Breast cancer screening has become even more controversial since I was in medical school. There are a number of different ways to present the data. The most rigorous analysis of the available evidence is presented in the Cochrane Review (meta-analysis), which I just looked at again.
To summarize:
1. The review found 7 decent-quality randomized controlled trials involving 600,000 women. The higher quality studies (adequate randomization, involving around 300,000 women from what I could tell) found that screening mammograms did not reduce breast cancer mortality. The lower quality studies (suboptimal randomization) found that screening reduced breast cancer mortality.
2. The overall body of evidence from all 7 studies taken together show reduced breast cancer mortality (a problematic end-point, since overtreatment with some combination of surgery/chemo/radiation itself may cause excess mortality, and other considerations).
3. The authors’ best estimate is that screening reduces breast cancer mortality after 13 years by around 15%, and overdiagnosis and overtreatment is at 30%.
4. This translates to, for every 2000 women invited to screening over 10 years:
a. 1 woman will avoid dying from breast cancer
b. 10 healthy women will be treated unnecessarily with some combo of surgery/chemo/radiation
c. 200 women will experience psychological distress from anxiety and uncertainty for years because of false positive findings.
Under implications for practice, the authors conclude, “We believe that the time has come to re-assess whether universal mammography screening should be recommended for any age group.”
Here’s the full analysis, with a layman’s summary towards the beginning:
http://cochranelibrary-wiley.com/doi/10.1002/14651858.CD001877.pub5/fullInterestingly, the independent Swiss Medical Board in 2014 reviewed all the available evidence, including the Cochrane Review above, became troubled at their findings, and recommended that Switzerland’s national screening programs be abolished, causing widespread uproar:
http://www.nejm.org/doi/full/10.1056/NEJMp1401875The Swiss authors conclude, “It is easy to promote mammography screening if the majority of women believe that it prevents or reduces the risk of getting breast cancer and saves many lives through early detection of aggressive tumors.4 We would be in favor of mammography screening if these beliefs were valid. Unfortunately, they are not, and we believe that women need to be told so.”
I offer screening mammograms in my practice because all the US society guidelines currently recommend it, but taking into account the available evidence, I don’t really believe in it, I don’t push it, and I’ll probably forgo it altogether myself. Medicine does many amazing things (vaccines, insulin, hep C cure, and yes, many cancer treatments), but I’m also aware of its limitations. I take care of myself, exercise, etc, but when my time is up, it’s up. Life is brief and precious, and there are no guarantees.
NB: I’m not offering anyone medical advice over the internet here. I’m just presenting my personal perspective as a woman who has considered the evidence and the very real medical controversy.