In a recent announcement, the US Food and Drug Administration (FDA) advisory panel voted against changes requested by two drug companies for the use of their drugs: finasteride (Proscar & Propecia) and dutasteride (Avodart & Jalyn), for reducing prostate cancer risk in certain patients.
The two companies presented results of clinical trials claiming the drugs reduce the risk of prostate cancer. However, in both studies, men who took these drugs for several years had a higher rate of the potentially lethal high-grade prostate cancers.
A manufacturer of finasteride (Proscar & Propecia) requested to change the section on adverse reactions in product information for finasteride (Proscar & Propecia) to indicate that the increased prevalence in high-grade disease for those taking this class of drug was secondary to detection bias.
The manufacturer of dutasteride (Avodart & Jalyn) requested that dutasteride (Avodart & Jalyn) be approved for reduction of prostate cancer risk in men who are considered to be at increased risk.
The advisory panel recommended against both these changes, and it found that the risks of more high-grade tumors with this class of drugs outweighed the benefits of fewer low-grade tumors.
The concern of the panel was that the findings showed a percentage of men taking the drugs developed more aggressive tumors than those in the control group.
The FDA panel report stated: “This observation suggests that some aggressive cancers may not be readily detected until they become more extensive in nature with less potential for cure even with aggressive therapy.”
Clearly, the major concern was that the 5a-reductase inhibitors (finasteride/Proscar/Propecia and dutasteride/Avodart/Jalyn) could be suppressing less aggressive tumors but might be delaying detection of more aggressive or deadly ones – or even possibly contributing to the development of more deadly ones.