title: Relationship Between Dual-Time Point FDG PET and Immunohistochemical Parameters in Preoperative Colorectal Cancer: Preliminary Study.
abstract: OBJECTIVE
  The clinical availability of 2-deoxy-2-[18F] fluoro-D-glucose (FDG) dual-time point positron emission tomography/computerized tomography (DTPP) has been investigated in diverse oncologic fields. The aim of this preliminary study was to evaluate the relationship between various immunohistopathologic markers reflecting disease progression of colorectal cancer and parameters extracted from FDG DTPP in colorectal cancer patients.
  
  
  METHODS
  Forty-seven patients with histologically confirmed colorectal cancer were analyzed in this preliminary study. FDG DTPP consisted of an early scan 1 h after FDG injection and a delayed scan 1.5 h after the early scan. Based on an analysis of FDG DTPP, we estimated the maximum standardized uptake value (SUV) of tumors on the early and delayed scans (SUVearly and SUVdelayed, respectively). The retention index (RI) was calculated as follows: (SUVdelayed - SUVearly) × 100/ SUVearly. The clinicopathological findings (size and T and N stages) and immunohistochemical factors [glucose transporter 1 (GLUT-1), hexokinase 2 (HK-2), p53, P504S, and β-catenin] were analyzed by visual analysis.
  
  
  RESULTS
  The RIs calculated from the SUVs ranged from -1.8 to 73.4 (31.8 ± 15.5). The RIs were significantly higher in patients with high T stages (T3 and T4) than with low T stages (T1 and T2; p < 0.05). Among the immunohistochemical analytic markers, GLUT-1 had the highest positive staining rate (93.6%) compared to other markers. Based on univariable analysis, it was shown that the RI of high-level GLUT-1 expression was significantly higher than low-level GLUT-1 expression (p = 0.01), and the RI of high-level p53 expression was slightly higher than low-level p53 expression (p = 0.08). Multivariate analysis to investigate a link between RI and clinicopathologic parameters of colorectal carcinoma showed that GLUT-1, p53, and T staging were independently connected with increased RIs (p < 0.05, total) using backward selection methods. There was no significant statistical relationship between SUVearly and SUVdelayed and clinicopathologic parameters in this study.
  
  
  CONCLUSIONS
  The RIs obtained from preoperative colorectal cancers had a significant relationship to tumor size, T staging, GLUT-1, and p53, in contrast to SUVearly or SUVdelayed. Compared with previous reports, our results showed that RI can better predict GLUT-1 expression than HK-2 and other immunohistochemical markers. This study demonstrated that the RI might have the potential to be applied as a prognostic marker in preoperative colorectal cancer.
authors.affiliation: Department of Nuclear Medicine, Dankook University College of Medicine, Dongnam-ku, Anseo-dong, Cheonan, 330-715 Republic of Korea.
authors.forename: Jai Hyuen
authors.initials: JH
authors.lastname: Lee
authors.affiliation: Department of Pathology, Dankook University College of Medicine, Cheonan, Korea.
authors.forename: Won Ae
authors.initials: WA
authors.lastname: Lee
authors.affiliation: Department of Nuclear Medicine, Dankook University College of Medicine, Dongnam-ku, Anseo-dong, Cheonan, 330-715 Republic of Korea.
authors.forename: Seok Gun
authors.initials: SG
authors.lastname: Park
authors.affiliation: Department of General Surgery, Dankook University College of Medicine, Cheonan, Korea.
authors.forename: Dong Kook
authors.initials: DK
authors.lastname: Park
authors.affiliation: Department of General Surgery, Dankook University College of Medicine, Cheonan, Korea.
authors.forename: Hwan
authors.initials: H
authors.lastname: Namgung
keywords: Colorectal cancer; Dual-time point imaging; FDG PET; Glucose transporter; Hexokinase