By Brian J. Moran, MD
Today, approximately 240,000 men will be diagnosed with
prostate cancer. There remains a large group of patients, however, that are
undiagnosed with this disease despite having had transrectal prostate biopsy.
It is not uncommon for an individual to have a rising PSA level despite having
had negative prostate biopsies where no carcinoma was identified. Stereotactic
Transperineal Prostate Biopsy (STPB) uses a perineal approach, where the
needles are placed through the skin below the scrotum and in front of the anus,
to obtain specimens from the prostate. Ultrasound guidance is used and the
patient is anesthetized at the time of the procedure.
This technique has many advantages, the first of which is
its increased ability to identify occult or “hiding cancers”. Our research and
the research of others have clearly demonstrated that the transrectal biopsy
does miss a significant percentage of cancers that occur in the anterior or front
portion of the prostate. Our data in over 2,200 patients suggests that as high
as 40% of patients are thought not to have malignancy, but indeed do have
malignancy. Our group has previously published this information in Urology and
the Journal of Urology. The second advantage to having a prostate biopsy using
the perineal approach is that the infection rate is essentially 0%. This is
simply because the rectal wall or rectum in general is not penetrated by the
biopsy needle. As we know, infection is not uncommon after transrectal prostate
biopsy and unfortunately the bacteria that are currently being identified have
significant resistance to commonly used antibiotics. Our initial experience
using STPB was confined primarily to patients who were diagnostic dilemmas in
that they had persistent elevation of PSA level, while the biopsies were
negative. More and more commonly today, patients are requesting perineal biopsy
as their initial biopsy technique. This is because they have learned of the
mapping ability using this procedure.
Specifically, the STPB is able to accurately identify the
location within the prostate from which the cancer was obtained. This has
dramatic implications because one is then allowed to apply therapy to only the
area of malignancy, while avoiding normal sections of the prostate gland that
have been proven NOT to contain malignancy. A whole new field of oncology will
soon appear, and that is the realm of focal therapy for prostate cancer.
Finally, due to the comprehensive information
that STPB establishes, one is able to make a decision as to whether watchful
waiting is a viable option. Watchful
waiting is NO treatment of the cancer. Certainly this option is pursued by many
individuals, however, with information based solely on transrectal prostate
biopsy, one risks the possibility that a higher grade malignancy may also exist
in the gland that was not identified. For these reasons, we think that STPB
will definitely have a place in the future of prostate cancer diagnostics and
therapeutics. With regard to prostate seed implants (brachytherapy), based on
perineal biopsy data, there is no question that the implants today are much
more sophisticated than those based on transrectal biopsies in the past.