Why somatic and hereditary cancer testing is crucial in oncology

One test isn't enough in precision oncology

In cancer care, a single test can shape critical decisions around treatment, risk assessment and inherited cancer risk, but what if it only tells part of the story?

For oncologists and pathologists navigating complex cancer cases, especially in solid tumors like breast, colorectal, ovarian, pancreatic, prostate, or uterine cancer, both somatic and hereditary cancer genetic testing (sometimes referred to as germline testing) are increasingly recognized as essential and complementary tools.^1,2 Yet, real-world data show that dual testing is often underutilized.³ Many patients never receive hereditary cancer genetic testing even when they meet rigid testing criteria, thus relying on somatic testing results alone to guide medical decisions.^1,2

“Every test has limitations. Somatic testing can miss germline variants and vice versa. When we combine both, we offer patients a more complete, actionable picture,” says Dr. Rebecca Previs, senior director of medical affairs at Labcorp.

Two tests, two powerful insights

Somatic testing identifies tumor-acquired mutations that can guide use of targeted treatments like poly(ADP-ribose) polymerase (PARP) or immune checkpoint inhibitors.^2,4 Hereditary cancer genetic testing identifies inherited variants (also known as germline variants) associated with cancer risk, and in some cases, therapy response, particularly in DNA repair genes like BRCA1/2, ATM, and PALB2.^5,6 When used together, these approaches offer a more complete view of a patient’s genomic landscape; relying solely on somatic testing can miss 8-18% of pathogenic germline variants.^7,8

Real-world evidence that demands broader access

“We wouldn’t want to miss one of these patients,” says Dr. Previs, “especially if targeted therapy or family risk is at stake.”

Invitae’s (now part of Labcorp) PROCLAIM study, one of the largest of its kind, underscores the case for universal hereditary cancer genetic testing in patients with prostate cancer.⁹ Among nearly 1,000 unselected patients with prostate cancer, 7.7% had a pathogenic variant, regardless of age, family history or disease stage. “There was no significant difference between groups, which tells us the current criteria are too restrictive and we're missing people,” adds Sarah Young, genetic counselor and senior clinical program manager at Labcorp.

The study also revealed disparities. Black patients who didn’t meet genetic testing criteria had higher rates of pathogenic variants than those who did. “Testing guidelines are largely based on data from White populations; they’re not sensitive enough for diverse groups,” says Young.

Bridging gaps in clinical workflows

So why does this gap persist?

Despite mounting evidence, hereditary cancer genetic testing remains underused in clinical practice.¹⁰ In prostate cancer, studies show that only 1% of all patients receive hereditary cancer genetic testing.¹⁰ Even among those with metastatic disease, where guidelines recommend testing, the rate only rises to about 13% to 30%.¹¹

The barriers are multifactorial. Many providers have limited genetics training. They also face unclear testing guidelines and time constraints that prevent them from evaluating comprehensive family histories. This often leads to hesitation in using both types of testing, not always due to a lack of perceived value, but because the process can feel complex, inaccessible, and lacking a streamlined workflow.

The good news is that these solutions already exist, and we provide them to make genetic testing accessible to providers and patients alike. We offer support at every step of the workflow, including tools that help identify patients who meet testing guidelines, educational resources, genetic counseling services, and more.

Why this matters now

“The therapeutic landscape is evolving fast, and having this information early can change the trajectory of care,” notes Dr. Previs. Targeted therapies like PARP inhibitors are being used after frontline treatment, making timely genomic insights more critical than ever. Trials are underway evaluating how certain variants may impact response to chemotherapy, radiopharmaceuticals, and hormone therapy. To make these insights actionable, early and broad testing is essential.

A partner in precision care

Labcorp offers both hereditary cancer and somatic testing solutions to support providers. From comprehensive genomic profiling through tissue or liquid biopsy to in-house precision oncology solutions and hereditary cancer panels with clinically actionable results, our solutions are built to fit into real-world workflows. All testing is backed by specialized teams including oncologists, pathologists, geneticists, and genetic counselors. Clear, actionable reports paired with patient education help translate test results into meaningful clinical decisions. Through education, posttest services, and tools that simplify complexity, we help bring clarity to even the most challenging cases. As Young puts it, “We’re not asking providers to take on more. We’re offering tools that make precision oncology more practical.”

A complete genomic picture for precision care

As clinical trials continue to expand the use of genomics in cancer care, the case for early, comprehensive testing grows stronger. Universal hereditary cancer genetic testing, paired with somatic profiling, offers patients the most precise and equitable care possible.

“Genetic testing is no longer exceptional; it is essential,” says Young.

At Labcorp, that vision is backed by a full suite of tools ranging from comprehensive test panels to post-test counseling and results education. For providers seeking clarity in complex cases, we offer a practical and scalable path to precision oncology.