The American Cancer Society is now saying that its previous guidelines on breast cancer screening are too aggressive. 

They are advising most women to begin mammograms later in life and to have them less frequently.

The new guidelines say most women should wait to start annual mammograms until they are 45, and suggesting women scale back to screening every other year at age 55.  They are also recommending foregoing breast exams performed by their doctor.

Until now, the American Cancer Society was urging women to get mammograms every year from age 40 and up.

It turns out that some cancers detected by mammograms would never have posed a threat to a woman’s health or life. Others are so slow-growing that even if they’re not detected until they cause symptoms, they are treatable. Still others are so aggressive that even catching them “early” is too late. In these situations, mammograms therefore have little effect on whether a woman will die of breast cancer.

As a result, about “85 percent of women in their 40s and 50s who die of breast cancer would have died regardless of mammography,” Drs. Nancy Keating and Lydia Pace of Brigham and Women’s Hospital wrote in a JAMA editorial.