"It's not the great lifesaver that people think it is. It's not a magic bullet," said Georgetown University researcher Dr. Jeanne Mandelblatt who was not involved in the study.
Study finds mammograms offer modest benefit →
So if you're 40 and have several risk factors _ like dense breasts and close relatives with the disease _ then you have the same risk as an average 50-year-old, not an average 40-year-old, and might consider earlier mammograms, Mandelblatt says.
Hit reset on cancer screening: 'Tests not perfect' →