These are not controversial, he said. These are not situations where some people think these patients should be tested and some people think they shouldn’t. Of course they should be.
While this study didn’t look at the reasons behind the low testing rates, previous studies suggest that some cancer patients don’t get information about genetic testing from their doctors. There may be a component of patients who aren’t getting the advice they need to get tested, Kurian said.
The study uncovered racial and ethnic disparities. Among all patients with male breast, female breast, and ovarian cancer, only 25 percent of Asian, black, and Hispanic patients received the test, compared with 31 percent of non-Hispanic white patients.
Even though overall testing rates increased from 2013 to 2019, the gap between different groups hasn’t narrowed.
Asian, Black and Hispanic patients were also more likely to receive equivocal results, which are genetic variants that differ from the normal gene but have not been linked to cancer risk. This is likely due to less genetic research in these populations to establish normal versus pathogenic variations.
The mixed results are more common in populations and groups of people who haven’t had as much access to testing because we haven’t had a sense of the full range of what is normal for those populations, Kurian said. He’s about which genes were sequenced and defined as normal.
More genes, more uncertainty
During the study period, the number of genes tested increased from a median of 2 to 34 as scientists identified more genes associated with cancer. The inclusion of newer and less studied genes increased the uncertain results for all groups, but particularly for Asian, Black and Hispanic patients.
The vast majority of equivocal results will eventually be classified as normal, so they shouldn’t be treated as pathogenic, Kurian said. He added that mismanagement of uncertain outcomes is another burden that could fall more heavily on people with less access to quality care, further exacerbating inequalities.
We need more research to improve the accuracy of test results, especially among populations that have had less access to genetic testing and research, she said. We also need to understand how the findings influence perceptions of cancer risk and behaviour.
The new findings reveal that reality is falling short of expectations when it comes to genetic testing for cancer, but also give insight into specific shortcomings and possible solutions. For example, telemedicine and mailed samples could make testing available to people in more remote areas. Better insurance coverage and more education for providers and patients could also boost testing rates.
We’ve shown that test results often come too late to inform cancer management, said Steven Katz, MD, professor of medicine and health management and policy at the University of Michigan and senior author of the study. It’s not just about getting tested, but integrating the findings into cancer management and prevention for patients and their families to save lives.
Emory University researchers; the University of Southern California; the University of California, San Francisco; Ambry Genetics; GeneDx; Invitations; and Myriad Genetics also contributed to the study.
The study was supported by a grant from the National Cancer Institute of the National Institutes of Health (grants R01 CA225697, P01 CA163233, P30 CA046592, HHSN261201800003I, HHSN26100001, HHSN261201800032I, HHSN261201800015, and HHSN26 1 201800009I), the Centers for Disease Control and Prevention and California Department of Public Health.
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