Blood Test Detects Colon Cancer in Single-Center Study

Kerry Dooley Young

June 01, 2020

A blood test detected 11 of 11 cases of colorectal cancer in a study involving 354 patients, and also spotted a majority of cases — 40 out of 53 — in which participants had advanced adenomas, an investigator said.

Results from a single-center study of CellMax Life's FirstSight blood test were released as a poster as part of the annual Digestive Disease Week®, which was canceled because of COVID-19.

For a study conducted at one site, the Veterans Affairs Palo Alto (Calif.) Healthcare System, Shai Friedland, MD, and colleagues recruited 354 patients between ages 45 and 80 who were scheduled for elective colonoscopy. The researchers excluded people with a personal history of cancer or inflammatory bowel disease. They used CellMax's FirstSight test on blood samples from the study participants.

The FirstSight test result was positive for colorectal cancer in all 11 patients in the study who were found by colonoscopy to have this condition, said Dr. Friedland, who is a professor of medicine at Stanford (Calif.) University and chief of gastroenterology at the VA Palo Alto Healthcare System. Thus, the test showed a sensitivity of 100% in this instance.

Among the 53 study participants found by colonoscopy to have advanced adenoma, 40 were positive on FirstSight; thus, so the test has a sensitivity of 75.5% for this result.

Among 79 patients who had negative colonoscopy results, meaning they were judged free of cancer or polyps, the test showed 8 as having signs of disease or growths.

"If you had a large adenoma that was removed years ago and now you have a negative colonoscopy, your score might still be high," Dr. Friedland said in a recorded presentation for DDW. "In other words, the changes that are detectable in your blood might persist even after the polypectomy."

He said there are plans to soon start a large-scale multicenter study of the CellMax assay.

"The blood test has the potential to fill an unmet need by giving patients a highly sensitive convenient option for colorectal cancer screening," he said.

CellMax already is seeking to position its test as a more convenient alternative to either colonoscopy or the Cologuard screening test. Many patients put off cancer screening because of the need to take time off from work and the invasive nature of colonoscopy. Exact Sciences has used direct-to-consumer advertising to promote its Cologuard home-based test as a more convenient alternative to colonoscopy, but its product requires patients to collect their own stool samples and mail them to a lab, a process many people find off-putting.

Public health advocates, including the U.S. Preventive Services Task Force (USPSTF), have for years been pressing for wider screening of American adults for colon cancer. USPSTF is in the midst of updating its recommendations on colon cancer. In announcing its latest update of these recommendations in 2016, USPSTF said "the best screening test is the one that gets done" (JAMA. 2016;315[23]:2564-75).

USPSTF pressed for maximizing the total proportion of the eligible population, a point Dr. Friedland echoed in a CellMax press release.

"For colon cancer screening to be most effective, it is essential to detect precancerous polyps and then perform a colonoscopy to remove the polyps," said Dr. Friedland in the CellMax press release. "Giving patients the option of getting a blood test for screening would undoubtedly increase compliance and thereby reduce mortality from colorectal cancer."

In the DDW presentation, Dr. Friedland and colleagues also said the CellMax test showed greater sensitivity (100%) for colorectal cancer and advanced precancerous lesions (75.5%) than did Cologuard (92.3% for colorectal cancer and 42.4% for advanced precancerous lesions).

Cara Connelly, Director of Public Relations and Corporate Communications for Exact Sciences said that the company "is dedicated to getting more people screened for colorectal cancer and applaud the researchers for their efforts. We look forward to hearing more about the performance of this test in a prospective multisite study with nonsymptomatic patients."

Naresh T. Gunaratnam, MD, a gastroenterologist and research director at Huron Gastro in Ypsilanti, Mich., said he is concerned that aggressive promotion of alternative tests may obscure the benefits of colonoscopy. Dr. Gunaratnam, a 2019 winner of the American Gastroenterological Association (AGA) Distinguished Clinician Award, has been a public critic of the marketing of colon cancer tests, which emphasize the convenience of these products. When asked by MDedge to comment on the CellMax-funded study, Dr. Gunaratnam said alternative tests do have a place for the care of patients who cannot or will not have a colonoscopy.

"But if you convince a patient who would be willing to have a colonoscopy not to, that's a disservice," he said.

"If you want the best test, the one that is best at finding cancers and finding polyps and the only one that can remove the polyp, that's colonoscopy," Dr. Gunaratnam added. "One day there may be a pill you can swallow that blows up the polyps, but we're not there yet. We have to mechanically remove them."

Digestive Disease Week (DDW) 2020: ePoster 575.

This article originally appeared on MDEdge.com.

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