Conflicting advice makes it hard to know when to get a mammogram
Deciding when to get routine mammograms can feel confusing for women who are considered “average risk,” because major groups are offering different starting ages and screening intervals. The American College of Physicians, in new guidance issued last month, urged average-risk women ages 50 to 74 to get mammograms every other year, and it recommended that women ages 40 to 49 discuss the pros and cons with a doctor. For women 75 and older, the guideline says doctors can ask whether they would like to stop routine screening.
Much of the disagreement comes down to how screening guidance is built. It is designed for women with no symptoms and with “average” risk, but breast cancer is common and risk can vary in ways that are not always easy to measure with certainty. Dr. Laura Esserman of the University of California, San Francisco, framed the problem this way: “Breast cancer is not one disease,” and she said, “So how in the world does it make sense to screen everybody the same when everyone doesn’t have the same risk?”
Esserman is leading research intended to better capture those nuances, with an eventual goal of tailoring screening recommendations more closely to a person’s risk level. Even as guidelines evolve, the stakes remain high: more than 320,000 women in the U.S. are expected to be diagnosed with breast cancer this year, according to the American Cancer Society, and breast cancer remains the second-most common cause of cancer death in U.S. women, even as death rates have dropped for decades due to improved treatments.
The new American College of Physicians advice arrived as a surprise to some because most other U.S. groups have urged women to start earlier, in their 40s. The influential U.S. Preventive Services Task Force recently switched its recommendation to start every-other-year mammograms at age 40 rather than 50. The American Cancer Society has long recommended yearly mammograms for women ages 45 to 54 and says women can choose to start at 40, and for women 55 and older it says they can switch to every other year or choose to keep getting yearly checks.
The groups also differ in how they handle stopping screening later in life. The American College of Physicians guideline says doctors can ask women 75 and older whether they wish to stop routine screening. The American Cancer Society’s guidance takes a different approach, saying there is no reason to stop as long as someone is still healthy.
One reason guidelines do not align is that benefits and harms can shift depending on individual risk. In general, a higher future risk can mean a woman gets more benefit from catching cancers earlier with more frequent screenings. But beyond well-known genetic factors such as BRCA1 and BRCA2, it can be difficult to know who has a higher risk of developing breast cancer, and age has long been used as a proxy because risk tends to rise as women get older.
Mammograms also have limits. They can miss cancer, and some aggressive tumors may appear after a routine mammogram. At the same time, guidelines aim to balance earlier detection benefits against potential harms, including the stress and pain of follow-up tests for findings that ultimately turn out not to be cancer. Dr. Carolyn Crandall of the University of California, Los Angeles, who chaired the American College of Physicians report, cautioned that “We’re not saying there’s no benefit” from mammograms in the 40s, but she said there is “a narrower balance between the benefits you could get and the harms in 40- to 49-year-olds.”
Breast density adds another layer to decision-making. Nearly half of women over 40 have dense breast tissue, which can make tumors harder to see on mammograms and can slightly increase the risk of developing cancer. After a mammogram, women are notified about their breast density, and many experts say it is not yet clear whether people with dense breasts benefit from adding ultrasounds or MRIs to screening. The American College of Physicians guidance, however, advises considering 3D mammography—what doctors call digital breast tomosynthesis or DBT.
Researchers are also exploring ways to refine the optimal screening schedule. One recent example highlighted by Esserman’s team is the WISDOM trial, which used factors including age, genetic testing, lifestyle, health history and breast density to classify women as low, average, elevated or high risk. The trial’s risk level determined whether participants waited to start mammograms at 50, went every other year or yearly, and the highest-risk group was told to screen twice a year, once with a mammogram and again with an MRI scan. Esserman’s team reported in the medical journal JAMA that risk-based screening worked as well as yearly screening.
Beyond WISDOM, the article notes that adding broader gene testing and risk factors could help refine schedules, and it also points to emerging AI tools intended to assess a woman’s risk of developing breast cancer in the next few years using clues from mammograms. For now, women are advised to talk with doctors about close relatives who have had cancer, their overall health, and other risk factors such as whether they have had children and at what age. Whatever schedule a woman chooses, the American Cancer Society’s Robert Smith said: “Breast screening works best when it’s done regularly.”