The American Cancer Society, the American College of Obstetrics and Gynecologists, and the National Comprehensive Cancer Network all recommend annual mammograms for women 40 and older. The U.S. Preventative Services Task Force does not recommend regular screening before age 50, but suggests making an individual decision with your doctor about when to begin screening. They do recommend mammograms every other year starting at age 50.
So why all the contradictions and controversy? Well, some people worry that too many mammograms lead to unnecessary anxiety and false positives, while others value the added emphasis on early detection. Pruthi says she goes along with the recommendation to screen annually starting at 40, but she makes sure to counsel patients on the risks and limitations of mammograms — like that they don't find everything, and they could possibly lead to false positives or unnecessary biopsies.
Some people at a higher risk of breast cancer may need to be screened even earlier. If you have a first-degree relative (mom, dad, sister, brother) with breast cancer, it's recommended that you start getting mammograms 10 years before the age that they were when they were diagnosed. (So if your mom was 45 when she got breast cancer, get screened at 35.)
NOTE: There are not explicit recommendations for transgender individuals, but if you have breasts or you're taking hormones to transition to a woman, talk to your doctor about how often you should be screened.