Paired genetic tests give patients better idea of their risk for cancer

Patients at risk of developing cancer can now get faster, more accurate diagnoses, thanks to new genetic and blood tests.

A new diagnostic tool called +RNAinsight allows clinicians for the first time to use paired genetic testing to detect the risk for hereditary cancers, possibly affecting thousands of patients. The biomedical firm Ambry Genetics Corp. manufactures the test, which launched Tuesday.

DNA testing is the standard for hereditary cancer screening, but it excludes large portions of hereditary material, thereby missing variants that increase risks for cancer. But adding RNA to DNA testing can provide more evidence about whether genes have the variants, according to Ambry Genetics.

“This is the first time we are offering paired DNA and RNA testing,” said Emily Dalton, director of the genetic specialist team at Ambry Genetics. “It’s going to allow us to identify more patients who are at risk for hereditary cancers and actually provide more accurate results to inform patient care as well.”

Researchers also have developed a single blood test that can detect numerous cancers with a degree of accuracy that exceeds 99%.

The test, made by the health care company GRAIL, uses next-generation sequencing technology to search for tiny chemical tags (methylation) in DNA that affect whether genes are active or inactive. It detected more than 20 cancers including breast, colorectal, esophageal, gallbladder, lung and leukemia.

When the test was applied to nearly 3,600 blood samples, it successfully picked up a cancer signal from cancer patient samples and pinpointed the tissue where the cancer began.

Geoffrey Oxnard, thoracic oncologist at the Dana-Farber Cancer Institute and one of the study’s researchers, said the blood test uses the cancerous genes to better find cancers.

“If we know what a cancerous DNA looks like, then we can go hunting for it,” Dr. Oxnard said. “We can hunt for all the cancers and then once we found a signal, we can clarify if that is a colon cancer signal or a head and neck signal. And that’s amazing.”

While some cancers are related to a patient’s inherited genetics, Dr. Oxnard said cancerous genes more often are “completely haywire” in different ways.

This year, an estimated 1,762,450 new cancer cases will be diagnosed in the United States and 606,880 people will die from the disease, according to the National Cancer Institute.

The most common types of cancer, according to 2018 figures, are breast, lung and bronchus, prostate, colon and rectum, melanoma, bladder, non-Hodgkin’s lymphoma, kidney and renal pelvis, endometrial, leukemia, pancreatic, thyroid and liver.

This year, almost 700,000 people in the U.S. are expected to seek testing to determine whether they have genetic mutations linked to increased risks of cancers. Of those, an estimated 16,000 people could be affected by the new paired genetic test, said Ambry Genetics.

Kara Milliron, genetic counselor at the University of Michigan’s comprehensive cancer center, said results from genetic testing for cancer screening could come back in three ways: positive, negative or “variant of unknown or uncertain significance.”

She said the paired genetic testing provides a better look and interpretation of these variants of unknown significance. The University of Michigan’s cancer center was one of more than 40 sites in a pilot study that used the +RNAinsight tests on patients.

“Cancer is a significant public health problem. It causes tremendous morbidity and mortality every year,” Ms. Milliron said. “Any improvements to genetic testing where we can get better answers for patients I think is really, really important. And it does have a significant impact on our ability to take care of patients in the best way.”

—

Updated from earlier to clarify the testing does not diagnose cancer but rather helps patients understand their risks of developing a hereditary cancer.