Are the new breast cancer guidelines putting patients at risk?

(CNN) -- Current guidelines for genetic testing of breast cancer are out of date and limits the number of women who can get tested, according to a new study in the Journal of Clinical Oncology.

A co-author of the study says insurance companies use those guidelines when deciding when to pay for testing. The result: nearly half of women with breast cancer-linked genetic defects could go untested.

The National Comprehensive Cancer Network established the guidelines about 20 years ago. In that time, scientists have discovered several mutations and genetic variants linked to the disease.

The test has also become easier to do and a lot cheaper. While the guidelines also evolved, the co-author of the study says they quote "got incredibly complicated" and "unusable."

Approximately 330,000 patients are diagnosed with breast cancer every year in the United States. Of these cases, an estimated 10% are likely due to hereditary causes.