Poorva Chavan
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Written By: Poorva Chavan | Updated : February 8, 2016 10:48 AM IST
Detecting cancer at an early stage is tough and usually involves invasive procedures. But now, researchers at the National Institute of Health (NIH) in the US have designed blood tests that can detect five different types of cancers in early stages. They have identified a signature in the DNA of the tumour that occurs in five types cancers namely, colon, lung, breast, stomach and womb. They also believe that this signature may be present in many more cancers. Read: 6 common tests to determine your risk of cancer!
DNA methylation
The researchers found that a particular part of the DNA of the tumour undergoes a chemical modification called methylation. This methylation controls the expression of genes and can turn it on and off like a dimmer on a light switch. The higher the amount of DNA methylation also called as hypermethylation, the lower the activity of the gene.
Researchers also explained finding a distinctive methylation pattern is a technical challenge but they found a high amount of methylation around the gene called ZNF154 that is unique to tumours. Read:10 ways to change your food habits and prevent cancer!
The study
Researchers developed a series of steps that identified methylation marks in colon, lung, breast, stomach and endometrial cancers. They observed that all tumour types and subtypes consistently produced a methylation mark around ZNF154. Researchers then sequenced the tumour DNA which was amplified using a technique called Polymerase Chain Reaction. On analysing the results, they found elevated levels of methylation at ZNF154 in different tumour types. To verify their findings they developed a computer programme that looked at methylation marks in the DNA of people with and without cancer.
To confirm the connection between increased methylation and cancer, they developed a computer programme that looked at the methylation marks in the DNA of people with and without cancer. With this computer programme, they were4 able to detect a threshold for detecting tumour DNA. Even after reducing the number of methylated molecules by 99%, the programme could detect the cancer-related methylation marks. The study was published in The Journal of Molecular Diagnostics.
The blood test
Based on the knowledge that tumours often shed DNA into the bloodstream, the researchers calculated the proportion of circulating tumour DNA in the blood. Based on these findings, researchers hope to develop a blood test that can be used to diagnose cancers at a very early stage when treatments are most effective. Even though identifying methylated genes is an arduous task, researchers believe that it is a step forward in designing a blood test that can detect cancers at an early stage.
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