Mammograms should begin at 40 for women with an average risk of breast cancer and by 30 for high-risk women, according to guidelines released by two groups.
The joint recommendations from the American College of Radiology and the Society of Breast Imaging also cover the use of magnetic resonance imaging and breast ultrasound in women who are at high risk of developing breast cancer.
New York-based Memorial Sloan-Kettering Cancer Center's Dr Carol Lee said mammography screening at 40 resulted in a significant decrease in breast cancer mortality, which amounts to nearly 30% since 1990, and is a major medical success.
The Society for Breast Imaging's President Dr Phil Evans said they also help fill in gaps in terms of how to screen high-risk women.
The recommendations contradict controversial guidelines from a US Preventive Services task force, which recommended against routine breast mammograms for women in their 40s.