title: Primary Tumor ¹⁸F-FDG Avidity Affects the Performance of ¹⁸F-FDG PET/CT for Detecting Gastric Cancer Recurrence.
abstract: The usefulness of (18)F-FDG PET in gastric cancer recurrence is limited by low sensitivity. Given that detectability by PET is dependent on the tumor's metabolic characteristics, we tested whether the performance of PET for gastric cancer recurrence is enhanced in patients with (18)F-FDG-avid primary tumors.
  
  
  METHODS
  Three hundred sixty-eight patients with advanced gastric cancer underwent (18)F-FDG PET/CT for initial staging and for recurrence surveillance after curative surgery. On initial PET/CT, primary tumors were (18)F-FDG-avid if they displayed focal uptake with an SUVmax 4 or more. Follow-up (18)F-FDG PET/CT was evaluated for recurrent disease.
  
  
  RESULTS
  On initial PET/CT, the primary tumor was (18)F-FDG-avid in 236 of 368 (64.1%) and nonavid in 132 patients (35.9%). During follow-up for 18.9 ± 13.3 mo, 72 patients (19.6%) had recurrence. Of the 63 PET scans with recurrence, 42 (66.7%) and 21 (33.3%) were scans of patients with (18)F-FDG-avid and nonavid primary tumors, respectively. PET sensitivity was higher in scans of patients with (18)F-FDG-avid than nonavid tumors for all recurrences (81.0% vs. 52.4%;P= 0.018) and nonanastomosis site recurrences (82.1% vs. 47.4%; P= 0.006). The sensitivity for detecting peritoneal recurrence was also higher for the avid tumor group. PET specificity was similarly high (97.1% and 97.5%) for both groups. Adding cell type and Lauren classification to tumor(18)F-FDG avidity further enhanced PET sensitivity.
  
  
  CONCLUSIONS
  Surveillance (18)F-FDG PET/CT after resection of gastric cancer has significantly higher sensitivity in patients with (18)F-FDG-avid primary tumors and may have greater value in this group.
authors.affiliation: Department of Nuclear Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea; and.
authors.forename: Soo Jeong
authors.initials: SJ
authors.lastname: Kim
authors.affiliation: Department of Nuclear Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea; and.
authors.forename: Young Seok
authors.initials: YS
authors.lastname: Cho
authors.affiliation: Department of Nuclear Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea; and.
authors.forename: Seung Hwan
authors.initials: SH
authors.lastname: Moon
authors.affiliation: Department of Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
authors.forename: Jae Moon
authors.initials: JM
authors.lastname: Bae
authors.affiliation: Department of Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
authors.forename: Sung
authors.initials: S
authors.lastname: Kim
authors.affiliation: Department of Nuclear Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea; and.
authors.forename: Yearn Seong
authors.initials: YS
authors.lastname: Choe
authors.affiliation: Department of Nuclear Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea; and.
authors.forename: Byung-Tae
authors.initials: BT
authors.lastname: Kim
authors.affiliation: Department of Nuclear Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea; and khnm.lee@samsung.com.
authors.forename: Kyung-Han
authors.initials: KH
authors.lastname: Lee
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics*; D005500:Follow-Up Studies; D005743:Gastrectomy; D006801:Humans; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000000981:diagnostic imaging; D010534:Peritoneal Neoplasms / Q000000981:diagnostic imaging; D049268:Positron-Emission Tomography / Q000379:methods*; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics*; D015203:Reproducibility of Results; D013274:Stomach Neoplasms / Q000000981:diagnostic imaging* / Q000378:metabolism* / Q000628:therapy; D016896:Treatment Outcome
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18
keywords: 18F-FDG-avidity; PET/CT; gastric cancer; recurrence; sensitivity