This study aims to investigate the long-term prognostic utility of circulating tumour DNA (ctDNA)
KRAS mutations in colorectal cancer (CRC) patients and compare this with
KRAS mutations in matched tissue samples. Tumour tissue (
n = 107) and ctDNA (
n = 80) were obtained from patients undergoing CRC resection and were analysed for
KRAS mutations. The associations between
KRAS mutation and overall survival (OS), cancer-specific survival (CSS), and recurrence-free survival (RFS) were analysed. All outcomes were measured in years (y). A total of 28.8% of patients had
KRAS mutations in ctDNA and 72.9% in tumour tissue DNA. The high frequency of
KRAS mutations in tissue samples was due to 51.4% of these being a detectable low mutation allele frequency (<10% MAF). Comparing
KRAS mutant (
KRASmut) to
KRAS wild-type (
KRASwt) in ctDNA, there was no association found with OS (mean 4.67 y vs. 4.34 y,
p = 0.832), CSS (mean 4.72 y vs. 4.49 y,
p = 0.747), or RFS (mean 3.89 y vs. 4.26 y,
p = 0.616). Similarly, comparing
KRASmut to
KRASwt in tissue DNA there was no association found with OS (mean 4.23 y vs. 4.61 y,
p = 0.193), CSS (mean 4.41 y vs. 4.71 y,
p = 0.312), or RFS (mean 4.16 y vs. 4.41 y,
p = 0.443). There was no significant association found between
KRAS mutations in either tissue or ctDNA and OS, CSS, or RFS.
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