Everyone has BRCA1 and BRCA2 genes, which help repair damaged DNA and keep the cells’  genetic material stable. But when these genes contain abnormalities or mutations that are passed from generation to generation, they don’t function normally, and the risk of certain cancers, including breast and ovarian, increase. 

This doesn’t mean that everyone who tests positive for a BRCA gene mutation will be diagnosed with cancer. According to the National Cancer Institute, women who inherit a harmful BRCA gene mutation are five times as likely to develop breast cancer compared with  women without it. Ten percent to 15 percent of all ovarian cancers are attributable to a BRCA1/2 mutation. 

Men with these mutations also have an increased risk of breast cancer, and men and women who have harmful BRCA1/2 mutations may be at increased risk for cancers such as melanoma, cervical, pancreatic and colon as well as prostate cancer in men. 

By the same token, BRCA gene mutations aren’t the only ones associated with hereditary cancers. Many other cancer syndromes are known, which may be less common than the BRCA1/2, and additional gene abnormalities are emerging. 

Recently commercial testing for these less common mutations has become available. The best indicator in terms of what to test for is based on personal and family history of cancer and other unusual tumors. Credentialed genetics professionals are trained to evaluate a three-generation pedigree (family tree) and select the correct test.

“One of the biggest myths is that testing negative for BRCA means a person doesn’t have an inherited gene mutation,” says Suzanne Mahon, a certified genetic counselor and professor at St. Louis University School of Medicine. “They very well may have a less common one.” 

Mahon explains that testing among the Ashkenazi Jewish population had mainly concentrated on three, specific recurring BRCA mutations (two in BRCA1 and one in BRCA2). 

That’s because higher incidences of genetic mutations tend to recur and become more common among small, insulated groups that marry into each other. This is known as a “founder’s effect.” 

But now, Mahon says, she is ordering what is known as next-generation testing, which can examine many more genes through different laboratory techniques. This new technology makes the sequencing of the genes much faster and cheaper than prior techniques. And while the chances of finding a mutation are much better, the interpretation can be more complicated because less is known about these abnormal genes.

“The trick is to understand what to do when we find a mutation,” says Dr. Matthew Powell, a gynecological oncologist at Washington University School of Medicine. 

“Some have genetic results called variants of unknown significance, and these may wind up being nothing, while others may be real. It takes time to fully understand if the mutation caused a person’s cancer. 

“That’s the frustration. We can find out a lot of genetic information, but we don’t always know what it means.”

This can be troubling to a patient who hears that a potential mutation has been found but that it is unclear how to treat it. 

“Eventually, we’ll know what these variants mean, but currently we encourage the patient to check in once a year,” Powell says. “That’s also why family history is so important, because if multiple family members have been tested and those with cancer have the same variants, that gives us much more information to work with.”

Testing for abnormal genes is usually done on a blood sample taken in a doctor’s office and sent to a commercial lab. There, genes are separated from the rest of the DNA and scanned for abnormalities. 

For years, a Utah-based company performed all commercial BRCA1/2 testing. But a U.S. Supreme Court decision last June opened the door for other companies and laboratories to offer BRCA genetic testing, which has helped lower the cost.