Factors affecting F-18 FDG uptake of metastatic lymph nodes in advanced gastric cancer

Objectives In gastric cancer, metastatic lymph node's variable FDG uptake makes it difficult to diagnosis accurately of metastatic lymph nodes by means of SUV levels. The aim of this study was to evaluate the factors affecting the degree of FDG uptakes in primary tumor and metastatic lymph nodes of advanced gastric cancer (AGC).

Methods 31 patients with newly diagnosed AGCs who underwent preoperative FDG-PET and gastrectomy were enrolled in this study. FDG uptake patterns and SUVs of 31 primary tumors and corresponding 31 metastatic lymph nodes were measured using FDG-PET to perform a one-to-one comparison study. In addition, the glucose transporter-1 (GLUT-1) intensity, proliferation index (Ki-67), microvessel density (MVD) scores, and lymphatic vessel density (LVD) scores were evaluated by immunohistochemical staining. Statistical analysis was performed to test correlations between characteristics of metastatic lymph nodes and primary tumors.

Results SUVmax of the metastatic lymph nodes correlated significantly with SUVmax (R = 0.54; P = 0.002), GLUT-1 intensity (R = 0.71; P < 0.0001), Ki-67 score (R = 0.43; P = 0.019), and MVD score (R = 0.48; P = 0.007), but not with LVD scores of the primary tumors. The SUVmean of the metastatic lymph nodes significantly correlated with SUVmax (R = 0.54; P = 0.002), GLUT-1 intensity (R = 0.57; P = 0.001), and Ki-67 (R = 0.47; P = 0.009), but not with MVD or LVD scores of the primary tumors. The SUVmax and SUVmean of the metastatic lymph nodes were significantly lower in tumors which had heterogeneous / faint patterns of FDG uptake, histological types of signet ring cell carcinoma, grade 0 or 1 GLUT-1 intensity, negative GLUT-1 cells, Ki-67 scores less than 10%, and MVD scores less than 0.03.

Conclusions In this study, significant correlation was found between metastatic lymph node’s SUVs and clinicopathologic parameters.

Research Support This study was supported by the Samsung Medical Center Clinical Research Depelopment Program grant, #CRS110-30-1