Ep. 79 Germline Testing in Prostate Cancer: Who, When, and How with Dr. Todd Morgan

In this episode of BackTable Urology, Dr. Aditya Bagrodia interviews Dr. Todd Morgan, chief of urologic oncology at the University of Michigan, about benefits and indications for germline testing in prostate cancer patients.

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SHOW NOTES

First, the doctors discuss the formal definition of germline testing, which is identifying inherited DNA mutations known to be pathological. This is different from molecular testing, which detects molecular markers specific to tumor cells. The term “genomic testing” is a broad and vague term that may confuse patients. Germline testing may be beneficial to patients and their families by notifying them to undergo cancer screening earlier. 12% of metastatic prostate cancer patients and 5 to 10% of localized prostate cancer patients have a germline mutation.

Next, they discuss critical criteria for germline testing besides having a high grade and high stage cancer. Dr. Morgan recommends germline testing for all prostate cancer patients with metastatic cancer. He also believes that taking a thorough family history is fundamentally important in deciding whether or not to order testing. He emphasizes the importance of collecting information about other family members with other types of cancer, their age of diagnosis, their relationship to the patient, and their mortality from cancer. Patients may not know family history well, but he has a low threshold of testing if he suspects a pattern of heritability.

Then, Dr. Morgan explains how germline testing may affect decision making. For patients with localized and low risk disease, he notes that prompt treatment may be beneficial in patients with a BRCA2 mutation, but there is still not enough evidence to eliminate active surveillance as an option. For high-risk disease, he always recommends treatment over active surveillance, regardless of germline mutation. For patients who have a BRCA2 mutation but no diagnosis of prostate cancer, he counsels them in his high risk prostate clinic. These patients receive close screening measures, such as lower PSA level thresholds, identification of urine biomarkers, and MRI scans.

Additionally, the doctors discuss various testing companies. They do not recommend using 23 and Me as a comprehensive screening panel because it is exceedingly limited in the germline mutations it tests. Dr. Morgan also emphasizes that as the ordering physician, he is responsible for giving the patient the result of the test. If there is a positive result on germline mutation testing, he refers the patient to genetic counselors, who are equipped to deal with conversations regarding mutations that have non-urological implications as well. Finally, they end the discussion by chatting about different research trials about germline testing.