Screening Mammograms: Choose Your Guidelines

Image of mammorgraphy patient at mammogram machine with technician.

This month, the American Cancer Society (ACS) issued new guidelines recommending women with an average risk of breast cancer get an annual mammogram starting at age 45 until they’re 54. After that, the nation’s largest cancer advocacy group says, they should get a mammogram every other year – more often if they want – for as long as they are sufficiently healthy and expected to live another 10 years.

The ACS also announced it no longer recommends a clinical breast exam, a physical examination of the breast by a health care provider looking for lumps or other changes, for women of any age who have no symptoms or abnormalities. Previously, the cancer society recommended them once a year for all women 19 and over. But in announcing the change the ACS cited inconsistency in the quality of these exams and noted there is little evidence they help detect breast cancer early overall and some data to suggest they actually trigger unnecessary testing.

The previous guidelines from ACS, which had been in place since 2003, recommended annual mammograms and clinical breast exams starting at age 40 for women at average risk of developing breast cancer.

ACS’s update, developed by a panel of generalist clinicians, biostatisticians, epidemiologists, economists and patient representatives, was two years in the making. Kirsten Sloan, the ACS Cancer Action Network’s senior director of policy, told Kaiser Health that the guidelines reflect “the society’s current thinking based on an analysis of existing science and changing technology.”

The society concluded that even though women in their early 40s can benefit from breast cancer screening, breast cancer in this group is more rare and they are more likely than older women to get false positive results, which can lead to unnecessary—and potentially harmful—tests and procedures.

Guide to the Guidelines

 This places ACS right in the middle of an array of recommendations with slight variations.

  • The National Comprehensive Cancer Network, an alliance of prominent cancer centers, the American College of Radiology, the American College of Obstetricians and Gynecologists, and the Society of Breast Imaging all recommend screening mammograms every year starting at age 40.
  • The American Cancer Society now recommends mammograms each year starting at age 45 and continuing yearly until age 54. After that they recommend screening once every two years for as long as a woman’s life expectancy is at least 10 years.
  • The United States Preventive Services Task Force (USPSTF), experts appointed by the Department of Health and Human Services, have recommended since 2009 that women get tested less often and start later, every other year from age 50 to 74.
  • The Canadian Task Force on Preventive Health Care recommends a mammogram every two to three years for women aged 50–74.

The differences may seem small, but a woman who followed the ACS guidelines to the letter would have 20 mammograms by the time she turned 74 – about 50 percent more than a woman who followed the USPSTF guidelines.

ACS’s revised guidelines are not expected to change decisions by insurance companies about payment for breast cancer screening. Health plans are required to cover preventive services that are recommended by the USPSTF, a nonpartisan group of medical experts, without charging consumers.

Adam Cifu, MD

Adam Cifu, MD

The new ACS guideline “comes closer to agreeing with the available evidence,” said Adam Cifu, MD, professor of medicine at the University of Chicago and an authority on changing medical practices. Cifu is also coauthor of the JAMA Clinical Guidelines Synopsis series, which summarizes guideline recommendations for physicians.

“Mammography does reduce breast cancer mortality but we do not have good evidence that it reduces all-cause mortality,” he noted. “It carries the risk of false positives, especially common in younger woman, and, potentially, over-diagnosis. The stress in these new guidelines on patient decision making is welcome.”

If women chose to start screening at age 45, rather than 50, “there might be a slight benefit to the ACS recommendations in term of breast-cancer mortality,” he said, “but there would certainly also be an increase in unnecessary procedures among woman following the ACS guidelines.”

A Woman’s Choice

The new ACS guidelines now more closely align with the task force’s recommendation to start screening at age 50. However, both groups’ guidelines note that some women may choose to be screened earlier than the recommended age, and argue that the decision should be an individual’s personal choice, after consulting with her doctor.

Olwen Hahn, MD

Olwen Hahn, MD

“It is important to note that the ACS’s new guidelines are for women with an average risk of breast cancer,” said breast cancer specialist Olwen Hahn, MD, assistant professor of medicine. “These new guidelines do not apply to women who may have a higher risk of breast cancer due to personal or family history of cancer, or women with a genetic mutation that increases their risk of cancer. Women should speak with their physician to discuss their individual risk for breast cancer and decide on the breast cancer screening approach is best for their individual situation.”

The different screening guidelines from various professional committees can be a source of confusion for women.

“But they can be individualized to best reflect a woman’s preferences and values for cancer screening as well as her individual risk of breast cancer,” Hahn said.

“Physicians are correct to debate the evidence about screening mammography,” said diagnostic radiologist David Schacht, MD, MPH. “At times we may draw different conclusions about that evidence, and that’s OK, an important part of what we do as academic physicians. From a societal perspective, and as it relates to our patient population in particular, it is more important to me to be aware of how many women do not follow any guidelines at all. So many of our patients, whether due to limited time or resources, limited access to primary care, or limited medical literacy, do not follow guidelines from any organization.”

David Schacht, MD, MPH

David Schacht, MD, MPH

“I also hope that in the future, the passion and vigor that has been applied to creating mammography recommendations will be expanded to other aspects of medical care in this country. There are many other medical interventions that deserve a similar or greater level of scrutiny

So Many Experts, So Many Opinions

Why are the various guidelines not consistent, and why do they keep changing?

They change because “the evidence underlying these guidelines remains weak,” Cifu said. “Aside from lung cancer screening, we adopted screening programs before we had a robust evidence base for them. The trials to assess the benefits and harms of these programs are difficult to perform and become more difficult as the screening programs become more entrenched.”

With so much conflicting advice, how should women make a decision?

There is one thing on which experts agree: there is no single answer that suits all women. Those who want to catch tumors when they are as small and treatable as possible should screen earlier and more often, even if it means they could be summoned back to the clinic for more tests because of a mistaken result.

Women who consider screening a distressing nuisance can start later and get tested less often, as long as they accept one possible consequence—if they do develop cancer, the tumor may be larger and more virulent than it might have been had they caught it earlier.

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