New and comprehensive analyses from six independent research teams examining breast cancer screening intervals have produced a unanimous finding -- that mammography screening every two years for average risk women ages 50 to 74 offers a favorable balance of benefits to harm.
The conclusion is consistent with the same groups' analyses published in 2009, even with newly added data from digital mammography, advanced treatments and molecular tumor subtypes.
The findings, presented to the U.S. Preventive Services Task Force as part of its evidence review for breast cancer screening recommendations, are published in the Jan. 12 issue of Annals of Internal Medicine.
The analyses were conducted by modeling research teams that are part of the Cancer Intervention and Surveillance Modeling Network (CISNET), funded by the National Cancer Institute. Researchers from the Breast Cancer Surveillance Consortium (BCSC) also contributed to the research.
"CISNET's charge is to create models that can test a large number of screening and treatment scenarios, and provide evidence that can be considered for public health recommendations for average risk women. But it's important to remember that none of us is the 'average' woman," says the paper's lead author, Jeanne S. Mandelblatt, MD, MPH, of Georgetown Lombardi Comprehensive Cancer Center, and a principal investigator with CISNET.
As first reported in the groups' technical report published online in April 2015, the CISNET/BCSC analyses used the six independent simulation models to analyze 10 different digital breast cancer screening strategies for the average risk U.S. female population.
The researchers examined screening strategies with different starting ages (40, 45 or 50), and one- or two-year intervals between screening exams. The modeling uses national data on breast cancer incidence, risks for breast cancer, mammography characteristics, treatment effects, and risk of dying from other diseases. Then, the lifetime impact including benefits and harms of breast cancer screening mammography is calculated.
"These new analyses include information not in our 2009 report," Mandelblatt says. "We added digital mammography outcomes and the most modern treatments including therapy based on tumor molecular subtypes such as HER2 and ER status. We also included additional results for risk levels, breast density, and women's other illnesses to help guide clinical practice considerations." (Studies have suggested that women with dense breasts are more prone to cancer development.)
With the new updated data, the CISNET results still demonstrate the same finding as in 2009 -- that screening average-risk women biennially from ages 50 to 74 provides a reasonable balance of avoiding deaths from breast cancer and potential screening harms, including over-diagnosis, false-positives, and benign biopsies.
The researchers found that for average risk populations, starting screening earlier or screening more often prevented a small number of additional deaths, but also caused a larger number of false positive mammograms and benign biopsies, and led to more over-diagnosis and over-treatment.
"Still, the bottom line is that mammography saves lives. When to start screening and how often to undergo mammography is a personal decision. No model can provide those answers," Mandelblatt says.
Other CISNET modeling findings include:
Materials provided by Georgetown University Medical Center. Note: Content may be edited for style and length.
Cite This Page: