Perhaps screening detects some breast cancers early enough so that a woman can live long enough to die of something else, or even die later of breast cancer. There is a hint that such a benefit was afforded the women of Malmö who ranged in age from 55 to 69 when the study began. For every 250 women screened for a decade, one breast cancer death was prevented.
Do you think this justifies screening? I have doubts that we can even reliably and reproducibly discern such a small benefit.
Many a mammogram will be read as suspicious, and many as suggestive of cancer. For most of the former and all the latter, women are subjected to biopsy. If the biopsy documents nothing evil, the mammogram is a false positive.
For the women whose suspicious mammogram was a false positive, for the women who were found to have noninvasive cancer on biopsy, for the women who were found to have cancer that would not have caused them grief in their lifetime, and for the women who are treated for invasive cancer when some other disease proves their reaper, mammographic screening is an exercise in overdiagnosis and overtreatment.
"Suspicious" and "suggestive" are in the eyes of the beholder; false positive rates vary dramatically from country to country and, to some extent, from reader to reader.
In the United States, radiologists are so hesitant to read a mammogram as "normal" that false positive rates can reach 80 percent. The more sensitive mammographic techniques, such a digital or magnetic resonance imaging, result in higher false positive rates. This hedging on the readings is driven in no small part by the fact that "missing a breast cancer" on mammography is the most frequent reason for malpractice litigation in the United States.
Breast cancer is viewed as a plague. A "war" on breast cancer is viewed as a crusade. Screening mammography is Excalibur. Blunt or not, it's the best we have.
But screening mammography is so terribly blunt that it approaches useless: It finds very few cancers that are truly treatable, it misses many of these and it is awash in false positives.
Norway, Sweden, Australia and the United Kingdom are re-examining their national experience with screening mammography because of appraisals similar to mine.
If a woman's life was saved because of early detection of an evil breast cancer, she should thank her lucky stars rather than her mammographer. I would relegate mammograms to the archives of false starts, next to radical mastectomy.
Dr. Nortin Hadler is professor of medicine and microbiology/immunology at the University of North Carolina at Chapel Hill, and an attending rheumatologist at University of North Carolina Hospitals.