WASHINGTON, June 26 (Xinhua) -- An epigenetic mechanism known as DNA methylation could effectively and accurately identify at least four common cancers of the lung, breast, colon and liver, a new study by U.S. and Chinese researchers suggested Monday.
The study, published online in the U.S. journal Proceedings of the National Academy of Sciences, showed that DNA methylation markers could correctly differentiate malignant tissues from normal, potentially providing "a new and more effective" way to diagnose cancers.
DNA methylation involves methyl groups -- one carbon atom bonded to three hydrogen atoms -- attaching to DNA molecules.
It is a fundamental epigenetic process that regulates gene function without changing DNA sequence of a gene, essential to normal development and associated with numerous key processes, including initiation and progression of cancer.
Researchers at the University of California (UC) San Diego, with colleagues in Xijing Hospital and Sun Yatsen Cancer Center in China, evaluated the utility of DNA methylation for differentiating tumor tissue and normal tissue for cancers of the lung, breast, colon and liver.
They did this using three different databases from the U.S. and China that involved about 2,800 tumor samples and 590 matched adjacent normal tissue samples in total.
The results showed that DNA methylation analysis could predict cancer versus normal tissue with more than 95 percent accuracy in the three cohorts, comparable to typical diagnostic methods.
Senior author Kang Zhang, founding director of the Institute for Genomic Medicine and co-director of Biomaterials and Tissue Engineering at the Institute of Engineering in Medicine, both at UC San Diego School of Medicine, suggested DNA methylation has the potential to improve outcomes by providing more accurate diagnoses, particularly of relatively indolent or aggressive tumors that may require more or less aggressive treatment.
"Although we focused on just four common cancers here, we expect that DNA methylation analysis could be easily expanded to aid diagnoses of a much larger number of cancers," said Zhang.
"A great benefit is that this approach requires only a small amount of tissue to obtain adequate DNA for analysis, potentially allowing the use of less invasive biopsies or biopsies of metastatic lesions where the tumor is of unknown primary cancer type."
In addition, the study correctly identified 97 percent colorectal cancer metastases to the liver and 94 percent colorectal cancer metastases to the lung.
"As 10 percent of cancers present as metastatic lesions or cancer of unknown primary, identification of tissue of origin is critical for choosing a correct therapy," said Michael Karin, co-senior author of the study, distinguished professor of Pharmacology, also in UC San Diego School of Medicine.
"This new simple method will be of great value to pinpoint the primary source of tumor," Karin said.
According to the researchers, more studies have been planned to fully explore the clinical applications and potential of DNA methylation and its role in future personalized cancer care.
