New study that's likely to be misreported [1].
Finasteride & Dutasteride are 5-alpha reductase inhibitors (5-ARIs). They are used to treat benign prostatic hyperplasia (BPH). They do this by inhibiting the aromatization of testosterone [T] to the more potent dihydrotestosterone [DHT]. BPH-related PSA is reduced.
The Prostate Cancer Prevention Trial (PCPT) & the Reduction by Dutasteride of Prostate Cancer Events [REDUCE] study showed that Finasteride & Dutasteride, respectively could lower the incidence of lesser cancer. PCa-related PSA due to low-level PCa was therefore also reduced.
"Asked for his perspective, Ian Thompson, Jr., MD, of the University of Texas Health Science Center at San Antonio and principal investigator of the ... {PCPT}, pointed out that in his experience, the "vast majority" of physicians know that finasteride suppresses PSA levels by about 50%."
The traditional PSA cutoff for a biopsy is designed on the basis that 20% of the men will be diagnosed with PCa, and that a high % of men with PCa would be detected. Most men in the group who are not diagnosed presumably have high PSAs due to BPH. Screening is a compromise that balances excess biopsies against seious cases with low PSA.
Men using a 5ARI will produce less BPH PSA 'noise' & less low-level PCa PSA. It's obvious that a lower screening PSA cut-off for biopsy should be used for such men.
I never used a 5ARI before diagnosis. My PSA was only 0.8 when a nodule was discovered - well below the cutoff for a biopsy. The probability of PCa at lower PSAs is low, but that doesn't mean that the probability of serious disease is also lower - in this case, far from it. In the 5ARI population, PCa is more likely to be serious. By the time that PSA has risen to the conventional cutoff, the PCa will be more advanced than in the non-5ARI population. Hence:
"Men receiving a 5-alpha reductase inhibitor (5-ARI) for treatment of benign prostatic hypertrophy who developed prostate cancer were more likely to have a delay in diagnosis as well as worse outcomes than non-users, a population-based cohort study found."
I am sure that many doctors knew this 20 years ago.
"In marked contrast to the non-users, 35% of 5-ARI users had a delay in diagnostic biopsy of more than 5 years after the initial PSA elevation compared with 12% of non-users," the authors wrote in JAMA Internal Medicine."
"Furthermore, 5-ARI users had a 39% greater risk of dying from prostate cancer ... and a 10% greater risk of all-cause mortality ..."
Some in this group feel that lowering PSA can mask the presence of serious disease. This is a case where a drug (not a supplement) does exactly that.
My feeling is that all men on a 5ARI should have an annual PSA test and doctors should look at the PSA doubling time trend - not the absolute PSA, which could be quite small.
I suspect, due to media coverage, that some 5ARI users will conclude that Finasteride/Dutasteride increases their risk for fatal PCa. In a sense they would be correct, but that would be due to doctor incompetence IMO.
-Patrick
New Data: Finasteride Safely Prevents Prostate Cancer'These Results Are Transformational,' Says Researcher May 20, 2018
