IMRT and Radioactive Seed Implants, The Newest Weapons Against Prostate Cancer
With Dr. Carl Olson, Columbia Hospital
"Even though it's relatively slow growing, prostate cancer still carries potential for morbidity, so we take it seriously and feel strongly that the earlier it's detected, the better the chances are for cure," said Dr. Carl Olson of Columbia Hospital. As a radiation oncologist he treats patients for that disease and knows that aggressive prostate cancer that spreads beyond the walls of the prostate gland kills more than 30,000 American men each year.
The prostate is a difficult and sensitive organ to treat because it's located so near the rectum, the bladder and the nerves that enable normal sexual function. Various forms of radiation therapy are among the weapons that he and his colleagues are using to battle prostate cancer.
According to Dr. Olson, the latest technology that can be effective and minimize side effects is Intensity Modulated Radiation Therapy (IMRT).
"The objective of any external beam radiation therapy," he explained, "is to define the target and the normal tissue accurately and irradiate the target area with high-powered x-rays to kill cancer cells.
"With IMRT we can do the job better than other external beam radiation therapy. Using IMRT we zero in on the target and identify the most sensitive areas surrounding it. We then create a computer-designed treatment plan that will deliver a radiation therapy pattern that spares normal tissue and delivers a higher dose to the target."
These treatments are generally given five days a week for about seven or eight weeks. Each treatment takes about 15 minutes. Anesthesia isn't required because the treatment isn't painful.
Another effective form of radiation therapy is radioactive seed implants, using iodine or palladium isotopes, depending on the grade of the cancer. Seed implants, also known as radiation brachytherapy, may deliver a higher dose of radiation to a more localized area than do external beams. The radiation emitted extends only a few millimeters beyond their location and isn't likely to escape the prostate area. The therapy is usually done on an outpatient basis.
"Our patients are sleep under a general anesthesia for about one or two hours. We use needles guided by ultrasound to insert and implant those rice-sized radioactive seeds into the prostate. It's done in one simple operation," he explained. "The seeds then emit the radioactivity over a period of months necessary to kill the cancer cells. With radioactive iodine seeds, half their energy (what we call half life) is lost after 60 days, and so on." All radiation inside the seeds is generally exhausted within a year.
If the therapy done early enough, there's an excellent chance for a cure and an excellent chance that there won't be any side effects to the surrounding areas, and that sexual function will be preserved, according to Dr. Olson.
He said there are many success stories about radioactive seed implant patients that can be reported. "We've been using this therapy for about five year at Columbia, where we have implanted over 300 patients. Obviously they're not all success stories. Some have had side effects. Some have had other complications. But over that time, most of our patients have done very well. If there's no recurrence after five years, chances are good that it won't recur."
According to Dr. Olson, radiation treatment of any kind is a collaborative effort between the urologist, radiation oncologist, medical oncologist and their support team. The patient's role in this, he said, is to become as educated as possible about the disease and the possible treatments. "Wives and girlfriends, too, should be part of this team, and should know as much as possible about prostate cancer."
