To the editor,
The article by Washington Post’s Marisa Bellack published in the Oct. 29 issue of the Pioneer Press under the somewhat demeaning headline “Don’t worry your pretty little head about cancer” misinformed women by focusing on the so-called “harms” of screening mammography, such as the distress and anxiety resulting from false positives, call-backs and unnecessary biopsies. These may cause inconvenience, irritation and worry, but what was not mentioned is the real potential harm of mammography: over-diagnosis.
Over-diagnosis is defined as a diagnosis of a disease or illness that, if left untreated, would never harm or cause death of the patient. Over-diagnosis in breast cancer most often occurs in patients with ductal carcinoma in situ (DCIS), fewer than 50 percent of whom will go on to develop invasive cancer. DCIS accounted for less than 3 percent of all breast cancers diagnosed in the US prior to the advent of screening mammography. But because DCIS is readily visualized on mammograms owing to its characteristic specks of calcifications, it now accounts for 27 percent of all breast cancers diagnosed annually in the U.S. The likelihood that DCIS will progress to invasive cancer is less than 50 percent, but because there is currently no way of determining whether a specific case of DCIS will or will not become invasive, virtually all cases must be treated as aggressively as invasive cancer – with radiation, chemotherapy and surgery.
This past year, an estimated 233,000 women in the U.S. were diagnosed with breast cancer, of which about 62,000 were diagnosed with DCIS. Thus, approximately 31,000 women who may never develop invasive breast cancer may well be over-treated; in other words, harmed by having undergone a mammogram.
The benefits of screening mammography are well-known and important; the so-called harms are also well-known but not important; the real harm, over-diagnosis, is not well-known but is important.
The following three books are among the excellent sources of accurate and unbiased information on this subject:
“The Big Squeeze: A Social and Political History of the Controversial Mammogram,” by Handel Reynolds
“How We Do Harm: A Doctor Breaks Ranks About Being Sick in America,” by Otis Brawley
“Overdiagnosed: Making People Sick in Pursuit of Health,” by H. Gilbert Welch, Lisa Schwartzl and Steve Woloshin
When deciding whether to undergo screening mammography, women should weigh the benefits, as well as the harms, of the procedure. Women should not worry about over-diagnosis. Rather, they should educate themselves about it and discuss with their physicians the pros and cons of screening mammography.
Leonard Berlin, MD
Wilmette, IL