Analysis of circulating cell-free DNA (cfDNA) of colorectal adenoma (AD) and cancer
(CRC) patients provides a minimally invasive approach that is able to explore genetic
alterations. It is unknown whether there are specific genetic variants that could
explain the high prevalence of CRC in Hungary. Whole-exome sequencing (WES) was performed
on colon tissues (27 AD, 51 CRC) and matched cfDNAs (17 AD, 33 CRC); furthermore,
targeted panel sequencing was performed on a subset of cfDNA samples. The most frequently
mutated genes were APC, KRAS, and FBN3 in AD, while APC, TP53, TTN, and KRAS were
the most frequently mutated in CRC tissue. Variants in KRAS codons 12 (AD: 8/27, CRC:
11/51 (0.216)) and 13 (CRC: 3/51 (0.06)) were the most frequent in our sample set,
with G12V (5/27) dominance in ADs and G12D (5/51 (0.098)) in CRCs. In terms of the
cfDNA WES results, tumor somatic variants were found in 6/33 of CRC cases. Panel sequencing
revealed somatic variants in 8 out of the 12 enrolled patients, identifying 12/20
tumor somatic variants falling on its targeted regions, while WES recovered only 20%
in the respective regions in cfDNA of the same patients. In liquid biopsy analyses,
WES is less efficient compared to the targeted panel sequencing with a higher coverage
depth that can hold a relevant clinical potential to be applied in everyday practice
in the future.
