Germline Genetic Testing After Cancer Diagnosis

Question  Among patients in the Surveillance, Epidemiology, and End Results registries diagnosed with cancer between 2013 and 2019, what was the prevalence of germline genetic testing?

Findings  In this observational study that included 1 369 602 patients diagnosed with cancer in California and Georgia, germline genetic testing after cancer diagnosis was low (6.8%; n = 93 052). Testing was highest in males with breast cancer (50%) and in patients with ovarian cancer (38.6%).

Meaning  Few patients diagnosed with cancer between 2013 and 2019 in California and Georgia underwent germline testing.

Importance  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.

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

Design, Setting, and Participants  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.

Main Outcomes and Measures  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.

Results  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.

Conclusions and RelevanceAmong 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.

Accepted for Publication: May 18, 2023.

Published Online: June 5, 2023. doi:10.1001/jama.2023.9526

Corresponding Author: Allison W. Kurian, MD, MSc, Stanford University School of Medicine, 300 Pasteur Dr, Stanford, CA 94305 (akurian@stanford.edu).

Author Contributions: Dr Kurian had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

Concept and design: Kurian, Abrahamse, Ward, Hodan, Hofer, Katz.

Acquisition, analysis, or interpretation of data: All authors.

Drafting of the manuscript: Kurian, Abrahamse, Berek, Katz.

Critical revision of the manuscript for important intellectual content: Kurian, Abrahamse, Furgal, Ward, Hamilton, Hodan, Tocco, Liu, Hoang, Yussuf, Susswein, Esplin, Slavin, Gomez, Hofer, Katz.

Statistical analysis: Abrahamse, Furgal, Hofer, Katz.

Obtained funding: Kurian, Tocco, Katz.

Administrative, technical, or material support: Hamilton, Tocco, Liu, Yussuf, Susswein, Slavin, Katz.

Supervision: Hamilton, Berek, Katz.

Conflict of Interest Disclosures: Mss Hoang and Yusuf reported being employed by Ambry Genetics. Ms Susswein reported being employed by and having stock options in GeneDx. Dr Esplin reported being employed by and owning stock in Invitae and serving on a scientific advisory board for and owning stock in Taproot Health. Dr Slavin reported being employed by and owning stock in Myriad Genetics. No other disclosures were reported.

Funding/Support: This research was supported by grant R01 CA225697 from the National Cancer Institute (NCI) (awarded to Stanford University) and grants P01 CA163233 and P30 CA046592 from the NCI (awarded to the University of Michigan). The collection of cancer incidence data in California was supported by the California Department of Public Health pursuant to California Health and Safety Code §103885 under cooperative agreement 5NU58DP006344 with the US Centers for Disease Control and Prevention (CDC) National Program of Cancer Registries, contract HHSN261201800032I with the NCI’s Surveillance, Epidemiology, and End Results (SEER) program (awarded to the University of California, San Francisco), contract HHSN261201800015I with the NCI’s SEER program (awarded to the University of Southern California), and contract HHSN261201800009I with the NCI’s SEER program (awarded to the Public Health Institute, Cancer Registry of Greater California). The collection of cancer incidence data in Georgia was supported by contract HHSN261201800003I and task order HHSN26100001 from the NCI and cooperative agreement 5NU58DP006352-03-00 from the CDC.

Role of the Funder/Sponsor: The National Cancer Institute, the US Centers for Disease Control and Prevention, and the California Department of Public Health had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.

Disclaimer: The views expressed in this article are those of the authors and do not necessarily reflect the opinions of the National Cancer Institute, the US Centers for Disease Control and Prevention, and the California Department of Public Health or their contractors and subcontractors.

Meeting Presentation: Presented in part at the American Society of Clinical Oncology annual meeting; June 5, 2023; Chicago, Illinois.

Data Sharing Statement: See Supplement 2.

Additional Contributions: We thank Nicola Schussler, BS (Information Management Services), Jill S. Dolinsky, MS, and Carolyn Horton, MS (both with Ambry Genetics), Michelle M. Morrow, PhD, MS (GeneDx), Sarah R. Poll, PhD (Invitae), and Brandon Ulm, BS (Myriad Genetics), for their collaboration on the genetic test data linkage to the Surveillance, Epidemiology, and End Results data. The acknowledged contributors were not compensated for their work.