Improved fecal DNA test for colorectal cancer screening.
OBJECTIVE
Fecal DNA testing has shown greater sensitivity than guaiac-based occult blood tests for noninvasive colorectal cancer (CRC) screening. The prototype assay (version 1), which analyzed 22 gene mutations and DNA integrity assay (DIA), showed a sensitivity of 52% for CRC detection and a specificity of 94% in average-risk individuals. The present study was conducted to determine the sensitivity and specificity of a second-generation assay (version 2) that uses improved DNA stabilization/isolation techniques and a new promoter methylation marker.


METHODS
Forty patients with CRC and 122 subjects with normal colonoscopy provided stool samples to which DNA preservation buffer was added immediately. DNA was purified using gel-based capture, and analyzed for the original panel of 22 mutations, DIA, and 2 new promoter methylation markers.


RESULTS
By using DNA that was optimally preserved and purified from stool, the sensitivity of the prototype version 1 assay increased to 72.5% because of enhanced performance of DIA. Vimentin gene methylation alone provided sensitivity and specificity of 72.5% and 86.9%, respectively. The optimal combination of vimentin methylation plus DIA resulted in 87.5% sensitivity and 82% specificity; cancers were detected regardless of stage or location. False-positive vimentin methylation was associated with older age.


CONCLUSIONS
An improved fecal DNA test that incorporates only 2 markers shows much higher sensitivity for CRC. The new assay is easier to perform and should be less costly, thereby facilitating its use for noninvasive CRC screening.
Itzkowitz
Steven H
SH
Department of Medicine and Oncological Sciences, Mount Sinai School of Medicine, New York, New York 10029, USA. steven.itzkowitz@msnyuhealth.org
Jandorf
Lina
L
Brand
Randall
R
Rabeneck
Linda
L
Schroy
Paul C
PC
Sontag
Stephen
S
Johnson
David
D
Skoletsky
Joel
J
Durkee
Kris
K
Markowitz
Sanford
S
Shuber
Anthony
A
D000367:Age Factors; D000368:Aged; D003113:Colonoscopy; D015179:Colorectal Neoplasms / Q000175:diagnosis / Q000235:genetics*; D053938:DNA Fragmentation; D019175:DNA Methylation; D004273:DNA, Neoplasm / Q000032:analysis*; D004268:DNA-Binding Proteins / Q000235:genetics; D005243:Feces / Q000737:chemistry*; D005260:Female; D006801:Humans; D008297:Male; D008403:Mass Screening / Q000379:methods*; D008875:Middle Aged; D017060:Patient Satisfaction; D016133:Polymerase Chain Reaction; D012680:Sensitivity and Specificity; D014157:Transcription Factors / Q000235:genetics; D014746:Vimentin / Q000235:genetics
D004273:DNA, Neoplasm; D004268:DNA-Binding Proteins; C100023:HLTF protein, human; D014157:Transcription Factors; D014746:Vimentin