When to Get a Screening Mammogram

How often and when to start routine mammograms is a matter of debate.

Medically Reviewed by Laura J. Martin, MD on September 19, 2011

Every year? Every other year? Not until you're 50? Once you turn 40? Will the real mammography screening recommendation please stand up?

If you're a woman approaching the age of 40, you've likely been told to prepare for your first screening mammogram around the time of your big birthday and then to have one every year (in some cases, every other year) thereafter. (Of course, that's just for routine mammograms; breast lumps always require a mammogram and/or other tests to start diagnosing whether it might be breast cancer.)

But in November 2009, the U.S. Preventive Services Task Force (USPSTF) updated its screening recommendations and said that women of average risk for breast cancer could wait until age 50 to start getting mammograms and then follow up only every two years, rather than annually.

These new guidelines set off a heated debate within the medical community and don't match up with most other mammogram recommendations from major medical organizations.

The debate is still going on, leaving many women unclear about when they should schedule their mammograms.

"We're having the scientific arguments back and forth and in the meantime, women, in a sense, get caught in the middle," says Len Lichtenfeld, MD, deputy chief medical officer of the American Cancer Society.

Your doctor can help you sort out the options. Here's the background you need.

The revised USPTF mammography screening guidelines marked a sea change from the recommendations being made by nearly all major medical associations, including the American Cancer Society, the American Medical Association, and the American College of Obstetrics and Gynecology.

Although some organizations were more flexible with regard to the frequency of screening -- in some cases, every one to two years was acceptable -- women previously were advised to start mammography screening at age 40. That was also the Task Force's position in 2002, the last time it made a statement on the matter before 2009.

What fundamentally changed in 2009 was that the USPSTF came out against routine screening mammography in women age 40-49. Instead, it stated that the decision to get routine screening mammograms before age 50 should be "an individual one and take patient context into account, including the patient's values regarding specific benefits and harms."

It was widely reported, however, that the USPSTF was against screening entirely for women with an average risk of breast cancer between the ages of 40 to 49. That wasn't the case, says Diana Petitti, MD, professor of biomedical informatics at Arizona State University and vice chair of the 2009 USPSTF committee.

The actual recommendation was not communicated well, according to Petitti. "The decision about the age to start being screened at 40, 42, 44, 48, should be one that was more individualized," she says, rather than a woman's 40th birthday triggering an automatic authorization slip from her doctor to get a mammogram.

The USPSTF's other recommendations included biannual, rather than annual, mammograms for women ages 50-74. And there is insufficient evidence, the task force said at the time, to accurately assess the benefits and drawbacks of regular mammograms for women older than 75.

The argument over when women should start breast cancer screening stems from a disagreement about the process the task force used to reach its conclusions. It relied on a sophisticated computer model rather than real-life, clinical, randomized studies to determine how many breast cancers are caught and treated in women ages 40-49.

Lichtenfeld says that the conclusions reached by multiple institutions using the same model were different. "So the reliability of that model to make a clinical decision, particularly when we have data from actual studies, we felt was not quite ready for prime time," he says.

Phil Evans, MD, representative of the Society of Breast Imaging and director of the Center for Breast Care at the University of Texas Southwestern Medical Center, concurs with Lichtenfeld.

"One of the assumptions the task force made was the reduction of mortality in between the ages of 40 and 49 was 15%, and we know from real-life studies ... that the number is closer to 30%, twice what they used in their modeling. That's a huge difference in the number of lives saved," he says.

"The task force did acknowledge at the time that mammography did reduce deaths for women between ages 40-49, Lichtenfeld says. "However, we said then, and I think it's fair to repeat today, that the task force didn't feel enough lives were saved for women in that age group, because breast cancer is more common as you get older."

The American Cancer Society, Lichtenfeld says, disagrees and continues to recommend routine screening mammograms for women age 40 and older.

One of the central issues upon which the USPSTF based its recommendations had to do with the harm that can come from mammography testing: psychological harm, unnecessary imaging tests and biopsies, and false-positive mammogram results in which the patient is told there could be cancer, when in fact none exists. False-positive results are more common for women aged 40 to 49 than for older women.

"They were saying they felt the risk of harm of having extra procedures outweighed the benefit from saving lives, " Lichtenfeld says of the Task Force's reasoning to delay mammography.

The fact is that as women age, false positive mammography results decline. That's mainly because the density of a woman's breasts tends to decrease with age, making it easier to find cancer.

"Any given test that is a positive is more likely to be [truly] positive as women get older," Petitti says. A woman in her 40s asked to come back for follow-up tests because of a positive mammography has a 1 in 10 chance of actually having cancer.

But experts say that women understand mammography has limitations and still want to be screened for breast cancer.

"Most of the women you talk to would much rather go through that process and find something early than wait, " Evans says. "No one likes to have a false positive about anything, but it's part of what has to be done to find breast cancer early."

Both Evans and Lichtenfeld say annual screenings, rather than biannual, are especially important for women in their 40s because cancer tends to grow faster and more aggressively in younger women.

The government task force found a benefit to screening every other year because it reduced the number of false-positive results. "We asked what the risk-benefit ratio between one-year and two-year intervals was and the trade-off seemed to be favorable," Petitti says.

But Lichtenfeld takes issue with the task force's analysis. It looked at the number of women that need to be screened in order to save a life but not the number of years of life saved, he says. "If you find breast cancer in a young woman and save her life, she has more years of life ahead of her. Had they used that analysis, the [task force] may have come to a different conclusion," he says.

The federal health reform law put mammograms on its list of preventive services, which mandate that insurance plans cover the test each year with no cost-sharing. The task force's 2002 recommendations, which state that women should begin mammography at age 40 on an annual basis, were used by the government in writing the law.

Medical experts express concern that at some point these new recommendations will be adopted, threatening women's ability to access and pay for annual breast cancer screening in their 40s. However, there is no indication that the government plans to stop requiring insurers to fully cover the cost of mammograms for women in this age group.

At this point, the task force's recommendations are in contrast with the majority of other major medical associations. Most of those groups recommend women begin getting routine screening mammograms at age 40 and do so every year.

In the end, Petitti says, the distance between the task force and everyone else isn't so wide. "There is more agreement than disagreement," she says. "The task force does not state that mammography has no benefit in women under the age of 50, just that the decision to start should not be automatic just because you turn 40."

Evans takes a firmer stance. "It's very clear that mortality is reduced if you do annual screening mammography," he says. "Even women in their 40s get a 30% reduction in [breast cancer] mortality. A 30% reduction in the chance of dying from breast cancer is a pretty good deal."

Show Sources


Annals of Internal Medicine, Nov. 17, 2009; vol 151: pp 716-726. 

Len Lichtenfeld, MD, deputy chief medical officer, American Cancer Society.

Diana Petitti, MD, professor of biomedical informatics, Arizona State University; vice chair, 2009 USPSTF committee.

Phil Evans, MD, representative, Society of Breast Imaging; director, Center for Breast Care, University of Texas Southwestern Medical Center.


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