Proton Therapy vs. IMRT for Low or Intermediate Risk Prostate Cancer

Overview

We are studying whether men being treated for prostate cancer have the same amount of side effects from either one of two different external radiation treatments: IMRT or PBT. With IMRT, a number of x-ray beams are used to shape the radiation to the prostate. PBT is another type of external radiation treatment for prostate cancer that is used in a few centers in the United States. Protons are tiny particles with positive charge that can be controlled to travel a certain distance and stop. PBT is precise like IMRT, but it uses proton beams instead of x-ray beams. IMRT and PBT aim to deliver most of the radiation to the prostate cancer while sparing surrounding tissues. Both IMRT and PBT have been used in the treatment of prostate cancer and are thought to be equally effective at curing prostate cancer. However, both treatments have also been shown to cause the potential side effects of radiation, including bowel, urinary and erectile problems. It is possible that side effect rates with PBT will be lower, the same, or even higher than with IMRT, but this has not been studied well to date. Though both of these radiation therapies have been used in the past to treat prostate cancer, there has never been a study that compares the effects of these two therapies to see which one has less side effects. In this research study, we are comparing IMRT to PBT to determine which therapy best minimizes the side effects of treatment.

Because no one knows which of the study options is best, you will be "randomized" into one of the study groups: IMRT or PBT. Randomization means that you are put into a group by chance, like flipping a coin. Neither you nor the research doctor will choose which group you will be in. You will have an equal chance of being placed in either group. Randomization makes the study better from a scientific point of view because it helps ensure that patients receiving IMRT and proton therapy are similar. You will be receiving only one type of radiation, either IMRT or PBT throughout your participation in the study. Before you begin radiation therapy you will have a pelvic CT scan in order to design your radiation treatment. Doctors will use information gathered from these scans to plan the best way to deliver radiation to your tumor. Both types of radiation therapy will be given once a day for 5 days (no weekends or holidays) for up to 9 weeks. Both IMRT and PBT will require that you lie on a table for less than 15 minutes to obtain your treatment. During each visit you will be asked questions about your general health and specific questions about any problems that you might be having and any medications you might be taking. You will also undergo a physical exam and complete some quality of life questionnaires. After your radiation therapy you will have follow up visits at 3,6,9,12,18,24,36,48 and 60 months.