Exact Sciences and Mayo Clinic study blood-based lung cancer detection

A new study from Exact Sciences and Mayo Clinic released by the American Association of Cancer Research shows a new blood-based test could make detecting lung cancer a more reliable process.

“These results reveal an opportunity to detect lung cancer from a simple blood draw,” said Kevin Conroy, chairman and CEO of Exact Sciences, which is currently marketing a home colon cancer test. “Our collaboration with Mayo Clinic is efficiently identifying biomarkers for additional cancer applications on the same technology platform as Cologuard.”

AACR released the abstract of the study, which involved multiple rounds of testing on almost 400 patients, on Wednesday.

Of the 398 patients, 311 were controls, meaning they were considered to be “apparently healthy smokers,” with no cancer. The other 87 patients had cases of lung cancer.

There were two groups in the study, balanced by age and gender. Group 1 had 64 cases of cancer and 231 controls, while Group 2 had 23 cases and 80 controls.

Scientists for Exact Sciences and Mayo Clinic used a process called “whole methylome sequencing” to find methylated DNA markers, or MDMs, signaling lung cancer in tissue.

Using these MDMs, they could locate lung cancer cells in patients with a high degree of certainty; sensitivity to the cancer cells was found to be as high 96 percent at a specificity of up to 94 percent, meaning the false positive rate is at least 6 percent.

Current lung cancer screening tests, which are approved for smokers using CT chest scanning, has a sensitivity of over 90 percent, but specificity can be less than 75 percent, meaning false positives show up in over 25 percent of all patients scanned.

“A blood-based test may help guide next steps after a scan reveals an indeterminate nodule,” Conroy said. “For example, a positive blood test might suggest the need for a biopsy or surgery. In contrast, a negative test might suggest a less aggressive approach. Such a test could offer the opportunity to significantly improve health outcomes and reduce the financial impact on the health care system.”

Lung cancer results in 1.7 million deaths globally and over 150,000 deaths in the United States every year. Most symptoms don’t show up until survival rates drop dramatically, so the earlier this type of cancer is detected, the better.

The new test shows promise for decreasing the number of false positives in lung cancer screening, but David E. Midthun, a pulmonologist at Mayo Clinic, says the study should be taken with a grain of salt.

“More studies are needed to corroborate accuracy; however, this plasma DNA test approach appears to be a promising new method and may serve as a rational follow-up to the common findings of lung nodules on CT scanning and may have application in screening for lung cancer,” Midthun said.

A presentation of the findings will take place during the AACR’s annual meeting on April 2, at the Walter E. Washington Convention Center in Washington, D.C.

–By Alex Moe