Patients who years ago breathed a sigh of relief because their genetic tests showed they were not at increased risk of developing cancer are not necessarily home free, said Suzanne Mahon, DNSc, genetic counselor for Saint Louis University Cancer Center.

"There is this group of people who think they don't need to worry about getting cancer and believe they don't have a high family risk of getting cancer, but unfortunately do," said Mahon, a professor in internal medicine at Saint Louis University.

Mahon says her requests for genetic testing for breast cancer have more than tripled since 2013, when actress Angelina Jolie announced she had a double mastectomy because she was at genetic risk of developing breast cancer.

Older genetic screenings were for the BRCA 1 and 2 genes, which are linked to the development of breast, ovarian, prostate, melanoma, pancreatic and other cancers.

However a new generation of genetic tests can detect as many as 25 other, less common genes that show a familial predisposition to cancer.

"It's important for people to understand what genetic test they were given and how complete they were," Mahon said.

"Many people have tested negative for BRCA 1 or 2 and mistakenly think they do not have an increased hereditary risk for developing cancer. It is possible that newer testing, through next generation platforms, could identify a less common susceptibility gene and clarify their risk."

For those who had early, less complete genetic tests, catch up panels are available to screen for other genes that raise their risk of developing cancer. "Most of these genes are associated with multiple cancers," Mahon said.

Those who could be at genetic risk of developing cancer include people who have:

Several close relatives on the same side of the family who have cancer

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Newer tests clarify hereditary risk of cancer