title: A simplified, noninvasive stool DNA test for colorectal cancer detection.
abstract: BACKGROUND
  As a noninvasive colorectal cancer (CRC) screening test, a multi-marker first generation stool DNA (sDNA V 1.0) test is superior to guaiac-based fecal occult blood tests. An improved sDNA assay (version 2), utilizing only two markers, hypermethylated vimentin gene (hV) and a two site DNA integrity assay (DY), demonstrated in a training set (phase 1a) an even higher sensitivity (88%) for CRC with a specificity of 82%.
  
  
  OBJECTIVE
  To validate in an independent set of patients (phase 1b) the sensitivity and specificity of sDNA version 2 for CRC.
  
  
  METHODS
  Forty-two patients with CRC and 241 subjects with normal colonoscopy (NC) provided stool samples, to which they immediately added DNA stabilizing buffer, and mailed their specimen to the laboratory. DNA was purified using gel-based capture, and analyzed for hV and DY using methods identical to those previously published.
  
  
  RESULTS
  Using the same cutpoints as the 1a training set (N = 162; 40 CRCs, 122 normals), hV demonstrated a higher and DY a slightly lower sensitivity, for a combined sensitivity of hV + DY of 86%. Optimal cutpoints based on the combined phase 1a + 1b dataset (N = 445; 82 CRCs, 363 normals) yielded a CRC sensitivity of 83%. The vast majority of cancers were detected regardless of tumor stage, tumor location, or patient age. Assay specificity in the phase 1b dataset for hV, DY, and hV + DY was 82%, 85%, and 73%, respectively, using the phase 1a cutpoints. Optimal cutpoints based on the combined phase 1a + 1b dataset yield a specificity of 82%.
  
  
  CONCLUSIONS
  This study provides validation of a simplified, improved sDNA test that incorporates only two markers and that demonstrates high sensitivity (83%) and specificity (82%) for CRC. Test performance is highly reproducible in a large set of patients. The use of only two markers will make the test easier to perform, reduce the cost, and facilitate distribution to local laboratories.
authors.affiliation: Department of Medicine and Oncological Sciences, Mount Sinai School of Medicine, New York, New York 10029, USA.
authors.forename: Steven
authors.initials: S
authors.lastname: Itzkowitz
authors.forename: Randall
authors.initials: R
authors.lastname: Brand
authors.forename: Lina
authors.initials: L
authors.lastname: Jandorf
authors.forename: Kris
authors.initials: K
authors.lastname: Durkee
authors.forename: John
authors.initials: J
authors.lastname: Millholland
authors.forename: Linda
authors.initials: L
authors.lastname: Rabeneck
authors.forename: Paul C
authors.initials: PC
authors.lastname: Schroy
authors.forename: Stephen
authors.initials: S
authors.lastname: Sontag
authors.forename: David
authors.initials: D
authors.lastname: Johnson
authors.forename: Sanford
authors.initials: S
authors.lastname: Markowitz
authors.forename: Lawrence
authors.initials: L
authors.lastname: Paszat
authors.forename: Barry M
authors.initials: BM
authors.lastname: Berger