VIENNA, Austria — Magnetic resonance (MR)-guided biopsy of the
prostate is a safe and effective alternative to the standard transrectal
ultrasound-guided biopsy, and patients prefer it, according to 2 new studies.
"The
problem with the transrectal approach is that significant cancers are missed,
insignificant cancers are detected by chance, and there's a high percentage of
undergrading of the lesions," lead researcher of one of the studies,
Stephan Polanec, MD, from the Medical University of Vienna in Austria, told Medscape
Medical News.
"MR-guided
biopsy is a targeted biopsy with pinpoint accuracy and a higher detection rate.
It also detects cancer in the anterior part of the prostate, which the
transrectal approach isn't able to do," he explained here at the European
Congress of Radiology 2013.
In the
first study, Dr. Polanec and colleagues analyzed 44 biopsies from 41 patients
that were initially identified as suspicious on multiparametric magnetic
resonance imaging (MRI), which combines several different MRI techniques to
render a complex image of the prostate.
Mean
patient age was 65 years and mean prostate-specific antigen (PSA) level was
8.17 ng/mL. All patients had at least 1 previous negative transrectal
ultrasound-guided biopsy.
Dr.
Polanec explained that for MR-guided biopsy, patients are placed in the prone
position with the head forward and an 18-gauge needle is inserted
transrectally. Approximately 3 or 4 biopsy cores are extracted during the
procedure.
On MR-guided biopsy, conducted in a 1.5 Tesla MR unit,
lesions were identified as malignant in 11 patients. In the remaining 30
patients, no prostate cancer was detected on MR-guided biopsy and no prostate
cancer was subsequently identified during active monitoring (mean follow-up, 36
months).
Of the 11
patients in whom prostate cancer was identified, 5 had a Gleason score of 6, 4
had a Gleason score of 7, 1 had a Gleason score of 8, and 1 had a Gleason score
of 9.
In 9
patients, the cancer was identified in the peripheral zone of the prostate, in
1 patient it was in the transition zone, and in 1 it was in the central zone.
"It's
very important to mention that no new prostate cancer was detected during our
follow-up of the benign lesions, so the sensitivity of MR-guided biopsy was
therefore 100%," Dr. Polanec said.
"While
I don't think MR-guided biopsy will replace the transrectal approach, if I were
a patient, I would prefer doing the multiparametric MRI in combination with
MR-guided biopsy because you reduce the number of cores you need and it's just
more comfortable," he said.
More
Comfortable for Patients
In the
second study, lead researcher Tobias Franiel, MD, from Charité Medical
University in Berlin, Germany, and colleagues compared acceptance, adverse
effects, and complications between MR-guided biopsy and transrectal
ultrasound-guided biopsy.
The
researchers looked at 54 patients with a median PSA of 12.1 ng/mL. All
patients had at least 1 previous negative result on transrectal
ultrasound-guided biopsy, during which 10 to 12 biopsy cores were harvested.
Patients
subsequently underwent MR-guided biopsy, and were then questioned about pain
duration and intensity, adverse events, and their preferred procedure.
"Sixty-five
percent of patients indicated they preferred the MR-guided biopsy because there
were fewer side effects and they expected better results than with the
transrectal approach," Dr. Franiel explained.
Patients
rated pain duration and intensity significantly lower with MR-guided biopsy,
and 82% said they would prefer the MR-guided approach for any subsequent
biopsies.
Both
approaches had a low complication rate (6% each).
However,
"our study had several limitations," Dr. Franiel acknowledged.
First, the
median interval between the initial procedure and subsequent MR-guided biopsy
was 13 months, which is admittedly "quite long," he said.
Second,
patients were questioned only after the MR-guided biopsy, not after the
transrectal approach.
It is
quite possible that these 2 issues could "have led to a recall bias,"
he pointed out.
In
addition, because all patients had at least 1 negative ultrasound biopsy, it
could be that they were negatively biased against that approach and favorably
predisposed to think positively about MR-guided biopsy.
"Nevertheless,
we think it's justified to conclude that patients prefer targeted MR-guided
biopsy of the prostate...due to lower pain intensity and fewer side effects,
Dr. Franiel said. "Targeted MR-guided biopsy is a suitable option for
patients with persistent suspicion of prostate cancer," he added.
Jurgen
Fütterer, MD, from Radboud University Nijmegen Medical Centre in the
Netherlands, who was asked by Medscape Medical News to comment on these studies, agrees
that ultrasound-guided biopsy has a poor yield for cancer detection (range,
~40% to 45%).
He also
agrees that the multiparametric MR-guided approach is a far more targeted
option and requires far fewer biopsies for histopathologic analysis.
"With
the MR-guided technique, you use imaging to guide the needle to the exact spot
identified on multiparametric MRI, so you need far fewer biopsies and you are
sure you're right on target," Dr. Fütterer said.
In
addition, in patients with a negative biopsy, the likelihood of picking up a
subsequent cancer on an additional ultrasound biopsy is only about 12% to 14%.
The
detection rate found by Dr. Polanec's team was approximately 27%, which is low
compared with the reported 40% to 50% detection rate for MR-guided biopsy in
patients with negative ultrasound-guided biopsy results, but better than an
additional ultrasound biopsy would have yielded, Dr. Fütterer noted.
Dr.
Polanec, Dr. Franiel, and Dr.
Fütterer have
disclosed no relevant financial relationships.
European
Congress of Radiology (ECR) 2013: Abstracts B171 and B172. Presented
March 7, 2013.
