Prostate Cancer
with Robert Brookland, MD
How is radiation therapy administered for prostate cancer?
Prostate cancer is the most common cancer among non-smoking men. At GBMC, men with prostate cancer have a lot of treatment options – depending on a number of diagnostic factors.
“The first challenge is trying to figure out the extent of the disease, which we call the ‘stage,’” says Robert Brookland, MD, Chairman of the Department of Radiation Oncology at GBMC. Physical exams, lab tests, biopsy and computer-guided imaging help physicians assign the cancer a stage between I and IV, with IV being most serious.
Today, prostate cancer is often being discovered earlier, thanks to the prostate-specific antigen (PSA) screening. PSA is an enzyme that is naturally produced by the prostate. However, when a higher than normal level is found, it could indicate cancer is present. “PSA screening tests permit us to identify prostate cancer before you can feel it, before there are symptoms and when it is most curable,” says Dr. Brookland.
According to the American Urological Association, men age 50 and older should have an annual PSA screening. Men age 40 and older who are at increased risk should also have the exam on a yearly basis.
If PSA levels are elevated, a biopsy may be needed. If cancer is confirmed, physicians need to determine if it is contained to one area of the gland or if it has spread. In a process known as grading, the cells are examined under the microscope by a pathologist who assigns the cancer a Gleason score between 2 and 10, with 10 being the most aggressive form of cancer.
“The stage, Gleason score and PSA level all allow us to categorize patients as having a low-, intermediate- or high-risk cancer. The treatment we recommend depends on all three of these categories,” says Dr. Brookland.
The patient’s overall health may also play a role. “When we recommend treatment, we have to decide if the person is suitable for surgery or radiation therapy,” says Dr. Brookland. “Someone with prostate cancer should always meet with both a urologist and a radiation oncologist to fully discuss their treatment options.”
A patient who is young and healthy with a long life expectancy may undergo more aggressive treatment than a man who is older and has additional health concerns. “Generally, prostate cancer progresses slowly and does not become advanced and incurable in a period of months, or even a few years,” says Dr. Brookland. “For a senior with other profound medical issues, we will likely recommend ‘careful watching’ rather than surgery or radiation therapy.”
Today, radiation therapy is an even more viable option than in the past. “With our newer technologies and elevated doses of radiation, the cure rates are identical for radiation therapy and surgery,” says Dr. Brookland. Although both procedures have the same success rate, radiation therapy patients tend to experience fewer side effects such as urinary incontinence and impotence than those who undergo surgery.
There are two ways to deliver radiation therapy. External beam radiation therapy makes use of high-powered x-rays to kill cancer cells. Because this type of radiation can also scar the surrounding healthy tissues, the first step is to pinpoint the exact location of the prostate. Computer-imaging software gives the radiation oncologist the ability to find the best angles for aiming the beams of radiation.
“At GBMC, we use sophisticated technologies to deliver a very high dose of radiation to the prostate while minimizing the doses that are delivered to the bladder, rectum and other surrounding tissue,” says Dr. Brookland. Two of those technologies include intensity modulated radiation therapy (IMRT) and image guided radiation therapy (IGRT), which allow the radiation oncologist to visualize exactly where the dose should be delivered.
External beam radiation therapy is generally administered five days a week for five to eight weeks (25-43 doses), based on each patient’s individual treatment plan. Each outpatient treatment takes only about 15 minutes.
Another type of radiation therapy, known as brachytherapy, involves radioactive seeds being implanted into the prostate. Based on the size of the prostrate gland, between 50 and 100 tiny seeds are implanted through ultrasound-guided needles under general anesthesia during one outpatient procedure. Prior to radiation therapy, hormonal therapy may be used to shrink the size of the prostate gland.
Brachytherapy delivers a higher dose of radiation than external beam radiation, but over a longer period of time. “Typically, we use either radioactive iodine or palladium. The seeds are implanted permanently and patients remain radioactive for several months,” says Dr. Brookland. Radiation safety precautions are thoroughly reviewed with all patients.
“In some cases, we may perform a partial seed implant in conjunction with a more limited dose of external-beam radiation therapy,” says Dr. Brookland. “Treatment plans are always customized to each individual’s circumstances.”
