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 sixtyeight 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 SUV max 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 5 0.018) and nonanastomosis site recurrences (82.1% vs. 47.4%; P 5 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. Conclusion: 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.

PET/CT for Predicting Occult Lymph Node Metastasis in Gastric Cancer

“…These results reveal that several significant challenges need to be addressed before 18 F-FDG PET/CT can be applied more widely for predicting OLNM in gastric cancer: As the histological types in gastric cancer vary, the proportion of FDG-avid tumors accounts for only 60%, especially for those with non-intestinal tissue types (diffuse, mixed, and indolent cells) [ 22 ]. In addition, 18 F-FDG PET/CT is not sensitive to lymph node metastases from non-FDG tumor metastases [ 50 , 51 , 52 ]. Some scholars believe that the size of metastatic lymph nodes is a critical factor in the evaluation of gastric cancer.…”

“…As the histological types in gastric cancer vary, the proportion of FDG-avid tumors accounts for only 60%, especially for those with non-intestinal tissue types (diffuse, mixed, and indolent cells) [ 22 ]. In addition, 18 F-FDG PET/CT is not sensitive to lymph node metastases from non-FDG tumor metastases [ 50 , 51 , 52 ].…”

Korean Practice Guidelines for Gastric Cancer 2022: An Evidence-based, Multidisciplinary Approach

“…A total of 13 studies with 1,567 patients were included in the meta-analysis [ 76 77 78 79 80 81 82 83 84 85 86 87 ]. The pooled sensitivity and specificity of FDG PET/CT for detecting the recurrence of gastric cancer were 81% (95% CI, 71% to 88%) and 88% (95% CI, 80% to 93%), respectively, with an area under the summarized receiver operating characteristic curve (AUC) of 0.91 (95% CI, 0.89 to 0.93).…”

The role of [18F]FDG PET/CT for gastric cancer management

“…PET had higher sensitivity (81.0%) for [ 18 F]FDG-avid tumours than both non-avid tumours and nonanastomosis site recurrences (52.4%). PET had high specificity (97.1% and 97.5%) in both groups [26].…”