Feasibility and robustness of amplification refractory mutation system (ARMS)-based KRAS testing using clinically available formalin-fixed, paraffin-embedded samples of colorectal cancers.
BACKGROUND
KRAS mutation testing is recommended for the discernment of metastatic colorectal cancer patients who are unlikely to benefit from anti-epidermal growth factor receptor antibodies. A recently developed amplification refractory mutation-Scorpion system is becoming a standard method for KRAS mutant detection. The feasibility and robustness of this system using DNA samples from clinically available formalin-fixed, paraffin-embedded specimens were evaluated.


METHODS
Genomic DNA from macro-dissected 110 specimens was applied for the KRAS mutant detection using a commercial amplification refractory mutation-Scorpion system kit. Success rate and mutant detection rate of the test were evaluated.


RESULTS
Small intra- and inter-lot deviations of the testing kit and a good concordance among different real-time polymerase chain reaction systems suggested the reliability of the amplification refractory mutation-Scorpion system. Though one-third of the 110 samples that were tested did not contain a sufficient amount of DNA to detect a 1% concentration of mutant alleles, the mutant detection rate was not impaired using tumor DNA concentrated by macro-dissection. Using a higher amount of template DNA, which supposedly contained abundant interfering substances, prevented the detection of the exogenous control amplicons, resulting in a reduced success rate. Adjusting the template amount according to the total DNA concentration might reduce the failure rate.


CONCLUSIONS
The amplification refractory mutation-Scorpion system with formalin-fixed, paraffin-embedded specimen-derived DNA samples exhibited an acceptable feasibility and robustness suitable for routine clinical practice.
Ogasawara
Naomi
N
Cancer Physiology Project, Research Center for Innovative Oncology, National Cancer Center Hospital East, Kashiwa, Japan.
Bando
Hideaki
H
Kawamoto
Yasuyuki
Y
Yoshino
Takayuki
T
Tsuchihara
Katsuya
K
Ohtsu
Atsushi
A
Esumi
Hiroyasu
H
D015179:Colorectal Neoplasms / Q000235:genetics*; D005240:Feasibility Studies; D005404:Fixatives; D005557:Formaldehyde; D005784:Gene Amplification; D006801:Humans; D009154:Mutation; D016612:Paraffin Embedding; D016133:Polymerase Chain Reaction; D011237:Predictive Value of Tests; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D016283:Proto-Oncogene Proteins p21(ras); D018631:ras Proteins / Q000235:genetics*
D005404:Fixatives; C117307:KRAS protein, human; D011518:Proto-Oncogene Proteins; D005557:Formaldehyde; D016283:Proto-Oncogene Proteins p21(ras); D018631:ras Proteins