Usefulness of preoperative F-18 FDG-PET/CT for detection of signet ring cell carcinoma of the stomach: Correlation with pathologic findings including immunohistochemical staining.

Abstract

e14621 Background: The role of F-18 FDG-PET/CT in gastric cancer is limited because of its low sensitivity. The sensitivity of F-18 FDG-PET/CT range from 26 to 63% in early gastric cancer (EGC) to 93 to 98% in locally advanced gastric cancer (AGC). Particularly signet sing cell carcinoma (SRC) is reported to have low detectability by F-18 FDG-PET/CT. The purpose of this study was to evaluate the clinical usefulness of F-18 FDG-PET/CT for SRC and pathologic characteristics associated with FDG uptake of gastric cancer. Methods: Thirty-nine patients with SRC (52.3 ± 13.7 years, M:F = 17:22) who underwent F-18 FDG PET/CT within 1 month before operation were included for this study. AGC was 17, and EGC 22. They were divided into 3 groups according to the abnormal FDG uptake and SUVmax. Group 1 was 17 patients with no abnormal FDG uptake, group 2, 15 patients with abnormal FDG uptake of tumor and its SUVmax 3.0–4.9 and group 3, 7 patients with SUVmax ≥ 5.0. Pathologic parameters were compared among 3 groups by Kruskal-Wallis test. Results: The detection rate of SRC with F-18 FDG PET/CT was 56.4% (70.6% for AGC, 45.5% for EGC) and it was associated with tumor size. The intensity of FDG uptake was associated with tumor and lymph node stage, p53 and Rb immunohistochemical expression. There was no significant difference in Ki-67, C-erbB-2, EGFR, tumor location, Ming classification, Lauren classification, and Borrmann type. Conclusions: The detection rate of SRC with F-18 FDG PET/CT was lower than that of previously reported data of entire gastric cancer, especially for AGC. The intensity of FDG uptake was associated with tumor and lymph node stage, tumor size, p53 and Rb expression. No significant financial relationships to disclose.