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Can a Pill Prevent Breast Cancer?

By Heather Millar

pills

Should healthy women take a pill to prevent breast cancer? Last week, a government-sponsored panel of experts said that perhaps women with a higher risk of breast cancer should … but only if their risk of blood clots and stroke is low.

The drugs in question are Tamoxifen and Raloxifene, both drugs that have been prescribed for years to women whose risk of breast cancer is higher than normal. These might be women who have a BRCA1 or BRCA2 gene mutation that predisposes them to breast cancer, women who have a “first degree relative” (mother, sister) who had cancer, women who’ve had pre-cancerous breast tumors. But there are several scales and systems for assessing risk. More on that later.

Both drugs work by blocking the body’s use of estrogen. This foils breast cancers that feed on estrogen like a toddler on candy, as 75 percent of breast cancers do.

After reviewing the most recent scientific literature, the United States Preventive Services Task Force (USPSTF)—a group of epidemiologists, public health officials, and physicians charged with reviewing research and making recommendations on preventive care—published a study that says these drugs can reduce the risk of breast cancer and that doctors should recommend them to their high-risk patients.

This is baby-step trying to encourage more prescribing of these drugs to appropriate women. It adds to a 2002 recommendation saying that women should “talk with their physicians” about taking these drugs to prevent breast cancer. But women didn’t seem to listen. The phrase in the most recent pronouncement about using these drugs for “chemoprevention” is that “use is low.” So I guess the hope is that strengthening the language will get more docs and women to discuss this option for high-risk women.

With all the pink ribbon hand-wringing about breast cancer (I can be flip because I’m a breast cancer survivor), you’d think there’d be a lot of coverage of this notion of encouraging high-risk women to take a pill to prevent one of the most common cancers to afflict humanity. But there was surprisingly little media reaction, perhaps because the bombings in Boston happened two days after the study went live: There was an excellent piece in The New York Times and a couple other newspapers, a bit of coverage in a few trade journals and on women-centered websites and there it mostly ended.

I wonder whether this USPSTF panel despaired or rejoiced about the relative lack of attention. It seems that almost every time a group of USPSTF scientists makes a pronouncement, there ensues great public gnashing of teeth and comment thread flame-throwing. In the last few years, they’ve been trashed for recommending that women don’t start mammograms until 50 (rather than 40), that men don’t really need prostate-specific antigen (PSA) testing for prostate cancer, that there’s not sufficient evidence to prove that lung cancer screening works.

All cancer issues seem to be fraught, both intellectually and emotionally. Do docs buy bulletproof vests, earplugs and extra therapy sessions when they agree to serve on a USPSTF panel?

The recent Tamoxifen/Raloxifene pronouncement is a “draft recommendation.” That means it’s not final, and the public can comment until May 13. The Times comment thread ranged from outraged (“Why isn’t there a cure yet?” “Why so much breast cancer?”) to sometimes analytical (taking issue with statistics, or questioning our nation’s approach to prevention) to sometimes paranoid (“bras cause cancer” or “the docs and insurance companies just want us to take more pills so that they can get rich”—never mind that Tamoxifen is old-ish, extensively-studied and not patent-protected, there is no “Sam Walton of Tamoxifen.”). So I’m guessing the USPSTF is going to get an earful.

So exactly how did these scientists come to their conclusion? They analyzed about 20 new studies from MEDLINE and Cochrane databases from 2007 to 2012, and found several new, large placebo-controlled studies that strengthened the case for high-risk women to consider taking these medications. Women who took tamoxifen and raloxifene had a 7.5% risk of developing breast cancer over a 10-year period, compared with a 21.3% risk for women who took nothing.  Both drugs reduced the incidence of invasive breast cancer, though tamoxifen caused more problems like strokes, a small risk of endometrial (uterine) cancer and cataracts.

But there are a couple problems:

  • First, even the leader of the  USPSTF panel admitted to a reporter for Blue Cross Blue Shield’s HealthDay news service [full disclosure: this is my insurance company] that “the tricky part is finding the right candidate.”  The National Cancer Institute recommends the Gail model to help doctors make a risk assessment, the original of its type. But there are others: a Breast Cancer Quiz developed by the Harvard Center for Cancer Prevention, a Breast Cancer Risk Calculator and Breast Cancer Prevention’s Risk Tool.  The USPSTF reviewed 13 different risk assessment models. And that’s before we even get into the more complicated matters of whether you’re at risks for strokes and so on, or whether you might be at greater risk because of your race.
  • Second, these drugs have no joke side effects. Tamoxifen seems to increase the risk of uterine cancer slightly (4 cases per 1000 women) and stroke (4 cases per 1,000). Raloxifene seems to add the risk of stroke (7 cases per 1,000).

Granted, these risks are all less than 1 percent, (1 percent would equal 10 cases per 1,000). But you’re talking about taking healthy women and then adding a risk of stroke or uterine cancer to prevent an, admittedly greater, risk of breast cancer.

I understand that, mathematically, it makes sense to take something with a small risk of something bad to avoid an even greater risk of something bad. But even understanding that, I’m still not sure I’d do it. What if you were a woman who might be at high risk but were actually never going to get breast cancer at all? Would you let fear goad you into taking a drug that might result in your getting another serious cancer, i.e. uterine cancer? Or cataracts? Or a stroke?

Apparently, according to the recent report, about 70 percent of patients will take these drugs at the doses their docs recommend. But you can see why physicians are having trouble convincing the remaining 30 percent of patients.

This is what journalists call “burying the lead:” I take Tamoxifen. I have taken it for almost two years, and will take it for at least three more years, perhaps eight more. But I’ve HAD breast cancer. I am at a much, much greater risk that someone who’s never had breast cancer. I don’t need a risk assessment tool to know that. I had early stage, but very aggressive cancer. For me, the benefits outweigh the icky risks. But for someone healthy? I get that there’s evidence to recommend it. Yet still, I struggle with the notion.

I also have a daughter. She’s 12. Because of my cancer, she’d be considered “high-risk” by most standards. When she turns 35 or 40, do I want her to start taking drugs like Tamoxifen or Raloxifene if she’s healthy in other respects? I really, really struggle with that. Right now, a woman has a 12 percent risk of getting breast cancer. Taking a preventative drug might knock that down to a 10 percent risk, or 9 percent. Would that be worth it? I just don’t know.

Let me tell you about the “minor” side effects of Tamoxifen from a pool of one: me. It makes it impossible to lose weight. I mean, IMPOSSIBLE. It causes hot flashes. It gives me painful cramps in weird places like under my chin, over my ribs, in my fingers. It turns my inner privates all raisin-y, and it grinds my sex drive into the dust. That’s a drag for me, but it’s really a drag for my husband. Thank God he’s understanding and adaptable.

Would I want my daughter to take all that on to knock a couple percentage points off her risk? Obviously, it will be her decision, and yes, Raloxifene does not have such severe side effects. Still, I think I’d advise her against it at this point.

I know the USPSTF is doing the best it can with the data it has. In science, the difference of two or three percentage points is huge. In life, I think it’s less so.  I’d like to wait for better odds before I’d push all those side effects onto my daughter.

And I do wish we’d expand our idea of “prevention” beyond scans and drugs. Diet, exercise, lifestyle, and the limiting of environmental toxins and excessive stress should all be much bigger parts of the mix.

What do you think? Would take these drugs? Or not? Do you think the U.S. is getting cancer prevention right? Or not?

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The opinions expressed in WebMD Second Opinion are solely those of the User, who may or may not have medical or scientific training. These opinions do not represent the opinions of WebMD. Second Opinion are... Expand

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