Finasteride and the Risk of Prostate Cancer

In a comprehensive New York Times article on the prevention of cancer, a large and rigorous study is described; finasteride, an alpha-blocker that is usually used to treat benign prostatic hypertrophy, prevents prostate cancer.  I was intrigued.  I clicked through the link provided to the National Cancer Institute site which described the study in general terms.  But I don't take the word of the National Cancer Institute as gospel; I wanted the actual study.

Unfortunately, the study in question was not readily available in electronic format.  But some follow up studies and commentary were available, and the picture is not somewhat more nuanced: the Prostate Cancer Prevention Trial demonstrated that men treated with finasteride were almost 25% less likely to develop prostate cancer than those treated with placebo, but more likely to develop high grade disease.  This finding was confirmed in a Cochrane Review, but the absolute risk reduction was small: after the treatment period, 3.5% of patients taking an alpha blocker were diagnosed with prostate cancer, compared to 4.9% of those taking placebo.  That's an absolute risk reduction of 1.4%, which means that 71 men would have to be treated with finasteride to prevent one case of prostate cancer.  That's pretty good, but the troubling finding that more men who took finasteride developed high grade (more advanced) disease persisted in the metaanalysis.  And there is no mention of mortality rate; without this, we are just making a guess that finasteride prevents death from prostate cancer, when in fact it may not.   

Please read our legal disclaimer.

Write a comment

Name:
Email:*
Subject:
Comment:*

I would like to receive news and updates from MedPie.com Yes No

Help prevent spam - enter security code above:
 

joe
Posts: 2

Finasteride and the Risk of Prostate Cancer
Reply #2 on : Sat November 14, 2009, 16:06:20

---

I think the source of the NYT article is a bit out of date. First when the conflicting news first were found several years ago I did a simple mathematical calculation. Supposing that it was true that the 5aR's did cause higher grade tumors--which I did/do not think -- I simply calculated the absolute number of total cancers in each group and than multiplied by the relative incidence of high grade tumors. The results were that even if the 5aR's increased grade level, the absolute reduction in incidence meant that the although the percentage of high grade tumors were higher, the absolute numbers of high grade tumors were less. It a pity more doctors and reporters don't utilize common sense math.

Since that time add'l studies, must not have been seen by the writer of the NYT piece, have shown that the supposed increase in high grade tumors were an artifact from the fact that the 5aR's reduce the size of the prostate enough so that it was more likely to find tumors in them and also that lower grade tumors were likely being suppressed/regressed. The most recent trials reconfirm the value of the 5aR's.

Joseph Fainberg
Posts: 2

Finasteride and the Risk of Prostate Cancer
Reply #1 on : Sat November 14, 2009, 02:46:05

---

See the following for a discussion.

http://www.cancer.gov/clinicaltrials/results/PCPT0608

Sponsored Links