STUDY RAISES QUESTIONS ABOUT OVER-DETECTION OF BREAST CANCER
Regular screenings for breast cancer detection have become almost as common as the twice a year visit to the dentist for an oral exam. Now, new evidence comes from a major study in Europe which suggests that an increased rate of screenings is leading to the discovery and treatment of cancers that may have spontaneously regressed had the woman not undergone a mammography.
What is most interesting about the results of this study conducted in four Norwegian countries is that breast cancer rates increased by a significant 22 percent when women began undergoing a mammography every two years. This data was recently reported in the Archives of Internal Medicine, a publication of the American Medical Association.
The research into the incidence of breast cancer began in 1996 at the Norwegian Institute of Public Health in Oslo, Norway. Between then and the year 2001, the results of 119,472 women age 50 to 64 who had 3 rounds of screenings during this time period were evaluated. The rates of cancer among this group were compared to the results of 109,784 women of the same age group who did not receive a screening but who would have, had screening existed in 1992. Cancers were tracked for 6 years with all participants undergoing a one-time screening at the end of that period.
What the researchers found was a much higher incidence of cancer in the screened group than in the control group, according to Per-Henrik Zahl, M.D., PhD of the Norwegian Institute of Public Health. Out of every 100,000 screened women, 1,909 had breast cancer during the six-year period. This was compared to 1,564 of every 100,000 in the control group. “The cumulative incidence of invasive breast cancer remained 22 percent higher in the screened group,” the study authors said, and screened women of every age were more likely to be told they had cancer.
This single study, of course, is not to say that women should not be screened for breast cancer or take the steps they feel necessary to be in charge of their own health and well-being. It simply points out, as did the authors of the study that much more needs to be known about how cancers develop in the body, why they develop and if some natural regression might occur.
Here is what might be the most significant statement regarding the findings, according to the authors. “Because the cumulative incidence among controls never reached that of the screened group, it appears that some breast cancers detected by repeated mammographic screening would not persist to be detectable by a single mammogram at the end of six years. This raises the possibility that the natural course of some screen-detected invasive breast cancers is to spontaneously regress.”
This evidence makes a person wonder just how many unnecessary breast cancer surgeries might be done each year in the United States. It also means that much more must be known about the different types of cancers that can develop, which ones need to be treated and which might be allowed to run their normal course and simply go away on their own.
Source: Norwegian Institute of Public Health. “Mammograms May Detect Some Cancers That Would Have Otherwise Regressed.” November 2008. http://www.eurekalert.org/pub_releases/2008-11/jaaj-mmd112008.php
Speak up and educate others,
Dr. Craig Burns
“Every human being is the author of their own health or disease.” Buddha
