Last night I read the following question on a public Q & A forum:
Why are doctors still ordering mammograms when I’ve seen it reported in several reputable sources that mammograms don’t reduce cancer risk via early detection, and may cause cancer?
The question, from a non-medical professional, I thought, was fair. I understand that there is a lot of confusion among patients and the public about screening mammograms. However, one of my colleagues, an oncologist, attempted to answer this question and actually agreed with the premise! I was floored by his answer. What nonsense! I couldn’t sleep. How could any physician hold this belief? I tossed and turned for an hour. At 3 AM I went into my office to write my own answer. Here it is…
Screening mammography is one of the biggest successes in modern medicine. Period. It is the poster child for a successful screening program. There is not an educated person in the world that can argue or would even attempt to argue that mammograms don’t save lives.
If you are a woman and you want to increase your chances for living longer, wear your seat belt, eat well, exercise, and…get your mammogram.
All major organizations in the United States and countries of the modernized world that have repeatedly analyzed the data have all come to the same conclusion and continue to recommend mammograms in order to save lives.
This includes the American Cancer Society, the United States Preventative Services Task Force, The American College of Radiology, Society of Breast Imaging, the American Congress of Obstetricians and Gynecologists, and the National Comprehensive Cancer Network, among others.
Unfortunately, to answer part of your question, for reasons that are hard for me to understand, it seems that lately harmful hysteria and disinformation that flies in the face of science and logic have been shamefully making their way into cult culture and even to a degree mainstream medicine.
With all due respect, look no further than the former answer by one of my oncology colleagues. He says, “Routine mammography has resulted in a huge increase in the number of women diagnosed with breast cancer but no corresponding decrease in mortality.” This could not be further from what the overwhelming majority of evidence demonstrates.
For example, randomized controlled trials of women invited to screening mammography (traditional screen film) from 1963 to 2000 demonstrate early detection and treatment of breast cancer have reduced the proportion of late stage breast cancer and led to a 20–30% decrease in mortality among these women.
Additionally, more recent data using more modern equipment and techniques have demonstrated even larger gains. In some age groups and demographics, this results in a near 50% decrease in mortality. This data is now well established and has been reproduced multiple times in multiple studies in several countries throughout the world including the United States, Canada, and Europe. (Broeders, et al. 2012; Lee, et al. 2010; Oeffinger et al 2015; Siu 2016).
So why is there any confusion about this subject at all?
One possibility is that the ideal frequency and timing when women should obtain mammograms is not as clear cut as their well established effectiveness. That is not because they may not be doing their job, but that at some point, the more you screen, the less the screening returns any significant results and the more that screening may begin to result in harm.
For example, it does no good to screen for breast cancer with a mammogram every day, every week, or even every month. As the author of this question rightfully points out, a small dose of radiation is given to the breast with every mammogram and it’s very unlikely that anything will change on a daily, weekly, or even monthly basis. Additionally, mammograms can sometimes result in extra biopsies which turn out to be nothing to worry about. So a few organizations have started to try and tweak the traditional yearly mammogram recommendations. However, this does not mean in any way that mammograms don’t work and don’t save lives!
The first organization to tweak the traditional recommendations was the United States Preventative Services Task Force (USPSTF). This organization is the somewhat “rogue” group that for better or worse likes to challenge the status quo in the medical world. In 2009, they changed their recommendation to state that a woman should have a mammogram every other year beginning at age 50 instead of every year beginning at age 40.
Their recommendation was based largely on the fact that they didn’t feel the extra cancers that would be detected or the advantage of earlier detection with an annual regimen were worth the extra biopsies that would be needed and the anxiety that they would produce. It was not based on the number of lives saved nor focused on radiation to the breast. In fact, their data acknowledged that more women would die from their recommendations, but that the number was acceptably small and not worth what they consider harm largely in the form of anxiety from extra biopsies.
You can now understand why this recommendation sent shockwaves through the medical community and became (and remains) one of the most hotly debated decisions in modern medicine. If you are interested in more detail about this decision, read an article I wrote here:
What Really was Said at the Water Cooler in 2009: USPSTF Breast Cancer Screening Recommendations and Current Physician Practice Patterns.
One final note in conclusion to try to completely answer the question. It is true that mammograms do give a dose of radiation to the breast. The best data I have available to put this into perspective in terms of risk benefit for a patient is as follows:
The potential risk from radiation to the breast is the risk of inducing a fatal breast cancer. For a woman at the age of 65 this risk (from a single mammogram) is estimated to be 0.3 in 100,000 (Hendrick 2010).
However, the benefit is the detection and treatment of cancer before it is clinically apparent. In this age group the likelihood of this is about 1 in 500. Furthermore, the chance that this detected cancer would be fatal without a mammogram is about 1 in 4.
In short, if you do the math, the benefit to risk ratio for a mammogram in this age group is somewhere between 90:1 and 180:1.
As you can see, like I said in the beginning of this article, if you are a woman and you want to live longer, do not bet against odds like this and get your mammogram. I hope this helps clarify some of the mammogram nonsense floating around out there.
Ryan Polselli, M.D., Diplomate of the American Board of Radiology, Fellowship Trained Breast Imaging Radiologist
Please note that this blog is intended for general informational purposes only and is not intended to be medical advice.