In brachytherapy, a type of radiation treatment for prostate cancer, 80 to 120 radioactive seeds (tiny metal pellets) are implanted directly into the prostate through the skin between the scrotum and rectum under ultrasound guidance. The pellets emit radiation for several months. After their radioactive energy is spent, they remain harmlessly in the body. Since the pellets are not removed and emit radioactivity over months, this approach is called permanent low-dose-rate brachytherapy.
According to guidelines from the National Comprehensive Cancer Network (NCCN), brachytherapy is an option for men with intermediate-, high-, and very-high-risk disease. Some physicians recommend a combination of brachytherapy and another type of radiation treatment known as external beam radiation therapy (EBRT) for men with more advanced disease. However, the combination may increase the risk of bowel-related side effects.
The side effects of brachytherapy—urinary and bowel problems—are similar to those of EBRT, but these complications may occur more often with brachytherapy among men with very large or very small prostates, those with lower urinary tract symptoms that are bothersome, and those who have previously had a transurethral prostatectomy (TURP). In addition, the radioactive seeds can migrate to other parts of the body, such as the lungs, although research suggests that seed migration has no negative consequences.
Another technique, which is known as high-dose-rate brachytherapy, is a refinement of low-dose-rate brachytherapy. In high-dose-rate brachytherapy, radioactive pellets are delivered to the prostate via hollow plastic needles. The pellets emit a high dose of radiation over a 24- to 48-hour period, after which they are removed.
Available research suggests that outcomes are similar among men treated with high- or low-dose-rate brachytherapy. But men treated with the newer technique experienced fewer side effects, including less urinary frequency, incontinence, blood in the urine, and rectal pain.
When radiation therapy is used to treat intermediate- or high-risk prostate cancer, adding hormone therapy has been shown to increase survival when compared to the use of radiotherapy alone. The timing of the hormone therapy is usually short term (four to six months) during and after radiation treatment of intermediate-risk disease, and longer (two to three years) during and after treatment of high-risk disease. Disease recurrence rates may be lower in men with high-risk cancers treated with a combination of EBRT and brachytherapy. Hormone therapy is sometimes given to men with larger prostates (greater than 1.5 oz.) who are scheduled to start brachytherapy, with the aim of shrinking the prostate before the radioactive pellets are implanted.