HD 3D view in robotic surgery for prostate cancer compensates for
lack of touch
21 April 2010
Robotic surgical technology with its three-dimensional,
high-definition view gives surgeons the sensation of touch, even as they
operate from a remote console.
A recent study describes the phenomenon, called intersensory
integration, and reports that surgical outcomes for prostate cancer
surgery using minimally invasive robotic technology compare
favourably with traditional invasive surgery.
Led by physician-scientists at NewYork-Presbyterian
Hospital/Weill Cornell Medical Center and appearing in the March
issue of British Journal of Urology International, the
study is the first to show that a lack of tactile feedback during
robotic surgery does not adversely impact outcomes in patients with
prostate cancer. It also identified various visual cues that
surgeons can use to improve clinical outcomes.
“Anatomical details and visual cues available through robotic
surgery not only allow experienced surgeons to compensate for a lack
of tactile feedback, but actually give the illusion of that
sensation,” says Dr Ashutosh Tewari, the study’s lead author;
professor of urology, urologic oncology, and public health at Weill
Cornell Medical College; and director of the Lefrak Center of
Robotic Surgery and the Institute of Prostate Cancer at NewYork-Presbyterian
Hospital/Weill Cornell Medical Center.
“For patients, this means the safety of knowing the benefits of a
robotic approach — including a quicker recovery — don’t compromise
the surgery’s primary mission of removing the cancer.”
In recent years, robotic-assisted laparoscopic prostatectomy
(RALP) has become a popular surgical method for treating prostate
cancer because it is less invasive than traditional surgery. No
studies have shown that RALP leads to worse outcomes, but doctors
have wondered whether this was the case because surgeons often use
their fingers to feel the prostate during traditional surgery to
refine how much they cut to achieve the best outcome.
Cancer cells produce changes in tissue firmness that surgeons can
sense. Because this tactile evaluation is not possible for surgeons
using RALP, clinicians have wondered whether the robotic approach
could lead surgeons to miss some cancer, and thus subject patients
to a greater risk of cancer recurrence.
To find out, the investigators videotaped 1,340 RALPs. After
every couple hundred procedures, they examined the pathology results
of the prostate that was removed to determine the incidence of
positive surgical margins, an indication that a surgeon might not
have removed all of the cancer. In this study, the investigators
focused on the posterolateral surgical margin (PLSM+), the area
where the prostate is attached to the nerves.
“When you look at the entire specimen after surgery is done, you
want to see cancer inside of the prostate but you don’t want to see
cancer touching the surface,” Dr Tewari says. “After surgery we look
at the specimen, and if there are no cancer cells touching the
surface, we call that a negative margin. If cancer is touching the
edge, then we say it has positive margins. This means there may be
some cancer left in the patient.”
The investigators then studied the videotapes to determine what
refinements in the procedure resulted in negative margins. Using
this new knowledge to refine the surgery, they conducted the next
couple hundred RALPs, reviewed the videotapes, refined their
techniques, conducted the next round of RALPs, reviewed, refined and
so on.
The investigators found that robotic surgery did not compromise
outcomes. The incidence of PLSM+ was 2.1%, which gradually declined
to 1 percent in the last 100 patients. Positive PLSMs are found in
2.8% to 9% of patients undergoing traditional prostatectomy.
The researchers say that the enhanced vision allowed by the
robotic approach brings about a “reverse Braille phenomenon” or the
ability to “feel” when vision is enhanced. They have identified a
number of visual cues that clinicians can use to improve outcomes,
including the colour of tissue, the location of veins as a landmark
for the location of nerves, signs of inflammation, and appreciation
of so-called compartments outside the prostate.
Surgeons use a three-level approach to optimize outcomes in
prostate surgery: the clinical exam including the prostate-specific
antigen (PSA) test, magnetic resonance imaging (MRI) tests, and cues
during the actual surgery itself. They use the clinical exam and MRI
to determine which one of four types of nerve-sparing surgeries to
conduct before the operation and then refine their technique during
the actual procedure if cues indicate a need.
“Treat each patient individually, get as much as information from
the clinical exam, biopsy, imaging, and learn to appreciate the
anatomical changes,” Dr Tewari says. “The outcomes of prostate
cancer surgery are not just technology dependent, but rather they
are dependent on surgical experience, anatomical details and
attention to basic surgical techniques. Robotic surgery does not
seem to compromise outcomes.”
“As someone with 30 years of experience as a pathologist, I, too,
have developed the ability described in this paper. I can look at a
tissue sample and know if it is firm or soft and what to expect in
its pathology — something that helps me to home in on the area with
the abnormality,” says Dr Maria M Shevchuk, the study’s senior
author, associate professor of pathology at Weill Cornell Medical
College, and a pathologist at NewYork-Presbyterian Hospital/Weill
Cornell Medical Center. “It is only natural that this ability would
also be present in experienced robotic surgeons.”