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Breast check: Do Mandatory Mammograms Do More Harm Than Good?


By Vonalda M. Utterback, CN
October 1, 2007

Reprinted with permission from Natural Solutions magazine.

“Time to make breast pancakes,” says one friend of mine, referring to her scheduled mammography screening. And although she may crack jokes about the experience, she’s never once questioned the need for her annual pilgrimage, nor has her physician discussed the risks versus the benefits it entails. After all, if you are a woman aged 40 or beyond, yearly mammograms are simply de rigueur.

When your doctor refers you for a screening, he or she is likely following the guidelines of the two leading national cancer research and information organizations primarily responsible for setting public health policy on cancer screening: The private American Cancer Society (ACS) and the government’s National Cancer Institute (NCI). Both, along with other well-funded, high-profile organizations, such as Susan G. Komen for the Cure, recommend regular mammogram screening of symptom-free women beginning at age 40.

All this official blessing shouldn’t make regular screening mammography sacrosanct, however. In fact, it’s way past time for women to start asking hard questions about the exam’s efficacy and its potential harm, say many women’s health experts, advocates, and researchers. “Screening mammography is clearly a double-edged sword,” explains Lisa Schwartz, MD, co-director of the Veteran’s Administration Outcomes Group in White River Junction, Vermont, and associate professor of medicine at Dartmouth Medical School.

False truths

According to the National Academy of Sciences 2005 publication, Saving Women’s Lives: Strategies for Improving Breast Cancer Detection and Diagnosis, the risk of a false-positive result in a mammogram is about 1 in 10. About three-quarters of the resulting biopsies turn out to be benign, it’s true, but to learn that a woman has to endure the fear that she has breast cancer and bear the cost, discomfort, and risk of additional medical procedures.

“Regular screening will save some lives, but it will cause even more women to be harmed through the unnecessary diagnosis and treatment of cancer that would never have affected their health, were it not for screening,” says Schwartz. She’s referring to false-positives associated with “ductal carcinoma in situ” (DCIS), a result that many experts consider one of the most harmful risks associated with screening mammography.

DCIS is a noninvasive condition in which abnormal cells are found in the lining of a breast duct. It is not cancer, but it may, in some cases, become invasive cancer and spread to other tissues. Because they can’t predict which lesions will become invasive cancer and which will remain contained in the breast duct, doctors usually treat DCIS like cancer. “Most women with DCIS will be advised to undergo invasive treatment of unknown benefit, such as lumpectomy combined with radiation,” reports Schwartz.

Harm from over-diagnosis of invasive cancer also may occur because many malignant cancers grow quite slowly, says Peter C. Gotzsche, MD, researcher and director of the Nordic Cochrane Centre in Copenhagen, Sweden. If cancer had not been found during screening, he explains, it would not have become apparent before the woman died from other causes. “This is a basic and critical factor, often ignored,” says Gotzsche, “that many cancers are histologically malignant, but biologically benign.

The search for balance

Many women don’t know about the negative side of mammography, and, it seems, they tend to overestimate its benefits. In a survey of more than 4,000 women designed to assess perception of the benefits of mammography, a full 68 percent believed screening prevents or reduces the risk of contracting breast cancer (screening has nothing to do with prevention); 62 percent believed screening reduces breast cancer mortality by half (although studies results vary, the 2006 Cochrane Review confirmed screening mammograms reduce the absolute risk of dying from breast cancer by a very modest 0.05 percent); and 75 percent believed 10 years of regular screening will prevent 10 or more breast cancer deaths per 1,000 women - approximately 10 times the most optimistic estimates.

One of the lone voices offering a balanced view on screening mammography (according to a 2004 study published in the British Medical Journal rating 27 cancer education websites) is the San Francisco-based breast cancer awareness and advocacy group, Breast Cancer Action (BCA). “The United States’ public campaign to eradicate breast cancer has not focused on prevention, but largely on efforts that promote mammography screening,” says BCA’s executive director, Barbara Brenner, herself a two-time survivor of breast cancer. (See “Prevention Is Key” for ways to stop cancer before it starts.) Since its inception in 1991, BCA has raised concerns about mammography’s effectiveness, and the dangers of misleading the public about the benefits of breast cancer “early detection” through screening mammography.

According to Brenner, mammography has several potentially harmful outcomes, especially for younger women, among them radiation risks (the earlier you begin screening mammography, the more radiation exposure you will experience) and a high incidence of false-negative (and false-positive) readings because younger women typically have denser breast tissue, which makes accurate mammogram readings more difficult. In sum, routine mammography screening, particularly for younger or pre-menopausal women, may cause more harm than good. (For more information on radiation risk, see “Why Fear Radiation?”)

The evidence is in

A group of researchers led by Gotzsche, whose nonprofit organization is part of the highly-regarded Cochrane Collaboration, an international organization providing health-care analyses worldwide, reviewed all seven randomized mammography trials conducted prior to June 2005, involving half a million women. Most of the trials enrolled women ages 45 to 64, although one, the Canadian National Breast Screening Study included women ages 40 to 49.

In Gotzsche’s review (updated several times, the latest in 2006), the four trials judged by the Cochrane researchers to have the poorest scientific quality yielded the greatest apparent benefit for screening mammography - a 29 percent reduction in the risk of breast cancer mortality after seven years and a 25 percent reduction after 13 years. In contrast, the two trials considered to have the highest scientific rigor, with adequate randomization, showed no significant reduction in breast cancer mortality.

One of the two highest quality mammography trials in Gotzsche’s review, a Canadian study led by Cornelia J. Baines, MD, of the University of Toronto, Ontario, followed more than 50,000 women. The results after seven years in 1992 showed 36 percent more deaths from breast cancer among screened women than among unscreened women. Called the “breast cancer mortality paradox” at the ten-year follow-up, this percent then fell to 14 percent.

Although the numbers aren’t statistically significant, Baines reports that similarly alarming trends were observed in other screening trials in women aged 40 to 49 years, including the Swedish Two-County Trial from 1985, as well as three other trials included in the Cochrane review. “Even if the results are not officially statistically significant, when the same results are observed multiple times, in multiple studies, the trend deserves attention,” says Baines.

And as mentioned, Gotzsche’s overall findings based on all trials, including those of poor quality, show an absolute risk reduction in breast cancer mortality of just 0.05 percent (for all women attending annual or semi-annual mammography screening). Screening also led to over-diagnosis and over-treatment, resulting in an absolute risk increase of 0.5 percent. “This means for every 2,000 women invited for screening throughout 10 years, one will have her life prolonged,” explains Gotzsche. “In addition, 10 healthy women will be diagnosed as breast cancer patients and will be treated as such, unnecessarily.”

What to do?

Simply put, the decision of whether to screen or not to screen is a tough one. Women have been sold on the idea that mammograms will save their lives. And yet the best studies don’t seem to support this claim. Additionally, the blanket recommendation for screening mammography comes without solid information on the risk involved and the potential harm the procedure can cause.

Even mammography’s most outspoken advocates acknowledge, however, that women should first focus on prevention and decide for themselves if the potential benefit of screening mammography outweighs the risks. Certainly, the controversy over screening should not deter a woman from getting a diagnostic mammogram if she has any troublesome symptoms or signs of breast cancer, such as a newly discovered lump, pain, or nipple discharge. (See “Assess Your Risk”.)

And it’s not as though you have many proven alternatives. Of the few options are available, none is a hands-down winner. (Look to “What Are the Alternatives?” for more information.) In the future, better, noninvasive tests may carry less risk than mammography. For now, says Lisa Schwartz, women face a difficult choice. “Our approach to breast cancer screening has fostered a climate where women are seen as irresponsible if they do not undergo screening. But screening has important trade-offs. We need to make sure that women understand this is a real decision that carries real consequences in both directions.”

Vonalda Utterback is a frequent contributor to Alternative Medicine (now called Natural Solutions) magazine.

Find Out More

According to a survey published in theBritish Medical Journal of 27 websites containing information on mammography screening, the following websites garnered a top rating for balanced, unbiased information:

National Breast Cancer Coalition:
Breast Cancer Action:
Center For Medical Consumers: