Colorectal cancer screening. MicroRNA in blood and feces. How to find early colon cancer. 15
Colon cancer screening by non-invasive methods is important. New sensitive colon cancer tumor marker is found. Identification of microRNA in fecal samples and in blood can predict cancer risk. Colon cancer screening by non-invasive methods. New sensitive colon cancer tumor marker is microRNA in fecal samples and in blood can predict cancer risk. Let’s continue speaking about the microRNAs. Colorectal cancer is the most common cancer, if you take women and men together. Almost 1.5 million people around the world are diagnosed with colon cancer each year. And yet colon cancer deaths can be entirely preventable by screening for precancerous polyps and early detection of colon cancer tumors. Dr. Anton Titov, MD. Colonoscopy remains the standard method of screening for colon cancer, but less invasive methods are being developed. MicroRNA identification is a non-invasive colon cancer screening method. You have shown that microRNA can be identified in fecal samples. So micro RNA from colon cancer tumors can serve as a biomarker for early detection of colorectal cancer by analyzing a small fecal sample. How can microRNAs be used in colorectal cancer screening? Dr. C. Richard Boland, MD. We have just discussed finding miR-21 and other microRNAs in the blood. Several years ago one of the research fellows in the lab suggested that microRNAs that are differentially expressed in the colon cancer might be present in stool [feces]. Initially I didn’t think that we could find microRNAs in fecal samples. I thought that microRNAs would be too fragile and broken down in the feces. But it turned out he was correct – we can isolate microRNAs in fecal samples. There is at least one company in the USA and more companies in Europe that work on methods of early detection of colon cancers by analyzing fecal samples. So identification of microRNAs is one of the ways how you can find early colon cancer. So far we have used for early colon cancer detection a guaiac test to detect blood in fecal samples. Now most people use fecal immunochemical test. But it still has sensitivity and specificity problems to detect cancer. One company in the United States is adding methylated DNA analysis and KRAS tumor mutations analysis to fecal testing for colon cancer. I think it’s too hard to do that – it’s going to be very hard to make such fecal sample tests work well. Micro RNAs should be very easy to measure. Also I’m hoping that they are going to start to incorporate microRNA analysis in fecal sample testing for colon cancer. The problem is that a lot of people find it difficult to collect a stool and put it in the mail and give fecal sample to their doctor. People just don’t like to do that. So a blood test will be better. But if people are going to do any kind of fecal test to detect colon cancer, they have to test for microRNAs. Because there are multiple copies of microRNAs in each cell. But there are just two copies of DNA. So in microRNAs you have an amplified signal by definition. So the companies, which are working on colon cancer early detection methods, must look at microRNAs. If you’re going to measure anything in stool [in feces], microRNAs will probably the most sensitive test for finding early stage colon cancer tumor. Dr. C. Richard Boland, MD. These microRNAs are present in colon cancer tumors. But they are present in advanced colon adenomas too. Colon polyp doesn’t have to be fully malignant to get these abnormal microRNA genetic signatures. So that will be a very exciting non-invasive earlier screening. And it’s important to identify precancerous lesions. Because finding blood in feces signifies that colorectal cancer has already became quite advanced. Yes, and also the problem with blood in feces is that blood can be coming from anywhere in the gut. You could have bleeding from your mouth gums. You can have bleeding from hemorrhoids. So if we can find a test for early colon cancer detection that is very specific for cancer identification, it will be much more powerful. Dr. Anton Titov, MD.
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