Controversial U.S. guidelines for mammography issued in 2009, calling for breast cancer screening every two years rather than annually for women over 50 years old, can result in potentially deadly cancers being missed, according to a new study by U.S. researchers. Their analysis refutes the warnings by some public health experts that too-frequent mammograms can lead to the unnecessary treatment of tumors that may not have been life threatening.
According to the study of more than 43,000 women ages 40 to 49 and 65 years and older, there were 205 breast cancer cases detected in screening mammograms conducted at the New York Presbyterian Hospital/Weill Cornell Medical Center.
Of these, nearly 20 percent of the breast tumors were found in women in their forties, and half of them were invasive.
The study’s lead author, Elizabeth Arleo is a professor of radiology at Weill Medical College. She says her finding challenges recent recommendations to reduce the frequency of screening to once every two years because, some experts contend, few women in their forties actually develop breast cancer.
“It’s not yet possible to determine which cancers are destined to progress to advanced disease. So, until the biology of breast cancer is understood, and modern medicine can make this determination, our study favors annual screening starting at 40," said Arleo.
Arleo’s study follows by just one week an article in the New England Journal of Medicine, which studied 30 years of U.S. government data on breast mammography.
The authors report that nearly one in three patients, or 1.3 million women, with tumors detected through routine screening were probably treated for a non-life threatening growths.
A firestorm erupted three years ago among radiologists and women’s groups when the independent U.S. Preventive Health Services Task Force recommended that instead of annual screenings beginning at age 40, women should have mammograms every two years, beginning at age 50.
The panel argued its guidelines would limit unnecessary and painful biopsies and tests, and minimize radiation exposure, among younger women who were less likely to develop breast cancer.
Task Force Panelist Diana Petitti justified the revised guidelines:
“Screening every two years captures most of the benefit in terms of reducing breast cancer mortality, while decreasing the harm," said Petitti.
Still, the American Cancer Society continues to recommend annual screenings for women beginning at age 40.
Professor Arleo at Weill Medical College believes the competing recommendations worry and confuse women. Arleo says she sees many patients in their forties who have developed breast cancer after waiting two years between mammograms.
“In the office every day, we really have no confusion, as we continue to advise woman after woman who comes in, understandably confused by the mixed messages she’s receiving, the same thing; practice good preventive medicine and have an annual mammogram starting at age 40," she said.
Arleo presented her study’s findings at a recent meeting of the Radiological Society of North America.