- Statistical analysis has been deployed in the fight against breast cancer, which claims the lives of more than 40,000 U.S. women each year. An online risk calculator developed by the National Cancer Institute-funded Breast Cancer Surveillance Consortium (BCSC) is helping to create a relaible health data standard for estimating five- and 10-year invasive breast cancer risk based on a combination of factors.
“Our tool is unique in that it combines both breast density and biopsy results,” said Charlotte Gard, assistant professor of applied statistics at New Mexico State University and a consultant for the BCSC project. “It’s the only risk assessment tool that includes BI-RADS breast density — the breast density [measure] that’s used in clinical practice.” BI-RADS stands for the Breast Imaging Reporting and Data System of the American College of Radiology.
When a woman has a mammogram, her radiologist assigns a breast density measure ranging from “a” to “d” — with “d” indicating extremely dense tissue, Gard explained. Research studies have shown that women who have dense breasts are at higher risk for developing breast cancer. By including breast density information with biopsy results, the calculator helps clarify a woman’s risk compared to other women of her age, race and ethnicity.
Twenty-four states currently require that women undergoing mammography who have density measures of “c” or “d” be notified of that status. Gard said federal legislation is under consideration to make such notification a nationwide requirement. “We’re hoping that having this tool available will be helpful to physicians and women when these discussions start taking place,” she added.
Gard is also conducting research on the potential misclassification of breast density by radiologists, who may differ in their interpretation of density. That variability could have an impact on subsequent reporting to patients. “You could create a false sense of security or you could alarm women unnecessarily when reporting based on a single density measurement,” she said. “If we can identify factors that can predict their variability, we could potentially intervene with some kind of training.”
For now, the online calculator should assist women who are trying to process their risk of developing breast cancer. “The concern is that women are going to be informed of their breast density and they’re not going to know what to do with that information,” said Gard. “So here’s something that we can give them that’s geared toward helping them better understand their risk and, with their physicians, determine the best next steps.”
BCSC reports that the risk calculator has been validated in 1.1 million women undergoing mammography across the United States. Among that group, approximately 18,000 were diagnosed with invasive breast cancer. The calculator was also externally validated in a mammography health study conducted by the Mayo Clinic.
The calculator is not applicable to women who meet any of the following criteria: younger than age 35 or older than age 74; previous diagnosis of breast cancer; previous diagnosis of ductal carcinoma in situ; previous breast augmentation; or previous mastectomy.
The breast cancer risk calculator is available here. BCSC said the tool may be updated as new data or research finding become available.