Germline Genetic Testing After Cancer Diagnosis.

Germline genetic testing is recommended by practice guidelines for patients diagnosed with cancer to enable genetically targeted treatment and identify relatives who may benefit from personalized cancer screening and prevention.

To describe the prevalence of germline genetic testing among patients diagnosed with cancer in California and Georgia between 2013 and 2019.

Observational study including patients aged 20 years or older who had been diagnosed with any type of cancer between January 1, 2013, and March 31, 2019, that was reported to statewide Surveillance, Epidemiology, and End Results registries in California and Georgia. These patients were linked to genetic testing results from 4 laboratories that performed most germline testing for California and Georgia.

The primary outcome was germline genetic testing within 2 years of a cancer diagnosis. Testing trends were analyzed with logistic regression modeling. The results of sequencing each gene, including variants associated with increased cancer risk (pathogenic results) and variants whose cancer risk association was unknown (uncertain results), were evaluated. The genes were categorized according to their primary cancer association, including breast or ovarian, gastrointestinal, and other, and whether practice guidelines recommended germline testing.

Among 1 369 602 patients diagnosed with cancer between 2013 and 2019 in California and Georgia, 93 052 (6.8%) underwent germline testing through March 31, 2021. The proportion of patients tested varied by cancer type: male breast (50%), ovarian (38.6%), female breast (26%), multiple (7.5%), endometrial (6.4%), pancreatic (5.6%), colorectal (5.6%), prostate (1.1%), and lung (0.3%). In a logistic regression model, compared with the 31% (95% CI, 30%-31%) of non-Hispanic White patients with male breast cancer, female breast cancer, or ovarian cancer who underwent testing, patients of other races and ethnicities underwent testing less often: 22% (95% CI, 21%-22%) of Asian patients, 25% (95% CI, 24%-25%) of Black patients, and 23% (95% CI, 23%-23%) of Hispanic patients (P < .001 using the χ2 test). Of all pathogenic results, 67.5% to 94.9% of variants were identified in genes for which practice guidelines recommend testing and 68.3% to 83.8% of variants were identified in genes associated with the diagnosed cancer type.

Among patients diagnosed with cancer in California and Georgia between 2013 and 2019, only 6.8% underwent germline genetic testing. Compared with non-Hispanic White patients, rates of testing were lower among Asian, Black, and Hispanic patients.

JAMA. 2023 Jul 03 [Epub]

Allison W Kurian, Paul Abrahamse, Allison Furgal, Kevin C Ward, Ann S Hamilton, Rachel Hodan, Rachel Tocco, Lihua Liu, Jonathan S Berek, Lily Hoang, Amal Yussuf, Lisa Susswein, Edward D Esplin, Thomas P Slavin, Scarlett L Gomez, Timothy P Hofer, Steven J Katz

Department of Medicine, School of Medicine, Stanford University, Stanford, California., Department of Health Management and Policy, School of Public Health, University of Michigan, Ann Arbor., Department of Epidemiology, Rollins School of Public Health, Emory University, Atlanta, Georgia., Department of Population and Public Health Sciences, Keck School of Medicine, University of Southern California, Los Angeles., Department of Pediatrics, School of Medicine, Stanford University, Stanford, California., Department of Obstetrics and Gynecology, School of Medicine, Stanford University, Stanford, California., Ambry Genetics, Aliso Viejo, California., GeneDx, Gaithersburg, Maryland., Invitae, San Francisco, California., Myriad Genetics, Salt Lake City, Utah., Department of Epidemiology and Biostatistics, University of California, San Francisco., Department of Internal Medicine, Michigan Medicine, University of Michigan, Ann Arbor.