For women and their doctors, early detection of breast cancer has always had a crapshoot quality to it. Regular mammograms seem like a wise precaution, but the tests may be expensive and unreliable--and in a very small number of cases, may actually help stir up the very disease they're designed to spot. Neglecting mammography can be even riskier, giving an incipient tumor a chance to take hold and grow. This year the confusion only increased, with the medical community clamoring for clarity just as various cancer advisory groups issued conflicting guidelines.
Last week the National Cancer Institute--part of the far larger...