title: Comparative detection of aberrantly methylated DNA in   preoperative and postoperative stool from patients with   colorectal cancers.
abstract: BACKGROUND
  Early detection of colorectal cancer (CRC) is crucial to reducing tumor-related mortality. Evaluating aberrantly methylated DNA in stool is promising for CRC screening. However, DNA methylation in the colonic epithelium of background mucosa may compromise stool DNA (sDNA) test results. Thus, we compared aberrant methylation of cancer-related genes in preoperative and postoperative sDNA, with the aim of demonstrating that a cancer-specific methylated allele in sDNA originates from CRCs.
  
  
  METHODS
  Patients who were to undergo CRC resection in Kyushu University Hospital during 2003-2010 were prospectively enrolled. Preoperative (pre) stool samples from 54 patients, postoperative (post) samples from 52 of the patients and tumor samples were collected. Aberrant promoter methylation of CDH4 and GATA5 was assessed in the primary tumors by methylation-specific polymerase chain reaction (MSP) and in stool samples by real-time MSP.
  
  
  RESULTS
  Aberrant methylation of CDH4 and/or GATA5 was detected in 45 of CRC tissue samples (83.3%) and identified in 23 pre sDNA samples (42.3%) from CRC patients. Aberrant methylation was not found in pre sDNA obtained from CRC patients without aberrant methylation of these genes or in post sDNA in any patient. The detection rate of methylated alleles did not correlate with depth of invasion or tumor stage.
  
  
  CONCLUSIONS
  Our findings demonstrate that aberrantly methylated alleles identified in sDNA originate from CRCs. Although tumor-specific aberrant methylation is found in sDNA from patients harboring early and advanced CRC throughout the colon and rectum, the sensitivity of this test needs to be improved for early detection of CRC.
authors: Yasunobu
authors: Y
authors: Nishioka
authors: Takashi
authors: T
authors: Ueki
authors: Koji
authors: K
authors: Hokazono
authors: Kinuko
authors: K
authors: Nagayoshi
authors: Masao
authors: M
authors: Tanaka
mesh_terms: D000368:Aged; D014408:Biomarkers, Tumor / Q000235:genetics*; D015820:Cadherins / Q000235:genetics; D015179:Colorectal Neoplasms / Q000235:genetics* / Q000473:pathology / Q000601:surgery; D019175:DNA Methylation; D005243:Feces; D005260:Female; D050992:GATA5 Transcription Factor / Q000235:genetics; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies
chemical_list: D014408:Biomarkers, Tumor; D015820:Cadherins; D050992:GATA5 Transcription Factor; C494755:GATA5 protein, human; C083970:R-cadherin