The study incorporates data from men who enrolled between 1993 and 1997 in the Prostate Cancer Prevention Trial (PCPT). The research was conducted by the SWOG Cancer Research Network.

Nearly 19,000 men enrolled in the study, making this one of the largest prostate cancer clinical trials ever to be conducted.

While the 25 percent reduction in risk of developing prostate cancer may seem significant, it doesn’t qualify as statistically significant.

The real value of this data is in eliminating old concerns about the effects of finasteride on prostate cancer.

An earlier SWOG study in 2003 reported that while finasteride reduced the risk of prostate cancer, it actually increased the number of high-grade prostate cancers. This finding caused the Food and Drug Administration (FDA) to post a warning on the finasteride label.

The long-term study was able to determine that there wasn’t a statistically significant increased risk associated with finasteride. While it may have increased the number of high-grade prostate cancers, researchers said this is actually because it made them easier to find.

“On the finasteride label, there is a clear warning of the increased risk of high-grade prostate cancer, which now appears to be very clearly related to the drug, making it easier to find the high-grade prostate cancer,” explained Thompson, who is the chair of SWOG’s genitourinary cancer committee and serves as president of CHRISTUS Santa Rosa Hospital-Medical Center in San Antonio, Texas, and as emeritus professor at the University of Texas Health Science Center. “There’s no impact from prostate cancer deaths.”

“Those concerns about high-grade disease have not been borne out and so that was the reason why finasteride has not been used for prevention of a quarter of all prostate cancer,” he continued. “You’re talking about 40,000 or more men per year.”

When someone is diagnosed with prostate cancer, there’s only so much that doctors are able to do to manage things.

“Many of those men will be treated with radical prostatectomies, which can cause incontinence or impotence, or radiation therapy, which can lead to problems emptying their bladder as well as impotence,” said Thompson. “If they get radiation they often get concurrent hormone therapy that can lead to weight gain, diabetes, cognitive and sexual dysfunction.”

Then there’s the cost.

Thompson says surgery runs anywhere from $20,000 to $30,000 while radiation can cost up to $100,000. He also notes that a cancer diagnosis can drive up the cost of healthcare.

While finasteride can’t do much for those who already have prostate cancer, it would appear to be a preventive option for middle-aged or older men who want to reduce their risk.

The drug can cause side effects.

Thompson notes that 5 to 6 percent of men can experience breast enlargement or tenderness or sexual dysfunction — but these side effects go away if the patient stops taking the medication.

Finasteride is inexpensive and accessible. It also helps reduce the risk of developing prostate cancer.

So why aren’t more men taking it?

For starters, the findings from this research are new. There’s also the matter of the FDA’s warning on finasteride, a result of the 2003 research.

Bureaucracy and regulatory bodies tend to move slowly and, as a generic drug, finasteride doesn’t have the heft of any big pharmaceutical companies who might want to nudge the FDA on their ruling.

“It’s beyond my expertise in the absence of a pharmaceutical company that would be able to recoup the investment and go through that process,” said Thompson. “I don’t see it happening, and it really is kind of a tragedy. It’s extremely unfortunate because we knew in advance that to be able to do a trial that looked at prostate cancer mortality, we need 60,000 to 100,000 men followed for 25 years. And what this clearly shows is that we were right.”

Thompson says that, in the absence of the warning label being rescinded, the best option is probably off-label prescriptions for doctors and patients who want to use finasteride as a preventive measure.

“Physicians can discuss with their patients the advantages and disadvantages,” said Thompson. “A man who is concerned about his risk of prostate cancer can have that discussion with his physician and his physician could write a prescription for finasteride.”

Researchers say a new study has alleviated concerns about finasteride and prostate cancer.

The drug is cheap, plentiful, and reduces the risk of prostate cancer, researchers say.

There’s still an FDA warning on the finasteride label, but patients can talk to their doctors about taking the drug.