Using a very sensitive method called Methylation on Beads (MOB) developed by Jeff Tza-Huei Wang, Ph.D., a professor at the Whiting School of Engineering at Johns Hopkins, the researchers were able to single out, in the blood, even the smallest strands of DNA of those two genes with their added methyl groups. The technique uses nanoparticle magnets to latch on to the few molecules being shed by the tumors, which are enough to signal the presence of pancreatic cancer in the body, the researchers found.
Specifically, researchers say, they found BNC1 and ADAMTS1 in 97 percent of tissues from early-stage invasive pancreatic cancers. Surgery is the best chance for survival in pancreatic cancer, because radiation and chemotherapy are not very effective against it. The smaller the cancer -- the earlier it is detected -- the more likely surgery will be successful and the patient will survive.
Ahuja says the practical value of any blood test for cancer markers depends critically on its sensitivity, meaning the proportion of tumors it detects, and its specificity, meaning how many of the positive results are false alarms. The specificity of this new pair of markers is 85 percent, meaning 15 percent would be false alarms. Ahuja says she hopes further research will help refine the test, possibly by adding another gene or two, in order to go over 90 percent in both sensitivity and specificity.
Ahuja also cautions that her team still needs to duplicate the results in a larger sample of tumors, but is encouraged by the results so far. She says she doesn't envision the blood test as a means of screening the general population, the way mammograms and colonoscopies are used to find early breast and colon cancers. Instead, she imagines it would be best used in people at high risk for developing the disease, such as those with a family history of pancreatic cancer, a previous case of pancreati
|Contact: Stephanie Desmon|
Johns Hopkins Medicine