The American Cancer Society published updated guidelines Oct. 20 that recommend annual mammograms for asymptomatic women at general breast cancer risk starting at age 45 until age 54, and then moving to screening mammograms every two years starting at age 55. This is the first time the American Cancer Society (ACS) has updated its breast cancer screening guidelines since 2003. The updated guidelines make a number of revisions, including changing the age to begin 1 screening mammogram per year from 40 to 45 years of age and extending the interval between screenings for postmenopausal women (JAMA. 2015;314[15]:1599-1614. i:10.1001/jama.2015.12783). The latest guideline is the first to address the question of when to stop routine mammography, and its recommendation is to stop routine screening for women with a life expectancy of less than 10 years. the ACS guideline also recommends against clinical breast screening at any age. In an accompanying commentary, Nancy L. Keating, MD, and Lydia E. Pace, MD, of Brigham and Women’s Hospital in Boston, note that these revisions bring the ACS guidelines more in line with the recommendations of the U.S. Preventive Services Task Force (USPSTF). The two organizations now agree on most of the recommendations and emphasize that breast cancer screening decisions should be individualized to reflect a woman’s values and preferences, not just her potential risk. Both sets of recommendations also give greater consideration to the potential harms of mammography: overdiagnosis and overtreatment of painless breast cancer, as well as false-positive results, additional imaging exams, and unnecessary biopsies. The latest ACS recommendations are based on the latest evidence accumulated from randomized controlled trials and long-term follow-up of population-based screening programs. For asymptomatic women at general breast cancer risk, the ACS guidelines give the following recommendations: Routine screening mammography once a year starting at age 45 years (rather than 40 years). An assessment of the burden of breast cancer by a 5-year age span, but not by a 10-year age span, found a significant difference in risk/benefit for women aged 40 to 44 years compared with older women and that it was no longer worthwhile to recommend screening starting at age 40 years. However, the ACS encourages clinicians to have discussions about breast cancer screening with patients in their 40s. For those women who want to begin screening mammography once a year before age 45, they should be offered the opportunity to screen after a clear trade-off between the pros and cons. Some women value the potential benefits of early screening and are willing to accept the risks associated with additional screening. Other women believe the risk of breast cancer is relatively low and choose to delay starting screening. Women aged 45 to 54 years should receive annual screening mammograms, moving to screening every 2 years starting at age 55. The relative benefit of annual screening decreases after menopause, as women age, and most women enter the postmenopausal period at age 55. Also, the relative harms of screening once a year increase at this age because the chance of a false-positive result increases with the number of screenings. However, women who prefer to continue screening once a year after age 55 should be given the opportunity to do so. Women should continue to have screening mammograms as long as they are in good general health and have a life expectancy of ≥10 years. The incidence of breast cancer increases with age up to 75-79 years, and the sensitivity and specificity of screening mammography improves with age, so screening mammography in this age group would reduce breast cancer deaths. However, recent studies have found that older women with severe or even advanced disease continue to have mammograms, even though such screening does not increase their life expectancy or improve their quality of life, a finding that raises concerns. Kevin C. Oeffinger, MD, of the ACS Guideline Writing Group, and colleagues noted that “health and life expectancy must be considered in screening decisions, and not age alone.” Clinical breast screening is no longer recommended at any age. Previously, the ACS had recommended regular clinical breast exams for women younger than 40 years and recommended 1 exam per year for women ≥40 years. However, there is no evidence that these exams (whether they are performed alone or in conjunction with mammography) improve the detection of breast cancer. Given that clinical mammography is somewhat time-consuming, clinicians should use this time to ascertain family history and to inform women to be on the lookout for any changes occurring in the breast and about the potential benefits, limitations, and harms of screening mammography. The authors note that this new recommendation should not be taken to mean that clinical mammography is not important, however, and that it has potential value in resource-poor settings where mammography screening is not available. In an accompanying commentary, Drs. Keating and Pace state that this recommendation is a clear departure from previous ACS guidelines and a clearer position than the U.S. Preventive Services Task Force (USPSTF), which merely states that the current evidence is neither sufficient to recommend nor not recommend clinical breast examinations. According to the most recent data, 85% of women in the 40-year age group and 50-year age group who die from breast cancer do so regardless of whether they receive mammography screening. Even this 15% relative benefit translates into a very small absolute benefit: routine mammography may prevent only 5 out of 10,000 women in the 40-year age group and 10 out of 10,000 women in the 50-year age group from dying of breast cancer. In the case of women over 40 years of age who are at general risk, there is not really a correct answer to the question of whether to perform mammography (JAMA 2015;314[15]:1569-71). The preparation of the latest ACS guidelines was funded by the ACS and the National Cancer Institute.Dr. Oeffinger declared no relevant financial conflicts of interest, and other authors declared ties to multiple drug companies. Ritu Salani, MD, associate professor of gynecologic oncology at The Ohio State University, and Monica Hagan Vetter, a third-year intern in obstetrics and gynecology at The Ohio State University, said the new screening guidelines are more flexible. The guideline’s recommendation to begin screening mammography at age 45 has good logic, and the recommendation to screen every 2 years after age 55 has a sound basis. Physicians are generally slow to accept new guidelines and may need to properly educate patients about new guideline recommendations, and patient adherence to new guideline recommendations may be low, at least initially. In the United States, where women’s life expectancy is close to 80 years and many women continue to function relatively well beyond that age, screening women who can be managed (if needed) and have good outcomes is possible given this factor. Although it will take some time for clinical practice to change, these recommendations will reduce unnecessary costs without compromising outcomes. Given that obstetricians and gynecologists are the primary source of education and prescribers of breast cancer screening, it is important that obstetricians and gynecologists are aware of the latest screening recommendations and know how to identify women at risk so that they can make the most informed individualized screening decisions. dr. Ritu Salani and dr. Monica Hagan Vetter declare no financial conflict of interest.