Prostate seed implantation at Princeton Radiation Oncology treats prostate cancer effectively.
Prostate seed implantation is a minimally invasive procedure for treating prostate cancer in which radioactive seeds are placed in the prostate gland to target cancer cells while maximizing the preservation of healthy tissue. This outpatient procedure requires general anesthesia and takes only a few hours. Most patients return to normal activities within two to three days.
At Princeton Radiation Oncology, our doctors are experts in treating prostate cancer patients using prostate seed implantation, having pioneered its use more than two decades ago.
A brief history of prostate treatment, from surgery to radiation.
Surgery (“radical prostatectomy”) has been the standard of care for prostate cancer for the past 150 years. Although effective, radical prostatectomies are invasive and not without complications. But then, shortly after the discovery of X-rays and radium at the turn of the last century, physicians began to explore how these modalities might improve survival and decrease potential side effects from the radical surgery. In 1917, Dr. Benjamin Barringer, chief of urology at what is now known as Memorial Sloan Kettering Hospital, espoused the use of radium needles for prostate cancer.
Initially, radioactive seed implantation was performed via “free-hand” technique, using direct visualization of the prostate to guide the radiation oncologist with seed placement. However, the results of this preliminary approach were hampered by suspect dose distribution in the prostate.
In 1987, Dr. John Blasko from Seattle described a reproducible system to implant radioactive iodine seeds in the prostate. This Seattle system employs a rectal ultrasound probe to directly visualize the prostate and a plastic template placed on the patient’s perineum (region between the scrotum and the rectum). The template guides the placement of the needles that are loaded with radioactive seeds. This technique allows a reproducible, uniform dose distribution to the prostate.
At Princeton Radiation Oncology, our radiation oncologists have been performing the prostate seed procedure since 1997. We use the Seattle group’s criteria for implant selection.
Who is a candidate for prostate seed implantation at Princeton Radiation Oncology?
Prostate seed implantation is not for everyone. Treatment decisions are based on important prognostic factors:
- Gleason grade
- PSA level
An ideal candidate should have a PSA level less than 10 and a Gleason grade 6 or less, with non-palpable disease. The size of the prostate is also an important factor. As a general rule, patients with prostate glands greater than 60cc are at increased risk for pelvic arch obstruction and poor dose distribution. Several months of androgen deprivation (hormone therapy) can be used to shrink large prostates to allow an optimal seed implant.
Patients who’ve previously had a vigorous transrectal resection of the prostate (TURP) for benign prostatic hypertrophy may not be ideal candidates for this implant procedure. Higher rates of urinary complications have been reported for this subset of patients.
The process for implanting prostate seeds.
- Step 1: The first step in the process is an outpatient consultation with a Princeton Radiation Oncology radiation oncologist. Your radiation oncologist will advise on the implant option based on your PSA, Gleason score, tumor stage, and other factors.
- Step 2: The second step is a planning transrectal ultrasound (TRUS). We place a transducer in the rectum and obtain images of the prostate gland in 5mm segments. Once the prostate is visualized, your Princeton Radiation Oncology radiation oncologist works with the radiation physicists to determine precisely where the seeds should be placed. Using a treatment-planning computer, we generate a series of “dose maps” called isodose curves. Our goal is to deliver a radiation dose of 150-160 Gy to the prostate with Iodine (I-125) and approximately 120 Gy with palladium seeds (Pd-103). We “peripherally load” the seeds to minimize the radiation dose to the centrally located urethra. This will minimize the risk of urinary side effects.
- Step 3: The third step is the implant procedure, which our doctors perform in the operating room while you’re under either general or spinal anesthesia. Under transrectal ultrasound guidance, the prostate is implanted through the perineum with needles loaded with radioactive seeds. Fluoroscopy confirms the seed placement into the prostate. After the procedure, we’ll monitor you for several hours. Typically, we discharge patients to home on the same day.
For prostate seed implantation, trust experience and skill.
The outcome of implantation is highly operator-dependent. As such, it is important for the radiation oncologist to be experienced and proficient with this procedure. The physicians of Princeton Radiation Oncology are among the most experienced and have been instrumental in pioneering this treatment option.
10-year data shows excellent results.
The Northwest Tumor Institute has documented excellent 10-year follow-up data for prostate seed implantation. Their long-term outcomes were comparable to those of external beam radiation therapy and surgery. Although 20-year data is not yet mature, prostate seed implantation appears to be just as effective as surgery or external beam radiation therapy for early-stage prostate cancers.
Side effects are part of all types of prostate radiotherapy.
A common misconception among prospective patients is that prostate implantation has fewer side effects than external beam radiation therapy. Nearly all patients suffer from some urethritis (inflammation of the urethra). Urinary retention requiring a temporary catheter occurs in 5% of patients.