Mammogram for women over 40: Debate continues

By Dr. Ananya Mandal, MDSep 30 2010

A report this Wednesday showed that routine screenings for breast cancer called mammograms cut the breast cancer death rate by 26 percent for women in their 40s. The results have been received in a mixed way by experts.

Authors include Dr. Hakan Jonsson, professor of cancer epidemiology at Umea University in Sweden, Dr. Stephen Duffy, an epidemiologist at the University of London, and Dr. Laszlo Tabar, professor of radiology at the University of Uppsala School of Medicine in Sweden. Their paper is published online in the journal Cancer and will be presented on Friday at a meeting sponsored by the American Society for Clinical Oncology and five other organizations.

Last year the United States Preventive Services Task Force (USPSTF), an independent group that issues guidelines on cancer screening had come up with a study that questioned the benefits of mammography in women below fifty.

USPSTF based its recommendations included eight largely older randomized trials, most of which ended more than 20 years ago. This study included 600,000 women in Sweden age 40 to 49 and took place since national guidelines were implemented in 1986 in Sweden calling for screening mammography -- making it the largest epidemiological study of mammography in this age group. The team compared breast cancer deaths in women who had a breast cancer diagnosis in counties that had screening with deaths in counties that did not. The rate was 26 percent lower in counties with screening.

Expert speak

For

• Dr. Jennifer C. Obel of the oncology society says that this study “captured the real-world experience of mammograms in this age group.” She suggested that all women, starting at age 40, should “speak to their doctors about mammograms.”
• Dr. Donna Plecha, director of breast imaging at University Hospitals Medical Center in Cleveland also said, “At this time, screening mammography is the best tool we have," said. "The earlier we catch breast cancer, the easier it is to cure.”
• “The risk of breast cancer is reduced in women under 50, [but] when it occurs, the impact on patient longevity, productivity and both the family and society is enormous,” said Dr. Gary Lyman, director of comparative effectiveness and outcomes research at Duke University in Durham, N.C., emphasizing the need to detect breast cancer early in younger women.
• Dr. Daniel Kopans, professor of radiology at Harvard Medical School and senior radiologist in the Breast Imaging Division at the Massachusetts General Hospital in Boston explained, “The facts are that the age of 50 has no biological or scientific importance when it comes to mammography screening…There is clear benefit for screening beginning by the age of 40, and age 50 should be dropped as a threshold.”

Against

• Dr. Peter C. Gotzsche of the Nordic Cochrane Center in Copenhagen, a nonprofit group that reviews health care research said that this study counted the number of women who received a diagnosis of breast cancer and also died of it. They did not compare the broader breast cancer death rates in the counties. He explained that screening finds many cancers that do not need to be treated or found early. With more harmless cancers being found in the screened group, it will look like the chance of surviving breast cancer is greater in that group. “The analysis is flawed,” he said. Lead author Dr. Jonsson said the aim of screening “is to find breast cancers early and to reduce mortality from breast cancer.” He and his colleagues plan to look at the over diagnosis later, he said.
• Donald Berry, a statistician at MD Anderson Cancer Center, said the over diagnosis problem was a serious one. “We are finding cancers that would never be found if we didn’t look,” he said. “Small wonder people think screening is great - some of the cancers it finds were not lethal in the first place.”
• Dr. Albert Levy of Mount Sinai School of Medicine in New York City feels this clash of findings is confusing. “The patients are naturally confused, as we practicing doctors are, hence the caution on changing recommendations too quickly,” he said.
• Fran Visco, president of the National Breast Cancer Coalition said, “So many other studies that have been done, where the methodology is clear and very well done, have shown no benefit in this age group… We need to focus on issues that will prevent breast cancer and that will truly save many lives.”
• Dr. Lee Green, professor of Family Medicine at the University of Michigan speaking on over-diagnosis said, “Analyses of screening have shown that there is a high rate of over-diagnosis, with many women undergoing radiation and surgery per woman saved, as well as many false positive mammograms… It's not enough just to know how many women were saved, we have to know how many were hurt to save them.”
• Dr. Ned Calonge, USPSTF panel chair and chief medical officer of the Colorado Department of Public Health and Environment has not yet read the study but was concerned about the study design. He said the study will be included in the USPSTF's review of new studies. However, he was skeptical that it would result in any changes in their recommendations.

Last word

At present, the American Cancer Society recommends annual screening of women 40 and older, while the National Cancer Institute recommends screening for women 40 and older every one to two years.