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Relapse
After Radical Prostatectomy As Prostate Cancer Treatment
March 28, 2007
Radiation therapy, with or without hormonal therapy, is the most
commonly used treatment for prostate cancer that recurs after
radical prostatectomy. This practice is largely based on small
studies and uses a wide range of radiation therapy techniques
and doses. More importantly, the studies do not include a randomization
comparison with the observation arm only as advocated by the
Johns Hopkins group. Thus, this is not a proven treatment option.
Of even greater concern is the fact that it is technically difficult
to give enough radiation without risk of significant damage to
bladder, bowel and loss of any sexual function that might have
survived surgery. The situation seems to have improved considerably
with the advent of IMRT as it allows for higher radiation doses
in the neighborhood of 6,500 cGy while lessening side effects,
particularly rectal complications. In sum, we have a treatment
with potentially severe side effects whose therapeutic value
has yet to be proven. This fact has led a number of the leading
figures in urologic surgery, in addition to the Johns Hopkins
group, to question the value of this approach. As you will see,
my own assessment is more positive, if still guarded.
Short of actually having a randomized controlled trial, there
is one large series that I think represents the most accurate
assessment of those patients most likely to benefit. This paper
pooled results from a large number of leading prostate cancer
treatment centers, including Memorial Sloan Kettering, Cleveland
Clinic, Baylor, University of Texas-Southwestern Medical Center,
and University of Florida, Gainesville. In this analysis, patients
most likely to be in remission at 45 months following radiation
were those with a PSA doubling time of greater than 10 months,
with a Gleason score of 7 or less, a PSA at the time of radiation
of 2 ng/ml or less. For patients with no adverse features, 77%
were still in remission at 45 months. PSA doubling time again
was quite important because men with Gleason scores of 8-10 who
had a PSA doubling time of greater than 10 months had an 81%
chance of not developing progressive disease compared with only
37% of those with a doubling time faster than 10 months. In the
wake of these and other studies, Lee and D’Amico nicely
summarized the results: “Therefore, the optimal candidate
for local-only salvage therapy is a man whose pretreatment PSA
velocity was 2 ng/mL/year or less, interval to PSA failure exceeds
3 years, and post-treatment PSA doubling time is at least 12
months, and who did not have biopsy or prostatectomy Gleason
score of 8 to 10 or seminal vesicle or lymph node involvement.” While
I have not asked Drs. Partin or Walsh, I suspect they would respond
that this is also a group that in their hands did well over a
ten- year time period with no treatment at all.
One problem with radiation therapy in this setting is that we
really do not know if the cancer is present in the prostate bed
or has already spread to adjacent lymph nodes or even to remote
areas like bone and lymph nodes outside the pelvis. One attempt
to improve this situation is the ProstaScint scan. This technique
uses a radioactive antibody that binds to prostate cancer cells
in order to identify where the cancer is located. In the clinical
trial leading to FDA approval of the ProstaScint scan, if the
scan failed to identify cancer outside the prostate bed, 70%
of the patients experienced long-term control with radiation
therapy to the prostate bed. Unfortunately, ProstaScint scans
are difficult to perform and difficult to read. The recent move
to fuse the ProstaScint scan with the CT scan appears to significantly
reduce these problems and the resulting fused images provide
the radiation therapists well-defined anatomical landmarks that
identify the location of the cancer. It is our practice here
at AIDP to refer patients to centers that fuse the ProstaScint
scan with the CT scan and that have experts capable of reading
these images appropriately. At the top of our list of ProstaScint
experts is Dr. Sodee at Case Western Reserve, who has done more
than anyone else to improve the usefulness of this technique.
Nevertheless, it would be useful to have a means of visualizing
cancer in the prostate bed and elsewhere that could be reliably
used at the community level rather than in a few select centers
with well-trained experts.
The rest of this article can be read in Volume 9 Issue 10 of
Prostate Forum. Click here to download this issue now. |
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