Practice guidelines recommend germline genetic testing after cancer diagnosis to inform targeted treatment and identify relatives who may have inherited genes that increase their cancer susceptibility. More specifically, universal genetic testing is recommended for all patients with ovarian and male breast cancers. Due to advances in sequencing technology, the number of genes tested has increased from 2 in 2013 to 34 in 2019. Results are typically available within 2 to 4 weeks, and costs have declined over time, yet genetic testing remains underutilized, as evidenced by a recent study conducted by Dr Allison Kurian and colleagues.
In this study, published in JAMA in June 2023, the authors aimed to understand the prevalence of germline genetic testing. They included patients from the Surveillance, Epidemiology, and End Results (SEER) registries in California and Georgia, US, who received a cancer diagnosis between January 2013 and March 2019. Out of nearly 1.4 million patients, only 93,052 (6.8%) underwent germline genetic testing. While testing varied by cancer type, the highest rates occurred in patients with male breast (50%), ovarian (38.6%), and female breast (26%) cancers, still well below guideline-recommended standards. Testing rates increased over time, particularly for patients with pancreatic cancer, but remained low in those with lung cancer. Even with these increases, genetic testing rates in 2021 were still far below the 100% recommended by practice guidelines for cancer types such as ovarian, male breast, and pancreatic.
Rates of testing were lower in older patients, and racial and ethnic disparities were observed in Asian, Black, and Hispanic patients compared with non-Hispanic White patients. Uncertain test results, defined as those not clearly indicating whether the variant is related to cancer, were also significantly more common in non-White patients. This can lead to suboptimal clinical management and increased patient anxiety. The authors recommend potential strategies to address these disparities such as clinician education, incorporation of genetic counselors into oncology practices, telemedicine, and electronic health record reminders.
In an accompanying editorial, Dr Zsofia Stadler and Dr Deborah Schrag explore potential healthcare system-related barriers and patient factors to help explain the underuse of genetic testing. Healthcare system barriers include lack of timely access to genetic counseling, and patient factors include preoccupation with coping with their diagnosis and treatment, lack of awareness or interest, mistrust, or fear of the potential consequences of testing. They present an alternative to the traditional genetic counseling pretesting visit with a point-of-care testing approach known as mainstreaming. In this model, nongenetic healthcare clinicians (ie, surgeons, oncologists) provide patient education, obtain consent, and order the tests during a single visit, and the results are delivered by a genetic counselor or other specially trained clinician to ensure patients are properly informed.
Dr Kurian suggests that the low rates of genetic testing after cancer diagnosis in this study should stimulate interventions to increase rates of testing with the goal of reducing cancer burden. Out-of-pocket costs are still in the range of $100 to $250, which may represent a barrier. Increased access to genetic testing and research may help begin to address the racial and ethnic disparities. Professional societies can also support the increase of genetic testing by ensuring consistency of practice guidelines across organizations to help clinicians understand when genetic testing is indicated. Integration of clinical decision-support tools within electronic records and automated clinician notifications could also assist in the systematic identification of patients eligible for cancer genetic testing.
Genetic testing after cancer diagnosis may improve outcomes by informing targeted treatment and risk-reducing measures such as preventive surgery. Clinicians must be familiar with practice guidelines for when genetic testing is indicated so they can recommend appropriate testing to their patients. They must also provide patients with information necessary to make informed decisions about whether to undergo genetic testing. Dr Stadler and Dr Schrag encourage the use of digital methods (eg, web-accessible videos) in the patient’s preferred language to ensure patients receive pretest and posttest genetic counseling. These videos can be supplemented by telehealth visits with genetic counselors when needed, with a follow-up survey to evaluate and ensure comprehension.