title: Comparison of histopathology and RT-qPCR amplification of guanylyl cyclase C for detection of colon cancer metastases in lymph nodes.
abstract: OBJECTIVE
  In colorectal cancer (CRC), the presence of lymph node (LN) metastases is an important prognostic factor. Approximately 20% of patients diagnosed as having node-negative (pN0) CRC will relapse. Pathological nodal stage misclassification due to sampling error resulting from the small volume of tissue tested has been proposed to explain this recurrence rate in pN0 patients. The authors compared the assessment of node positivity by histopathology (HP) with a molecular method which can accommodate larger tissue volumes.
  
  
  METHODS
  Detection rate of guanylyl cyclase C (GCC) mRNA was determined in 1,495 LNs from 99 CRC patients. Using a subset of 647 LNs, multiple levels of HP analysis were compared with GCC mRNA molecular detection. Finally, clinicopathological factors were correlated with the molecular detection of GCC and clinical outcome in 123 patients with pN0 colon cancer.
  
  
  RESULTS
  GCC mRNA was detected in 8.0% of the 560 nodes initially identified as HP-negative, whereas two repeat HP examinations detected 3.0% of these cases. In HP-positive LNs, the GCC mRNA detection rate was 90% (78/87) when half-LN were tested. Testing the entire LN remaining after HP by GCC increased the detection rate of HP-positive LNs to 95% (p=0.027). In comparison, 75% (65/87) and 92% (80/87) of the LN positive by clinical HP remained positive when one or two subsequent sections were examined by HP. Finally, patients with pN0 disease who were GCC-positive exhibited an earlier time of recurrence (hazard ratio, 3.54; 95% CI 1.40 to 8.98; p=0.0077).
  
  
  CONCLUSIONS
  Molecular detection of tumour cells in LNs may have prognostic value in identifying patients diagnosed as having pN0 colon cancer who will relapse following surgery.
authors.affiliation: DiagnoCure Inc., Québec, Canada. jf.haince@diagnocure.com
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Haince
authors.forename: Michel
authors.initials: M
authors.lastname: Houde
authors.forename: Guillaume
authors.initials: G
authors.lastname: Beaudry
authors.forename: Sylvain
authors.initials: S
authors.lastname: L'espérance
authors.forename: Geneviève
authors.initials: G
authors.lastname: Garon
authors.forename: Marie
authors.initials: M
authors.lastname: Desaulniers
authors.forename: Laurie J
authors.initials: LJ
authors.lastname: Hafer
authors.forename: James I
authors.initials: JI
authors.lastname: Heald
authors.forename: Stephen
authors.initials: S
authors.lastname: Lyle
authors.forename: Steven R
authors.initials: SR
authors.lastname: Grossman
authors.forename: Bernard
authors.initials: B
authors.lastname: Têtu
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Sargent
authors.forename: Yves
authors.initials: Y
authors.lastname: Fradet
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000096:biosynthesis* / Q000235:genetics; D003110:Colonic Neoplasms / Q000473:pathology*; D004812:Epidemiologic Methods; D006162:Guanylate Cyclase / Q000096:biosynthesis* / Q000235:genetics; D006801:Humans; D008207:Lymphatic Metastasis / Q000175:diagnosis*; D008875:Middle Aged; D009367:Neoplasm Staging; D011379:Prognosis; D012333:RNA, Messenger / Q000235:genetics; D012334:RNA, Neoplasm / Q000235:genetics; D000074261:Receptors, Enterotoxin; D050705:Receptors, Guanylate Cyclase-Coupled; D018000:Receptors, Peptide / Q000096:biosynthesis* / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D055815:Young Adult
chemical_list: D014408:Biomarkers, Tumor; D012333:RNA, Messenger; D012334:RNA, Neoplasm; D018000:Receptors, Peptide; D006162:Guanylate Cyclase; D000074261:Receptors, Enterotoxin; D050705:Receptors, Guanylate Cyclase-Coupled