Organized Screening Leads to Breast Cancer Overdiagnosis?

Journal Watch reported on the following study done by BMJ, a British journal:

“Mammography-detected cancers represent “overdiagnosis” in about one third of cases, according to an international study published online in BMJ. (Overdiagnosis is the detection of cancers that will not ultimately cause symptoms or death.)

Researchers reviewed published trends in breast cancer incidence for 7 years before and 7 after the full implementation of publicly organized screening in the U.K., Canada, Australia, Sweden, and Norway. After adjustment for the presence of older, previously screened women, the researchers concluded that about half the cancers detected represented overdiagnosis. When carcinomas in situ were excluded, the proportion was about one third.

An American editorialist writes: “The question is no longer whether overdiagnosis occurs, but how often it occurs.” He recommends a trial “to test higher thresholds [of diagnosis], such as only recommending biopsy for breast masses larger than a certain size.””

Ed Clifford, MD, Breast Surgeon with Surgical Group of North Texas had this to say regarding the study and article. “Breast cancer is not a uniform disease–all cancers do not behave in the same way. The biology of this is not clear, and may have as much to do with the immune system of the patient as it does with the cancer. The research does seem to indicate that some cancers do not pose an immediate threat to the patient. Unfortunately this study is not accompanied by any article indicating a means of distinguishing between dangerous and non-dangerous cancers. While scientifically interesting, this article changes nothing regarding current management of biopsy proven breast cancer.”

Link for complete story from BMJ: http://www.bmj.com/cgi/content/full/339/jul09_1/b2587