Genetic testing guidelines for breast cancer are out-of-date and miss nearly half of patients diagnosed with the malignancy, doctors found in a new analysis of who gets tested and who doesn’t.

Health insurance companies and government payers base how they reimburse patients for tests and procedures on existing medical guidelines. Genetic testing recommendations for breast cancer are two decades old, established by the National Comprehensive Cancer Network, a group of 28 cancer centers nationwide.

The guidelines focus on two well-known breast cancer mutations — BRCA 1 and BRCA 2 — which were discovered in the 1990s. Since then, dozens of other genes related to breast cancer have been found, and if patients do not undergo appropriate genetic screening, they may not receive appropriate care for their form of the disease, doctors said in the report.

Ten percent to 15 percent of about 250,000 women diagnosed annually in the United States with breast cancer have some type of genetic flaw, according to the American Cancer Society.