Wednesday, December 2, 2009

Mammography not always a smashing success

Thanks to FeministPeaceNetwork on Facebook for a link to a commentary on the breast cancer screening controversy by the ever-wonderful Barbara Ehrenreich.

A federal government advisory panel recently proposed that women not receive routine mammograms before age 50, and to receive mammograms only every other year after that. These new proposals quickly became controversial, with many people, including feminist activists, charging that they were an effort to save money at the expense of women's lives. Ehrenreich argues that feminists should embrace the new guidelines, using her own experience as a cancer survivor to illustrate:
One response to the new guidelines has been that numbers don’t matter -- only individuals do -- and if just one life is saved, that’s good enough. So OK, let me cite my own individual experience. In 2000, at the age of 59, I was diagnosed with Stage II breast cancer on the basis of one dubious mammogram followed by a really bad one, followed by a biopsy. Maybe I should be grateful that the cancer was detected in time, but the truth is, I’m not sure whether these mammograms detected the tumor or, along with many earlier ones, contributed to it: One known environmental cause of breast cancer is radiation, in amounts easily accumulated through regular mammography.

And why was I bothering with this mammogram in the first place? I had long ago made the decision not to spend my golden years undergoing cancer surveillance, but I wanted to get my Hormone Replacement Therapy (HRT) prescription renewed, and the nurse practitioner wouldn’t do that without a fresh mammogram.

As for the HRT, I was taking it because I had been convinced, by the prevailing medical propaganda, that HRT helps prevent heart disease and Alzheimer’s. In 2002, we found out that HRT is itself a risk factor for breast cancer (as well as being ineffective at warding off heart disease and Alzheimer’s), but we didn’t know that in 2000. So did I get breast cancer because of the HRT -- and possibly because of the mammograms themselves -- or did HRT lead to the detection of a cancer I would have gotten anyway?
Ehrenreich also links to a post by noted breast cancer specialist Dr. Susan Love, explaining the new guidelines. Love notes that the guidelines don't say that no women under 50 should receive mammograms, but that the test shouldn't be done routinely. It should be an individual decision made by a woman and her doctor with an understanding of both the benefits and risks:
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; 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," before it had spread. That's how we developed the notion of early detection. And it works, sometimes.

In the best of hands, mammographic screening in women over 50 will reduce a woman's risk of dying from breast cancer by 30%. That is a lot, but it is not 100%. 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. Some are so aggressive that they will have spread before they are visible on a mammogram or form a lump. Some are very slow growing or may not even have the ability to spread, so there is no benefit from finding them early. This is because of the biology of the disease, not the limitations of screening.

One of the reasons that mammography is a less effective tool in young women is that they have a higher rate of these 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.
Ehrenreich says, at the end of her post, that what we really need is a new women's health movement that is willing and able to ask hard questions about the causes and treatments of breast cancer, and not falling for the propaganda of what she calls "the cancer industrial complex." I wholeheartedly agree.

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