Trial to compare radiation therapies for treating prostate cancer

MUSC Hollings Cancer Center

is enrolling patients in a national clinical trial to help to determine the best, most cost-effective approach for treating prostate cancer through radiation therapy.

The trial, known as the COMPPARE study, will compare the quality of life, side effects and cure rates for prostate cancer patients who are treated with one of two radiation types: proton therapy or photon therapy.

Photon therapy uses multiple X-ray beams that target the prostate from all angles, delivering a high dose of radiation to the prostate and a low dose to the areas around the prostate. Proton therapy typically uses only two beams that target the prostate from opposite sides, still delivering a high dose of radiation to the prostate but limiting the amount of radiation delivered to the surrounding areas.

The main difference between the two radiation types is that X-ray beams travel all the way through a patient while protons only travel a certain distance before stopping, allowing them to deliver more concentrated doses of radiation.

Both therapies are currently considered standard of care for treating prostate cancer, and the type of treatment patients receive depends on the facility where they’re receiving treatment, their insurance coverage and their personal preference. Hollings treats patients using photon therapy, which is roughly three times less expensive than proton therapy and has shown to be just as effective as treatment with protons.

“The reason we like this trial at Hollings is because it doesn’t change our patients’ course of treatment. They can still choose how they get treated, and they’re able to help future patients determine the best, most cost-effective way to get treated.”

– Dr. David Marshall

According to David Marshall, M.D., a radiation oncologist and principal investigator for Hollings’ portion of the study, proton therapy may be more beneficial than photon therapy in treating certain types of cancers, but he doesn’t expect prostate cancer to be one of them.

“There are a lot of interesting things you can do with protons, including reducing toxicity in pediatric cases and decreasing serious side effects when targeting tumors around the eye, face and skull,” said Marshall. “In general, facilities that treat prostate cancer with proton therapy get good results, but the results aren’t better than using photons for this specific cancer type.”

While Marshall doesn’t expect to see any differences between the two patient groups enrolled in this study, having the data to back that up is important for shaping the future standard of care for patients with localized prostate cancer and for helping patients to make the treatment decisions that are best for them.

Because proton therapy is significantly more expensive than photon therapy, and there is no evidence to suggest that it provides better outcomes when treating prostate cancer, the therapy often isn’t covered by insurance. Patients may choose to pay for the service out of pocket.

If this study finds that both methods work equally well, with similar side effects and potential risks, the result could save patients and health systems a lot of money. Patients could have confidence knowing that choosing the less expensive photon therapy will still provide them with the best health outcomes, and health systems may choose not to build proton facilities, which can cost upward of $200 million.

The goal of the study, which involves the participation of more than 50 sites across the country, is to enroll 3,000 patients, with 1,500 receiving photon therapy and 1,500 receiving proton therapy. All patients enrolled at Hollings will receive photon therapy for their prostate cancer. For those who participate in the trial, the only extra step required is filling out questionnaires about their side effects and quality of life for at least three years.

“It’s also important for our community to participate in this clinical trial so that we can set the appropriate standard of care for our own patient population, which includes minorities who historically have not been appropriately represented in clinical trials.”

– Dr. David Marshall

“The reason we like this trial at Hollings is because it doesn’t change our patients’ course of treatment. They can still choose how they get treated, and they’re able to help future patients determine the best, most cost-effective way to get treated,” said Marshall.

“It’s also important for our community to participate in this clinical trial so that we can set the appropriate standard of care for our own patient population, which includes minorities who historically have not been appropriately represented in clinical trials.”

Aside from arming doctors and patients with the knowledge they need to make informed treatment decisions, Marshall believes it’s important to continue improving therapies for men with prostate cancer, which is the most common cancer in American men, other than skin cancer.

“Around 200,000 men are diagnosed with prostate cancer every year in the United States, and somewhere between 15% and 20% of those patients will eventually die of their disease,” said Marshall. “We’re going to learn a lot from this trial that can help us continue to improve outcomes for these men going forward.”

This research is funded by the Patient-Centered Outcomes Research Institute (PCORI).

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