KRAS fluorescence in situ hybridisation testing for the detection and diagnosis of pancreatic adenocarcinoma.
The aim of our study was to analyse correlations between mutation status, chromosomal changes that affect status in cells from pancreatic tumours. We collected 69 cases of surgically resected pancreatic ductal adenocarcinoma (PDA) and seven cases of chronic pancreatitis (CP). Chromosomal abnormalities of and CEP12 were detected using fluorescence in situ hybridisation (FISH). The number of CEP12 signals per cell ranged from 1.78 to 2.04 and 1.46 to 4.88 in CP and PDA samples, respectively, while the number of signals per cell ranged from 1.94 to 2.06 and 1.88 to 8.18 in CP and PDA samples, respectively. The 'chromosomal instability index', which was defined as the percentage of cells with any chromosomal abnormality, was over 5.7 times greater in PDA than in CP. We performed mutation analysis by direct sequencing and found that tumours with mutations have a significantly higher mean signal per cell from PDA samples compared with tumours with wild-type amplification was noted in 10% of cases. Although we found that lymph node metastasis and distal metastasis of PDA were more frequent in cases with amplification, this was not correlated with overall survival. Using a threshold of 40%, we found that the chromosomal instability index robustly discriminated PDA cells from CP cells. Based on these findings, we concluded that FISH testing of using cytology samples may represent an accurate approach for the diagnosis of PDA.