Skip to Main Content

The American Cancer Society recently urged most women — those who aren’t at high risk of breast cancer — to postpone having their first mammogram until age 45 and to have the test less frequently after age 54. But those guidelines conflict with recommendations from other equally well-respected organizations, such as the American Congress of Obstetricians and Gynecologists (begin mammograms at 40) and the US Preventive Services Task Force (begin at 50).

What’s a woman to do? And why is it so tough to come up with standardized guidelines that everyone agrees on? We asked a half-dozen experts to weigh in.


Ruth O’Regan: “Nothing magical” in a woman’s breasts at age 40, 45, or 50
Brian Zikmund-Fisher: Women’s stories, experiences may trump data
Maryanne Bombaugh: Preferences play a role
Harold Burstein: Decision requires “nuanced and detailed” conversation
Mohit Bhandari: When guidelines conflict, prior beliefs may rule
Andrea LaCroix: Look to WISDOM for guidance

By Ruth O’Regan: Nothing magical happens to a woman’s breasts when she is 40, 45, or 50, the ages at which the American Congress of Obstetricians and Gynecologists, the American Cancer Society, and the US Preventive Services Task Force, respectively, have picked at which women should start having mammograms. Each of these groups has, based on its interpretation of the data, developed the strategy it believes best identifies dangerous breast tumors while minimizing false positives and the treatment of cancers that would never have harmed health.

The ongoing controversy over the timing of breast cancer screening shows the beauty — and the hazards — of the scientific process. Editors, with the help of peer reviewers, decide which articles to publish. Editorials, commentaries, letters to the editor, and subsequent research help the scientific community determine what a particular piece of evidence means and its importance to medical practice. Each step involves personal judgment, and can sometimes be as subjective as it is objective.


Legitimate differences in opinion help us make sense of the data. But they can also confuse the public, not to mention health care providers. You can see this in the conflicting recommendations for breast cancer screening.

Nothing magical happens to a woman’s breasts when she is 40, 45, or 50.

New and better evidence could help close the gaps, but that likely won’t be appearing soon. In the meantime, it’s important to make sure women know that mammograms are an important preventive strategy but that they have limitations: some women with “negative” mammograms have breast cancer, and some women with mammogram-detected tumors don’t need treatment. We need to focus efforts on improving the accuracy of mammograms, especially in younger women, and determining which cancers don’t need treatment.

Ruth M. O’Regan, MD, is a breast cancer specialist and professor of medicine at the University of Wisconsin School of Medicine and Public Health, where she heads the division of hematology and oncology.

By Brian Zikmund-Fisher: Every woman wants to know, “How can I best protect myself from breast cancer?” Unfortunately, identifying the best policy about breast cancer screening is complicated.

One complication is the natural tension between population-level data and the individual stories that women and their doctors experience, hear, and tell. The fact that both are relevant ways to think about risk causes confusion and frustration at all levels.

Guideline makers look at populations. Their main focus is probability, or risk: By how much does mammography decrease the risk of dying from breast cancer across a population? By how much does it increase the risk of false positives or, more importantly, identifying and treating cancers that would never affect health or longevity? And how does age affect these risks?

Guidelines try to balance population-level benefits against risks. That makes perfect sense. As a society, we don’t want to invest resources in a strategy that doesn’t pay off in better health on average.

But individual women and their health care providers don’t see averages. Instead, they rightly care about the individual outcomes they see around them. As a result, they tend to look at breast cancer risk as a possibility rather than a probability. A 40-year-old woman can get breast cancer. A mammogram might find that cancer and save her life. Many women have a family member, acquaintance, or coworker who fits this story. Concrete stories like these are emotionally powerful. They make it difficult to say no to 40-year-old women who want to do whatever they can to prevent the possibility of dying from breast cancer. Statistics never feel as real as personal stories.

Statistics never feel as real as personal stories.

On the flip side, there are certain stories we never hear — stories of overtreatment. These are about women whose mammograms found cancer and who went through challenging treatment but didn’t really need it because their cancers would never have caused problems. Yet these women call themselves cancer survivors, just like those whose lives truly were saved by screening and treatment. We can’t tell them apart.

At the population level, there is little doubt that mammograms save lives when done at the right time — the ages when breast cancer is most likely to occur and when treatment is most likely to save a woman’s life. They probably don’t save lives on the population level when done at the wrong times — the ages when the risk of overtreatment outweighs the potential benefits of breast cancer screening.

The problem is that we can always find at least a few women who have benefitted from mammography at any age and hear their stories, even when the population-level data shows us that many more women have been harmed by screening.

Brian J. Zikmund-Fisher, PhD, is associate professor in the Department of Health Behavior and Health Education at the University of Michigan School of Public Health.

By Maryanne Bombaugh: The existence of multiple guidelines with different recommendations on when to start breast cancer screening with mammograms, how often to have mammograms, and when to stop creates confusion for women and their care providers. I hope that experts will come to consensus on breast cancer screening. To that end, the American Congress of Obstetricians and Gynecologists (ACOG) is planning a meeting in January to develop uniform guidelines for breast cancer screening that can be implemented nationwide.

Until consensus is reached, physicians and other care providers need to translate current recommendations for their patients and help them make good decisions about breast cancer screening. I tell my patients that it is a good idea to begin having mammograms at age 40 and to have them regularly, as recommended by ACOG. But I also share with them the uncertainties — that mammograms don’t detect every cancer and that false-positive results can lead to additional testing, biopsies, or procedures that may turn out to be unnecessary, expensive, and possibly harmful.

It is important to ask women how they feel about having mammograms. Their preferences should be part of the shared decision-making process, along with their individual risks and current recommendations for breast cancer screening.

Maryanne Bombaugh, MD, chairs the Massachusetts section of the American Congress of Obstetricians and Gynecologists.

By Harold Burstein: There’s a little bit less to the “controversy” about the new guidelines from the American Cancer Society than meets the eye. Two main messages shouldn’t be lost:

  • Mammograms save lives.
  • Women should get them.

That said, the guidelines reflect the fact that the mammogram is not a perfect test. The guidelines essentially ask women to sit down with their health care providers and discuss the reasons for breast cancer screening, along with the pros and cons of mammography. The conversation should also focus on a woman’s medical history, family history, risk factors, and preferences. With this information in hand, she and her health care provider can make a careful and personally appropriate decision about when to start having mammograms and how often to have them.

That’s an important conversation, but it is quite nuanced and detailed. It can be a challenge for a busy physician to convey all that information to a woman as she is making her decision.

In addition, the guidelines may have overstated the impact of a “false positive” mammogram finding. A false positive happens when a mammogram detects something in the breast that is later shown not to be cancer. It can be distressing to go through that experience, but recent studies suggest that most women manage this experience quite well.

Harold Burstein, MD, is a breast cancer specialist at the Dana-Farber Cancer Institute in Boston and associate professor of medicine at Harvard Medical School.

By Mohit Bhandari: It can be difficult to get doctors to accept a shift in practice, such as putting aside a procedure shown to be ineffective or changing the timing of mammography. They are more likely to change what they do if they strongly believe in the evidence on which the call for change is based. That poses a problem for breast cancer screening guidelines, because essentially the same data have been used to create conflicting guidelines.

It can be difficult to get doctors to accept a shift in practice.

Doctors also want to know, “Does the recommendation apply to the patient in front of me?” That appears to be an open question. The new American Cancer Society guidelines list a variety of factors that could alter the timing of mammography for individual women.

In situations like these, doctors tend to fall back on their prior beliefs, or use the recommendations from the professional society with which they most closely identify.

Mohit Bhandari has studied how physicians adopt new guidelines and recommendations for clinical care. He is professor of orthopedic surgery at McMaster University in Hamilton, Ontario.

By Andrea LaCroix: It is time to stop relying on data collected from studies done 30 years ago to determine how best to screen women for breast cancer today. We need new data derived from trials that employ state-of-the-art mammography and that harness what we have learned over the past three decades about the biology of breast cancer.

The WISDOM trial (Women Informed to Screen Depending on Measures of Risk) gets underway in early 2016. The goal of the five-year trial is to determine if a personalized approach is as safe and effective at detecting breast cancer as annual mammograms, and if it will reduce both false-positive results and the overdetection and overtreatment of tumors that would never harm a woman’s health.

WISDOM will compare two breast cancer screening strategies among 100,000 women:

  • Usual care: Women in this group will have mammograms every year beginning at age 40.
  • Personalized care: In this group, a woman’s risk of developing breast cancer — determined by her family and medical history, breast density, and genes linked to the development of breast cancer — sets the starting age and frequency of mammograms. Those at high risk would be urged to start having mammograms at an earlier age, have them more often, and continue having them until a later age. Those with a low risk would begin having mammograms later, have them less often, and stop having them earlier.

We hope that the WISDOM results will help guide the way to better, clearer guidelines for breast cancer screening.

Andrea LaCroix, PhD, is professor and chief of epidemiology at the University of California, San Diego and principal investigator in San Diego for the WISDOM trial.