Identifying the Methylation Patterns of cfDNA Aids in Identifying Cancer’s Origin

July 17, 2018
Identifying the Methylation Patterns of cfDNA Aids in Identifying Cancer’s Origin
[Source: jamesbenet / Getty Images]

Julianna LeMieux, Senior Editor

There will be roughly 1.7 million new cases of cancer diagnosed in the United States this year. For each one, the earlier the diagnosis the better. Although some cancers have routine screening methods such as colon cancer, multiple barriers prevent one-third of eligible people from being screened. For many cancers, with no routine screening methods, the cancer is frequently recognized past the point of available treatment options. Taken together, these hurdles make methods to detect cancer in its earliest stage, in as many people as possible, two major goals of cancer research.

One of the most exciting areas of development in early cancer detection lies in cell-free DNA (cfDNA). These short fragments of DNA circulate in the blood after being released from cells, including cancerous cells. One way cfDNA can signal the presence of cancer is through genetic variation. Because the DNA sequence in cancer cells has differences from non-cancer cells, those sequence variations, present in cfDNA, can be used to detect the presence of cancer. However, as Kristina Warton Ph.D., a researcher within the Gynaecological Cancer Research Group at the University of New South Wales in Sydney, Australia points out, “identifying cancer based solely on its DNA mutations requires a preexisting idea of all of the mutations associated with the cancer. This is difficult without prior access to tissue from each particular tumor. This is work that is being done, but is both laborious and expensive.”

A cheaper and easier way to use cfDNA in cancer screening is to harness the information held in the epigenetic marks on the DNA. Epigenetic marks, such as the addition of methyl groups to DNA, are highly tissue specific and also dysregulated in cancer. Therefore, when the methylation pattern on the DNA is analyzed, it identifies from which tissue the cfDNA has been released, uncovering the location of the cancer.

 

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