 One-third of diagnosed breast cancers might recede on their own.Screening mammography efficiently finds non-life-threatening, asymptomatic breast cancers and precancers, even while overlooking serious cancers.According to H. Gilbert Welch of the Dartmouth Institute for Health Policy and Clinical Practice, research on screening mammography has taken the "brain-dead approach that says the best test is the one that finds the most cancers" rather than the one that finds dangerous cancers.