Characterization, diagnosis, and treatment of colorectal cancers (CRC) is difficult due to limited biopsy information, impracticality of repeated biopsies, and cancer biomarker fallibility. Circulating tumor DNA (ctDNA) has recently been investigated as a non-invasive way to gain representative gene mutations in tumors, in addition to monitoring disease progression and response to treatment. We analyzed ctDNA mutations and concentrations in 47 early- and late-stage CRC patients using a targetted sequencing approach using a panel that covers 50 cancer-related genes. ctDNA mutations in 37 genes were identified in 93.6% of the patients (n=47). The results showed that TP53, PIK3CA, APC, and EGFR were the most frequently mutated genes. Stage IV patients had significantly higher ctDNA concentration than Stage I patients, and increased ctDNA concentration correlated with increased tumor size. Additionally, ctDNA detection was found to be a greater predictor of disease when compared with five known commonly used tumor biomarkers. The present study supports the use of ctDNA as a liquid biopsy to gain clinical tumor information that may facilitate early diagnosis and treatment and improve CRC patient prognosis.
DETECTION OF CIRCULATING TUMOR DNA IN EARLY AND LATE STAGE HUMAN MALIGNANCIES