Despite the recommendations of multiple guidelines to perform genetic testing of individuals who have breast cancer or ovarian cancer less than one-quarter of women diagnosed with breast cancer in a recent study and fewer than one-third of those diagnosed with ovarian cancer underwent any genetic testing. Yet when tested for all genes that current guidelines designate as associated with their cancer type, nearly 8% of patients with breast cancer and almost 15% of patients with ovarian cancer had pathogenic variants, information which could be used to guide their therapy.

The researchers found testing particularly underutilized among ethnic minority patients with ovarian cancer. Findings appeared in the Journal of Clinical Oncology.

The National Comprehensive Cancer Network, American Society of Clinical Oncology, American College of Obstetricians and Gynecologists, American Society of Breast Surgeons, and U.S. Preventive Services Task Force all have guidelines that recommend genetic testing of breast cancer patients and ovarian cancer patients. “There is general consensus that all ovarian cancer patients should be tested, whereas guidelines are evolving about which breast cancer patients should be tested,” Allison Kurian, MD, MSc, associate professor of medicine and health research and policy at Stanford University and the study’s lead author, told CLN Stat.

Testing women who already have breast or ovarian cancer can inform clinicians on the best treatment options to take, whether it’s poly-ADP ribose polymerase inhibitor therapy for metastatic breast cancer or ovarian cancer, or risk-reducing surgeries, Kurian explained. “Moreover, there are important implications for subsequent screening (e.g., screening for the possibility of a second breast cancer) after the initial cancer is successfully treated,” Kurian said. However, not much is known about the rate of compliance with these guidelines in the clinic. Researchers also know little about the prevalence of cancer mutations in racial and ethnic minorities with breast or ovarian cancer.

To assess the situation in real-world clinical settings, investigators drew data from the National Cancer Institute’s Surveillance, Epidemiology, and End Results Program, zeroing in on 83,000 women diagnosed with breast or ovarian cancer in two states, California and Georgia, between 2013 and 2014. Linking data on these cases with laboratory data on cancer genetic tests from 2013 and 2014, they found that 24.1% and 30.9% of the women diagnosed with breast and ovarian cancer respectively had undergone genetic testing. In addition, 7.8% and 14.5% of patients with breast and ovarian cancer respectively, harbored cancer-associated mutations, a finding that could guide care decisions not just for the patients but also for family members.

With so many different guidelines recommending that all ovarian cancer patients undergo genetic testing, “the observed testing rate of 30% is completely inadequate for ovarian cancer patients,” Kurian said. Because there’s still no consensus on whether every breast cancer patient should get tested, the observed rate of 24% in the patients diagnosed with breast cancer didn’t raise the same concern, she added.

BRCA1 and BRCA2 were the two most common pathogenic variants found in patients with breast and ovarian cancer, followed by CHEK2. Variants specific to breast cancer patients included PALB2, ATM and NBN, whereas BRIP1, MSH2, and ATM were found in ovarian cancer patients.

Investigators noticed specific testing disparities among ovarian cancer patients. Just 22% of black women and 24% of Hispanic women underwent genetic tests, compared with 34% of non-Hispanic white women. Testing prevalence was lower in low-income areas and in patients without insurance.

Among the study’s breast cancer patients who were screened for a panel of guideline-designated genes, prevalence of mutation variants of unknown significance was significantly lower in non-Hispanic whites (14.5%) compared with African Americans (28.5%), Asians (26.6%), and Hispanics (19.3%).

“The racial/ethnic disparities observed among ovarian cancer patients were very concerning” and need to be resolved, Kurian said.

Next steps are to study the survival outcomes of these patients and how they were treated. “We are also planning studies to better understand the reasons that patients are not tested when they should be and to improve on this,” she said.

The case for these types of genetic tests is building. A recent study that looked at the monetary impact of using Oncotype DX gene test based on the results of a landmark trial, determined that the test could potentially save $50 million nationwide in first-year breast cancer costs. The Trial Assigning IndividuaLized Options for Treatment or TAILORx had found no benefit to administering chemotherapy to women whose Oncotype DX scores showed a low recurrence risk. Assuming that women with low to intermediate risk scores would forgo chemotherapy and that all women would get Oncotype DX testing, researchers compared treatment and testing costs, arriving at a net savings of approximately $50 million.

“The gene tests are not perfect predictors of who will ultimately have a recurrence of breast cancer, so it will be important to model the long-term outcomes and costs from diagnosis to death,” suggested the study’s corresponding author Jeanne S. Mandelblatt, MD, MPH, in a statement.