The number of genes tested for ovarian and breast cancer has grown in recent years, but most patients do not undergo testing. Thus, variant-of-unknown-significance (VUS) results are common, especially among minority populations, according to the results of a study published in the Journal of Clinical Oncology.
The study evaluated genetic testing trends and results among 187,535 patients with breast cancer and 14,689 patients with ovarian cancer, all of whom had their diagnosis made between 2013 and 2017. The results revealed that testing was done in only 34% of patients with ovarian cancer and 25% of patients with breast cancer. Although the number of genes tested grew each year by 28% and the rates of detection of VUS also increased markedly, the number of patients undergoing testing rose each year by only 2%. Among patients with breast cancer, 8.5% who received a diagnosis in early 2013 had a VUS-only result compared with 22% in late 2017. Among patients with ovarian cancer, the rate of VUS-only results was 8% in patients who had received their diagnosis in early 2013 and 28% in late 2017.
The rates of VUS-only results were found to be significantly higher for members of racial minority groups with breast cancer or ovarian cancer compared with White patients. Multivariate analysis identified race or ethnicity as a significant predictor of VUS-only results (P<.001).
Most pathogenic variants of breast and ovarian cancer were identified in 20 genes. The study authors explained that exclusive focus on these 20 genes could maximize clinically relevant pathogenic variant results while minimizing VUS results, particularly in patients of racial or ethnic minority groups.
“Quality improvement efforts should focus on closing the genetic testing gap in indicated patients . . . rather than adding more genes per test,” the study authors wrote.
Kurian AW, Ward KC, Abrahamse P, et al. Time trends in receipt of germline genetic testing and results for women diagnosed with breast cancer or ovarian cancer, 2012-2019. J Clin Oncol. Published online February 9, 2021. doi:10.1200/JCO.20.02785