In a large study published 2 days ago in the Journal of the American Medical Association (JAMA), Internal Medicine researchers suggest mammogram screening for breast cancer every 2 years for women age 50 to 74 is safe and leads to fewer false positive results. The finding was true even for women with dense breasts and those who use hormone replacement therapy.
The study authors say it is still important for women to make individual decisions about how often to have a mammogram, based on family history and individual risk factors.
Karla Kerlikowske, MD, a professor of medicine at Univeristy of California, San Francisco and a physician at the UCSF-affiliated San Francisco VA Medical Center led the study that included over 900,000 women.
Younger women with dense breasts more likely to have advanced breast cancer
The study also found women with extremely dense breasts in their 40s were more likely to have advanced breast cancer with larger tumors compared to women who undergo yearly mammogram.
Yearly breast cancer screening at a young age also led to more false positive results, the study found, meaning women are called back for more mammograms, biopsy and ultrasound.
The authors say 12 to 15 percent of women in their 40s have extremely dense breasts, as do 3 to 6 percent of women age 50 to 74.
Kerlikowske said in a press release, “Increasing age and high breast density are among the strongest risk factors for the disease.”
Breast density is determined only from having a mammogram. Dense tissue makes it difficult for x-rays to pass through breast tissue
The study results come from the Breast Cancer Surveillance Consortium (BCSC), one of the largest breast cancer surveillance databases in the United States.
Last year the UCSF group recommended breast cancer screening decisions should be based on individual risk factors that should be discussed with your doctor. As an example, family history of the disease may raise the chances of cancer, but not necessarily advanced stage or large tumors.
Of note, the new finding contradicts a January, 2011 analysis from Edward Hendrick, Ph.D., clinical professor of radiology at the University of Colorado School of Medicine, and Mark Helvie, M.D., director of breast imaging at the University of Michigan Comprehensive Cancer Center that suggested annual mammogram could save 71 percent more lives by starting breast cancer screening at age 50 and continuing yearly until age 84.
“These individual decisions involve evaluating the balance between the benefits of screening – detecting cancer early – and the potential harms, such as false positives among healthy women,” Kerlikowske said. “Some people who are at higher risk of disease may be more willing than those at lower risk to accept such potential harms of screening.”
The new study was designed to explore other risks for breast cancer, other than age. In 2009 the U.S. Preventive Services Task Force updated mammogram guidelines for women, based on age; advising screening every 2 years for women age 50 to 74.
Extremely dense breasts and combine hormone therapy (estrogen and progestin) are known risks for advanced breast cancer. But the new study shows no additional benefits for annual screening even for women whose breasts are dense or those taking combined HRT.
Diana L. Miglioretti, PhD, a senior investigator at Group Health Research Institute who is also at the University of California at Davis adds the finding also shows there are no benefits for mammogram screening before age 50 – “unless your breasts are extremely dense and you have other strong risk factors.”
March 18, 2013