Colorectal Cancer Screening: Micro-RNAs Help to Find Early Cancer (12)


– Let’s continue speaking about the microRNAs. Dr. Anton Titov MD 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. 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? 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. 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.

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