Recent Articles on Breast Cancer Screening are Bunk
Sadly, two recent articles in respected medical journals underestimate the value of mammography. While I believe the authors’ intentions were well-meaning, I fear the articles do a disservice to women and may undermine a very serious and well-established message: Screening mammography saves lives.
As we’ve stated previously, we in the UCSF Women’s Imaging Section continue to advocate for annual mammography screening starting at age 40, which is one of the guidelines of the American Cancer Society (ACS).
An article in the February 4 issue of the Annals of Internal Medicine (AIM) concluded that there is little outcome difference between using the United States Preventive Services Task Force (USPSTF) and American Cancer Society (ACS) screening guidelines and indicates that using the ACS guidelines therefore adds unnecessary costs.
That article is misleading because it provides an incomplete picture of the costs vs. benefit of breast cancer screening programs. After all, the goal of health care is saving lives, not dollars.
In fact, an analysis published in the American Journal of Roentgenology showed that, if USPSTF breast cancer screening guidelines were followed, approximately 6,500 to 10,000 additional women each year in the U.S. would die from breast cancer.
In addition, the financial analysis performed by the authors of the AIM article is faulty because it used only the cost of screening and did not include the costs associated with the failure to screen. The costs of morbidity, lost income, treatment of metastatic disease, death and other real financial implications associated with a diagnosis of advanced breast cancer due to less frequent screening were not considered in the analysis.
A second article in the February 11 issue of the British Medical Journal (BMJ) also argued against annual mammography screening in women aged 40-59.
That article is an appallingly misleading analysis based on the deeply flawed and widely discredited 1981 Canadian National Breast Screening Study (CNBSS).The results reported in the recent BMJ article, and others resulting from the CNBSS trial, should not be used to create breast cancer screening policy because that would place countless women at increased risk of dying unnecessarily from breast cancer.
Daniel B. Kopans, M.D., F.A.C.R., one of the experts called on in 1990 to review the quality of the mammograms used in the CNBSS, recently wrote a scathing critique of the BMJ paper because of its basis on the CNBSS.
“To save money they used outdated and even second hand mammography machines. The images were compromised by scatter since they did not employ grids for much of the trial. They failed to fully position the breasts in the machines so that cancers were missed because the technologists were not taught proper positioning, and their radiologists had no specific training in mammographic interpretation,” Dr. Kopans said of the CNBSS.
In the CNBSS only 32 percent of the cancers were detected by mammography alone, which is half the number of the cancers that should be detected by mammography alone. The extremely low number is consistent with poor quality mammography.
Furthermore, the CNBSS used unsound research methodology. In order to be valid, randomized, controlled trials (RCT) require that assignment of the women to the screening group or the unscreened control group is totally random. A fundamental rule for an RCT is that nothing can be known about the participants until they have been randomly assigned so that there is no risk of compromising the random allocation. Additionally, a system needs to be employed so that the assignment is truly random and cannot be compromised. The CNBSS violated these fundamental rules.
There are many more sound scientific reasons for discounting results of the CNBSS, which is why Dr. Kopans said that, “it would be an outrage for women if access to screening was curtailed because of the poor results in the Canadian National Breast Screening Study (CNBSS) when it has been known for years that the trial was compromised from the start.”
What a shame that these two recent articles happened to be published so close together. That coincidence could raise doubts about the value of a screening technique that has been shown to lower the death rate from breast cancer.
Clearly, screening mammography saves lives, which is why we continue to recommend that women be screened annually at age 40— to maximize early detection and save the most lives.