Blood Test Could Identify Gastrointestinal Cancers in Asymptomatic Individuals

A blood-based screening test using cell-free DNA may be able to identify cancer at earlier stages than what was previously possible, according to research to be presented at the American Society of Clinical Oncology (ASCO) Gastrointestinal Cancers Symposium, held January 23 to 25 in San Francisco.

Gastrointestinal (GI) cancers are particularly difficult to identify early because the affected organs are deep inside the body and cannot be easily seen or felt during physical exams. Furthermore, no screening tests are currently available for certain cancer types, such as those of the gallbladder, bile duct, and pancreas. Because of these barriers, GI cancers are often diagnosed at advanced stages that are more difficult to treat, according to a press release by ASCO.

The blood test utilizes degraded DNA fragments circulating through the blood stream, which can come from sources such as tumor cells that have died and released DNA fragments. The test is based on DNA methylation, which plays a role in the development of cancer.

The study included patients with more than 20 tumor types at all disease stages, as well as non-cancer controls. In the second substudy of the Circulating Cell-free Genome Atlas study, plasma DNA underwent targeted methylation analysis to develop an algorithm that could identify the presence of cancer and its location in the body, including in the esophagus/stomach; the pancreas, gallbladder, and extrahepatic bile duct; the liver and intrahepatic bile duct; and the colon and rectum. The data included training and validation sets.

Researchers found that the technology had an overall sensitivity of 82% for cancer detection in the training set and 81% for the validation set. The specificity was more than 99%. The overall accuracy for defining the GI tissue of origin was 91% and 89% for training and validation sets, respectively. The researchers also noted that the test had a low rate of false positives.

“If further validated with additional testing, this approach has the potential to allow us to diagnose gastrointestinal cancer earlier, when they’re more treatable,” said Brian Wolpin, MD, MPH, director of the Gastrointestinal Cancer Center at the Dana-Farber Cancer Institute in Boston, in a press release.

In order to further validate these findings, the developers have enrolled 100,000 women undergoing screening mammograms in the STRIVE study, as well as 50,000 men and women without a known cancer diagnosis in the SUMMIT study.

REFERENCE

Blood-Based Test Could Help Identify Hard-to-Detect Gastrointestinal Cancers [news release]. Alexandria, VA; Jan 21, 2020. ASCO website. asco.org/about-asco/press-center/news-releases/blood-based-test-could-help-identify-hard-detect. Accessed Jan 24, 2020.