Assessment of the Integrity of Cell-free DNA via DNA Repeats in Lung cancer Plasma

Abstract

Circulating cell-free DNA (cfDNA) consists of highly diverse, short DNA fragments that reflect the physiological or pathological conditions of the body. Cancer patients exhibit higher concentrations of cfDNA, but its integrity—assessed via the cfDNA integrity (cfDI) index—is decreased compared to healthy individuals. The cfDI ratio based on Alu repetitive sequences (cfDI-Alu) is considered a potential biomarker to support early diagnosis and progression monitoring of cancer. This study develops a novel cfDI index based on two types of repetitive sequences: Alu and LINE-1 (L1). Initial evaluation of 122 cfDNA samples from lung cancer patients and 127 cfDNA samples from healthy controls showed that the cfDI-Alu/L1 index achieved a higher AUC value (0.72) than cfDI-Alu (0.69), suggesting that further studies with larger sample sizes are required to determine the diagnostic value of this new index.