By Kathleen Doheny
TUESDAY, Dec. 2, 2014 (HealthDay News) -- Women diagnosed with breast cancer in their 40s commonly lack well-known risk factors for the disease, according to new research that could fuel debate about preventive screening for this age group.
The study of 136 women diagnosed with breast cancer after a mammogram found few had dense breast tissue and a family history of the disease. Both traits are linked to higher odds for breast cancer and often help determine whether a woman aged 40 to 49 is referred for mammography screening.
"Of the screen-detected cancers, the very strong family history was only present in 12 percent of the young women," said Dr. Elissa Price, director of clinical breast imaging operations at the University of California, San Francisco.
And only 14 percent of those diagnosed with cancer had extremely dense breasts, Price said.
Limiting screening to women with these risk factors would reduce the number of screening-detected cancers by more than 75 percent, she said.
Price was scheduled to present the findings Tuesday at the Radiological Society of North America annual meeting in Chicago. Studies presented at medical meetings are usually viewed as preliminary until published in a peer-reviewed journal.
Women in their 40s get conflicting advice about screening mammograms from different organizations. In 2009, the U.S. Preventive Services Task Force issued a recommendation that these younger women discuss with their doctor the pros and cons of routine mammograms, taking the woman's own situation, or risk factors, and values into account.
The task force felt that the harms of screening, including false alarms, outweigh the benefits in younger women. The recommendation is in the process of being updated.
Other organizations, including the American Cancer Society, recommend annual screenings for women at average risk beginning at age 40.
In response to the new research, the American College of Radiology said in a statement that the finding "would appear to echo previous evidence" that risk-based screening would miss the majority of cancers. About 75 percent of women diagnosed with breast cancer have no family history or other risk factors that elevated the disease risk, said Dr. Carol Lee, a spokeswoman for the college.
Having a very strong family history means having a first-degree relative (daughter, mother, sister) with breast cancer before age 50, Price said. "If you have a sister diagnosed at age 45, you have a very strong family history," Price said. "If you have a mother diagnosed at age 65, you have a strong family history."
Breasts can be classified as dense or extremely dense, both risk factors that can make it harder to detect cancer on the mammogram.
In the new study, researchers evaluated 136 breast cancer patients diagnosed from 1997 to 2012 as a result of mammograms. Half of the cancers were invasive, and half early stage and noninvasive, the researchers said.
The researchers also looked at the hormone profiles of the cancers, such as whether or not they required estrogen to grow (ER-positive).
More than 90 percent of the women had cancers known to be linked to excellent survival rates, Price said, adding this further supports routine screening of younger women.