Urinary incontinence is uncommon in men undergoing interstitial seed therapy affecting < 1%. However, in men who have had a prior TURP, the risk of incontinence is 25% and is up to 40% if more than one TURP has been performed.
Rectal irritation does not occur as commonly as urinary symptoms and tends to improve quicker than urinary symptoms do. Fewer than 5% of patients will have a rectal ulcer or rectal bleeding, which occurs as a result of irritation of the rectal lining. It may be associated with pain, rectal spasms, and the feeling that one needs to have a bowel movement. This condition can be treated with several topical medications, including Anusol, hydrocortisone, Proctofoam hydrocortisone, mesalamine (Rowasa) suppositories, Metamucil, and a low-roughage diet.
PSA "Bounce" or "Blip"
This occurs when the PSA increases on two consecutive blood draws and then decreases and remains low without rising again. The cause of this phenomenon is not
known. It occurs in about one-third of men treated with interstitial seeds and typically occurs around 9 to 24 months after the treatment. It may or may not be accompanied by symptoms of prostate inflammation; if such symptoms are present, then treatment for prostatitis may decrease the symptoms and the PSA level.
This narrowing of the urethra is related to the development of scar tissue and occurs in 5 to 12% of men, and tends to develop later. It may present with a change in the force of stream or the need to strain to void. A stricture is identified by cystoscopy in the doctor's office. Treatment of the stricture depends on the location and the extent of the stricture; it may require simple office dilation or an incision under anesthesia.
This condition may occur in as many as 40 to 60% of men who undergo interstitial seed therapy. Unlike radical prostatectomy, the erectile dysfunction tends to occur a year or more after the procedure and not right away. As with post radical prostatectomy ED, there are a variety of options available to treat it (see Part Three, Erectile Dysfunction).
Who is a candidate for interstitial seed therapy?
Similar to radical prostatectomy, the goal of interstitial therapy is to cure the patient of prostate cancer. With this in mind, the candidate should have a life expectancy of more than 7 to 10 years and no underlying illness that would contraindicate the procedure such that he will not benefit from a cure. Men with significant obstructive voiding symptoms and/or prostate volumes greater than 60 mL are at increased risk for voiding troubles and urinary retention after the procedure. Men who
have undergone a prior TURP are at increased risk for urinary incontinence after brachytherapy. Men with clinically localized prostate cancer of low to intermediate risk are candidates for interstitial seed therapy. Men with high-risk prostate cancer (PSA > 20 ng/mL, Gleason score > 8, or stage T3a prostate cancer) should not be treated with interstitial seed therapy alone. Depending on your risk, hormonal therapy may be used in addition to interstitial seed therapy.
In some individuals who are deemed to be at higher risk, external beam radiation therapy may be used in addition to interstitial seed therapy. Interstitial seed therapy is limited in its ability to reach tissue outside of the prostate, especially the back of the prostate. The addition of EBRT may help in patients who are judged to be at high risk for disease penetrating through or outside the prostate capsule. Use of interstitial seeds alone is appropriate for patients with tumors in clinical stage T1c to T2a, a Gleason score < 6, and a PSA < 10. Patients with a Gleason score of 7 or greater, a PSA > 10, tumors in clinical stage T2b or minimal T3a, and at least four of six biopsies positive for cancer or perineural invasion on the biopsy appear to be the best served by the combination of interstitial seeds and EBRT.
How is one monitored after interstitial seed therapy and what is the success rate?
Unlike with radical prostatectomy, the prostate remains in your body, and thus the PSA does not decrease to an undetectable level. In addition, it may take at least 2 years for the PSA to reach its lowest level (PSA nadir). The PSA is typically checked 1 month after seed placement, then every 3 to 6 months for 2 years thereafter if the level remains stable. After 2 years, the PSA is checked yearly. In January 2005 the definition of PSA failure after radiation therapy was refined. The Phoenix definition defines PSA failure after radiation therapy as a rise by 2 ng/ml or more above the nadir PSA with or without the use of androgen blockade.
A rise in PSA may occur in as many as one third of the patients between the first and second year after the implantation. This is called a benign PSA bump, and it appears to be related to late tissue reactions to the radiation, but it does not mean that the seeds have failed or that you are at increased risk of failure. In this situation, the PSA does not continue to rise, and this is how one differentiates a PSA bump from a failure.
The results of prostate brachytherapy are comparable to those of radical prostatectomy for 5 to 7 years after treatment. The long-term data (i.e., the data for longer than 10 years after treatment) are limited. Reported studies demonstrate success rates of 64 to 85% at ten years, with success being defined by either a PSA < 0.5 ng/mL or the absence of three consecutive rises in PSA in patients who received brachytherapy EBRT.