Relationship Between 18F-FDG PET/CT Findings and HER2 Expression in Gastric Cancer

¹⁸F-FDG PET has been widely used in the management of malignant tumors. In gastric cancer, the status of human epidermal growth factor receptor 2 (HER2) predicts the response to anti-HER2 antibody therapy, and testing of HER2 expression is now routine in the management of gastric cancer patients. However, to date, the relationship between ¹⁸F-FDG uptake and HER2 expression has not, to our knowledge, been investigated. In this study, we aimed to investigate whether HER2 expression is associated with ¹⁸F-FDG uptake and whether ¹⁸F-FDG PET/CT can be used to predict the HER2 status of gastric cancer. Methods: A retrospective analysis was performed on 64 gastric cancer patients who had undergone ¹⁸F-FDG PET/CT before surgical resection. Tumor SUV_max was calculated from the level of ¹⁸F-FDG uptake. Results: No significant correlation was found between SUV_max and HER2 expression in gastric cancer. However, when signet-ring cell carcinoma was excluded, SUV_max was significantly higher in the HER2-negative group than in the HER2-positive group (8.619 ± 5.878 vs. 3.789 ± 2.613, respectively; P = 0.021). Multivariate analysis indicated that SUV_max and tumor differentiation remained significantly associated with HER2 expression (P = 0.048 and P = 0.028, respectively). HER2 expression was predicted with an accuracy of 64.4% when an SUV_max cutoff of 6.2 was used. Conclusion:¹⁸F-FDG uptake by gastric cancer is associated with HER2 expression. ¹⁸F-FDG PET/CT may be useful for predicting the HER2 status of gastric cancer and for determining the therapeutic strategy.