Prostate Cancer Update
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JIM LEHRER: Now, a closer look at recent news about a drug that prevents prostate cancer, and to Ray Suarez.
RAY SUAREZ: Scientists said the drug, known as Finasteride, and already sold under the brand name of Proscar for other uses, prevented about 25 percent of prostate cancer cases. But there were significant concerns, as well. For one thing, a larger number of men who took the drug developed tumors that seemed more aggressive. About 221,000 men in the U.S. will be diagnosed with prostate cancer this year. Nearly 29,000 will die from it, making it the second deadliest cancer for men.
For more on this finding we’re joined by Dr. Peter Greenwald, director of cancer prevention at the National Cancer Institute. Welcome to the program. What results did you get from this drug test that led you to conclude that the drug was preventing prostate cancers?
DR. PETER GREENWALD: We studied over 18,000 men. They were randomized to where half of them took the drug and half did not. We compared the results over the course of seven years. That is, during those seven years, the men who had a rise in PSA to the point where they needed the diagnostic test…
RAY SUAREZ: PSA, the chemical they look for as a marker for prostate cancer?
DR. PETER GREENWALD: A test to look for prostate cancer. We had to adjust because the drug affects the level of that PSA, and so there were men who were diagnosed during the course of the trial. And then at the end of the seven years, all of the men had a biopsy of their prostate. So we took tissue from the prostate gland through needle and examined it. We found that there was a one- fourth reduction in the occurrence rate of prostate cancer in the men taking Finasteride.
RAY SUAREZ: What does this substance do once inside the human body that might lead it to give you this result?
DR. PETER GREENWALD: The prostate gland is controlled in part by the male hormone. Testosterone is the common male hormone, but in the prostate, testosterone is converted to a much more potent male hormone. This drug prevents that conversion, so we felt that it prevented some of the drive, the male hormone drive, that contributes to the development of some prostate cancer.
RAY SUAREZ: And what about the placebo group? Did they get the expected number of prostate cancer cases for a group of that size?
DR. PETER GREENWALD: They did get roughly the expected number during the course of the seven years. But in addition, we did a biopsy at the end, and therefore we found many more tumors that were present in the prostate, something that is well known in older men.
RAY SUAREZ: So it wasn’t a case that your sample might have been flawed because they weren’t quite what a control group would be? That’s a result that you roughly expected?
DR. PETER GREENWALD: This is what we expected. It was a careful comparison, a randomization that made the control group very similar to the men getting the Finasteride.
RAY SUAREZ: Now, what about the drug group? What beyond the reduced number of tumors did you find about them, and what gives you some concerns?
DR. PETER GREENWALD: There are two side-effects, one good and one bad, according to how you feel about them. There is an effect on sexual functioning, some decline in sexual functioning in a small percent of men. And by that I mean the difference between those taking the dummy pill, the placebo, and those taking Finasteride had a small difference where there was more of a decline in the men on Finasteride. In the dummy group, more than 50 percent of the men had some decline in sexual functioning. That’s because they’re old men. So that’s a side-effect. The other effect is actually a good effect of the drug. The drug will cause the prostate gland to shrink, and therefore it’s used in the treatment of obstruction of urine flow in men who have an enlarged prostate. So this reduced the frequency that some men have where they have to get up at night to urinate or urinate frequently. And it reduced the number of operations men needed to relieve obstruction of the prostate.
RAY SUAREZ: Weren’t there also some results in the drug trial group that caused you some concerns about the nature of the tumors they were getting, among those who did develop prostate cancer?
DR. PETER GREENWALD: Yes. There is a concern that in those on Finasteride, a higher proportion who developed cancer had cells that looked more aggressive, they looked worse. We don’t know if that’s a true effect, that is, that they really are worse, or whether it’s something to do with the drug Finasteride. Some pathologists tell us that this drug just makes the cells look different, more difficult to interpret, so they read them as more of a problem. There’s not complete agreement on that. That is an area where we need more study. So we will follow the men and we will study the cells that we’ve obtained to find out more about the fact that there were somewhat higher number who developed the cancer who had cancers where the cells looked a little bit more aggressive.
RAY SUAREZ: Dr. Greenwald, who are the high risk groups that might consider looking at Finasteride as a long-term preventive medicine?
DR. PETER GREENWALD: Well, first of all, prostate cancer is common in older men. It accounts for one-third of all cancer in men and 10 percent of cancer deaths in men. So any man who is getting older has a risk. Black men have a higher risk. They have a 40 percent higher risk of getting the disease and almost a two-times higher risk of dying from cancer of the prostate. Men with a family history have a higher risk, so family history, race and just growing older are the major risk factors.
RAY SUAREZ: As we’ve already mentioned, the drug has been approved for other uses.
DR. PETER GREENWALD: Yes.
RAY SUAREZ: Does this test establish this Finasteride as a drug that you can take safely long-term? Is this larger than other studies and longer than other studies?
DR. PETER GREENWALD: This is much larger and longer than the other clinical trials that have been completed. So it does give us good information about taking it for seven years. We will follow the men even longer to find out if there are any other effects we should know about.
RAY SUAREZ: And you took the medicine yourself.
DR. PETER GREENWALD: I’m — in the trial. I believe in clinical trials. It’s the gold standard of research in cancer research and in medicine. I felt since this is the first clinical trial to see if we can actually prevent cancer of the prostate that I wanted to be part of it. Also, as a member of the National Cancer Institute, my colleagues and I felt that if I was part of it, it might be reassuring to the other 18,000 participants. It would show we’re doing something we really believe in ourselves, so I’m delighted to be part of this trial.
RAY SUAREZ: Dr. Greenwald, thanks a lot.
DR. PETER GREENWALD: Thank you.