Posts Tagged ‘new technique’

Is a Non-Invasive Method of Early Detection of Colon Cancer Possible?

Friday, September 13th, 2013

logo1267406_mdA new study published in Cancer Prevention Research reports on a new highly sensitive method to detect genetic variations that initiate colon cancer that could readily be used for noninvasive screening for colon cancer. The researcher said “Tumor cells are released into stool from the surface of precancers and early-state colon cancer, but detecting a cancer-intitating genetic mutation among a large quantity of normal ;DNA from a patient’s stool is like looking for a needle in a haystack>” “By combining for the first time locked nucleic acid based, wild-type blocking polymerase chain reactions and high resolution melting, we were able to achieve the desired sensitivity, The extremely high sensitivity of this technique allows us to find very low amounts of different types  of the cancer-indicating mutations in patient ‘ stool samples.”  she continued “Colon precancer cells carrying these genetic variations are routinely shed in stool samples, but these cells can be detected in blood only after the cancer has advanced, so stool is better than blood if we are to catch these cancer cells at a very early stage.”

The method discussed in this study can detect a single cancer-specific gene variation among 10,000 times the amount of normal DNA, and is up toi 5,000-fold more sensitive than other noninvasive screening methods. Sixty human colon tissue samples representing cancers and precancers were used to detect genetic variations using a combination of two techniques. The first locked nucleic acid (LNA) -based, wild type blocking (STB) polymerase chain reaction-suppressed normal DNA present iun large quantities in the sample, and the second technique-high-resolution melting (HRM)-enhanced the detection of genetic variations. They were able to detect APC variations in 41  of the 80 samples and also detected previously unknown variations, In contrast, the routinely used direct sequencing technique detected APC variations in 28 of the  of the 80 samples.

Researchers also analyzed 22 stool specimens from patients whose colon tissue had APC variations, and nine stool specimens from patients without APC in the colon tissue. They were able to detect APC variations in 21 of the 22 samples. “By using our technique for examining a selection of genes that become mutated during the process of colon cancer formation, it is possible to detect the very first stage of colon cancer and even precancers in a stool sample” the research stated. They warned however, that a multicenter study is needed to validate the sensitivity and specificity of this new method in comparison with standard screening methods. (more…)