This article appears in Healthy Living Winter 2018.
Major news about breast cancer: A broad international collaboration recently announced 72 new genetic markers associated with the risk of the disease.
“The most important thing to know is that this gives us much more information about what factors drive the risk of breast cancer,” said Peter Kraft, professor of epidemiology, Harvard T.H. Chan School of Public Health, and co-senior author of two studies published about the findings. “It opens up possibilities. The potential for a personalized test (for breast cancer) is absolutely possible in the future.”
Before the announcement, there were 107 known markers that predisposed women to breast cancer. Now there are 179.
Most women know about the BRCA 1 and 2 genes, which dramatically increase a person’s risk of developing breast cancer. These new markers do not have the same effect. A single marker will increase or decrease a person’s risk level.
Taken together, though, they will have a greater impact especially when considered along with a person’s family history, said Dr. Leigha Senter-Jamieson, associate professor, The Ohio State University Comprehensive Cancer Center – Arthur G. James Cancer Hospital and Richard J. Solove Research Institute. Other risk factors include breast density and lifestyle choices such as drinking alcohol, being overweight and not having children, according to the American Cancer Society.
“The good news is that this gives us additional information,” Kraft said. “The findings could be used to identify women at high risk of breast cancer who might benefit from more intensive breast-cancer screening or other risk-reducing strategies.”
Breast cancer is the most commonly diagnosed non-skin cancer and the second-leading cancer killer among U.S. women.
Learning about family link
There is a strong inherited familial component to the disease. For instance, a woman whose sister has been diagnosed with breast cancer has about a twofold increased risk of getting breast cancer herself, relative to average risk among all women. Rare, high-risk mutations in genes such as BRCA1 and BRCA2 have been found to account for less than 25 percent of the shared risk within families. The other 100 genetic variants found in previous genome-wide association studies are linked with small changes in breast cancer risk and explain some, but not all, of the remaining family-related clustering.
“These new studies make clear how much of the familial risk of breast cancer remains to be explained, despite everything we’ve learned,” Kraft said. “We are still on the steep part of the discovery curve when it comes to identifying common variants individually associated with small differences in breast cancer risk.”
Tool for prevention
There’s much discussion about screening depending on risk, Kraft said. Currently, women should start getting mammograms at age 50, Kraft said. With the new genomic markers, doctors can determine a person’s risk profile. If a woman is considered more at risk, her doctor can screen for breast cancer earlier, more frequently or with additional tests such as MRI or ultrasound.
In addition to improving the precision of risk prediction, the new findings will lead to improved prevention, Kraft said.