Abstract
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.
Highlights
Colorectal cancer (CRC), with over 1.3 million new cases worldwide annually, can be difficult to detect at early stages due to non-specific symptoms which may lead to delayed diagnosis [1,2]
Tumor biomarkers in blood, including carcinoembryonic antigen (CEA) and carbohydrate antigen19-9 (CA19-9), have been used for detecting and monitoring tumor progression in CRC patients, and elevated levels of both these markers are associated with poor prognosis [4,5]
Plasma Circulating tumor DNA (ctDNA) samples obtained from CRC patients during surgery were analyzed for mutations in a panel of 50 CRC-related genes
Summary
Colorectal cancer (CRC), with over 1.3 million new cases worldwide annually, can be difficult to detect at early stages due to non-specific symptoms which may lead to delayed diagnosis [1,2]. Tumor biomarkers in blood, including carcinoembryonic antigen (CEA) and carbohydrate antigen (CA19-9), have been used for detecting and monitoring tumor progression in CRC patients, and elevated levels of both these markers are associated with poor prognosis [4,5]. These biomarkers are not specific to a single cancer type and may be elevated due to unrelated conditions and are not entirely reliable [6]. As tumors are not always accessible for biopsy or repeated biopsy taken together with the fact that other biomarkers are not totally infallible, there is an urgent need to develop standardized, non-invasive techniques to characterize tumors, monitor disease progression, and response to treatment
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