Advocates on all sides of the breast screening debate are agreed that the earlier a malignant tumour is detected, the greater the chances of prolonging a patient’s life. The standard screening method worldwide is mammography – a two-dimensional X-ray (seen right, © Los Angeles Times) – and, adopted in the past decade, digital breast tomosynthesis (DBT), a type of three-dimensional X-ray of the breast. Two key questions that drive this debate are: (1) At what age should screening begin? And (2) How often should screening be conducted?
Women living in the USA could be forgiven for their bewilderment when considering recommendations from two competing organisations: the American College of Radiology (ACR), and the US Preventive Services Task Force (PSTF). The ACR has been consistent in its advice that women judged to be at average risk of breast cancer should begin screening at age 40 and this should be conducted annually until age 79. The PSTF, which previously – and controversially – suggested that women should wait until age 50 for their first mammogram, has now recommended lowering the age to 40 but retained the advice that screening be conducted every other year instead of annually.
Dr Debra Monticciolo (seen left), professor of radiology at Harvard who co-authored the ACR’s recent guidelines, was highly critical of the PSTF’s recommendations, stating: “Their own evidence shows that the most lives are saved with yearly screening. With annual screening of women 46-to-79, you get a 42% mortality reduction. Limit that to every other year, and it drops the mortality reduction to 30%. These are women’s lives that could be saved. I don’t know what their thinking is here.”
Dr Carol Mangione (seen below right), an internal medicine specialist at UCLA in Los Angeles, was chair of the PSTF’s panel that wrote the new guidelines which she believes “will help save lives and prevent more women from dying due to breast cancer.” Her panel, which was devoid of radiologists, expressed their concern that annual mammograms would significantly increase the number of false positive findings and rate of overdiagnosis.
Among the reasons given by Mangione’s panel to reduce the age from 50 to 40 was the evidence that certain females – especially Black and Jewish women – tend to develop more aggressive breast cancer and die earlier than white women. AuntMinnie.com has recently highlighted studies showing that screening with DBT can lead to false negative findings, particularly in women with dense breast tissue, while supplemental screening with ultrasound and MRI can be key to diagnosing interval cancers.
As pointed out in the Blog, everyone, including the USPSTF, agree that screening saves lives for women ages 40-74 (the ages of the women who participate in the randomized, controlled trials of screening). This was proven years ago in 1997 (Hendrick RE, Smith RA, Rutledge JH, Smart CR. Benefit of screening mammography in women ages 40-49: a new meta- analysis of randomized controlled trials. Journal of the National Cancer Institute Monograph 22: 87-92, 1997.) and acknowledged by previous Task Forces, but then ignored. There has never been an RCT to test screening every year compared to biennial or longer, however, the CISNET models, supported by the US National Cancer Institute, all show that annual screening starting at the age of 40 saves the most lives.
The USPSTF is misleading women and their physicians by suggesting that screening every two years reduces the “harms” of screening. In fact, the only “harms” that this reduces are pejoratively called “false positives”. They are not, in fact, women being told they have cancer when they do not – they are merely women “recalled” from screening who need a few extra pictures or an ultrasound to resolve something seen on the screening study and most are told there is nothing to worry about.
The intentional lack of experts on the USPSTF means that they have been misled by the claim that “overdiagnosis” will be reduced by a longer time between screens. The inexpert Task Force members likely believe the scientifically unsupportable claim that screening mammography finds cancers that would disappear if left undetected – hence two years between screens will allow “overdiagnosed” cancers to disappear. The arguments that have been claimed to support this are based on “nonscience”. No one has ever seen a mammographically detected breast cancer disappear on its own. Consequently, although screening every two years will reduce “recalls”, it will have no effect on “overdiagnosis” (if that even exists). The main effect of screening every two years is to give cancers an extra year to grow, spread, and become incurable.
If the Task Force persists in its biennial recommendation, the Panel should explain how many fewer recalls balance allowing one woman to die a death that annual screening would have prevented.