Mammograms Reduce Breast Cancer Deaths by Almost Half, Study Says

En español | In the continuing debate over whether or not regular mammograms help prevent breast cancer deaths, the pro-screening camp has some powerful new ammunition: A new Dutch study shows that women who participated in at least three screening mammograms had a nearly 50 percent lower risk of dying from breast cancer.

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In addition, the study presented strong evidence that mammograms help detect tumors in their early stages, thereby increasing a woman's odds of survival.

Dutch researchers reported that advanced (stage 4) tumors were found in 30 percent of women who had never been screened before they were diagnosed, but only in 5 percent of women whose cancer was detected during screening.

"Our study adds further evidence that mammography screening unambiguously reduces breast cancer mortality," said senior researcher Suzie Otto with the department of public health at Rotterdam's University Medical Center.

Photo by Jim McGuire/Getty Images

Mammography screenings are key to detecting breast cancer early.

"It reaffirms what most clinicians in the U.S. have been saying all along. Women should be regularly screened," says William Gradishar, M.D., a breast cancer expert with the Robert H. Lurie Comprehensive Cancer Center of Northwestern University, who was not part of the study.

Robert Smith, director of cancer screening at the American Cancer Society, called the Dutch study "a very careful analysis" that has produced results similar to several recent large international studies in Sweden, Denmark, Italy and Australia.

"All of these studies show that women who are not screened, their rates of advanced disease is much higher," Smith says. "Mammography allows a woman to begin treatment when her prognosis is going to be much better."

The Dutch study, published this week in the journal Cancer Epidemiology, Biomarkers & Prevention, was the largest of its kind in the Netherlands, which began a nationwide screening program in 1989 for women 50 and older.

The researchers looked at 8,369 women over age 50 with breast cancer, including 755 patients who died from the disease between 1995 and 2003.

Next: How often should women be screened for breast cancer? >>

Overall, women who had at least three mammograms prior to being diagnosed had a 49 percent reduced risk of dying from breast cancer. The greatest reduction was seen in women ages 70 to 75, where death was reduced by 84 percent. Among women ages 50 to 69, the reduction was nearly 40 percent.

The Dutch government "considers it imperative that everyone eligible for a screening program is given the opportunity to participate," Otto said.

Free mammograms are offered to Dutch women 50 and older every two years, and this study shows that women who took part in the screening program cut their risk of dying from breast cancer by half, Otto said.

The Dutch research comes at a time when the benefits of mammograms are being questioned in the United States. A series of contradictory findings, debated among doctors and patients, leave many women bewildered about how often they should be screened for breast cancer. New federal guidelines in 2009 called for less frequent mammograms, and a controversial Dartmouth College analysis in October criticized breast cancer survivors for saying that having a mammogram had saved their life.

That report, by H. Gilbert Welch, M.D., suggested that only a small percentage of those diagnosed with breast cancer were really helped by screening, a conclusion some experts questioned. According to his analysis, at most 13 percent of those diagnosed with breast cancer had been helped by having a mammogram.

"To criticize women who had their breast cancer diagnosed by mammography and say they're delusional because they believed it saved their life — I'm not sure what you gain by that criticism. It seems condescending," Smith says.

What the Dutch study shows, he adds, is that mammogram screening is doing what it's supposed to do — "reduce the rate of advanced disease."

Also of interest: Your guide to screenings and vaccines. >>

Candy Sagon writes about health and nutrition for the AARP Bulletin.