Tracey Koehlmoos: To screen or not to screen—mixed messages on mammography

Tracey KoehlmoosYou might not know this, but I am over 40 and I am a woman.

In the US having breasts and being over 40 means something to doctors and patients. It is a healthcare trigger to start having annual mammograms. If you are reading this in the UK, Canada, or Europe, you might be surprised because your own guidelines are so different—starting at 50 and with greater spacing (2-3 years), which is where the evidence show us we get the most benefit from routine screening.

When I registered with my new healthcare centre in the Washington, DC area, I was asked repeatedly why I had not had a mammogram and did I not want to schedule one soon? I responded that I was following the recommendations of the US Preventive Services Task Force (USPSTF) which recommended that women under 50 years of age do not require routine screening via mammography.

No one who I encountered at the clinic had heard of the USPSTF, which made its recommendations in November 2009. Most of the health professionals whom I encountered thought I was seriously misinformed and put sincere effort into trying to change my mind.

Most American women whom I meet have not heard of the recommendation to save routine screening until after age 50 and none have heard about the potential risks of routine and frequent mammography. Further, in US healthcare reform (the Affordable Care Act) the recommendation for 40 as the starting point has been enshrined in the mandate for insurers to cover routine mammography.

Last week, the debate flourished again in the mainstream US media when a report came out covering thirty years of screening and cancer incidence. They report that 1.3 million women may have been overdiagnosed or more than 70,000 women in 2008 alone.

As with so many important issues in health, there is a Cochrane Review that deals with mammography’s impact on mortality. It comes across as being rather against the use of mammograms, as mammograms risk turning healthy women into cancer patients or overtreats them more often than it saves their lives. Below is the plain language summary:

“The review found that screening for breast cancer likely reduces breast cancer mortality, but the magnitude of the effect is uncertain. Screening will also result in some women getting a cancer diagnosis even though their cancer would not have led to death or sickness. Currently, it is not possible to tell which women these are, and they are therefore likely to have breasts or lumps removed and to receive radiotherapy unnecessarily. The review estimated that screening leads to a reduction in breast cancer mortality of 15% and to 30% overdiagnosis and overtreatment. This means that for every 2000 women invited for screening throughout 10 years, one will have her life prolonged. In addition, 10 healthy women, who would not have been diagnosed if there had not been screening, will be diagnosed as breast cancer patients and will be treated unnecessarily. Furthermore, more than 200 women will experience important psychological distress for many months because of false positive findings.”

There is, of course some part of me that is now worried…what if? No one wants to be the person who takes an evidence based stand and subsequently dies of that disease. In some small part of my brain I am thinking, “If I die of breast cancer before I am 50, it will be universal bad karma because I did not say ‘Yes’ to the nice ladies at the clinic and schedule a free mammogram.”

Tracey Koehlmoos is adjunct professor at George Mason University, Washington DC, and adjunct scientist at ICDDR,B.