Internal radiation therapy: Treatment options for prostate cancer
This article is not intended to replace professional medical care or advice. If you have any questions or need additional information, please talk with your doctor.
Radiation is one of the most common forms of cancer treatment. It may be given alone, or in addition to chemotherapy and surgery. There are several different radiation therapies available, and each works to destroy or damage cancerous tissue with high-energy waves or particles such as protons, x-rays, gamma beams or electron beams.
Understanding prostate radiation therapy
Learning about prostate radiation therapy for the first time can be overwhelming, but understanding a little bit more about radiation and how it works may help to minimize that daunting feeling. Unlike the majority of normal, healthy cells that grow and divide at a regular rate to form new cells in the body, cancerous cells divide and multiply more frequently. The high doses of radiation cause tiny breaks in the DNA within these cells, which in turn prevents them from growing and dividing, according to the American Cancer Society (ACS). Often times, the radiation causes these cancer cells in and around the prostate gland to die altogether.
Internal radiation therapy
Internal radiation therapy, also called brachytherapy – from the Greek word brachys, meaning “short-distance” – is used to treat the disease when it’s found in the early stages in men with low-risk prostate cancer that is slow growing, stated the National Cancer Institute (NCI). While external beam radiation therapies are administered from a machine outside of the body to treat local tumors, internal radiation therapy places radioactive material near the cancer cells inside of the body. An advantage of brachytherapy, is it allows a physician to use a higher total dose of radiation to treat a smaller area and in a shorter time than is possible with external beam radiation treatment. There are two types of this internal form of radiation therapy: low-dose-rate and high-dose-rate.
1. Permanent low-dose-rate brachytherapy
In this form of low-dose-rate brachytherapy (LDR) seeds of radioactive material such as iodine-125 and palladium-103 are stored in titanium cases and then placed into laser thin needles, detailed the Prostate Health Education Network (PHEN). These needles are then inserted into the prostate through the skin between the rectum and scrotum. As the needles are removed, the brachytherapy seeds, which are about the size of a grain of rice, are left in the prostate gland where they remain permanently.
The seeds, anywhere from 40 to 100 in number, will eventually stop giving off radiation over time. This could take weeks or months, each case is different, according to the ASC. The seeds are no longer active after the radiation has been used up and they will generally stay in place without causing any harm or concern. Generally, they’ll cause very little discomfort because they are so small. Additionally, the seeds can produce a large amount of radiation in a small area, because the radiation only travels a short distance and are therefore less likely to damage the healthy surrounding tissue. Spinal or general anesthesia will need to be administered for the procedure and sometimes conscious sedation is also used.
2. Temporary high-dose-rate brachytherapy
Unlike the permanent technique of LDR, temporary high-dose-rate brachytherapy (HDR) uses higher doses of radiation that are left in place for a much shorter period of time – typically 5 to 15 minutes. Very small, hollow catheters are inserted into the prostate gland transperineally, with the help of ultrasound guidance, according to the National Institutes of Health (NIH). Then, a brachytherapy seed of radioactive iridium-192 or cesium-137 is inserted through the catheter with millimeter precision to ensure that it directly reaches the tumor. Advanced technology helps doctors control how far the brachytherapy seed must go and for how long it must remain in the catheter to release the appropriate dose of radiation.
The ACS reported that this procedure is typically done over the course of two days in the hospital. During this time, there will generally be three treatments and after each one the radioactive material will be removed but the catheter will remain in place. The catheter is removed following the final treatment. Pain and swelling in that area for several days after the treatment are normal and urine may temporarily be a reddish-brown color.
Potential risks and side effects
As with any form of cancer treatment, there are going to be potential risks and side effects. Perhaps the biggest one when it comes to LDR is seed migration. According to PHEN, this occurs when a brachytherapy seed does not stay in its intended place and travels to another part of the body such as the bladder or urethra. While seeds have been reported to travel further through the body, there is no research to infer that this can cause illness and the occurrence rate is very low. Patients may be asked to strain their urine for several days following an LDR brachytherapy procedure to catch any seeds that may come out. Patients who undergo HDR brachytherapy do not have this risk, as the source is removed after treatment.
A Radiation Oncology report, titled “Incidence of seed migration to the chest, abdomen, and pelvis after transperineal interstitial prostate brachytherapy with loose seeds,” reviewed 267 patients for seed migration following prostate brachytherapy. Throughout all 267 patients were 19,236 seeds. Overall, it was found that only 91 of 19,236 seeds migrated in 66 patients. Furthermore, the report found that none of the 66 patients had any symptoms related to the migration.
Similar to the risks of external beam radiation therapy, bowel, erectile and urinary side effects may occur but are not typically very serious. Less than 5 percent of those who undergo this type of therapy experience long-term bowel complications, asserted the ACS. Serious urinary incontinence is not that common and normal erectile function is typically restored soon after. Additionally, prescribed precautions may include wearing a condom during sex.
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Internal radiation therapy limitations
The ACS also reported on the limitations that may exist for some men looking to receive internal radiation therapy. For those with large prostate glands, getting each of the seeds in their exact locations can be quite difficult. One way that doctors are attempting to get around this issue is by administering hormone therapy to shrink the gland before the procedure. Prior urinary complications and transurethral resection of the prostate may increase the risk of urinary side effects.
The benefits of internal radiation therapy
According to the NIH, brachytherapy was first used more than 100 years ago and has quite a lengthy heritage with cancer treatment. Perhaps the biggest advantage of internal radiation therapy is that doctors can use a higher total dose of radiation to treat a smaller area in a shorter time. Not only does this permit safe increases in radiation dose, according to the NIH, but also minimizes the damage to surrounding tissues.
An important benefit of LDR brachytherapy is that the procedure is a one-time treatment, normally done on an outpatient basis within a half or full day. It does not require a lengthy hospital stay, under normal circumstances, which promotes efficiency for patients. Additionally, in comparison to external beam radiotherapy (EBRT), movement of the prostate does not need to be monitored during either LDR or HDR brachytherapy thanks to the implanted radioactive sources that move with the gland.