Blood Test Detects Colon Cancer
CCSA Screen Also Reveals High-Risk Growths Bound to Become Cancerous
Missed 9% of Cancers
In preliminary studies, the researchers tried the test on 135 people who had
undergone colonoscopies: 28 had colon cancer, 18 had advanced adenomas, 59 had
non-advanced adenomas or polyps, and 30 showed no sign of colon cancer. Blood
samples from 125 more people with disorders other than colon cancer were also
Results showed that the test had an overall sensitivity of 91%, meaning that
only 9% of colon cancers or advanced adenomas were missed.
The specificity was 80%, meaning that the test gave false-positive results
to 20% of people who didn't have the cancer or advanced adenomas. The research
was funded by Onconome Inc., which holds the license for the technology.
The next step is to validate the findings in studies of larger groups of
people, Leman says.
Results Early, but Exciting
Petrelli, a spokesman for the conference, says, "In view of the fact
that we don't have a blood test to determine if a patient has colon cancer or
premalignant polyps, the specificity and sensitivity rates are not bad in the
If the results can be reproduced, Petrelli says he foresees that people with
positive test results would be sent on to colonoscopy to confirm the diagnosis.
What about people with negative results? At this point, the need for a
colonoscopy can't be ruled out, Petrelli says.
Leman agrees, but says that in the future the researchers hope to develop a
blood test with 100% sensitivity and specificity, perhaps by testing for
CCSA-2, CCSA-3 and CCSA-4 simultaneously. "Then, if you had [a low level of
these blood markers], you might not need a colonoscopy," he says.
"The results are exciting, but there is so much more research that still
has to be done," Petrelli says.