The Food and Drug Administration (FDA) has announced that it is looking into reports that Glaxo Smith Kline’s prostate drug Avodart and Merck & Co’s prostate drug Proscar may be contributing to an increase of male breast cancers.
Avodart and Proscar are used to treat baldness besides the “off label” use in prostate cancer as a drug that shrinks the size of the prostate prior to radiologic therapy and as a part of hormone therapy (ADT).
This is only an investigation; the FDA has not concluded that either drug poses any breast cancer risk.
Merck spokeswoman (Proscar) Pam Eisele said the prescribing instructions for Proscar already mention cases of male breast cancer seen in clinical trials. However, she said that “A causal relationship has not been established.”
Glaxo spokeswoman (Avodart) Sarah Alspach said the company evaluates all reported cases of breast cancer in men taking Avodart. She said that, “Based on reports evaluated to date, there is not conclusive evidence of a causal association between Avodart and male breast cancer.”
The investigation has been triggered by information supplied to the FDA through its Adverse Event Reporting System (AERS) Database for the period of October – December 2009.
I want to emphasize that the appearance of a drug on the database does not mean that FDA has concluded that the drug has the listed risk. It means that FDA has identified a potential safety issue, but does not mean that FDA has identified a causal relationship between the drug and