April 6, 1998
According to a recent study by the National Cancer Institute, the drug tamoxifen reduced the risk of breast cancer by 45 percent among high risk patients. Jim Lehrer speaks with a researcher to discuss the study's findings.
A RealAudio version of this segment is available.
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Information about tamoxifen from the National Cancer Institute.
National Cancer Institute
JIM LEHRER: Forty-three thousand women are expected to die from breast cancer this year, another one hundred and eighty thousand will be diagnosed with the disease. Today there was news of a drug that might change those numbers. It came from the National Cancer Institute. Dr. Richard Klausner is its director. Doctor, welcome.
DR. RICHARD KLAUSNER, National Cancer Institute: Thank you.
JIM LEHRER: It's correct to use the term "breakthrough?".
A medical breakthrough?
DR. RICHARD KLAUSNER: Well, I think the study we described today is historic. I think it does represent something we've never had before and, therefore, quite amazing, and that is for the first time we have an option to actually prevent breast cancer. It's the first time we've had something, in this case a pill, a pill that had previously been used to treat breast cancer. Not only is it dramatic that we have something could prevent breast cancer but the extent of that prevention--nearly 50 percent--in women at increased risk for breast cancer that were involved in this clinical trial, the study that gave us that information, is again striking.
JIM LEHRER: All right. Let's go through the study. How many women were involved in the study?
DR. RICHARD KLAUSNER: Over 13,000 women were involved in the study.
JIM LEHRER: And how did they get involved, for what reasons were they involved?
DR. RICHARD KLAUSNER: We had a series of criteria that established whether they are at increased risk that include whether they had had a history of breast disease, whether they had had a family history of breast cancer, their reproductive history, and other things that we know can predict, in general, a woman's risk of breast cancer. The only women that qualified for this study were women above the age of 35 who were predicted to have a significantly increased risk of breast cancer than the general population.
JIM LEHRER: And how long did this study go?
DR. RICHARD KLAUSNER: The study began in June of 1992, and it was closed in the way we've closed it just this week before it was finished because a data monitoring committee determined that the question had been answered, answered clearly, and that is breast cancer was prevented in the women taking the drug.
JIM LEHRER: And so most--as is the case in most of these kinds of studies, what--percentage of the women were given tamoxifen and another percentage were not?
DR. RICHARD KLAUSNER: About 50/50.
JIM LEHRER: About 50/50. Okay. Now you say the results were about 50 percent. Of those 50 percent, they had less incidence of breast cancer, correct?
DR. RICHARD KLAUSNER: That's right.
JIM LEHRER: And how much of a lesser instance?
The study's findings.
DR. RICHARD KLAUSNER: Between 40 and 50 percent. So the incidence of breast cancer was down 40 to 50 percent. There were other effects as well. The instance of fractures were down by about 50 to 50 percent, but there were side effects--and that's an important part.
JIM LEHRER: Tell us about the side effects.
DR. RICHARD KLAUSNER: It has been known that the potential side effects of this drug, tamoxifen, one, was that it can cause another type of cancer, cancer of the uterus, endometrial cancer.
JIM LEHRER: Can cause it?
DR. RICHARD KLAUSNER: Can actually cause that. That had been seen before, and this study confirmed that. There is about a two- to two-and-a-half-fold increased risk of uterine cancer. Now, we only saw it in women above the age of 50. In other words, about 40 percent of the women in the study were below the age of 50, where we saw no increase in incidence. And the increased risk of uterine cancer did not in numbers equal the decreased risk of breast cancer because breast cancer is a much more common disease. There was another significant side effect, and that was an increased incidence of blood clots. Again, this had been seen before.
JIM LEHRER: That's mostly in the lung, right?
DR. RICHARD KLAUSNER: Well, mostly it was in the veins of the leg but there was also an increased incidence of blood clots to the lung, which is quite serious.
JIM LEHRER: All right. So, is it a case of trading one bad disease for another, or is it that simple?
"It is a case of trading benefits and risks."
DR. RICHARD KLAUSNER: It's not that simple. It is a case of trading benefits and risks. There is no simple answer to this. Each woman needs to work out with her physician what her risk of breast cancer is. The higher the risk for breast cancer the more effective, the more valuable reducing that risk of breast cancer would be. There are other issues, such as whether women are at risk for uterine cancer. If a woman has had a hysterectomy, of course, she's not at risk for uterine cancer. There are other risks that we might be concerned about in terms of blood clots, where the woman smokes, do they have hypertension, diabetes, et cetera, and so this--
JIM LEHRER: And so those folks--to interrupt for a moment--those folks should probably--it would be up to the doctor, though--but those folks should probably not take tamoxifen, or not as readily take tamoxifen, correct?
DR. RICHARD KLAUSNER: Well, I think there's no clear answer.
JIM LEHRER: Sure.
DR. RICHARD KLAUSNER: Each woman will decide with her doctor what her risks are for breast cancer, what her risks are for these other side effects, and based upon this study, how much the risk for breast cancer will be reduced, fractures will be reduced, and how much the risk of other cancers go up.
JIM LEHRER: Now, tamoxifen has been in use for 25 years, correct?
DR. RICHARD KLAUSNER: That's right.
JIM LEHRER: What is it? What is it made of? Where does it come from?
DR. RICHARD KLAUSNER: Well, it is a steroid, and it looks like estrogen. In fact, it works in some tissues like estrogen and in some tissues it works as an anti-estrogen. It opposes estrogen. That's exactly why--
JIM LEHRER: What does that mean exactly?
DR. RICHARD KLAUSNER: So estrogen is a hormone that stimulates the growth of a variety of cells, and it is required in many cases for the development of breast cancer. An anti-estrogen is a molecule that looks like estrogen but is slightly chemically different so it actually finds the place in the body where the estrogen binds, prevents the estrogen from binding, and you don't get the estrogen effect. This drug is an anti-estrogen in the breast, but is an estrogen in the uterus, and that's why it lowers the risk of breast cancer but raises the risk of uterine cancer.
JIM LEHRER: Why did it take 25 years for somebody to say, hey, let's see if it'll prevent breast cancer, as well as treat it?
DR. RICHARD KLAUSNER: Well, this is, in fact, is a marvelous story of a continuous succession, through clinical research and clinical trials, of gradually learning how to use this drug. The way the idea of prevention came up was in a trial that was done by the same group funded by the NCI, NACPB it's called, that did this trial, they were treating women who had had breast cancer with tamoxifen and they knew that it reduced the recurrence of breast cancer, but what they noted was that there was about 35 percent reduction in the incidence of breast cancer in the other breast that hadn't had the breast cancer, in other words, new cancer, and that study gave the idea that maybe this can be used not only to treat breast cancer but to prevent it.
JIM LEHRER: And that led to the study that you all just stopped because it was going so well.
DR. RICHARD KLAUSNER: That's exactly right.
JIM LEHRER: After six years.
DR. RICHARD KLAUSNER: That's exactly right. And it's not over. This will lead to other studies. There are still many unanswered questions: What's the best time to start tamoxifen? What are some of the other long-term side effects? How long to take it--these need to be answered, and they will be answered with new clinical trials.
JIM LEHRER: There are also some very practical questions that people are going to want answers to tonight. For instance, is this something that women who have any--who believe they're at risk or their doctors think they're at risk or have any of those things you mentioned earlier, what is it--members of the family have had--
DR. RICHARD KLAUSNER: Right.
JIM LEHRER: --breast cancer; are there any biopsy things in the past; they should go to their doctor immediately and say let's do something about tamoxifen?
DR. RICHARD KLAUSNER: No. I mean, I don't think they should run to their doctor immediately for a number of reasons. We don't view this as an emergency. It's very important that now women know this; doctors know this. We will provide information to allow doctors to figure out how to calculate risk. Often people misperceive their risk. In fact, we've done many studies to show many women overestimate their risk of breast cancer. It's very important to get a clear risk so you can make a clear decision.
JIM LEHRER: Is there enough of this drug available for everybody who's going to need it in the next few weeks or months or year?
DR. RICHARD KLAUSNER: One thing that is very important is that this drug has not been approved yet, of course, by the FDA for this indication. The data from the study has now been presented to the FDA, and they announced today that they will do an expedited review to examine the data to determine whether they will approve a new drug indication for prevention of breast cancer in high-risk women.
JIM LEHRER: Now wouldn't that be a terrible frustration for a woman who believed that she was high risk, watches this program right now, or reads about it in the newspaper, and is told, wait a minute, you can't do anything about it now because the FDA hasn't said it's okay?
DR. RICHARD KLAUSNER: Well, I think the FDA will be moving very quickly on this.
JIM LEHRER: Like what? How quickly?
DR. RICHARD KLAUSNER: They certainly said that they'd be able to do this within six months.
JIM LEHRER: And that's quickly?
DR. RICHARD KLAUSNER: Yes, that is quickly. It's very important to carefully analyze this data. This is brand new. We just stopped the study. There's much we have to analyze. It is very important that we're sure--we are sure of these benefits. We want to analyze more to find out can we learn more about who is at risk, for example, who might get blood clots, or who might be at risk for uterine cancer when they take this drug? That's going to be very important in doctors and women together making the decision for when to start this drug.
JIM LEHRER: Meanwhile, in anticipation of approval in six months, the drug will be made available, is that right?
DR. RICHARD KLAUSNER: We are sure that this drug will be made available, yes.
JIM LEHRER: All right. Doctor, thank you very much.
DR. RICHARD KLAUSNER: Thank you.
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