title: Expression of COX-2 is increased with age in papillary thyroid cancer.
abstract: OBJECTIVE
  To study cyclooxygenase-2 (COX-2) and matrix metalloproteinase-2 (MMP-2) expression in papillary thyroid cancer (PTC). Expression of COX-2 is elevated in various human tumours and it has an important role in carcinogenesis. MMP-2 is also an important component of the metastatic potential of tumours. In PTC the most important factor affecting survival is age, but it is poorly understood why older PTC patients have a worse prognosis.
  
  
  RESULTS
  This retrospective study comprised 108 patients with PTC, and we compared patients who were either younger than 35 (n = 59) or older than 55 (n = 49). Paraffin-embedded tumour samples were analysed for COX-2 and MMP-2 protein expression using immunohistochemistry. High (scores 2-3) COX-2 immunostaining was observed in 38/108 (35%) of the tumours, and COX-2 expression was significantly (P = 0.002) higher in the older age group (25/49; 51%) than in the young one (13/59; 22%).
  
  
  CONCLUSIONS
  Our study shows that COX-2 expression increases with age. It is possible that the age-related increase in COX-2 expression could explain the more aggressive behaviour of PTC in the older age group compared with the young one.
authors.affiliation: Department of Surgery, Heksinki University Central Hospital, Helsinki, Finland.
authors.forename: P
authors.initials: P
authors.lastname: Siironen
authors.forename: A
authors.initials: A
authors.lastname: Ristimäki
authors.forename: S
authors.initials: S
authors.lastname: Nordling
authors.forename: J
authors.initials: J
authors.lastname: Louhimo
authors.forename: R
authors.initials: R
authors.lastname: Haapiainen
authors.forename: C
authors.initials: C
authors.lastname: Haglund
mesh_terms: D000328:Adult; D000375:Aging; D002291:Carcinoma, Papillary / Q000201:enzymology* / Q000473:pathology / Q000532:radiotherapy; D051546:Cyclooxygenase 2; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007457:Iodine Radioisotopes / Q000627:therapeutic use; D007527:Isoenzymes / Q000378:metabolism*; D008297:Male; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism; D008565:Membrane Proteins; D008875:Middle Aged; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism*; D012189:Retrospective Studies; D013964:Thyroid Neoplasms / Q000201:enzymology* / Q000473:pathology / Q000532:radiotherapy
chemical_list: D007457:Iodine Radioisotopes; D007527:Isoenzymes; D008565:Membrane Proteins; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases; D020778:Matrix Metalloproteinase 2