title: Immunohistochemical evaluation of thymidylate synthase (TS) and p16INK4a in advanced colorectal cancer: implication of TS expression in 5-FU-based adjuvant chemotherapy.
abstract: BACKGROUND
  Our previous analyses on the expression of thymidylate synthase (TS) and p16(INK4a) in colorectal cancer patients administered 5-fluorouracil (5-FU) pre-operatively demonstrated that a high level of TS expression was a predictor of 5-FU resistance, and that the combination of a low level of TS expression and induction of p16(INK4a) after chemotherapy implicated chemosensitivity. The present study aimed to assess the relationship between the biological behavior of advanced colorectal cancer treated post-operatively by 5-FU-based chemotherapy and the expression of TS and p16(INK4a) in primary tumors.
  
  
  METHODS
  Formalin-fixed, paraffin-embedded specimens from 132 colorectal cancers (Dukes' B, 36 cases; Dukes' C, 60 cases; and Dukes' D, 36 cases) treated by 5-FU post-operatively were immunostained for TS and p16(INK4a). Antigenicities were suitably retrieved.
  
  
  RESULTS
  Primary tumors expressing high levels of TS in the Dukes' C group showed a significantly shorter recurrence-free interval (RFI) (P = 0.0002). The overall survival (OS) was shorter in high TS expressors than in low TS expressors (P = 0.001). A high level of TS expression also correlated with advanced Dukes' staging and the severity of nodal metastasis (Dukes' B versus Dukes' D, P = 0.001; Dukes' C versus Dukes' D, P = 0.008; N0 versus N2, P = 0.002; N1 versus N2, P = 0.03). p16(INK4a) expression was not correlated with the prognosis or clinicopathological features.
  
  
  CONCLUSIONS
  Appropriate immunohistochemical evaluation is essentially important. We suggest that, in the Dukes' C group, a 5-FU-based regimen can be chosen as a first-line chemotherapy for low TS expressors. TS-high cancer should be treated with anti-cancer agents acting through different mechanisms. Further research should be conducted on applying TS immunostaining to the treatment strategy.
authors.affiliation: Department of Pathology, Fujita Health University School of Medicine, Kutsukake-cho, Toyoake, Aichi 470-1192, Japan. skamo@fujita-hu.ac.jp
authors.forename: Shingo
authors.initials: S
authors.lastname: Kamoshida
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Matsuoka
authors.forename: Taro
authors.initials: T
authors.lastname: Ishikawa
authors.forename: Kotaro
authors.initials: K
authors.lastname: Maeda
authors.forename: Ryoichi
authors.initials: R
authors.lastname: Shimomura
authors.forename: Ken-ichi
authors.initials: K
authors.lastname: Inada
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Tsutsumi
mesh_terms: D000964:Antimetabolites, Antineoplastic / Q000008:administration & dosage; D000970:Antineoplastic Agents / Q000008:administration & dosage*; D017024:Chemotherapy, Adjuvant; D003110:Colonic Neoplasms / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000096:biosynthesis*; D004338:Drug Combinations; D005260:Female; D005472:Fluorouracil / Q000008:administration & dosage*; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D011184:Postoperative Period; D012004:Rectal Neoplasms / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology; D005641:Tegafur / Q000008:administration & dosage; D013940:Thymidylate Synthase / Q000378:metabolism*; D014498:Uracil / Q000008:administration & dosage
chemical_list: D000964:Antimetabolites, Antineoplastic; D000970:Antineoplastic Agents; D019941:Cyclin-Dependent Kinase Inhibitor p16; D004338:Drug Combinations; C096910:UFT(R) drug; D005641:Tegafur; D014498:Uracil; D013940:Thymidylate Synthase; D005472:Fluorouracil