August 15, 2013
News Review From Harvard Medical School -- Drug Cuts Prostate Cancers; Deaths Unchanged
A drug used to treat an enlarged prostate also reduces prostate cancer cases by nearly one-third and does not affect the risk of death, a new study finds. The research is an 18-year follow-up on an earlier study. Nearly 19,000 men were randomly assigned to receive either finasteride (Proscar) or placebo (fake) pills. The first phase of the study showed fewer prostate cancers for men who took finasteride. But they had a higher rate of high-grade cancers, which are more likely to spread. The new study looked at what happened to these men over time. Prostate cancer diagnosis was reduced by about 30% for those who got the real drug. About 3.5% of the cancers in this group were high-grade, compared with 3% in the placebo group. But death rates were the same whether men received the real drug or not. The drug also did not change death rates for men with high-grade cancers. Experts told HealthDay News that the drug's main value may be in preventing diagnosis of low-grade cancers that did not need to be treated. Prostate cancer treatments can lead to serious side effects. The New England Journal of Medicine published the study August 15.
By Robert H. Shmerling, M.D.
Harvard Medical School
What Is the Doctor's Reaction?
Prostate cancer is among the most common and well-studied types of cancer. Decades of research have led to widely used screening tests and effective treatments.
Yet few diseases have been the subject of such dramatic changes in screening and prevention advice over time.
For example, not long ago doctors routinely recommended a screening blood test (the prostate-specific antigen, or PSA) for all men ages 50 and older. More recently, this has been called into question.
The U.S. Preventive Services Task Force started raising questions about PSA testing in 2002. The task force is an independent (and highly influential) organization that assesses the usefulness of preventive measures.
First, the task force declared that the value of PSA testing was uncertain, so each man should discuss the option with his doctor. Then, in 2008, the task force changed its position. The new statement argued against screening for men over age 75. Just last year, the task force went even further and recommended that men of all ages not have routine PSA screening.
This evolution of screening advice reflects the results of continuing research and concerns about the accuracy of the PSA test. In particular, the test often shows abnormal results even though a man does not have prostate cancer. This is called a false-positive result.
Advice about ways to prevent prostate cancer has also changed over time. The latest edition of the New England Journal of Medicine provides some welcome news in this regard.
Finasteride (Proscar) is a medicine that can shrink an enlarged prostate and improve urination. Past research has shown that men taking finasteride had a lower risk of prostate cancer. But they also had tumors that were more aggressive ("higher grade") than those of untreated men. So doctors have not been sure whether to recommend finasteride as a preventive treatment.
This new study included nearly 19,000 men.
- Prostate cancer developed in 10.5% of those treated with finasteride and 15% in the placebo group. So prostate cancer was reduced by about one-third among men treated with finasteride.
- Men receiving finasteride developed more high-grade tumors (3.5%) than those receiving placebo (3%). But survival was similar between these groups.
- Even among the men with high-grade tumors, survival between the two groups was similar.
These results are reassuring. They confirm that finasteride treatment can prevent prostate cancer. They also show that the higher rate of advanced tumors among men treated with this drug does not translate into shorter survival.
What Changes Can I Make Now?
Finasteride treatment may be worth considering as a way to prevent prostate cancer. Talk about this option with your doctor.
Know the risk factors for prostate cancer. They include:
- Age -- Prostate cancer is usually diagnosed in men older than age 65.
- Family history -- Having a father or brother with prostate cancer increases your risk of developing the disease.
- Race -- African-American men are at an increased risk of developing prostate cancer compared with white men.
Finasteride and related medicines can have side effects. They may include impotence or other problems with sexual function, breast enlargement and allergic reactions.
You can take steps that may prevent prostate cancer or help detect it an early stage. Here's what you can do:
- Change your diet. A low-fat diet that's high in fish and lycopene may lower the risk of prostate cancer. Lycopene is found in watermelon, cooked tomatoes and over-the-counter pills.
- Have a prostate examination. Your doctor can perform a rectal exam to determine whether your prostate is enlarged or has growths that might be cancer. The overall value of routine prostate exams is also uncertain.
- Have a PSA test. As noted above, questions have been raised about the usefulness of PSA screening. Ask your doctor whether he or she routinely recommends PSA tests and why it is (or isn't) a good idea for you.
- Have a biopsy. If your prostate exam shows a growth or irregular area, your doctor may recommend a biopsy. The results can help you and your doctor to make an informed decision about whether to have treatment or to consider "watchful waiting."
If you've already been diagnosed with prostate cancer, review your treatment options with your doctors. Options range from no treatment to a variety of medicines, radiation and surgery. Prostate cancer and its treatment can affect a man's quality of life and that of his spouse or significant other. Therefore, your own preferences matter a great deal. After learning about your options, let your doctor know what treatment (or no treatment) you prefer.
What Can I Expect Looking to the Future?
In the near future, we should learn more about finasteride treatment to prevent prostate cancer. This includes:
- Which groups benefit most from treatment
- The most effective dose
- The best time to start
- The ideal length of treatment
I also hope we will have new and better ways to prevent, detect and treat prostate cancer in the coming years. The changing advice in recent years is a sign of how much we have learned -- and how much remains uncertain.