There are a number of reasons why early detection is often oversold as a way to improve survival rates (which is not to say that early detection is bad, it just

There are a number of reasons why early detection is often oversold as a way to improve survival rates (which is not to say that early detection is bad, it just might not always help). The article doesn't seem to reference all of them directly, though I'll admit to skimming a bit. Here's a brief list, paraphrased from here: http://www.ncbi.nlm.nih.gov/books/NBK20938/ http://www.ncbi.nlm.nih.gov/books/NBK20938/ Lead-Time Bias: The earlier you detect, the earlier the clock on your survival starts. 5/10 year survival rates go up simply because the cancer is at an earlier stage when we started tracking how long people survive, not because early detection necessarily lead to more effective treatment. Length Bias: More screening means a higher probability of finding cancers which would have stayed relatively benign for a very long time (as opposed to cancers presenting very obvious symptoms). Survival rates appear to go up simply because you're detecting less threatening cancers. I believe the article references this idea. Overdiagnosis: Heavy screening means finding cancers that may never have become threatening at all (as the referenced link states, an extreme example of length bias). Survival rates go up, but not because screening helped. It's been suggested that countries which screen more often have better survival rates simply because they find cancers which would have benignly resolved themselves and gone unnoticed in countries which screen less often. Patient Self-Selection: Patients who seek out screening may be more likely to live healthy lifestyles.