Related Experiment Video
Updated: Jun 17, 2026
Simple and Rapid Method to Obtain High-quality Tumor DNA from Clinical-pathological Specimens Using Touch Imprint Cytology
Published on: March 21, 2018
KRAS mutation: comparison of testing methods and tissue sampling techniques in colon cancer
Wilbur A Franklin1, Jerry Haney, Michio Sugita
1Department of Pathology, University of Colorado Denver, Fitzsimons Campus, 12801 E. 17 Ave., Aurora, CO 80045, USA. wilbur.franklin@uchsc.edu
Abstract:
Treatment of colon carcinoma with the anti-epidermal growth factor receptor antibody Cetuximab is reported to be ineffective in KRAS-mutant tumors. Mutation testing techniques have therefore become an urgent concern. We have compared three methods for detecting KRAS mutations in 59 cases of colon carcinoma: 1) high resolution melting, 2) the amplification refractory mutation system using a bifunctional self-probing primer (ARMS/Scorpion, ARMS/S), and 3) direct sequencing. We also evaluated the effects of the methods of sectioning and coring of paraffin blocks to obtain tumor DNA on assay sensitivity and specificity. The most sensitive and specific combination of block sampling and mutational analysis was ARMS/S performed on DNA derived from 1-mm paraffin cores. This combination of tissue sampling and testing method detected KRAS mutations in 46% of colon tumors. Four samples were positive by ARMS/S, but initially negative by direct sequencing. Cloned DNA samples were retested by direct sequencing, and in all four cases KRAS mutations were identified in the DNA. In six cases, high resolution melting abnormalities could not be confirmed as specific mutations either by ARMS/S or direct sequencing. We conclude that coring of the paraffin blocks and testing by ARMS/S is a sensitive, specific, and efficient method for KRAS testing.
Insights
Accurate KRAS mutation testing is crucial for colon cancer treatment. Amplification Refractory Mutation System (ARMS/S) using paraffin cores is a sensitive and specific method for detecting these mutations.
Area of Science:
- Oncology
- Molecular Biology
- Genetics
Background:
- Cetuximab treatment for colon carcinoma is ineffective in KRAS-mutant tumors.
- Accurate KRAS mutation detection is essential for effective patient stratification.
- Current mutation testing methods require evaluation for sensitivity and specificity.
Purpose of the Study:
- To compare three KRAS mutation detection methods: high-resolution melting, ARMS/S, and direct sequencing.
- To evaluate the impact of tissue sampling techniques (sectioning vs. coring) on assay performance.
- To identify the most sensitive and specific method for KRAS mutation analysis in colon carcinoma.
Main Methods:
- Compared high-resolution melting, ARMS/S, and direct sequencing for KRAS mutation detection.
- Analyzed 59 colon carcinoma cases using DNA from paraffin-embedded blocks.
- Evaluated DNA extraction from paraffin sections versus 1-mm paraffin cores.
Main Results:
- ARMS/S using 1-mm paraffin cores demonstrated the highest sensitivity and specificity.
- This optimal combination detected KRAS mutations in 46% of colon tumors.
- ARMS/S identified four mutations missed by initial direct sequencing, later confirmed by re-sequencing cloned DNA.
Conclusions:
- Coring paraffin blocks and employing ARMS/S is a highly sensitive, specific, and efficient method for KRAS testing.
- This approach improves the accuracy of identifying KRAS mutations in colon cancer.
- Optimized tissue sampling and molecular testing are critical for personalized cancer therapy.
