Getting A Clearer Picture Advances In Technology Help Doctors Battle Prostate Cancer
It is said that seeing is believing. In the case of prostate cancer, seeing is treating the disease more accurately and effectively.
And only in recent years has technology allowed doctors to take off the blinders in fighting the most common form of cancer for men, a scourge that affects 2.8 million Americans and kills some 32,000 each year.
Over the past couple of decades, computer imaging systems have gradually advanced to the point where procedures that had been performed ‘blind’ with mixed results before, such as external beam radiation and radioactive seed implant therapy, are now aided by accurate pictures of the diseased area.
It has opened up a whole new level of treatment, as the precision gained from these images allows doctors to use higher doses of radiation focused on a specific point without fear of harming non-diseased organs, as was the concern before.
“It’s a more sophisticated way to do it,” said Dr. Allan J. Stark, medical director of the Sr. Caritas Cancer Center at Mercy Medical Center. “It gives us the exact size, shape, and location of the prostate in the body, so that we can direct the radiation more accurately to the prostate, while shielding other parts of the body.”
As Stark and other area medical professionals told The Healthcare News, sight is a wonderful thing when it comes to fighting such a common — and often deadly — foe.
Just down the hall at Mercy’s cancer center, Timothy Klapproth, a medical dosimetrist, worked with two computers to develop images of the prostate for both external beam radiation and brachytherapy, or seed implantation therapy.
The ADAC 3-D Radiation Treatment Planning System uses ultrasound images to create a map of a person’s prostate, over which are laid the planned beam patterns and how much radiation each area will receive; this template is then used in the actual treatment.
Another computer, the Variseed Brachytherapy Treatment Planning System, is used in seed therapy, which is the implantation of between 70 and 130 tiny radioactive pellets into the prostate. The computer creates a 3-D map based on the original ultrasound image that shows exactly where each ‘seed’ — actually a pellet of Iodine-125 — will be placed. Later on, a needle carrying up to six pellets at a time is inserted from outside the body, delivering the treatment directly to those predetermined sections of the diseased organ.
Brachytherapy itself is nothing new. The first case published in medical literature, in 1911, used a catheter to insert radium into the prostatic urethra. An open-surgical method was developed in 1972, but it did not gain wide acceptance due to unsatisfactory clinical results and various complications. To that point, doctors remained blind to the internal structure of the organ while implanting the radiation.
“It was done during the course of an open operation,” said Dr. Mary Ann Lowen, a radiation oncologist at Baystate Medical Center. “The problem with the earlier technique was that it was difficult to know where to put the radioactive sources. So the outcomes were not very impressive, probably because the dose distribution was not even and did not cover the prostate very well.”
However, by the early 1980s, brachytherapy was beginning to get another look, thanks to the development of transrectal ultrasound (TRUS) and computerized tomography (CT) scans. These technologies opened up the organ, so to speak, and allowed doctors to plot out a uniform seed distribution while still using a non-surgical method.
“We’re now using better imaging techniques to get good pictures of the prostate and get much more reliable placement of the sources, giving a good, even dose of radiation to the prostate,” she said.
The recent 3-D programs have improved upon those early breakthroughs and given both seed therapy and external beam radiation treatments a new precision never before attainable. That, Stark noted, allows doctors to begin using higher doses of radiation, both from beams and pellets, without fear of damaging surrounding healthy organs — or other bodily functions.
“It’s not a new treatment, but now we have a greater preservation of both urinary and sexual function for the future,” said Dr. Raphael J. deLima, acting chief of Urology at Baystate Medical Center. “That’s where the most significant advances have been made — in preservation of potency and urinary continence, which today is almost taken for granted but at one time used to be a big risk from surgery.”
Also easy to take for granted is the minimally invasive aspect of seed implant therapy, Lowen said. After the pellets are implanted and the urologist checks for any that might have fallen in the bladder, the patient is roused from anesthesia and generally goes home the same day.
“Some people are concerned about whether patients are radioactive when they leave the hospital, but the energy from the seed travels only a very short distance,” she said. “The tissues of the body pretty much filter out all the radiation emitted from the seeds.”
That means that, while the patient shouldn’t have a child or a pregnant woman on his lap or otherwise too close over the next couple of weeks, there is no radioactive hazard to the body or to other people.
Brachytherapy isn’t for everyone, she noted. The ideal candidate is someone whose disease is confined to the prostate area, as opposed to those whose condition extends beyond the gland. “We’re trying to be selective with the patients we apply this treatment to.”
Some patients qualify for a high-dose form of brachytherapy in which a few highly radioactive seeds are placed in the prostate and later removed, deLima said. And sometimes, he added, patients are treated with a combination of seed therapy and external beam radiation.
The external treatment itself has come a long way since its early days of use, deLima said. Early on, it was sometimes ineffective because doctors worried about damage to the nearby bladder or rectum and therefore didn’t use high enough doses of radiation. The 3-D imaging technology in use today keeps the beams closely focused on the damaged areas, allowing for greater doses where treatment is needed. “It was an inefficient method,” Klapproth said. “Now we can control the variables better.”
First, Lowen said, a CT scan is used to define where the prostate is in relation to other bones. That information is used to determine how big the radiation fields will be.
“Then we use that information to shape the beams. Very carefully, we’re able to block out more effectively the organs we would rather not radiate while concentrating multiple beams on the prostate, where they need to be.”Some hospitals have begun to look into a new advance, intensity-modulated radiation therapy, which aims the highest allowed doses of radiation at very specific spots. “Dose painting,” as it is often called, is still too expensive and labor-intensive to see wide use, Stark said, but the technology is becoming more commonly employed.
Other techniques for stemming prostate cancer have been used with varying degrees of success and risk. Hormonal therapy, or androgen deprivation, prevents the body from producing testosterone, but doctors worry about long-term damage to the man’s bone structure, deLima said. And cryotherapy, or freezing the prostate using liquid nitrogen, has the potential for harmful side effects, like injuries to the urethra or infrequent — but potentially catastrophic — damage to the rectum, he said.
Thus, for increasing numbers of patients, prostate cancer treatment is a matter of external beams of radiation or permanently implanted pellets — and because of the ability to protect other organs, doctors are seeing their way clear to fight the condition more effec- tively than ever before.
And in the struggle for victory over a disease that
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