Standardized Practices Address Challenges With Germline Genetic Testing in Prostate Cancer

Although updated guidelines and targeted therapies have led to the routine recommendation of germline genetic testing for patients with prostate cancer, increasing demand for tests and limited access to genetics providers have created an unmet need, according to a review performed by the Germline Genetics Working Group of the Prostate Cancer Clinical Trials Consortium that was published in the Journal of Clinical Oncology.¹

Despite the inclusion of this testing in multiple guidelines, practitioners still find challenges in implementing it on a clinical level. In order to help bring the field closer to an actualized version of precision medicine, the review touched on existing germline testing guidelines, challenges, possible solutions, and the current benefits and limitations of testing.

Challenges in Genetic Counseling

Several sets of guidelines for germline testing in prostate cancer have placed a notable amount of demand on the clinical workflows and resources for genetic counseling. According to the authors of the review, this proves problematic, as there is currently limited access to genetic providers, the majority of whom are located within urban areas or academic institutions.

“In 2016, the Genetic Counselor Workforce Working Group estimated a growth of 72% in the workforce between 2017 and 2026, with demand not expected to meet population equilibrium until 2024 to 2030,” wrote the authors. “This limited access may necessitate other health care providers, including oncologists, urologists, and primary care physicians, to absorb some responsibility for genetic testing.”

This can present an additional problem should providers be insufficiently trained in genetics, as it could lead to incorrect testing or misinformation.

In order to resolve these unmet needs, it's necessary to expand beyond historic delivery models and incorporate novel approaches, such as phone conferences and telemedicine, the utility of which has been well documented throughout the coronavirus disease 2019 (COVID-19) pandemic.² A multidisciplinary approach could also prove useful in hybrid service models that see responsibilities divvied up between physicians and genetic counselors.

“Collaboration between genetic counselors and clinicians is critical to determine which approach best suits a practice, because there is no one-size-fits-all solution,” wrote the authors.

Identifying the Right Patients and Testing Options

In order to ensure the right patients are being systematically identified for testing, the authors recommend assigning screenings to a single team member within a given institution or utilizing questionnaires to obtain a patient's family history in order to establish referral and testing processes. 

Upon identifying the appropriate patients for testing, the review highlighted several counseling and testing options available. These include referral to a genetic counselor or geneticist, whether it be in-person or through telemedicine; germline testing provided directly by the provider depending on urgency; and patient-initiated testing platforms, which offers clinical-grade testing initiated through the patient themselves, though concerns remain regarding test selection, limitations in genetic counseling, and lack of follow-up. 

Similarly, direct-to-consumer testing platforms have become popular due to its ease of access and lack of medical provider oversight, though the tests are not comprehensive, nor should they be substituted for clinical-grade testing, the authors noted.

Consideration for Family History

Germline genetic testing is recommended to all patients with high-risk localized or metastatic prostate cancer regardless of family history. However, the authors emphasize that personal and familial history could help to influence the need for a broader germline panel. 

“Cancer counseling sessions include a 3- to 4-generation pedigree with information on maternal and paternal relatives with cancer, age of diagnosis, age/cause of death, and any prior genetic testing,” the authors wrote. “For relatives with prostate cancer, the Gleason grade, metastatic status, and/or cause of death can be useful.”

Additional information such as ancestry and consanguinity should also be noted during these counseling sessions. This will better help to inform genetic testing, as well as ensuring cost-effectiveness. Expanded testing should also be considered to include genes related to observed cancers within a family's history, the authors noted.

Selecting the Right Panel

A wide array of testing panels is currently available to patients across numerous clinical laboratories, including those that are targeted, guideline-based, comprehensive, and pan-cancer, which may encompass preliminary evidence genes.

The review recommends individualizing genetic testing panels based on a handful of factors, including the quality and reputation of the lab in question, insurance networks, genes offered on the panel and how customizable the tests are, laboratory billing practices, options for follow-up tests for family members, turnaround times, and availability of genetic counselors.

“Clinical workflows must ensure that tasks involved with ordering genetic testing include determination of insurance coverage and submission of orders, standardized collection and shipment of samples, and a clear chain of responsibility,” the authors wrote.

Delivering Genetic Testing Results to Patients

Lastly, the review recommends a handful of options in order to return genetic testing results to patients.

Referring a patient for post-test counseling via a genetic counselor or telehealth service is 1 option. For patients with complex results, a blended approach should be utilized when referring the patient for post-test counselling; however, in the event a patient receives negative results, those may be disclosed via a phone call, follow-up appointment, or letter. 

It's an additional possibility for the ordering provider to disclose all results types, though the authors note that a posttest genetic counseling referral can still be given in this scenario. While positive results indicate a need for the provider to discuss and document result implications and potential associated cancer risk with the patient, those who have variants of uncertain significance should have their results reviewed carefully to determine whether it's a disease-causing or benign variant.

References

1. Szymaniak BM, Facchini LA, Giri VN, et al. Practical considerations and challenges for germline genetic testing in patients with prostate cancer: recommendations from the Germline Genetics Working Group of the PCCTC. JCO Oncol Pract. 2020. doi:10.1200/OP.20.00431.
2. State of the Physician Survey: Patient Communication Results. MJH Life Sciences. Published June 5, 2020.