No it isn't a metaphor. Not a good one anyway. Medical screening tests are a costs benefits analysis. Science does this. There is a cost for everything. If yo

No it isn't a metaphor. Not a good one anyway. Medical screening tests are a costs benefits analysis. Science does this. There is a cost for everything. If you have a disease that isn't causing any symptoms, do you treat it, even though it will probably never cause symptoms? There is a risk in all treatments, some more than others. There is a study that most prostate cancers don't show symptoms, ever and our super sensitive cancer diagnostics tests are causing more harm than good. More diagnostics does not mean more good. That's why we no longer do the Prostate-Specific Antigen (PSA) Test. It finds too many cancers that aren't going to cause harm and then people get unneeded treatment that causes side effects. (Source in: http://en.wikipedia.org/wiki/Prostate-specific_antigen http://en.wikipedia.org/wiki/Prostate-specific_antigen) For example, it used to be recommended that all women perform a breast self exam every month, then data showed us this didn't prevent cancer and actually caused harm because it lead to needless surgeries and biopsies. (Sources here: http://en.wikipedia.org/wiki/Breast_self_exam http://en.wikipedia.org/wiki/Breast_self_exam) We just don't throw more diagnosis and screening at patients and assume that is a good thing.