Genetic Testing: The 'Train That Keeps On Chugging'
Although genetic testing could be crucial in developing treatment plans and improving outcomes in women with ovarian and breast cancer, less than 20 percent of eligible patients actually get tested, according to Mike Janicek, M.D.
Janicek, who is the medical director of the genetics division at Arizona Oncology, recently sat down with OncLive, a sister publication of CURE, to discuss the importance of genetic testing, as well as some progress that still needs to be made in the field.
“There have been incremental changes in ovarian cancer with gene panels, targeted therapies, PARP inhibitors, targeting genetic mutations and immunotherapies,” he said. “We have made some astounding progress, and we are starting to see genetics creep into other fields such as breast cancer and prostate cancer indications. We are headed in the right direction.”
When asked who should undergo testing, his answer, in one word, was simple: everybody.
The decision to undergo genetic testing was previously determined by family history. However, more patients are now presenting with mutations but have no family history of cancer.
While the answer of “who” seems cut and dry, the “when” part remains more unclear, Janicek said.
For example, it might be a bit more difficult to have a patient undergo genetic testing after she has just undergone debulking surgery or is preparing for chemotherapy. In this situation, physicians may wait until the second round of chemotherapy to do the testing, as “the dust has settled,” at this point, said Janicek, and patients are not so overwhelmed with their diagnosis and following procedures. Not to mention, genetic testing is a complex process.
A genetic counselor can be of huge help throughout this process, Janicek said “I am a big fan of genetic counselors; they do a way better job than we do because they have expertise and more time to dedicate to this area,” he added. “A lot of time goes into testing. It is a complicated topic, but there is no going back on this. We need to do more genetic testing; there is more genetic information coming up. It is hard to keep up, but it is a ‘train that keeps on chugging.’”
Aside from the who and when, patients and providers must also consider cost and insurance coverage, too.
Somatic testing – meaning that the actual tumor is tested – is important, Janicek said, but not always covered by insurance. Germline testing, which is a blood test that can lend insight regarding inherited mutations, is usually better covered.
“A lot still needs to be worked out in the clinical oncology and genetics world,” Janicek said.
Once genetic testing is performed, the results can have a major impact on the treatment a patient receives. For example, data has shown that patients with deleterious homologous recombination deficiency (HRD) alterations are more likely to have better responses with PARP inhibitors.
However, the Food and Drug Administration did not include patients with these alterations in the approved treatment indications for PARP inhibitors due to lack of data. Therefore, Janicek believes knowing about HRD status is up to the patient and clinician.
“As a clinician, I believe looking a patient in the eye and helping them understand what their likelihood is of responding to a drug is critical,” he added.
Also, a small amount of patients with ovarian cancer have tumors that test positive for microsatellite instability-high (MSI-H) status. While only about 3 percent of patients with ovarian cancer have this genetic defect, immunotherapy checkpoint blockades have proven to have high efficacy rates in MSI-H cancers.
“Given the power of some of these immune checkpoint inhibitors for select patients, ruling that out would be a shame,” Janicek said.