title: The prognostic value of hTERT expression levels in advanced-stage colorectal cancer patients: a comparison between tissue and serum expression.
abstract: OBJECTIVE
  Telomeres are regions of highly repetitive, non-coding DNA located at the termini of chromosomes whose principal function is to maintain the structural stability of these ends. In 90% of human tumours, telomere length is maintained by the expression and activation of telomerase reverse transcriptase. Various studies have demonstrated an increase in telomerase activity in tumour tissue, which suggests its possible prognostic value. The main objective of our study was to study the prognostic value of the expression level of telomerase catalytic component (hTERT) in patients with colorectal cancer (CRC).
  
  
  METHODS
  We analysed the prognostic value of the ratio of telomerase expression in tumour tissue to telomerase expression in the adjacent healthy mucosa and the prognostic value of the expression level of hTERT in the serum of patients diagnosed with CRC. As secondary objectives of the study, we (1) analysed the correlation between telomerase expression in the serum and that in the tumour tissue and (2) analysed the relationship between telomerase expression and different clinical parameters.
  
  
  RESULTS
  Peripheral blood and tissue samples taken from 48 patients with CRC were analysed. No significant differences were observed in disease-free survival (DFS) or overall survival time (OST) between the groups of patients categorised based on the ratio of telomerase expression between tumour tissue and healthy tissue. The correlation index (Pearson's coefficient) between telomerase levels in the serum and those in tissue was 0.32. Our study of the relationship between telomerase levels in the serum and different clinical variables, such as tumour size, ganglion affectation, preoperative carcinoembryonic antigen levels and stage, revealed a higher telomerase expression level in patients with stage IV CRC. There was no significant association between telomerase expression in tumour tissue and the clinical parameters analysed.
  
  
  CONCLUSIONS
  The results obtained in our study do not allow us to propose that the level of telomerase expression be used as a prognostic factor in colorectal cancer. Thus, we cannot consider telomerase expression in the serum as a surrogate marker of its expression in tumour tissue.
authors.affiliation: Servicio de Oncología Médica, Hospital General Universitario de Valencia, Valencia, Spain.
authors.forename: María José
authors.initials: MJ
authors.lastname: Safont
authors.forename: Mireia
authors.initials: M
authors.lastname: Gil
authors.forename: Rafael
authors.initials: R
authors.lastname: Sirera
authors.forename: Eloísa
authors.initials: E
authors.lastname: Jantus-Lewintre
authors.forename: Elena
authors.initials: E
authors.lastname: Sanmartín
authors.forename: Sandra
authors.initials: S
authors.lastname: Gallach
authors.forename: Cristina
authors.initials: C
authors.lastname: Caballero
authors.forename: Nieves
authors.initials: N
authors.lastname: Del Pozo
authors.forename: Eugenio
authors.initials: E
authors.lastname: Palomares
authors.forename: Carlos
authors.initials: C
authors.lastname: Camps
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000235:genetics / Q000378:metabolism*; D003106:Colon / Q000166:cytology / Q000378:metabolism; D015179:Colorectal Neoplasms / Q000235:genetics* / Q000378:metabolism* / Q000473:pathology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D012333:RNA, Messenger / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D044967:Serum / Q000201:enzymology*; D015996:Survival Rate; D019098:Telomerase / Q000235:genetics* / Q000378:metabolism*
chemical_list: D014408:Biomarkers, Tumor; D012333:RNA, Messenger; C509186:TERT protein, human; D019098:Telomerase