Abstract
BACKGROUND: Accurate staging of tumors is paramount in the management of cancer patients. Current noninvasive modalities like computed tomography (CT) and fluorodeoxyglucose positron emission tomography (FDG PET) scan offer viable approaches to stage the disease; however, the role of FDG PET-CT in gastric cancer remains unclear, in comparison to esophageal and gastroesophageal junction cancers, where they have proven usefulness. AIM: The primary outcome was to assess the usefulness of FDG PET-CT in staging gastric cancer in our population. The secondary outcome was to compare the positive yield of PET-CT with staging laparoscopy and avidity of FDG PET-CT scan in gastric cancer. MATERIALS AND METHODS: In our institution, FDG PET-CT is routinely used in staging gastric cancer, where CT scan does not show metastases. We did a retrospective analysis of data of gastric cancer patients, who were not known to have metastatic disease, who underwent pretreatment staging workup at our institute between January 2018 and December 2022. Tumor and lymph node (LN) avidity and their association with Lauren classification was assessed. Multivariate regression analysis for factors associated with metastases on FDG PET-CT scan with tumor size, nodal status, and node avidity was also assessed. Data were analyzed using SPSS version 26 for descriptive and comparative statistics; multivariate regression analysis was performed to identify factors affecting the diagnosis of metastases on PET-CT. P =0.05 was considered statistically significant. RESULTS: Tumor avidity was shown in 181 (89.16%) patients, and LN avidity in 80 (39.4%) patients. This was independent of the Lauren classification. In addition, previously unidentified metastases were highlighted in 16 (8%) patients. Multivariate regression analysis for factors associated with metastases on FDG PET-CT scan showed a significant association with tumor size (P < 0.001), nodal status (P = 0.005), and node avidity (P = 0.024). CONCLUSIONS: FDG PET-CT scan can identify an additional 8% of previously unidentified metastases, thereby playing a useful role in the staging workup of advanced gastric cancer patients. Approximately 90% of gastric cancers and 40% of LNs were PET avid in our population.