Thursday, September 3, 2009

Is breast cancer really the WORST enemy?

I got a chain e-mail from a good friend of mine urging me to get my screening mammogram done. The message contained cute comics about mammography (mostly about the lasting effects of squishing the boobs, you can imagine), and at the end it had the following message:
Mail this to 13 other women. Now, don't break the chain! One female broke the chain, her plumbing became so bad, she now has an outhouse! OK gals, now that you have had your laugh, remember... Breast Cancer Awareness... Go have those boobs checked out and stay healthy! Pass the message on to your mothers, sisters, daughters, aunts, cousins, friends, and even your enemies. Because the WORST enemy is Breast Cancer.
Now, by now you,my reader, know that I am a great skeptic of over-diagnosis and over-treatment; I think it causes more harm than good, though we have not really bothered to quantify the harm yet. But a recent study from Europe fueled my fires on the mammo front. This study, a systematic review of the literature on the subject, concluded that about 1 in 3 cancers in a screened population is an over-diagnosis. In an accompanying editorial, H. Gilbert Welch from Dartmouth, a perennial skeptic of the "more is better" approach, provided a sober view of the dilemma:
Mammography is one of medicine’s "close calls"—a delicate balance between benefits and harms—where different people in the same situation might reasonably make different choices. Mammography undoubtedly helps some women but hurts others. No right answer exists, instead it is a personal choice. (emphasis mine)
Dr. Welch, one of the foremost experts on over-diagnosis in mammography, in fact provided this very useful, in my opinion, table:

Draft balance sheet for screening mammography in 50 year old women*
1 woman will avoid dying from breast cancer2-10 women will be overdiagnosed and treated needlessly
10-15 women will be told they have breast cancer earlier than they would otherwise have been told, but this will not affect their prognosis
100-500 women will have at least one "false alarm" (about half of these women will undergo a biopsy)

*For every 1000 women undergoing annual mammography for 10 years

This tally is chilling, given that the end-result is that, to avoid 1 breast cancer death, 2 to 10 women will be treated unnecessarily with disfiguring surgery, toxic chemo and radiation therapies, and 100 to 500 others will be subjected to follow-up testing, some of it invasive. Now, you may be saying that it is all worth it to avoid dying from breast cancer. Unfortunately, what we do not have a solid idea about is how much harm, in the form of complications and deaths from the unnecessary work-up and treatment, comes from this "better-safe-than-sorry" approach. We also have very little knowledge of the long-term effect of the radiation exposure from mammo. 

So, the bottom line is that, if a woman decides against the current dogma to have annual screening mammography, don't make her into a pariah -- she is exercising her good judgment. Peer pressure in this situation is not only unwarranted, but may be detrimental. We as the medical and public health profession need to start developing a much more nuanced message about cancer screening in general, and mammography in particular. There is too much evidence now that one size does not fit all. 


  1. I've known several women who had breast cancer of the DCIS (ductal carcinoma in situ) variety--not palpable, not having grown outside the duct--and invariably these women are given options to receive the whole treatment spectrum from axillary dissection to radiation. Although in some women with circumstances such as family history or genetic predisposition these options are wise to consider, in the majority they may not only produce the everlasting possibility of such collateral damage as lymphedema, they also further skew the coverage and swell the profits of the healthcare industry.

  2. Thanks for your comment, anonymous! Not to mention pre-existing condition...