In recent years, liquid biopsies have rapidly become the focus of clinical attention as tumor treatment techniques have evolved. The advantage of liquid biopsy, which is the early diagnosis of cancer through blood or urine, is that it is a non-invasive sampling method that can effectively reduce the harm of biopsy.
The alpha fetoprotein (AFP) test and ultrasound are currently the most commonly used methods for early diagnosis of liver cancer, but their specificity and sensitivity remain unsatisfactory. About 30% of patients with liver cancer have normal AFP; AFP may also be elevated in patients with chronic liver disease only or in pregnancy.
Recent studies have found that circulating tumor DNA methylation, another serum diagnostic indicator of liver cancer, is more sensitive and specific than AFP and can detect liver cancer earlier than imaging tests such as ultrasound and CT.
Today, we’ll take a look at circulating tumor DNA methylation and the value of “liquid biopsy” technology in the diagnosis of liver cancer.
What is circulating tumor DNA methylation?
Circulating tumor DNA methylation is a tumor-specific technique.
Circulating tumor DNA is a nucleic acid fragment that is released into the bloodstream when tumor cells become necrotic, apoptotic, or active, and recent studies have demonstrated its value in tumor screening and diagnosis.
Liquid biopsy, a branch of in vitro diagnostics, refers to a non-invasive blood test that detects circulating tumor cells (CTCs) and circulating tumor DNA (ctDNA) fragments released into the bloodstream from tumors or metastases, and is a breakthrough technology for detecting tumors and cancers and aiding treatment.
And DNA methylation is an epistatic regulation of gene expression that can cause changes in chromatin structure, DNA stability, and other changes that control the expression of genes in the body.
In the early stages of development of many malignant tumors, the methylation level of oncogenic DNA is increased, a phenomenon that suggests that DNA methylation may play an important role in the early diagnosis of hepatocellular carcinoma.
How accurate is liquid biopsy for hepatocellular carcinoma?
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Based on these assumptions, researchers at Sun Yat-sen University conducted a multicenter, large-sample, retrospective study to examine the value of circulating tumor DNA methylation in the diagnosis and prognosis of hepatocellular carcinoma, and the results were published in Nature Materials in 2016.
The study found that DNA methylation in liver cancer tissue samples and circulating tumor DNA methylation profiles were consistent, suggesting that circulating tumor DNA methylation can be a good indicator of liver tissue, and that the application of circulating tumor DNA methylation for liver cancer diagnosis is significantly more accurate than AFP and has better specificity and sensitivity than AFP.
Clinical significance of liquid biopsy
In summary, the use of “liquid biopsy” to detect circulating tumor DNA methylation is useful for the early diagnosis and prognosis of hepatocellular carcinoma, and is even more sensitive and specific than AFP.
Unfortunately, circulating tumor DNA methylation is still complex and expensive to isolate, and further optimization and cost reduction are needed.
In addition, this study alone is not sufficient to advance the technology in the clinic, and clinical studies with larger sample sizes are needed to confirm its accuracy.