radical prostatectomy is an operation to remove the prostate gland and tissues surrounding it. Because so many nerves surround the prostate, damage to the nerves is a significant risk for all patients undergoing surgery. Patients electing to have surgery will want to find a surgeon who specializes in this procedure and has many years of experience. Most men stay in the hospital two to three days after the procedure. A urinary catheter is inserted during surgery, and some men may need to wear it home for a few days or weeks. Potential short- and long-term side effects include pain around the incision, urinary incontinence and sexual dysfunction.

“Watchful Waiting” or Active Surveillance

For this choice, patients are regularly tested and not given therapy unless their cancer progresses.

Request more information or call 877.887.5807 to learn if you can benefit from proton therapy.

Proton therapy prostate

What to Expect With Proton Therapy

Proton therapy is considered safe, non-invasive and painless. Depending on the patient's diagnosis, treatments are usually given five days a week for up to nine weeks. The time spent actually delivering the protons to the tumor is about one minute, but a prostate cancer treatment session can range from 15 to 30 minutes due to time spent positioning the patient for this precise treatment.

Patients continue with normal activities before and after treatment. Some patients choose to work; others go on a “radiation vacation” and spend their days doing recreational activities before or after treatment.

Learn more about what to expect when getting treated.

Patient Stories

Read what our patients have to say about their proton therapy treatment and how proton therapy and our staff impacted their lives.

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Contact Us

To discover if you or a loved one could benefit from proton therapy, please call us at 877.887.5807 (TTY 711).

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