Proscar, a widely used drug used to shrink the prostate, may not cause aggressive prostate cancer tumors after all. Back in 2003, a big government study found that Proscar reduced risk of developing prostate cancer by 25 percent--but appeared to boost the incidence of aggressive, potentially lethal tumors.

Well, five years later doctors have taken a second look at that data and decided Proscar doesn't appear to boost risk of those tumors. Another maddening medical research fliip-flop? Yes. But let's look.

Three things you need to know

1. The conclusion that Proscar doesn't cause aggressive prostate cancer is based on a new hypothesis: That the shrinking of the gland simply allowed doctors to detect a greater number of aggressive tumors--not that there actually were more agressive tumors. The reanalysis seems to verify this. [Note: Some researchers on the government-funded study work for Merck, the maker of Proscar. D'oh!]

2. There are numerous drugs used to shrink an enlarged but non-cancerous prostate (a condition known as BPH, for benign prostatic hyperplasia). All have side effects. Some are used in combination rather than singly. Some are being investigated to see if they also reduce risk of prostate cancer. Results are inconclusive.

3. Essentially, this research leaves basic patient recommendation unchanged: If you have symptoms of BPH--usually it's pain or difficulty urinating--talk to your doctor. Drugs, surgery or watchful waiting may be prescribed. If your doctor recommends Proscar, mention these recent findings and be sure to discuss all of your options.

For more information, here's a recent Question and Answer about drugs and BPH.

Here's a good SharePost by medical expert Jay Motola on treatment for BPH