The Relationship Between HER2 Status Acquired From Pathological Data and Metabolic Parameters From Pre-treatment 18F-FDG PET/CT in Gastric Adenocarcinomas

Abstract Aim This study aimed to investigate the relationship between pathological data with strong importance to Human Epidermal Growth Factor Receptor 2 (HER2) status, and pre-treatment 18F-FDG PET/CT semi-quantitative metabolic parameters in gastric adenocarcinomas and their impact on survival. Methods A retrospective analysis was conducted on 117 patients with gastric cancer who underwent 18F-FDG PET/CT for staging. PET/CT results were evaluated for SUVmax, SUVmean, metabolic tumor volume (MTV), total lesion glycolysis (TLG), HER2 status, pathological data, and tumor markers. Results Of the 117 patients, 17.1% were HER2 + and 82.9% were HER2-. SUVmax was significantly lower in tubular adenocarcinoma (TA) patients with signet ring cell (SRC) component compared to those without SRC component. Tumor size > 5 cm positively correlated with MTV and TLG in patients who underwent total resection. Vascular invasion and local invasion (T3/T4) were associated with higher SUVmax. Patients with distant metastasis had significantly higher SUVmax, SUVmean, and TLG. Stage 3/4 patients showed positive correlations with CEA and CA19-9 values. The tumor's localization in the cardia correlated significantly with HER2 positivity in the TA group. Survival analysis revealed higher 1-year and 3-year survival rates in the HER2 + group compared to the HER2- group. Conclusion 18F-FDG PET/CT evaluation for staging provides non-invasive guiding findings for treatment and prognosis. The histological components should be performed in tubular adenocarcinomas PET/CT can predict histological components, local invasion, and vascular invasion. Evaluating metabolic parameters in the primary tumor focus using PET/CT can demonstrate the presence of distant metastasis. The relationship between tumor localization in the cardia and HER2 positivity may be useful in predicting anti-HER2 antibody treatment options. Further extensive studies are needed on this topic.