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Recent Studies Raise Questions
About Effectiveness of
Radioactive Seed Implantation
After a decade of being abandoned, the implantation of radioactive seeds
for prostate cancer has become popular again and is being marketed aggressively
in many places.
Implantation of radioactive seeds was first popularized in the 1970s,
but the long-term results were unsatisfactory, at least in part because
the seeds could not be placed accurately by hand in the prostate gland.
Consequently, "seeds" were largely abandoned until the late 1980's, when
ultrasound guidance for seed placement was developed.
Now, two recent reports in medical journals have raised other questions
about the effectiveness of seeds as compared with radical prostatectomy
or external bean radiotherapy.
One report is from the Pacific Northwest Cancer Foundation in Seattle,
Washington, where ultra-sound-guided seed therapy was popularized.
In the publication, Cancer, Dr. Haakson Ragde and his associates presented
10-year follow-up results in two groups of patients.
A low-risk group with low PSA, low Gleason grade, and low tumor stage
who were treated with seeds alone and a high-risk group with higher PSA,
higher Gleason grade and higher tumor stage who were treated with seeds
plus supplemental external beam radiotherapy.
The results showed that in the low-risk group, the group percentage
of men who remained free from tumor recurrence (measured by their PSA remaining
at less than 0.5) decreased by 19 percentage points between 7 and 10years
of follow-up. After 7 years, 70 percent of the men were tumor free.
The tumor recurrence rate is the same as that achieved with the crude,
hand-held techniques of seed implantation used in the 1970s.
Surprisingly, the tumor recurrence rate was higher in the low-risk patients
who received seeds alone than in the high-risk patients who received both
seeds and external beam radiotherapy. This finding suggests that,
even with ultrasound guidance, seed implantation alone was not very effective
in the long-term.
In another report in the Journal of the American Medical Association
from the Joint Center for Radiation Therapy at Harvard Medical School and
the University of Pennsylvania, Dr. Anthony V. D'Amico compared the results
of treatment with seeds, external beam radiotherapy, and radical prostatectomy
at 5 years of follow-up.
For patients with low-grade tumors (Gleason 2-4), there was as yet no
appreciable difference between the groups in tumor recurrence rate after
5 years. However, for men with moderately (Gleason 5-7) or poorly-differentiated
(Gleason 8-10) tumors, patients treated with seeds had a higher tumor recurrence
rate than those treated with either radical prostatectomy or external beam
radiotherapy.
Taken together, these studies suggest that, in the long term, seeds
alone may not be as effective a treatment as surgery or external beam radiotherapy
for
many patients with early-stage prostate cancer.
Source: Quest, By William J. Catalona, M.D.
and published by the Urological Reserach Foundation
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