Friday, November 27, 2009

Keeping Abreast of the Recommendations

When I first heard the news that the U.S. Preventive Services Task Force had recommended against teaching women to do breast self exams, and that mammograms become biennial generally and optional for women in their 40s, I have to admit I felt vindicated.

I used to do self-exams, more or less, until I read an article by Dr. Susan Love, a breast cancer specialist, around 20 years ago in the now-defunct feminist newspaper Sojourner. As I recall it, Love made the case that self-exam turns women against their bodies, making us feel as though we are on a search and destroy mission. I recall she said that having a doctor do the exam once a year was sufficient. In reading her current writing on the topic, I see that she clearly makes the point that women should be familiar with their bodies, including their breasts, but that the systematic exam is overrated, whether done by women or their doctors.

Large randomized studies of women taught to do self-exam found no benefit in doing the exam. But there was a 50 percent increase in the number of biopsies done on the women who were doing self-exam. Which led to no decrease in mortality -- only increased stress and cost.

I did get mammograms annually throughout my 40s. I had to have one retaken as a follow-up once. I've known many women who had false positives, sometimes leading to ultrasounds for followup, sometimes to biopsies. I also know multiple women who have had breast cancer, one of whom died from it in her 70s (after ten years of remission from surgery and chemo). One woman was well under 40 at the time; all the others were 50 or over at onset. I don't know the details of how any of their cancers were detected.

According to the most recent research, 1,904 women in their 40s would have to be screened for 10 years (over 19,000 mammograms) to prevent one death. (Contrast this with 1,339 women in their 50s screened for 10 years to prevent one death, and 377 women in their 60s for the same result). And those 1,904 women in their 40s will experience more than 1,000 false positives and the necessary follow-up testing.

Some of the best articles I've read about the Task Force recommendations:

Susan Perry's work on Minn Post. Strongly asserting the evidence-based approach, Perry is a voice of calm and clarity on this contentious issue.

Kevin Sack's news analysis from the New York Times. A balanced view of the controversy.

NPR's Talk of the Nation from Nov. 18, with Drs. Jeffrey Tice and Constance Lehman. A conversation between two doctors, one for and and one against the recommendations.

A New York Times op-ed by Robert Aronowitz, M.D. He reminds us that this controversy is not new, and reviews the past 30-plus years of studies that have indicated the dubious benefits of mammography for women in their 40s. He also supplies a brief history of the medical field's understanding of cancer, and the idea that "catching it early" matters. (Aronowitz is an internist, professor at the University of Pennsylvania, and author of Unnatural History: Breast Cancer and American Society.)

The key thing I take from both the anecdotal testimonials and the well-thought out analyses is that what we need is a better mammogram. As Cynthia Pearson of the National Women's Health Network said (as quoted by Susan Perry on MinnPost):

We’re glad that the [Task Force] has done what they’re supposed to do. They’ve told the truth about what studies have found... But, I’m not at all happy today. Not even to be proven right about things that I took a lot of criticism for saying [in 1993, when the NWHN came out against routine mammograms for women in their 40s]. Rather, I’m outraged. We’ve known for 16 years that mammography screening doesn’t work well for women before menopause, and not at all for women under 40. And at the same time, we’ve known that a significant number of breast cancer cases occur in women under 50. So once we knew mammography wasn’t good enough, the next step was obvious -- we need to find something better.
I don't know if digital mammography is the answer.

(Digital image at left; analog at right.)

It sounds as though it may have fewer false negatives (finding 7.9 cancers per thousand, vs. 4. 5 per thousand with film mammography), but I haven't seen mention of studies on whether it affects the rate of false positives. And maybe those 3.4 additional finds per thousand were all relatively benign cancers that wouldn't have led to the woman's death. Who knows.

It's all about the odds, though, and people clearly are bad at understanding risk: 19,000 mammograms and over 1,000 false positives to save one life. The odds are pretty darn bad that the one life would be yours, and in fact, ten times better that you'll think you had life-threatening cancer when you actually didn't. (According to the Wikipedia's summary of the Task Force report, those false postives lead to overdiagnosis of "cancers [that] would never have affected these women in their lifetimes. An estimate of this overdiagnosis is 10 breast cancers diagnosed and unnecessarily treated per life saved when 2,000 women are screened for 10 years.")

But all it takes is one story from a breast cancer survivor in her 40s to make everyone throw logic right out the window. If only we could hear from a few car crash victims killed by head injuries, maybe we'd all be wearing helmets when we drive to work each day.
Update: Dr. Susan Love had a well-written op-ed in the Los Angeles Times, reprinted in the Star Tribune on Nov. 28.

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