THURSDAY, Jan. 18, 2018 (U.S. News & World Report/HealthDay News)
A simple, cheap blood test to detect colon cancer — even in its early stages — appears highly effective and accurate, new research indicates.
The test detects so-called “circulating tumor cells” (CTCs). Researchers tested it on 620 people in Taiwan who were scheduled for a routine colonoscopy at a local hospital.
By comparing the blood test results with the colonoscopy results, the study team found that the blood test identified colon cancer in 87 percent of cases, ranging from stage I to stage IV cancer. The blood test also was able to detect 77 percent of pre-cancerous lesions indicating early stage disease. The researchers described the test as highly accurate, noting that it correctly identified cancer 84 to 88 percent of the time. Less than 3 percent of the time did it produce a “false positive” result, which mistakenly indicates the presence of cancer when there is none.
“Because the test can easily be made available for under $150, it could potentially be offered directly to consumers and ordered by physicians, with colonoscopy being the confirmatory diagnostic,” said study author Dr. Ashish Nimgaonkar.
The test is not yet available in the United States. If and when it does come to market, he said, it probably would not replace colonoscopy as the gold standard for screening. Rather, it most likely would supplant the preliminary stool-based tests that people often are reluctant to use, Nimgaonkar said. “This test could be an option for such individuals, boosting compliance” because it has a “higher sensitivity” than the stool-based screening options now available, he said.
Nimgaonkar is a gastroenterologist and medical director of Johns Hopkins University’s Center for Bioengineering Innovation and Design, in Baltimore. He and his colleagues are scheduled to present their findings Jan. 20 in San Francisco at the American Society of Clinical Oncology’s Gastrointestinal Cancers Symposium.
Experts note that research presented at meetings should be considered preliminary because it has not been subjected to the rigorous scrutiny given to research published in medical journals. Of the 620 people, all older than 20, included in the study, 438 were found to have either pre-cancerous growths, known as polyps, or colorectal cancer ranging from early to late-stage in development. For the blood test, the researchers used about a half-teaspoon of each participant’s blood. Earlier research had indicated that the test could detect very small amounts of CTCs — as low as one CTC per billion blood cells — with that size blood sample.
The researchers calculated that the blood test’s accuracy had a “specificity value” of more than 97 percent — meaning that any result indicating the presence of cancer or pre-cancer lesions should be considered very reliable.
Still, Nimgaonkar stressed that the blood test is envisioned as another tool in the screening arsenal rather than a replacement for colonoscopies.
“Just like stool tests, this test would not replace diagnostic colonoscopies,” he said. Those “would still be the confirmatory diagnostic for positive patients and would be needed for tumor or polyp biopsy and removal and examination if a person has a positive CTC test.”
Nimgaonkar said that planning is underway to launch the test in the United States, and he expects it to become available sometime this year.
Dr. Andrew Chan offered a more tempered take on the test’s potential. He’s a professor of medicine at Harvard Medical School and a gastroenterologist at Massachusetts General Hospital in Boston.
“These early results appear promising, but the sensitivity of the test is still not optimal. The number of patients in the study is also relatively small,” Chan said.
“In the long-term, there is the possibility that this type of liquid biopsy method could be used for screening,” he said. “However, I think it will require the development of more sensitive techniques tested in larger populations of patients before it will be a plausible alternative to current screening approaches.”
More information
The U.S. National Cancer Institute has more on colon cancer screening.
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THURSDAY, Jan. 18, 2018, 11:06 P.M. E.S.T. (New York Times/The Associated Press)
Scientists are reporting progress on a blood test to detect many types of cancer at an early stage, including some of the most deadly ones that lack screening tools now.
Many groups are working on liquid biopsy tests, which look for DNA and other things that tumors shed into blood, to try to find cancer before it spreads, when chances of cure are best.
In a study Thursday in the journal Science, Johns Hopkins University scientists looked to see how well their experimental test detected cancer in people already known to have the disease. The blood tests found about 70 percent of eight common types of cancer in the 1,005 patients. The rates varied depending on the type — lower for breast tumors but high for ovarian, liver and pancreatic ones. In many cases, the test narrowed the possible origin of the cancer to one or two places, such as colon or lung, important for limiting how much follow-up testing a patient might need. It gave only seven false alarms when tried on 812 others without cancer.
The test is nowhere near ready for use yet; it needs to be validated in a larger study already underway in a general population, rather than cancer patients, to see if it truly works and helps save lives — the best measure of a screening test’s value. “We’re very, very excited and see this as a first step,” said Nickolas Papadopoulos, one of the Hopkins study leaders. “But we don’t want people calling up” and asking for the test now, because it’s not available, he said. Some independent experts saw great promise. “It’s such a good first set of results” that it gives hope this approach will pan out, said Dr. Peter Bach, a health policy expert at Memorial Sloan Kettering Cancer Center who consults for a gene testing company. “Anything close to 50 percent or 40 percent detection is pretty exciting stuff,” and this one did better than that, he said. Dr. Len Lichtenfeld, deputy chief medical officer of the American Cancer Society, was encouraged that the test did well on cancers that lack screening tests now. If a blood test could find 98 percent of ovarian cancers at an early stage, as these early results suggest, “that would be a significant advance,” he said. But he cautioned: “We have a long way to go to demonstrate its effectiveness as a screening test.”
TESTING THE TEST
The test detects mutations in 16 genes tied to cancer and measures eigh proteins that often are elevated when cancer is present.nIt covers breast, colon and lung and five kinds that don’t have screening tests for people at average risk: ovarian, liver, stomach, pancreatic and esophageal. Prostate cancer is not included. A blood test already is widely used — the PSA test — but its value for screening is controversial. Researchers tried the new test on people whose cancers were still confined to where it started or had spread a little but not widely throughout the body. It detected 33 percent of breast cancers, about 60 percent of colon or lung cancers and nearly all of the ovarian and liver ones. It did better when tumors were larger or had spread. It did less well at the very earliest stage.
CAVEATS AND NEXT STEPS
The test probably will not work as well when tested in a general population rather than those already known to have cancer, researchers say. Hopkins and Geisinger Health System in Pennsylvania have started a study of it in 10,000 Geisinger patients who will be tracked for at least five years. The work was financed by many foundations, the Mayo Clinic, the National Institutes of Health and Howard Hughes Medical Institute, which provides The Associated Press with funding for health and science coverage. Many study leaders have financial ties to gene testing companies, and some get royalties for patents on cancer detection methods. Researchers say the test could cost around $500 based on current materials and methods, but the ultimate goal is to commercialize it, so what a company would charge is unknown.
OTHER LIQUID BIOPSY NEWS
Also this week, Taiwan-based CellMax Life gave results on its liquid biopsy test, which looks for whole tumor cells shed into blood, at an American Society of Clinical Oncology conference. Researchers tested 620 people getting colonoscopies or with confirmed colon cancer at a hospital in Taiwan. The company said its test had an overall accuracy of 84 to 88 percent for detecting cancer or precancerous growths and a false alarm rate around 3 percent. The company’s chief executive, Atul Sharan, said U.S. studies should start this year. The test is sold now in Taiwan for $500, but should cost around $150 in the U.S., he said. Dr. Richard Schilsky, chief medical officer of the oncology society, said results are encouraging, but the test needs more study, especially to see if it gives too many false alarms. “The last thing you’d want is a test that tells you you might have cancer if you don’t,” he said.
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