A: It differs from any other radiation program. First, we implant radioactive I-125 seeds into the prostate. These tiny, metal seeds give off radiation for about a year. Since they are metallic, they are easily seen on x-rays and are a perfect target. After we implant the seeds, we then give external beam radiation with IGRT using a linear accelerator targeted at these metal seeds in the prostate. Because of this, the cancer cells are irradiated at the same time by both the seeds and the beam.
A: The key to our radiation program is to have your cancer cells irradiated by both seeds and beam simultaneously. This makes it different from any other prostate cancer radiation program for it causes irradiation synergy (sin-er-gee).
A: Synergy means that the combined effect of giving both forms of radiation simultaneously is more than just adding them together. Think of synergy this way: instead of 1 (seeds) + 1 (beam) = 2, by giving them in combination, 1+1=4 or 5. Another way to understand synergy is to think of the gases hydrogen and oxygen. When mixed together, these gases form a completely different substance: water, a liquid. The combination irradiation creates a different killing effect on prostate cells, cancer and normal.
A: Yes. It is called ProstRcision® which basically means excision of the prostate with irradiation. We are destroying the prostate cancer cells and normal prostate cells with radiation just as if they were being cut out with surgery except that the muscles that control urination are not removed and, most of the time, the sex nerves are preserved.
A: Let’s assume that you have 100 cancer cells; 95 are in the prostate and 5 have leaked outside the prostate. Since most cancer cells (95) and all normal cells are inside the prostate, more irradiation is required within the gland. This is accomplished by irradiation synergy from the iodine seeds combined with the IGRT beam radiation. Since there are fewer microscopic capsule penetration cancer cells (5) the IGRT beam radiation, which radiates both inside and outside the prostate, would also destroy cancer cell leakage: microscopic capsule penetration of cancer. Thus, ProstRcision would destroy all 100 cancer cells. However, we leave behind the muscles that control urination, and most of the time, the sex nerves.
A: The beam radiation irradiates all around the prostate which would destroy the microscopic amount of capsule penetration cells that you might have.
A: We are not sure, but it probably does this in two ways. First, some cells are killed outright by ProstRcision. A second method is to stop growth of cancer cells which is more likely how ProstRcision works. As noted, cancer cells have uncontrolled growth – one cell becoming two cells, four cells, eight cells, etc. ProstRcision stops cancer cells from multiplying. But they would continue living for a time and continue making PSA until the cancer cell died.
A: Following ProstRcision, men get a PSA test every six months so we can measure what is happening to both the normal and cancerous cells. Instead of dropping to zero immediately after treatment, as would happen if all prostate cells were suddenly killed, the PSA falls slowly. ProstRcision stops the cancer cells from multiplying. With no new cancer cells being made and as the old cancer cells gradually die, there are less and less cells to make PSA so the PSA falls until there are no prostate cells left and the PSA is <0.2 or, in effect, zero. By twelve months after ProstRcision, most of the normal and cancer cells are dead because the PSA has dropped to less than half of what it was before treatment.
A: The first part of ProstRcision is a prostate I-125 seed implant which is a minor operative procedure, performed in an outpatient surgical center by a team of a urologist and radiation oncologist and takes about 40 minutes. After general anesthesia, a man’s legs are placed in stirrups. Then, an ultrasound probe, which is connected to a television monitor, is inserted into the rectum. While watching the prostate on the television monitor, an average of 21 hollow, 8-inch long needles are inserted through the perineum (the area located between the anus and the testicles) into the prostate and some into the seminal vesicles (an organ attached to the top of the prostate).
To explain needle insertion more, the radiation oncologist attaches a seed implant device to one of the needles through which seeds are injected. After injection of the first seed, the needle is pulled back and another seed is injected until reaching the bottom of the prostate, after which the needle is pulled out of the patient. He then goes to the next needle and repeats the process. A different number of seeds are injected through each needle, depending on where the needle is located within the prostate. Based on the prostate biopsy, seeds are typically placed closer together to increase the amount of radiation in the prostate parts that have cancer.
A: A radioactive I-125 seed has radioactive iodine (125) attached to a very tiny bar of silver, all of which is placed in a small titanium capsule that is 1/5-inch long (4.5 mm) and 1mm wide. Each seed produces a tremendous amount of low energy gamma radiation (28 KEV) within 2-4 mm of the seed, but then radiation drops off rapidly. Thus, each seed will irradiate an area about the size of a very small marble. Each radioactive I-125 seed slowly gives off radiation for about one year. The seeds have a 60-day half-life, which means that half the total seed irradiation is given off in the first two months after the implant.
A: An average of 74 seeds. However, this varies a lot because each implant is tailored for each prostate cancer patient depending on the size of his prostate, and extent of the cancer based on the prostate biopsy pathology report.
A: The IGRT (Image Guided Radiation Therapy) beam radiation is started three weeks (21 days) after the seed implant. By beginning the beam 21 days after the implant during the first half-life of the seeds, the beam radiation is given when the radioactive iodine seeds are producing lots of irradiation so the beam and seed irradiation are combined for synergy.
A: First, we make x-ray pictures to document where the seeds are located. These metallic seeds outline the prostate and are a target for beam irradiation, which is why it is called image guided. With the seeds as a target, we plan the follow up beam radiation to be given by a linear accelerator.
A: Using the gold and I-125 seeds to outline the prostate, computers open the accelerator machine to the shape of a man’s prostate. Then, the accelerator cross-fires the prostate from five or more different angles with beam irradiation so that the surrounding normal organs – hips, bladder, rectum and sex nerves – receive a relatively small amount of radiation. Using computers to calculate irradiation doses, the IGRT beam radiation is delivered precisely to the prostate and outside the prostate to destroy possible microscopic capsule penetration.
A: Treatment is similar to getting a pelvic x-ray each day. After a patient is placed on the accelerator table, the gold and I-125 seeds are targeted. The prostate is cross-fired from multiple directions. After a man’s treatment is finished, which usually takes less than 10 minutes, he may go back to his normal daily activities. The patient returns the next day and the process is repeated. Beam irradiation treatments are given daily, Monday through Friday for a total of 30 to 35 treatments.
A: Your doctor is wrong and does not understand ProstRcision. Since we plan on irradiation synergy and give beam irradiation after the implant, we reduce the seed implant dose by almost half compared to the amount typically given when men are treated only with seeds. Likewise, we reduce the accelerator radiation dose by almost half compared to what is given to men when treated only with accelerator irradiation. So, we are giving about half the regular seed dose plus half the regular beam dose. By reducing the dose of both seed and accelerator radiation, we combine both treatment methods to produce irradiation synergy. It is important that the physician has a lot of experience with this type of treatment.
A: No. You can have a Radical Prostatectomy if our radiation program failed to get your PSA to zero and biopsy showed persistent cancer in the prostate. However, due to the synergistic effect, we rarely fail to destroy all the cancer in the prostate. The vast majority of failures after ProstRcision is because the cancer had spread (metastasized) before we ever treated a man but the metastases was too tiny to be found by tests before treatment such as bone or CT scans.
A: Yes. Since all normal prostate cells and, hopefully, all cancer cells are suddenly removed with Radical Prostatectomy, a man’s PSA should fall to 0.2 ng/ml within six weeks of surgery. In contrast, after ProstRcision, the average time to achieve an undetectable PSA is 42 months. The hallmark of cancer is growth – cancer cells reproducing and making more cancer cells. Irradiation primarily kills cancer by preventing cancer cells from reproducing. Thus, cancer cells may live for a period of time and make PSA. However, these cells will not be able to reproduce and will eventually die. This is measured by the slower time for PSA to achieve PSA 0.2 ng/ml after ProstRcision.
A: It would be impossible to know if this could happen since cancer cells can naturally have microscopic capsule penetration. However, if needles could pull cancer into the rectum, that would not be a problem with ProstRcision. The beam part of ProstRcision irradiates into the rectum a slight amount to destroy microscopic capsule penetration of any cause.