Real-time seed plant system and stereotactic body radiation therapy - two innovative approaches to fight prostate cancer

Philadelphia, Dallas 21 September 2007Radiation oncologists and urologists at the Kimmel Cancer Center at Jefferson and Thomas Jefferson University Hospital in Philadelphia have begun using a real-time system to implant radiation-emitting seeds in prostate cancer patients. While the system, which is made by Nucletron, a technology company based in The Netherlands, is only being used for imaging and planning purposes so far, it ultimately will help with the actual placement of the seeds. To date, Jefferson is the first medical centre in the Delaware Valley to begin employing the new system. At the University of Texas (UT) Southwestern Medical Center on the other hand Dr. Robert Timmerman, vice chairman of radiation oncology, is leading a national clinical trial testing the effectiveness of stereotactic body radiation therapy (SBRT) to treat prostate cancer in five, 30-minute sessions. The SBRT technique is a relatively new procedure used for treating localized tumours by delivering very high doses of focused radiation.

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"There are a number of good treatments for prostate cancer, but they all have some drawbacks - they're inconvenient; they're invasive; or they cause impotence, rectal injury or urinary incontinence", stated Dr. Timmerman.

The three standard treatment options for early stage prostate cancer are:

  • Prostatectomy, the surgical removal of the prostate gland, which can be done with minimally invasive techniques and robotic assistance;
  • Brachytherapy, in which doctors implant numerous small radio-active seeds about the size of a grain of rice into the prostate gland using multiple large needles inserted through the skin. Once implanted, the seeds release their radioactivity directly into the prostate gland; and
  • External beam radiation, which involves 42 to 45 treatments administered over two or more months, five days a week.

At the Kimmel Cancer Center in Philadelphia a multi-disciplinary team of urologists, surgeons, radiation oncologists, radiation physicists and others have launched a more advanced type of brachytherapy using a real-time system to place the seeds. The team involved in using the device is hoping that the new federal Food and Drug Administration-approved technology will make an already good system even better, adding scientific precision to a treatment that currently relies mainly on physician experience and skill.

"The device is a step above the traditional technique because it makes use of a more sophisticated approach that allows for a co-ordinated, real-time imaging-based implantation of seeds", Richard Valicenti, M.D., associate professor of radiation oncology at Jefferson Medical College of Thomas Jefferson University, stated about the Nucletron device.

Patients have two options for treatment for localized, low-risk prostate cancer confined to the prostate: surgery or radiation therapy. In brachytherapy, tiny pellets - seeds - about the size of a grain of rice blanket the prostate, giving off radiation that travels only a few millimeters to kill nearby cancer cells. The seeds are carefully placed inside the cancerous tissue and positioned to efficiently attack the cancer. Brachytherapy has been proven to be very effective and safe, providing a good alternative to surgical removal of the prostate, while reducing the risk of certain long-term side effects, such as impotence. The seed radio-activity decays with time, while the seeds stay within the treatment area.

"This new approach is automated, so what normally takes us many steps to do we can do very quickly", Dr. Valicenti stated, noting that brachytherapy is highly operator-dependent. "For example, putting in the rectal ultrasound probe has to be done slowly by hand. Now, the device does it and takes measurements of the size and location automatically of the target gland." It collects the imaging information - the dimensions of the patient-s prostate - and downloads this into a computer system, where it is rapidly processed.

The doctors, radiation physicists and other specialists then specify the parameters of treating the cancer, such as how much dose to give the prostate, how much extra dose to give to the area of the tumour and the positions in which to give the radiation, all in less time than previously possible with standard techniques, according to Dr. Valicenti.

"Up until recently, we would produce a plan in the outpatient setting that we hoped to recapitulate in the operating room", explained Adam Dicker, M.D. Ph.D., professor of radiation oncology at Jefferson Medical College. "But there was always the concern that what we saw initially might not match the situation later." Planning, he explained, can be affected by the patient's position and the location - and condition - of his prostate.

Because the device enables real-time planning in the operating room, he stated: "If an area is under-dosed, you can find out right away and make corrections." The system provides a multi-dimensional view of the prostate and the "ability to process and accumulate more precise information, constantly updating and re-adjusting the treatment plan."

At the UT Southwestern Medical Center, patient Breihan Bridgewater suffers from emphysema. He sleeps on his side because when he lays flat on his back it feels like there's a boulder resting on his chest. When the 74-year-old semi-retired electronic technician was diagnosed with prostate cancer, the thought of undergoing surgery or having to lie on his back and undergo more than 40 radiation treatments left him with an uneasy feeling - and a decision to make. The Lewisville resident decided he would not seek treatment for his early-stage prostate cancer. After Mr. Bridgewater told his UT Southwestern Medical Center doctors that the decision was determined because he didn't believe he could withstand the standard treatment for prostate cancer, they referred him to Dr. Robert Timmerman.

Dr. Timmerman has successfully used the SBRT technique to treat patients with lung and liver cancers. "This new treatment mimics the dose deposition of brachytherapy, but it is done non-invasively, in an outpatient setting, without making any incisions, needle punctures or anaesthesia", Dr. Timmerman stated. "The beauty of it is that the patient only has to come in for five outpatient treatments and is finished in a week and a half."

Dr. Timmerman has treated 11 patients at UT Southwestern using this new method with only minor side effects. As part of the study, he is trying to establish the treatment's proper dose protocol. He also is establishing study sites at the University of Minnesota, University of Colorado and at a rural practice in South Dakota.

Health care experts predict that about 218.000 new cases of prostate cancer will be diagnosed in the United States this year, and more than 27.000 men will die from the disease. Dr. Timmerman stated that the SBRT treatment might be ideal for people who live far away from an academic medical centre or who can't stay away from their jobs for extended periods of time to receive treatment or recover.

"We're targeting this population because they clearly need a better treatment", Dr. Timmerman stated. "If the treatment ends up being favourable in its toxicity and side effects, then even 'city slickers' might want to have it too."

For Mr. Bridgewater, "the treatment was a breeze. I didn't have to do anything except breathe." And his prognosis is excellent. Tests show that the level of prostate-specific antigen (PSA) in Mr. Bridgewater's blood, which is elevated in men who have prostate cancer, was nearly non-existent.

"Actually, we are seeing that the PSA levels in patients undergoing this new therapy are declining more rapidly than one would expect with conventional treatment", Dr. Timmerman stated. "It's still early in the study process, but it looks promising."

Participants are still being recruited for the study at UT Southwestern Medical Center. To qualify, patients must have early stage prostate cancer and a Gleason score of 7 or below.


Leslie Versweyveld

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