title: Colonic methanogenesis in vivo and in vitro and fecal pH after resection of colorectal cancer and in healthy intact colon.
abstract: OBJECTIVE
  We compared colonic methanogenesis in vivo and in vitro as well as fecal pH in healthy subjects and in patients with resected colorectal cancer thus without the possible confounding effects of the tumor.
  
  
  METHODS
  A total of 144 subjects, 96 with resected colorectal cancer (of whom, 48 were with metastatic disease), 48 healthy subjects with intact colon, were analyzed for breath methane, fecal methanogenesis in vitro and fecal pH. In addition, the association between methanogenesis and pH with cancer site, operation technique and abdominal discomfort was investigated.
  
  
  RESULTS
  In vivo and in vitro methane measurements were in agreement. The percentage of breath methane excretors and fecal pH did not significantly differ in participants resected for colorectal cancer, either with (46%, 6.76) or without (46%, 6.77) metastatic disease, from healthy participants (40%, 6.80). Breath methane excretors had higher fecal pH than nonexcretors (7.05 versus 6.57, P< 0.001) and less abdominal discomfort (30% versus 54%, P = 0.016). Among patients with resected right-sided cancer (n = 15), there were less breath methane excretors (20%) than among those with resected left-sided cancer (51%, n = 81, P = 0.029) as well as lower fecal pH than among those with resected left-sided cancer (6.27 versus 6.86, P = 0.002) and among healthy subjects (6.80, P = 0.010).
  
  
  CONCLUSIONS
  Patients with resected colorectal cancer were as frequently methane producers as healthy subjects with intact colon, and there was no difference in their fecal pH. Low methanogenesis was found in patients with abdominal discomfort and is a possible characteristic, along with low fecal pH, to right-sided colorectal cancer.
authors: Institute of Biomedicine, University of Helsinki, P.O. Box 63, FIN-00014, Helsinki, Finland. reetta.holma@helsinki.fi
authors: Reetta
authors: R
authors: Holma
authors: Pia
authors: P
authors: Osterlund
authors: Ulla
authors: U
authors: Sairanen
authors: Mikko
authors: M
authors: Blom
authors: Merja
authors: M
authors: Rautio
authors: Riitta
authors: R
authors: Korpela
mesh_terms: D000005:Abdomen / Q000473:pathology; D000368:Aged; D001944:Breath Tests; D003106:Colon / Q000378:metabolism* / Q000473:pathology*; D015179:Colorectal Neoplasms / Q000378:metabolism* / Q000601:surgery*; D005243:Feces / Q000737:chemistry*; D005260:Female; D006262:Health; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008297:Male; D008697:Methane / Q000378:metabolism*; D008875:Middle Aged
chemical_list: D008697:Methane