In many families, cancer genes are passed down through generations like an unwanted heirloom. But thanks to ever-improving genetic testing, doctors are able to identify these genes better than ever before – and offer patients treatment options to not only stop cancer from setting in, but to stop the gene from being passed on as well.

The most widely-known gene that confers an increased risk of cancer is the BRCA mutation, which can raise your risk for breast cancer by up to 85 percent. Between 1 in 400 and 1 in 800 women carry either the BRCA1 or BRCA2 mutation, which are thought to be responsible for up to 10 percent of breast cancer diagnoses and 15 percent of ovarian cancer diagnoses, according to the National Cancer Institute. Genetic tests also exist for Lynch syndrome, a hereditary condition that increases your risk for colon cancer by 80 percent, according to the American Society of Clinical Oncology. Colon cancer affects 140,000 people every year, and 5 percent of cases can be attributed to a genetic mutation. “We know that most cancers, probably 90 percent, are not hereditary,” says Sharona Cohen, a genetic counselor and program director of cancer genetics at North Shore-LIJ Health System. “But for people who do have these genetic mutations, the implications are huge.”

Not everyone is a candidate for genetic testing – simply having a family history of cancer isn’t enough, Cohen says. “What we do is look for red flags,” she says. “We refer anyone who is diagnosed with breast cancer before menopause to a genetic counselor. And anytime there are three generations of breast cancer diagnoses on one side of the family, that’s a pretty strong indication that there’s a genetic component at play.”

In addition, certain ethnicities, like anyone of Ashkenazi decent, are a good candidate for genetic screening, Cohen says, which is done via an oral swab or a blood test. A genetic counselor will go through the various red flags and help you sort out whether genetic testing is right for you. “The goal of genetic testing and counseling is to give you the information you need to make an informed decision about the course of action you should take,” she says.

If you are found to be a candidate, your insurance likely covers the cost of the procedure, which can otherwise cost upward of $4,000, says Homayoon Sanati, medical director of the MemorialCare Breast Center at ​​Orange Coast Memorial Medical Center in California. “If you decide to undergo the genetic test and it comes back positive, you need to decide on a course of action,” he says. “When it comes to breast cancer, one option is remove both breasts, which reduces your risk of breast cancer dramatically.”

However, not all women want to jump to that step, he says. “If they opt to not undergo the surgery, we recommend they get routine mammograms and MRIs every six months to catch any cancer that develops early,” Sanati says.

And since the BRCA mutation also increases your risk for ovarian cancer by up to 15 percent, Cohen says, doctors recommend you have your ovaries removed once you're done having children. “We strongly recommend that because we don’t have good surveillance for ovarian cancer, and it’s very deadly,” she says.

Finding out you carry one of the mutations after you’re diagnosed with cancer might sound like it doesn’t do you much good, but Cohen says it can help you figure out which ​treatment to pursue. "Genetic cancers tend to be very aggressive, and you might want to opt for an aggressive treatment strategy," she says. For example, if you have the BRCA gene, you might opt to go for a bilateral mastectomy, removing both breasts completely, instead of a lumpectomy, where just the tumor is removed.

Regardless of whether your genetic status impacts your treatment choice, genetic testing results have implications for your entire family, Sanati says. “When someone is diagnosed with a genetic mutation, it's not one person,” he says. “If you carry the mutation, there’s a 50 percent chance your immediate family does as well.”