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For more than two decades, doctors, researchers, even the government have dispensed the same unfailing and authoritative advice: Women over the age of 50 should have an annual mammogram; women over the age of 40 should get the test every two years (depending on whose recommendations you follow). Any number of studies reported that women who had the test once a year or once every two years could reduce their risk of dying from breast cancer by 30 percent.

That all changed in October 2001.

An article by Danish researchers Drs. Peter Gotzsche and Ole Olsen of the Nordic Cochrane Center in Copenhagen published in the British medical journal Lancet, challenged assumptions about mammograms, calling previous studies "flawed". Those studies, which examined mammography's ability to reduce the risk of death from breast cancer, failed to meet rigorous scientific standards and were unreliable, according to the Danish researchers, who analyzed seven large studies of mammography conducted over the past few decades.

Newer studies from Canada and Sweden showed no lower mortality rate in women who had regular mammograms than in those who never had the test.

Mammograms, the researchers' analysis suggested, do not prevent women from dying of breast cancer, nor do they prevent mastectomies. Specifically, the researchers found:

• While it is often asserted that early detection spares patients from more aggressive treatments, screening actually results in over-diagnosis, which has led to a 20 percent increase in mastectomies and a 30 percent increase in the removal of tumors.

• Mammograms not only pick up slow-growing tumors but also identify cell changes that under a microscope look like cancer that may be biologically benign. As a result, doctors may aggressively treat something that might have gone unnoticed during a woman's lifetime.

U.S. experts stand by guidelines

In fact, the policy makers, such as experts at the National Cancer Institute (NCI) and the American Cancer Society (ACS), still consider mammograms to be "the gold standard" for early detection of breast cancer.

"We have no plans at this point to change the national guidelines that have been in place for more than 20 years," says Dr. Peter Greenwald, the director of NCI's division of cancer prevention in Bethesda, MD. "The Lancet study reviewed files that we've known about for over a decade. They did raise some questions about the quality of the research design, but we don't think there is enough information to cause us to change our minds."

"It's not an ideal technology, but I would think women would want to know if they have a possible tumor growing in their breast," Greenwald says. "Mammography does offer some protection and some reduction of risk by catching sight of a tumor earlier, when it's likely there will be greater benefits from therapy."

The ACS also plans to stick with its recommendation for annual mammograms. Robert Smith, director of cancer screening for the society, contends the meta-analysis by Gotzsche and Olsen undermines efforts in this country to educate women about breast cancer screening.

"It is discouraging. Over a period when we've been working so hard to increase the number of women who get regular mammograms, and when deaths from breast cancer are declining in the United States mostly because of this effort to encourage women to have mammograms, to see this poor study getting the kind of attention it's getting," Smith says.

There are going to be a lot of medical studies like this and that produce confusing information, says Linda Frame, senior clinical advisor for the Susan G. Komen Breast Cancer Foundation (Komen) in Dallas. "But we need to keep doing what we've always done," she says. "The bottom line is that mammography remains the gold standard in breast cancer treatment."

Apart from skin cancer, breast cancer is the most common cancer among American women and is second only to lung cancer as the leading cause of cancer-related death. The Centers for Disease Control and Prevention predicted that 192,200 new cases of breast cancer would be diagnosed in 2001, and 40,200 women would die of the disease.

Other diagnostic tools

While a mammogram may still be the screening of choice for breast cancer, it's not the only available diagnostic tool. In 1999, the Institute of Medicine (IOM), a branch of the National Academy of Sciences, studied several new technologies and concluded that no single imaging technology can uncover all breast abnormalities.

Combining ultrasound and magnetic resonance imaging with mammography has shown "significant diagnostic potential", the IOM concluded, particularly when trying to get a clear picture of the denser breast tissue of women under the age of 40.

Frame says that Komen continues to recommend "yearly mammograms in conjunction with a clinical breast exam before women have the mammogram. And we continue to recommend monthly self-examination of a woman's breast beginning at age 20."

Women should know and understand how their breasts normally look and feel to perform a good self-examination, Frame advises. According to Frame, any of the following physical changes is a sign to go to the doctor:

• A lump that doesn't feel like anything in that breast or the other breast
• A change in how the breast looks, such as a localized area of redness
• A change in the breast nipple. (It is retracted or there's a discharge.).

Annual screenings at 40 or 50?

Controversy over mammograms isn't exactly new. The medical community hasn't been able to agree on when a woman should start getting an annual mammogram. The ACS, the Susan G. Komen Breast Cancer Foundation and the American College of Obstetrics and Gynecology advise women who reach the age of 40 to begin annual mammograms. However, the NCI recommends annual screenings for women beginning at age 50 and suggests that women in their 40s get screenings every one or two years, depending on their risk factors.

The differences in opinion center on data. The NCI recommends annual screening start at 50 because it concluded that the mortality of younger women screened more regularly was not statistically significant.

Doctors often have trouble accurately reading mammograms in younger, or pre-menopausal, women. Before menopause, a woman's breasts are typically more dense because they are more glandular. The mammogram image is darker and foggier, making it more difficult to identify abnormalities.

The result, is more false positives and unnecessary biopsies. While 86 percent of women over the age of 50 with an abnormal mammogram turn out not to have cancer, the number skyrockets to 97 percent in women between the ages of 40 and 49, according to the NCI.

So what should women 40 and older do? They should talk to their doctors. If women are at increased risk for breast cancer, an annual mammogram may be the wisest choice.

Women may need to be screened more closely if they have the following risk factors:

• Family history of breast cancer or previous treatment for breast cancer

• Benign tumors called atypical hyperplasia or lobular carcinoma in situ (LCIS)

• No children or first child after age 30

• Over age 45 with breast density of 75 percent or more

• Chest irradiation at age 30 or younger (for conditions like Hodgkin's disease)

• Menstruation starting at or before the age of 12

External Resources: National Cancer Institute American Cancer Society Susan G. Komen Breast Cancer Foundation National Center for Health Statistics Centers for Disease Control and Prevention The Lancet, Oct. 20, 2001

This article was published on 2001-12-20
This article was reviewed on 2003-02-03