The Prostate Seed Implant
Dear OncoLink "Ask the Experts,"
I have prostate cancer. PSA = 13.5. I'd like to know the pros and cons of seeding. Can you help?
Li Liu, MD, OncoLink editorial assistant, responds:
Thank you for your interest and question.
The seed implant treatment for prostate cancer is also referred to as "interstitial brachytherapy." In this therapy, small pellets of radioactive materials (isotopes such as iodine-125 or palladium-103) are placed inside thin needles, which are inserted through the perineal area (area between the scrotum and anus) into the prostate gland. The permanent types of pellets, which are sometimes called seeds, are implanted through these needles, and become lodged in the cancerous area. Alternatively, the needles containing radioactive material can be kept in place for less than a day and then removed. This approach is called high dose-rate brachytherapy. In both cases, exposure to surrounding tissues and to other personnel is minimized.
The advantage of seed implant compared with external beam radiation is primarily convenience. Permanent seed implant only requires a brief stay in the hospital when the radioactive material is inserted. Usually this procedure is very well tolerated.
This treatment is most useful for patients whose cancer is still localized to the prostate. The efficacy of seed implant relative to external beam radiation therapy and radical prostatectomy remains a debatable issue. One large retrospective study demonstrated that, in men with low-risk tumors (early T stage, serum PSA ¾ 10 ng/mL, and Gleason score ¾ 6), seed implant achieved similar PSA free survival compared to external beam radiation and radical prostatectomy (JAMA 1998 Sep 16; 280(11): 969-74). The outcome measured was PSA failure rather than survival because of the relatively short duration of follow-up. No definitive conclusions can be reached regarding the efficacy of seed implant until randomized clinical trials have been completed.
Seed implantation is a surgical procedure. The potential acute complications may be related to anesthesia and/or include, bleeding, and infection. The late complications of seed implant include irritative voiding symptoms, persistent urinary retention, rectal urgency, increased bowel movements, rectal bleeding or ulceration, and prostatorectal fistulas (International Journal of Radiation Oncology Biology Physics 1994 Mar 1; 28(4): 985-90). The incidence of erectile dysfunction and urinary incontinence appears to be lower than with external beam radiation.
As always, you should discuss treatment options with your doctor.
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