Breast Cancer, Mammograms, And The Fear Factor
Apr 14, 2014 - 12:03:04 AM
From Hippocrates on, causes of the disease were proffered by the leading minds of the day. These would include excess of black bile; lack of sexual activity; overly vigorous sexual activity; depression; childlessness, and sedentary lifestyle. Famed French physician Henri Le Dran was among the first to advocate surgical removal of the tumor and infected lymph nodes, and radical mastectomy remained the treatment of choice until the 1950s. It was also common to remove any gland that produces estrogen, as lack of this hormone was observed to retard tumor growth.
Treatment modalities gradually improved, and now tend to favor conservative surgeries, as well as radiation and chemotherapy. That being said, breast cancer is still--by far--the most common cancer in women. As to deaths from cancer, breast cancer is second only to lung cancer, for all groups except Hispanic women (for them, it's number one).
No other disease is as feared by women, and with very good reason. Notwithstanding feminist efforts to the contrary, women are still--at least partially--judged by their appearance. For many victims, a cure will leave some disfigurement, with attendant emotional scars, as well. But fear is a great motivator--indeed the greatest of all motivators. We must discover what causes this dreaded disease, and determine how to prevent it.
The etiology and prevention of cancer is the Holy Grail of medicine, and despite hundreds of billions of dollars being spent on research, we can say little more than don't smoke, and avoid pre-OSHA levels of chemical and radiation exposure. Of course, we have also learned how to cause and cure cancer in rodents, with precious little applicability to humans. Yet, a public policy must be put forth, and ever since Medicare was thrust upon us in 1965, few aspects of daily life are more politicized than health care.
Since we cannot prevent breast cancer, the next best thing is to detect it early. To drive the early detection movement, policy makers began to focus less on the hard numbers of mortality rate, and concentrated more on the squishy-soft statistics of "survival rate." Survival rate is simply the percentage of victims who survive a disease for a specified time period (often five years) after first diagnosis. Talk about your stacked deck.
The crushing fallacy of survival rate is that it can be enhanced merely by achieving an earlier diagnosis, even if the affected individual dies one day beyond the specified time period, or the early screening was a false positive, and no disease ever occurred. Which brings us to the heavyweight champion of breast cancer early diagnosis: Mammography.
The technical allure of mammography is that it can spot tiny tumors well before they are palpable in a breast self-exam. The financial allure of mammography is that radiology centers can bill virtually all forms of insurance for this procedure. The widespread use of mammography raises two important questions: Is it effective, and is it overdone? Bear in mind that Americans spend well in excess of $7 billion annually on mammography, and yes, this colors the debate a whole lot.
There have always been plenty of naysayers on mammography, but let's consider the latest big study, entitled "Twenty five year follow-up for breast cancer incidence and mortality of the Canadian National Breast Screening Study: randomised screening trial." Appearing on February 11, 2014 in BMJ (formerly the British Medical Journal), this work sought to "[C]ompare breast cancer incidence and mortality up to 25 years in women aged 40-59 who did or did not undergo mammography screening."
Note that this age cohort is the most highly-touted group for mammography. The study involved 89,835 women, randomly assigned to mammography (five annual mammography screens) or control (no mammography). Here's the conclusion:
Annual mammography in women aged 40-59 does not reduce mortality from breast cancer beyond that of physical examination or usual care when adjuvant therapy for breast cancer is freely available. Overall, 22% (106/484) of screen detected invasive breast cancers were over-diagnosed, representing one over-diagnosed breast cancer for every 424 women who received mammography screening in the trial.
In other words, mammograms do not improve mortality, and they are prone to false positives, with all of the expense and heartache--for good measure. Not surprisingly, the American College of Radiology and the Society of Breast Imaging attacked the study, using the classic (and ridiculous) straw man argument against retrospective studies: "That study goes back 25 years, and 25 years ago, older methods were used." Kind of makes your head explode.
For me, the best comment comes from longtime student of mammogram efficacy Dr. Russell Harris, of the University of North Carolina School of Medicine. Acknowledging the large population and significant time period, the BMJ study "[S]hows that if mammography makes a difference, it can't be very big. If there were a knock-your-socks-off difference, we would have seen it in this study."
Michael D. Shaw
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