@Matt: ...just because you've fallen into the category of "machine says you have cancer" doesn't mean you have cancer. It doesn't even mean you're LIKELY to have cancer. It just means that more tests need to be carried out.
And not only that, but those additional tests sometimes have side effects that may, depending on your personal valuation, be worse than the risk of missing something. Hence the somewhat recent controversial recommendations re. routine breast & prostate cancer screenings, in which doctors no longer encourage it from as early an age in general. (E.g. I think routine mammograms are no longer recommended for 40-50 year olds? I forget. Which isn't to say that it's recommended to NOT get them.) Yes, by skipping them people will be more likely to miss cancer -- but they'll also be more likely to skip damaging side effects as well. Where the tradeoff is probably varies significantly from person to person.