Each year in May the American Urology Association meeting provides a treasure-trove of new scientific information. As noted in my reviews from earlier scientific meetings, the results of new studies are communicated in 350-word Abstracts which concisely summarize the efforts of a team of scientists working on a specific clinical question. Several thousand abstracts are published in the proceedings of the meeting, amounting to over a million published words. On the topic of prostate cancer there were merely hundreds. This year I selected 46 for comment. This blog briefly comments on only a few of these abstracts. Each bullet point is for a separate abstract.
Active Surveillance
· A
large registry in Michigan that tracks prostate cancer treatment reports that
about 50% of men with low-risk prostate cancer who are eligible for active
surveillance actually undergo active surveillance (the other half get radical
therapy). As sad as this sounds, 50% is double the reported active surveillance
rates from 3-4 years ago, showing progressively increasing acceptance of active
surveillance by doctors and patients.
· Laurence
Klotz, the father of active surveillance and the lead investigator of the longest
study of over a thousand men on active surveillance, reports that after more
than ten years of monitoring, 3.6% of patients have developed metastatic
disease and 1.7% have died of prostate cancer. Dr. Klotz points out that these
statistics are similar to the expected mortality in low-risk patients that get
treated with initial surgery or radiation.
Can Gleason 3 + 3 = 6 Metastasize?
· 2500 surgical patients were reviewed to
determine if Gleason grade 6 can spread outside the prostate into the seminal
vesicle. In this study not a single case
of seminal vesicle invasion was documented when the cancer was exclusively
grade 6.
· Out of 173 men with Gleason grade 6 who had
their lymph nodes removed, not a single case of lymph node spread was observed.
After an average of five years of observation, no patient has developed
metastases.
Metformin and Statins
A number of previous
reports have suggested that metformin and statins have anticancer effects. The
anticancer effects of metformin have been only studies in diabetics but there
is no reason to believe that metformin would be ineffective as an anticancer
agent in non-diabetic men. Four abstracts at the AUA elaborate further on this
active area of interest.
· In Denmark, men taking metformin (for diabetes)
were at one-third lower risk of being diagnosed with prostate cancer compared
to men who were not taking metformin.
·
Men undergoing surgery for prostate cancer who
were taking both metformin plus a statin had a reduced risk of cancer relapse—from
30% down to 15%.
· In Finland, prostate cancer survival was
evaluated in 6000 men depending on whether they were taking statins. Statin use
reduced prostate cancer mortality by two-thirds.
· In a study from Europe, there was a 60%
reduction in overall mortality in men with advanced prostate cancer who were
taking statins compared to those who were not. Both cancer mortality and
cardiovascular mortality were reduced by a similar increment.
· In
Denmark, the estimated length of life gained with surgery compared to the
general population was only 0.4 years after 10 years of observation.
· In
France within 60 days following surgery, the mortality rate was one in a
thousand surgeries. Mortality after surgery was nearly twice as high in
hospitals performing less than 10 prostate operations a year compared to more
experienced centers.
Treatment of a PSA Relapse
Here I quote directly
from two abstracts on the topic of a rising PSA after surgery or radiation:
·
“We found that salvage radiation was associated
with decreased use of salvage hormone therapy, as well as lower risks of local
recurrence, systemic progression, and death from prostate cancer.”
·
“Approximately 16% of patients with a detectable
PSA after radical prostatectomy may have false
biochemical failure. Repeating the serum PSA in all patients with a
detectable level is paramount before making treatment recommendations,
especially if the patient had Gleason score 6, negative margins, and the cancer
was organ−confined.”
Accuracy of Prostate MRI
One of the problems with
random biopsy is that it finds too much grade 6 disease, leading to too much
unnecessary radical treatment. Previous studies have indicated that multiparametric
MRI finds high-grade disease quite well, only missing small tumors. However, multiparametric MRI “sees” low-grade
tumors much less, which is a good thing. Below are two new reports on this
important new technology.
· A multiparametric prostate MRI showing no cancer
in the prostate is accurate 82% of the time for grade 6 cancer and 98% of the
time for grade 7 or higher using a 12-core biopsy as the reference standard.
· A multiparametric prostate MRI showing no
high-grade cancer is accurate 74% of the time when using surgical removal and
pathologic dissection of the prostate as the reference standard. The types of
high-grade cancers that were missed by MRI tended to be smaller, secondary
tumors that were organ confined.
I was encouraged to see so many abstracts
on active surveillance at this year’s meeting. Also gratifying were the
numerous reports on imaging, which in my opinion is the technology of the
future that will eventually supplant random biopsy. All the 46 abstracts I
judged interesting have been posted here: http://goo.gl/ZzwmpB
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