The lady doth protest too much, methinks. Hamlet: Act 3 Scene 2. William Shakespeare.
Some see in the intense scrutiny on screening mammograms a coordinated effort to discredit screening for breast cancer . However, screening generates controversy because there is so much uncertainty about the actual survival benefits of screening. There is so much uncertainty precisely because the benefits are so small at a population level .
Mammograms are one of medicine’s marginal calls but mammography is no longer solely in the purview of science as it extends into domains such as anthropology, political philosophy, and psephology . Science can no longer referee the mammography debate .
The results of the 25-year follow-up of the Canadian National Breast Screening Study (CNBSS) have added to the impasse . The study, which enrolled 89,835 women, has been cited 233 times in just over a year and has received considerable media attention . We will analyze the CNBSS for its signal, against the noise.
Canadian National Breast Screening Study
To rationally inform policy for screening of breast cancer, the Canadian government instituted the CNBSS. This randomized control trial (RCT) divided women in two groups: age 40 to 49 years (CNBSS 1) and 50 to 59 years (CNBSS 2).
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The noise
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Randomization
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Power of the study
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Are the participants generalizable?
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How much does the efficacy of treatment matter?
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Are we measuring screening correctly?
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Quality of mammograms
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The signal
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Should CNBSS influence policy?
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How should CNBSS influence radiologists?
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References
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