Circulating tumor cells (CTCs) in the blood had an accuracy of up to 88% in detecting colorectal cancer and 84% in identifying adenomas, in a study from Taiwan presented at the 2018 Gastrointestinal Cancers Symposium by Wen-Sy Tsai, MD, of Linkou Chang Gung Memorial Hospital in Taipei.1
It’s the first study to show high sensitivity in the detection of precancerous colorectal lesions.— Wen-Sy Tsai, MD. Photo ©ASCO/Todd Buchanan 2018
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“The study demonstrated high accuracy for the detection of colorectal cancer using a novel CTC assay. It’s the first study to show high sensitivity in the detection of precancerous colorectal lesions,” Dr. Tsai said. “The simple blood draw can be easily integrated into a patient’s routine physical, which will increase test compliance. This 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.”
Dr. Tsai said the detection of CTCs via this assay could be a potential solution to these screening barriers. The investigators estimated the cost of the blood test at about $100.
The study enrolled 620 individuals (aged 20 or older) presenting to Chang Gung Memorial Hospital for routine colonoscopies or had a confirmed diagnosis of colorectal cancer. Based on the colonoscopy and biopsy findings, 438 of them were found to have either adenomatous polyps or colorectal cancer (early- to late-stage), whereas the remaining 182 had no signs of these conditions and served as controls.
All participants had blood samples analyzed for the presence of CTCs with the CellMax biomimetic platform (CMx). The CMx test is a proprietary microfluidic biochip that minimizes nonspecific binding and accurately enumerates CTCs. Prior studies have shown that this assay can pick up as few as a single CTC per billion blood cells in most polyps. The results of the assays were compared in a blinded analysis with the colonoscopy and biopsy results. A multivariate analysis was also performed to assess the clinical performance of the assay, and disease status was evaluated by a standard clinical protocol that included colonoscopy and biopsy results.
The identification of CTCs proved to be a highly accurate means of identifying the presence of adenomatous polyps or early-stage colorectal cancer, Dr. Tsai reported. The test’s overall accuracy was 88% for all stages of disease, including the precancerous condition.
Dr. Tsai noted that the 87% sensitivity for detecting cancer compares favorably with the sensitivity of guideline-recommended screening tests: 75% to 93% for colonoscopy, 92% for stool DNA plus fecal immunochemistry, 73% to 88% for fecal immunochemistry alone, and 62% to 79% for guaiac-based fecal occult blood test. Its sensitivity for adenomas is 77%, compared with 79% to 94% for colonoscopy, 42% for stool DNA plus fecal immunochemistry, 24% for fecal immunochemistry alone, and 2% to 10% for fecal occult blood test.
The next step is to validate the use of CTC testing in the general population in Taiwan and to conduct studies in the United States. This assay could potentially be used in screening for other solid tumors, including those of the lung, breast, and prostate, Dr. Tsai suggested. ■
DISCLOSURE: Dr. Tsai reported no conflicts of interest. Several coauthors have relationships with industry, including CellMax Life.
1. Tsai W-S, et al: Prospective clinical study of circulating tumor cells for colorectal cancer screening. 2018 Gastrointestinal Cancers Symposium. Abstract 556. Presented January 20, 2018.
In a discussion of the study, Douglas Corley, MD, PhD, of the Division of Research at Kaiser Permanente, San Francisco Medical Center, California, said it remains unclear whether blood tests can improve the early detection of cancer, though such an approach would be welcomed.
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