The US Preventive Services Task Force reviewed the breast-screening guidelines and concluded the benefits before 50 were too small to justify universal screening. The controversy that followed says as much about medicine as the evidence does.
The United States Preventive Services Task Force issued a report in November 2009 that stirred an astonishing amount of controversy. The task force, I should add, is an independent panel of experts especially chosen because they are experts in the field of preventive medicine, and are free of external influences and have no bias.
The team reviewed the guidelines concerning breast screening and came to the conclusion that the benefits of screening for women before 50 years old was too small to justify universal screening. But the benefits in the age group 50-59 years was such that each woman should be helped to decide for herself when to start getting mammograms.
[Screening for breast cancer: U.S. Preventive Services Task Force recommendation statement. Ann Intern Med 2009.151(10)716-236]
Since that time there has been a steady stream of articles, editorials and news reports criticising the report and suggesting that women should continue having regular mammograms, even in the younger age group.
This is not the first time that such a recommendation has been followed by attempts to nullify and even ridicule the recommendations. In 1997 a National Institute of Health (NIH) sponsored consensus conference concluded that “data currently available does not warrant a universal recommendation for mammography for all women in their forties”. There was such an outcry that even the NIH disowned the report and the decision came in front of the US Senate, which voted 98 to 0 in favour of mammography for women in their 40s.
[Fletcher SW. Whither scientific deliberation in health policy recommendations? Alice in Wonderland of breast cancer screening. N Eng J Med 1997;336(16)1180-3]
One can therefore imagine how difficult it is to try to sort out the false from the true and why trying to get patients to understand the complexity is both difficult and time consuming. As indicated in the early part of this letter, there is enormous bias both conscious and unconscious, towards mammograms. Many specialists, radiologists, companies involved in the industry and cancer associations all have an investment in mammograms, and will not shift their viewpoint lightly.
The very key to the confusion is that it does seem that some lives are saved by mammograms, but at a great cost to other women. The regular screening of 2000 individuals in the 40 to 49 age group avoids one breast cancer related death. In the group between 50 to 59 years of age 1,4 per 2000 are saved. The small probable benefit however must be balanced by the potential harm of screening which includes over-diagnosis and over-treatment, which includes surgery, psychological stress and damage, false positives and all that goes with such a diagnosis and possibly even death to a healthy woman.
The Cochrane Review of 2009, summarizing the harm done by mammograms, showed that screening 2000 women regularly for 10 years will result in 10 healthy women being turned into cancer patients and treated unnecessarily. These women will have surgery and often radiotherapy and chemotherapy. Of the 2000 screened women 200 healthy women will experience a false alarm.
[Gotzsche S Screening for breast cancer with mammography.Cochrane database Syst Rev 2009;(4)CD001877]
So this is the problem …. In order to save one life, 200 women may be given a false positive diagnosis and 10 healthy women will be treated as if they have breast cancer.
