Background: Positron emission tomography (PET), using 18F-fluoro-2-deoxy-D-glucose (FDG) as a tracer, can detect malignant neoplasms with altered glucose metabolism. To clarify the usefulness of FDG-PET for detecting gastric cancer, we evaluated preoperative PET imaging in gastric cancer patients.
Methods: Sixty-two gastric cancer patients who underwent FDG-PET imaging and gastric resection with lymphadenectomy were evaluated.
Results: For primary tumor assessment by PET, detection rates were significantly different in the following order: tumor size 30 mm or more (76.7%) > tumor size less than 30 mm (16.8%); advanced gastric cancer (AGC, 82.9%) > early gastric cancer (EGC; 25.9%); with nodal involvement (79.3%) > without nodal involvement (39.4%). In EGCs, the detection rate of the intestinal type, according to Lauren's classification (43.8%) was significantly higher than that of the diffuse type (0%). Two of the 7 EGC patients who were PET-positive had nodal involvement and their tumors were the intestinal type. For the assessment of nodal involvement, the accuracy of nodal involvement detection was 67.7% with PET and 75.8% with computed tomography (CT). Preoperative FDG-PET revealed colon cancer in 2 patients, adrenal tumor in 1 patient, lung cancer in 1 patient, and lung metastasis in 1 patient.
Conclusion: Larger or more advanced tumors with nodal involvement had a higher detection rate by PET. In EGCs, only the intestinal type was detectable by PET. PET-positive EGC may be aggressive, and an adequate lymphadenectomy must be done. Preoperative PET was useful for the detection of other malignancies and distant metastasis.