Avodart, Propecia, Proscar Prostate Cancer Warning Issued in Canada

Canadian health officials are warning that side effects of Propecia, Proscar and Avodart may increase the risk of developing high-grade prostate cancer, following similar warnings issued last year in the United States. 

The prostate cancer warning was issued by Health Canada on March 19, indicating that new label warnings will be added to all drugs containing the active ingredients finasteride and dutasteride. The warnings came after the agency conducted a review of two large, international clinical trials.

High-grade prostate cancer is a serious form of cancer that grows and spreads rapidly. According to Health Canada, it is a rare form of cancer and the increased risk by the drugs is believed to be small.

In June 2011, the FDA issued a similar warning about the risk of prostate cancer from Propecia, Proscar and Avodart.

In October 2011, the prominent consumer group Public Citizen warned men not to use Avodart, Proscar or similar drugs for the treatment of enlarged prostate, due to the potential increased risk of prostate cancer. The group indicated that the medications posed an unreasonable risk, and placed the entire class of medications, known as 5-alpha reductase inhibitors (5-ARI) on their “Do Not Use” list, recommmending that men use alpha-blockers like Flomax instead.

The prostate cancer risk was identified in to two large, randomized controlled trials, known as

the Prostate Cancer Prevention Trial (PCPT) and the Reduction by Dutasteride of Prostate Cancer Events (REDUCE). Both studies showed that long-term use of Propecia, Proscar, Avodart and Jalyn (sold in Canada) by men over the age of 50 resulted in a small but statistically significant increased prostate cancer risk.

The trials had attempted to show that the drugs could be used to prevent prostate cancer, which none of the drugs have been approved to treat.

Avodart (dutasteride) was approved by the FDA for the treatment of urinary problems in October 2002. The GlaxoSmithKline drug works by reducing the size of an enlarged prostate, by reducing the enzymes that turn testosterone into DHT, which is the primary cause of prostate growth.

Proscar (finasteride) was approved in 1992 for the treatment of benign prostatic hyperplasia. Propecia is a lower dose version of Proscar, which is prescribed for treatment of male patter hair loss.

Side effects of Propecia have come under increased scrutiny in recent months, due to the risk of permanent erectile dysfunction and other sexual problems linked to the hair-loss medication.

Dozens of men throughout the United States are currently pursuing a Propecia lawsuit against Merck, the drug manufacturer, alleging that inadequate warnings are provided about the risk of sexual dysfunction, which may persist even after the medication is stopped. Later this month, the U.S. Judicial Panel on Multidistrict Litigation is scheduled to hear arguments over whether the Propecia litigation should be consolidated before one judge for pretrial proceedings.