Comparison between FDG uptake and histopathologic parameters in the gastric carcinoma

Abstract

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Objectives: The purpose of this study was to find any histo-pathologic parameters that may affect F-18 FDG uptake of primary tumor in the gastric carcinoma.

Methods: Eighty nine stomach cancer patients who underwent pre-operative FDG PET/CT scans were included in the study. In all cases which showed perceptibly increased FDG uptake in the primary lesion, the peak standardized uptake (pSUV) value was calculated. The histopathologic results such as depth of invasion (T stage), tumor size, lymph node (LN) metastasis, tumor differentiation, Lauren’s classification, Ki-67 index, and expression of p53, EGFR, Cathepsin D, c-erb-B2, COX2 were reviewed.

Results: Nineteen out of 89 gastric carcinomas were undetectable on PET/CT images, which the depth of invasion was within the submucosa (T1 stage). FDG uptakes were significantly higher in the T2, T3 and T4 tumors than in the T1 tumors (5.8±3.1 vs. 3.7±2.1, p=0.002). The mean pSUV of the large tumors (above or equal to 3 cm) was also significantly higher than the mean pSUV of small (less than 3 cm) ones (5.7±3.2 vs. 3.7±2.0, p=0.002). The intestinal type of gastric carcinomas according to Lauren showed higher FDG uptake compared to the nonintenstinal type. (5.4±2.8 vs. 3.7±1.3, p=0.003) And the mean pSUV of tumor was significantly different between p53 positive group and negative group (6.0±2.8 vs. 4.4±3.0, p=0.035). No significant difference was found in the presence of LN metastasis, tumor differentiation, Ki-67 index, and expression of EGFR, Cathepsin D, c-erb-B2 and COX2.

Conclusions: T stage of gastric carcinoma influences the detectability of gastric cancer. When the gastric carcinoma is detectible on the PET/CT scan, T stage, size of primary tumor, Lauren’s classification and p53 expression are related to the degree of FDG uptake.