From the Journals

‘Test all patients with cancer’: One in eight have inherited mutations


About one in eight patients with cancer have inherited genetic mutations that may have contributed to the development of their cancers, but nearly half of these mutations would have been missed using current clinical guidelines.

These findings come from the largest study of its kind so far, conducted in nearly 3,000 patients with a wide range of cancer stages and types, including breast, colorectal, lung, ovarian, pancreatic, bladder, prostate, and endometrial cancers.

“This study tells us that the clinical practice guidelines are not very sensitive for identifying who does or doesn’t have a genetic mutation that is predisposing them to cancer,” commented first author Niloy Jewell Samadder, MD, director of the high-risk cancer clinic at the Mayo Clinic in Phoenix.

Finding a genetic mutation can alter clinical management of the cancer.

“This really does open up treatment and management options that might not have been accessible to these patients,” Dr. Samadder emphasized.

The results were published online on Oct. 30 in JAMA Oncology and were presented simultaneously at the American Society of Human Genetics. Dr. Samadder discussed details of the study in a video posted on YouTube.

A clinician not involved in the study said the new results should lead to changes in practice.

“For cancer patients, I think the debate is over. We should test everybody,” Peter Beitsch, MD, surgical oncologist at the Dallas Surgical Group, said in an interview.

The Mayo Clinic is changing its daily practice at all four of its cancer centers. The changes will begin in the first quarter of 2021 at its Arizona campus.

“Every cancer patient who comes to Mayo Clinic will be offered genomic evaluation that includes genetic testing to identify if they have an underlying genetic mutation that predisposes to their cancer and [helps physicians decide] how to incorporate that knowledge into designing the best surgical and treatment options for that patient and their family,” Dr. Samadder said.

Study details

The study included 2,984 patients with cancer who were receiving care for a variety of solid tumor cancers at Mayo Clinic cancer centers in Arizona, Florida, Minnesota, and a community cancer center in Wisconsin.

Patients were tested for about 84 genes using next-generation sequencing provided by Invitae.

Among participants, 13.3% (n = 397) tested positive for pathogenic mutations. Of these, about 70% (282 of 397 patients) carried moderate- and high-penetrance genes that increased their risk for cancer. For almost 28.2% (n = 42) of patients with high-penetrance mutations, changes were made in treatment as a result of genetic testing. These included changes in surgical management, immunotherapy, chemotherapy, or enrollment in a clinical trial for which they may otherwise have not been eligible.

Researchers also compared their universal testing approach with targeted testing recommended in guidelines from the National Comprehensive Cancer Network, the National Society of Genetic Counselors, and the American College of Medical Genetics.

They identified pathogenic mutations in 192 patients whose mutations would have been missed using guideline-recommended criteria, such as tumor pathology or family history. This represents 6.4% of all participants in the study (192 of 2,984 patients) and 48.4% of patients who tested positive for pathogenic mutations (397 of 2,984 patients).

“Genetic testing is underutilized in cancer care, both for patients and for their families, often due to outdated guidelines that restrict testing to a narrow group of high-risk patients. All cancer patients should have access to complete genetic information that can guide their care and inform their families’ health,” coauthor Robert Nussbaum, MD, chief medical officer of Invitae, said in a statement.

Some clinicians have been pushing for genetic testing of all patients with cancer, including Dr. Beitsch, who was lead author of a similar study in breast cancer patients published last year in the Journal of Oncology. That article made waves when the authors concluded that all breast cancer patients should have expanded panel genetic testing.

This new Mayo Clinic study extends the findings in breast cancer to “all cancer patients, not just breast cancer patients,” Dr. Beitsch said in an interview.


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