By Rachael Rettner, Senior Writer
Published: 09/09/2013 06:30 AM EDT on LiveScience
Whether women in their 40s benefit from getting mammograms to detect breast cancer is controversial, but a new study argues in favor of more frequent screening in this age group.
The researchers analyzed information from 7,301 women who were diagnosed with breast cancer at several hospitals in Boston between 1990 and 1999, and were followed until 2007.
Of the 609 women who died from breast cancer, 71 percent were women who had not undergone regular breast cancer screening, or were never screened, while 29 percent of those who died did undergo regular screening. [6 Foods That May Affect Breast Cancer Risk]
About half of those who died of breast cancer deaths were younger than 50, while only 13 percent of those who died were 70 or older (most deaths among older women were not related to their breast cancer).
The findings "suggest less, or less frequent screening at ages older than 69 years, but more, or more frequent screening for women younger than 50 years," the researchers wrote in their study published today (Sept. 9) in the journal Cancer. Breast cancer tends to be more aggressive in younger women, but less aggressive in older women, said Dr. Blake Cady, a professor emeritus of surgery at Harvard Medical School in Boston.
The study is the latest to weigh in on the debate over what age breast cancer screening should begin. In 2009, the U.S. Preventive Services Task Force changed its breast cancer screening guidelines, and recommended that women ages 50 to 74 receive a mammogram every two years. However, the American Cancer Society still recommends yearly mammograms beginning at age 40.
Some experts criticized the new study, pointing out that the researchers did not look at screening rates among women who survived.
The results show "only half the story," said Dr. H. Gilbert Welch, a professor of medicine at Dartmouth Institute for Health Policy & Clinical Practice. "If, among women who live, 30 percent were screened and 70 percent were not, everyone would agree that screening had no effect," Welch said.
The study also did not take into account which cancer treatments patients received, which could have affected the risk of death from breast cancer. It was assumed that the best, standard of care treatments were used.
There have been concerns that screening women for breast cancer increases their risk of "overdiagnosis," that is, diagnosis of cancers that would not cause noticeable disease during women's lifetimes. A 2012 study found that up to 25 percent of women diagnosed with breast cancer through a mammogram were actually overdiagnosed.
Another study, conducted by Welch and colleagues, found that, while mammograms have increased detection of early-stage breast cancers, they have done little to reduce the risk of death from advanced stage breast cancer.
The Centers for Disease Control and Prevention recommends mammograms every two years for women ages 50 to 74. Women ages 40 to 49 should speak to their doctor about when and how often to undergo mammogram screening, the CDC says.