New Research Shows Blood Test Can Find Colorectal Cancer

2018 Gastrointestinal Cancers Symposium
January 16, 2018
Monika Sharda, ASCO staff

The 2018 Gastrointestinal Cancers Symposium begins this week in San Francisco, running from January 18th to the 20th. This meeting covers the latest science in cancers of the esophagus, stomach, pancreas, small bowel, colon, rectum, and anus. Drawing experts from the United States and internationally, it is an opportunity for people to exchange ideas about how to improve the treatment of cancers that affect parts of the gastrointestinal system. You can learn more about research from this symposium by following the #GI18 hashtag on Twitter.

One of the studies that will be presented at the symposium has found that a new blood test can find colorectal cancer, even at its earliest stages.share on twitter This blood test is a type of “liquid biopsy.” During the procedure, a health care professional collects a routine sample of blood that is then analyzed with a blood assay called CMx to see if there are circulating tumor cells (CTCs).

This study took place at a hospital in Taoyuan, Taiwan. There were a total of 620 participants who were over the age of 20 and were coming to the hospital for either a routine colonoscopy test or an already known colorectal cancer diagnosis. In the study, the same group also had their blood tested for CTCs. The testing results were then compared, to see how well the blood testing results identified people who had precancerous polyps or any stage of colorectal cancer. The accuracy of the blood test was calculated to be 84% to 88%, which is higher than that of a standard colorectal cancer screening test called a fecal occult blood test (FOBT). The chance for a “false positive” test result was less than 3%, according to the study. “False positive” means that the test results incorrectly showed signs of CTCs in a person without colorectal cancer.

What does this mean?

The technology used in this study shows promise because of its reported accuracy in finding evidence of colorectal cancer at an early stage and even a pre-cancerous stage, when it is easier to treat successfully. Previous research has shown that the CTC blood testing found later stages of colorectal cancer. Currently, colorectal cancer is usually found through such tests as FOBT, colonoscopy, sigmoidoscopy, barium enema, or stool test. Though these methods are reliable, studies show that people can find them to be uncomfortable or inconvenient. A simple and accurate blood test could be an easier and more affordable screening option.

Next, the researchers plan to further test this liquid biopsy technique in additional studies in Taiwan and in the United States. According to the researchers, this blood test could eventually be used to screen for other types of cancer, such as breast, lung, and prostate cancers. 

“Our study is important because there is still some reticence among patients to use stool-based tests or have an invasive exam like colonoscopy to detect colorectal cancer. Our results may point to a solution.” 

—   lead study author Wen-Sy Tsai, MD
Linkou Chang Gung Memorial Hospital
Taipei, Taiwan