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.
· 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.
Benefits of Surgery
· 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