Women who have an average risk of breast cancer should have mammograms every two years from ages 50 to 74, according to the latest recommendations released today by the U.S. Preventive Services Task Force (USPSTF).
Women in this 50-to-74 age group are the most likely to benefit from regular breast cancer screenings, suggested the USPSTF, a 17-person, government-appointed panel of medical experts that makes recommendations on the effectiveness of preventive health services.
Average-risk women in their 40s also may benefit from getting mammograms, but their overall likelihood of seeing a benefit is smaller, and the potential for harm is larger than for average-risk women age 50 and older, according to the USPSTF's recommendations, published online today (Jan. 11) in the journal Annals of Internal Medicine.
These latest USPSTF guidelines are basically the same as those the panel released in 2009. But since that time, there has been greater agreement among the guidelines of several major groups of experts, such as the American Cancer Society, the American College of Physicians and the American Academy of Family Physicians, said Dr. Albert Siu, chair of the task force and a professor of geriatrics and palliative medicine at the Icahn School of Medicine at Mount Sinai in New York City. [6 Things Women Can Do to Lower Breast Cancer Risk]
These groups have independently concluded that mammography is effective and that its benefits increase particularly in women age 50 and over, Siu told Live Science.
All of the groups recognize that there is a role for starting mammograms in women in their 40s and support the idea of a personal, informed choice for women in this age group, he said.
"The decision to start mammogram screening before age 50 should be an individual one" for average-risk women, the new guidelines state.
In other words, women ages 40 to 49 should consider starting breast cancer screenings, but their doctors should inform them about the potential benefits and possible harms of the screening test so that they can weigh both sides in making their decision.
After reviewing the newest scientific evidence on mammograms, the task force found that the number of deaths from breast cancer that the screening test can prevent in average-risk women under 50 is smaller than that in older women, and that the number of false-positive results and unnecessary biopsies is larger.
A false positive is a result that suggests a woman may have cancer but additional testing and procedures later show that she does not. False-positive findings can be stressful and provoke anxiety, and they may lead to the possibility of overdiagnosis and overtreatment.
Still, the task force supports the decision of women who want to start screening in their 40s, and the new guidelines note that the risk of problems from screening may increase decrease as women move from their early 40s to their late 40s, Siu said.
Weighing risks and benefits
Various organizations that make breast cancer recommendations have come to relatively similar conclusions in the areas where the science is fairly black and white, Siu said.
Where the groups diverge is in their different interpretations of the gray areas, where studies have not been done, or the areas for which the groups weigh the benefits and risks differently, he said.
For example, one gray area is whether average-risk women in the 45-to-55 age group should start mammograms and, if so, how frequently they should get them, he noted.
Unlike the USPSTF recommendations to start mammograms at age 50 and rescreen every two years, the American Cancer Society advises women to begin mammograms at age 45 and to have them yearly until age 54. Then, at age 55, women should get mammograms every two years, according to the group's latest recommendations, released in 2015.
Recommendations from other groups, such as the American College of Obstetricians and Gynecologists and the National Comprehensive Cancer Network (a worldwide alliance of cancer centers), call for yearly mammograms in average-risk women age 40 and older.
The differing recommendations about when and how often to get mammograms can leave women feeling confused, but ultimately, the decision all boils down to personal choice and consideration of the benefits and risks, Siu said.
The majority of American women fall into the average-risk breast cancer category, Siu said. Women are considered to have average risk if they do not show symptoms of breast cancer, such as a breast lump or high-risk breast lesion, have never had breast cancer, do not have a known genetic mutation for breast cancer, such as a BRCA1 or BRCA2 gene mutation, and did not receive chest radiation at an early age.
The average-risk group also includes women age 40 and over who have breast cancer in their family, such as a mother, sister, aunt or daughter who was diagnosed with the disease, but did not have a genetic mutation for it.
New to the USPSTF guidelines this year was the group's evaluation of the effectiveness of three-dimensional mammography, as well as an evaluation of the effectiveness of adjunctive treatment for dense breasts with MRI, ultrasound or 3D mammograms, Siu said. The task force made no recommendations in these two areas because they found insufficient evidence to determine the balance of benefits and harms. [6 Foods That May Affect Breast Cancer Risk]
The task force also said that there was insufficient evidence to recommend that average-risk women age 75 and over continue getting mammograms.
Mammography is an effective but imperfect tool, Siu said. Over the past decade, science has begun to recognize that there are potential harms from cancer screening, including overdiagnosis, or the detection and treatment of cancer in people who would have never been bothered by the disease in their lifetimes, he explained.
There is increased recognition that overdiagnosis does exist, and it may be on the order of one in five women diagnosed with breast cancer over approximately 10 years, Siu said.
Even knowing this chance for overdiagnosis, the task force recognizes that many women, especially women under 50, may choose to get screened more often, but they should be aware and informed of the risks, he said.