Susan Love: Mammogram shift: Not a conspiracy

Although we all would like to think that public health pronouncements are the unmitigated truth about any issue, rarely is that the case. We can only give our best guess, based on the available data and our understanding of the disease. Luckily, research continues, hypotheses are reformulated and new recommendations are made.

Sometimes clinical practice gets ahead of the data and has to be pulled back. This is what happened with postmenopausal hormone therapy when the large Women's Health Initiative trial demonstrated that the then-common practice of giving women hormones at menopause was causing more harm than good. How big was the harm? We know that after the report came out, many women abruptly stopped taking their hormones, and that year, the incidence of breast cancer went down 15 percent.

I offer this example in an attempt to put the controversy regarding the new mammography guidelines into perspective. The shift in guidelines is not a conspiracy of the insurance companies or the government. It is pure coincidence that they came out while we are in the throes of the health care reform debate.

The U.S. Preventive Services Task Force was formed to periodically review the available data and come up with the best recommendation. A lot has changed since its last recommendations in 2002.

One key shift has been in our understanding of the biology of breast cancer. We used to think there was just one kind of cancer that grew at a steady pace, and that when it reached a certain size, it spread to the rest of the body. As a result, it seemed to make sense that we could save lives if a screening test could identify the cancer while it was still "early."

In the best of hands, mammographic screening in women older than 50 will reduce a woman's risk of dying from breast cancer by 30 percent. That is a lot, but it is not 100 percent. Why? It turns out that breast cancers are not all the same. There are at least five kinds, with different growth rates and levels of aggression.

One of the reasons that mammography is a less effective tool in young women is that they have a higher rate of aggressive tumors. Younger women also have breast tissue that is more sensitive to the carcinogenic effects of low-dose radiation. Calculations by a research team in Britain published in the British Journal of Cancer in 2005 suggest that it is possible for women to develop cancer because of the cumulative radiation from yearly mammograms starting at 40 or younger. Finally, mammograms are generally less accurate in younger women who have dense breast tissue, which can mask a cancer. Thus the balance of risk versus benefit is not as clear.

Since the 2002 task force guidelines were released, there has been new data from Britain, which was the first study to look at whether there was any benefit to having women start mammography at 40. To date, they have not shown a statistically significant decrease in mortality. This means if there is a benefit, it must be very small.

The new guidelines are based on this information. They do not say that no women younger than 50 should get mammograms, but that we should not routinely screen women younger than 50.

This has left many young women confused and asking how will we find our cancers if we don't have mammograms. The alternative to mammographic detection of cancer is not death. The alternative is that a woman will find a cancer herself or her physician will find it. The normal "poking around" that women do has been found to be just as good at finding breast cancer as a monthly self-exam.

That's why the task force recommended that doctors encourage women to be familiar with the look and feel of their breasts but to stop teaching formal breast self-exam.

The public anger at these recommendations is understandable. But it should not be directed at an honest effort to evaluate the benefit of mammography, but at the fact that we still don't know the cause of breast cancer or how to prevent it. Early detection is not our best prevention -- it's not even prevention. It just finds cancers that are already there.

Let's redirect our energy from protesting these guideline changes to finding the answers so that no woman ever has to hear the words, "You have breast cancer."

Susan Love, a physician, is the founder and president of the Dr. Susan Love Research Foundation, dedicated to eradicating breast cancer. She wrote this article for the Los Angeles Times.