Mammogram screening for breast cancer has become controversial. It's an emotional topic and the science is persuasive but not definitive. The danger of over-screening is ever present not just for breast cancer but for all types of diseases. False positives do have victims although the medical establishment doesn't often talk about it.
Here are two recent articles of new studies:
Screening has little impact on breast cancer deaths: study (link)
It's very hard, and often impossible, to measure directly the impact of a health policy because we cannot randomly assign people into treatment and control groups for comparison. Once a policy is in place, everyone is subject to the policy. If, as in this case, there are women who elect not to have mammograms, it may seem like we have two comparison groups: those who did and those who did not have mammograms. The challenge is that the women who choose not to do them are different from those who choose to do them in many ways. For instance, uninsured women are probably less likely to do them, and women who don't have insurance are probably poorer, less educated, etc. Such factors could explain any change in breast cancer deaths, as opposed to the use of mammograms.
This new study does a sort of pre-post analysis. In different countries, the mammogram guidelines went into effect at different times. If such screening truly reduces breast cancer deaths, then one should observe a marked drop in deaths when comparing the period before to the period after adoption of those guidelines. Thus, we can look at the timing of the policy and the timing of drop in cancer deaths to test this hypothesis.
The analysis is tricky. Many other factors may be contributing to the decline in breast cancer deaths. So the researchers find pairs of countries that have similar health care systems but different timing of mammogram policies. Of course, the analysis would break down if the matching procedure is found to be flawed.
Their conclusion is that the timing of the drop in breast cancer deaths is unrelated to the timing of regular use of mammograms.
Mammograms: computer-aided detection doesn't help (link)
This study confirms earlier findings that having computers help radiologists read results does not lead to higher accuracy. Sadly, it leads to over-diagnosis. This reminds me of the issue in Chapter 1 of Numbers Rule Your World: this technology may be worthless but what if patients perceive them to be useful?