A recent study found that testing a limited, clinically relevant subset of genes, as opposed to broadening the range over time, optimizes genetic testing for women diagnosed with ovarian or breast cancer, particularly among racial or ethnic minorities (J Clin Oncol. 2021; JCO2002785. doi:10.1200/JCO.20.02785).
“Genetic testing is important for breast and ovarian cancer risk reduction and treatment, yet little is known about its evolving use,” wrote Allison W Kurian, MD, MSc, Departments of Medicine and of Epidemiology & Population Health, Stanford University, and colleagues.
This study aimed to explore how germline genetic testing for breast and ovarian cancer are evolving over time.
Women age 20 and older diagnosed with breast or ovarian cancer from 2013-2017 were identified using SEER records. Trends, rates of variants of uncertain significance (VUS), and pathogenic variants (PVs) were measured for clinical germline testing though 2019.
Of the 187,535 patients with breast cancer identified, 25.2% were tested. Of the 14,689 patients with ovarian cancer, 34.3% were tested. While testing increased by 2% annually, the number of genes tested increased by 28%.
The tests from breast cancer cases in 2017 showed a prevalence of BRCA1 and BRCA2, PVs 5.2% and VUS 0.8%. Breast cancer-associated genes or ovarian cancer-associated genes has PVs 3.7% and VUS 12%, while other genes had PVs 0.3% and VUS 2.6%. The tests from ovarian cancer cases in 2017 also showed a prevalence of BRCA1 and BRCA2, with PVs 11% and VUS 0.9%. Other genes had PVs 0.3% and VUS 0.6%, with VUS rates doubling over time.
Dr Kurian and colleagues reported “most pathogenic variant results were found in 20 breast cancer-associated genes and/or ovarian cancer-associated genes,” adding that “testing more genes per patient is associated with a growing racial or ethnic disparity in uncertain results.”
“Quality improvement should focus on testing indicated patients rather than adding more genes,” they concluded.—Marta Rybczynski