Clinical significance of multiple gene detection with a 22-gene panel in formalin-fixed paraffin-embedded specimens of 207 colorectal cancer patients.

BACKGROUND: Simultaneous detection of multiple molecular biomarkers is helpful in the prediction of treatment response and prognosis for colorectal cancer (CRC) patients.

METHODS: A 22-gene panel consisting of 103 hotspot regions was utilized in the formalin-fixed paraffin-embedded (FFPE) tissue samples of 207 CRC patients, using the next-generation sequencing (NGS)-based multiplex PCR technique. Those 22 genes included AKT1, ALK, BRAF, CTNNB1, DDR2, EGFR, ERBB2, ERBB4, FBXW7, FGFR1, FGFR2, FGFR3, KRAS, MAP2K1, MET, NOTCH1, NRAS, PIK3CA, PTEN, SMAD4, STK11, and TP53.

RESULTS: Of the 207 patients, 193 had one or more variants, with 170, 20, and 3 having one, two, and three mutated genes, respectively. Of the total 414 variants identified in this study, 384, 25, and 5 were single-nucleotide variants, deletion, and insertion. The top four frequently mutated genes were TP53, KRAS, PIK3CA, and FBXW7. There was high consistency between the results of NGS-PCR technique and routine ARMS-PCR in KRAS and BRAF mutation detection. Univariate and multivariate analyses demonstrated that advanced TNM stage, elevated serum CEA, total variants number ≥ 2, AKT1 and PTEN mutation were independent predictors of shorter DFS; poor differentiation, advanced TNM stage, total variants number ≥ 2, BRAF, CTNNB1 and NRAS mutation were independent predictors of shorter OS.

CONCLUSIONS: It is feasible to detect multiple gene mutations with a 22-gene panel in FFPE CRC specimens. TNM stage and total variants number ≥ 2 were independent predictors of DFS and OS. Detection of multiple gene mutations may provide additional prognostic information to TNM stage in CRC patients.