Abstract
Background/Aims
Accurate preoperative detection of regional lymph nodes and evaluation of tumor resectability is critical to determining the most adequate therapy for gastric cancer. The aim of this study is to identify a possible link between 18F-fluorodeoxyglucose (18F-FDG) uptake on PET scan combined with CT scan (PET/CT) and predictions of lymph node metastasis and non-curative surgery.
Methods
This study included 156 gastric cancer patients who underwent preoperative 18F-FDG PET/CT and surgery. In cases with perceptible FDG uptake in the primary tumor or lymph nodes, the maximum standardized uptake value (SUVmax) was calculated.
Results
In multivariate analysis, non-curative surgery (OR, 11.05; 95% CI, 1.10-111.08; p=0.041), tumor size (≥3 cm) (OR, 7.39; 95% CI, 2.41-22.70; p<0.001), and lymph node metastasis (OR, 5.47; 95% CI, 2.05-14.64; p=0.001) were significant independent predictors for 18F-FDG uptake in the primary tumors. Tumor size (tumor size ≥3 cm) (OR, 3.15; 95% CI, 1.16-8.58; p=0.025) and lymph node metastasis (OR, 3.36; 95% CI, 1.23-9.14; p=0.018) showed significant association with 18F-FDG uptake in lymph node. When the SUVmax of the primary gastric tumor was greater than 3.75, the sensitivity and specificity of PET/CT with regard to the diagnosis of metastatic lymph node were 73.5% and 74.5%. When the SUVmax of the primary gastric tumor was greater than 4.35 and the FDG uptake of lymph nodes was positive, non-curative surgery was predicted with a sensitivity of 58.8% and specificity of 91.6%.
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![]() | Fig. 1.Receiver operator characteristics (ROC) curve of the maximum standardized uptake value (SUVmax) of primary tumor. (A) In ROC for detecting lymph node metastasis, an area under the curve of 0.795 was obtained (95% CI, 0.719-0.871; p<0.001). (B) In ROC for predicting non-curative surgery, area under the curve was 0.801 (95% CI, 0.722-0.879; p<0.001). |
Table 1.
Patient and Tumor Characteristics
Table 2.
Comparison between the Status of 18F-FDG Uptake and Primary Tumor Characteristics in the Gastric Cancers
Table 3.
Significant Predictors of 18F-FDG Uptake by Multiple Regression Analysis
Table 4.
Prediction of Lymph Node Metastasis in Patients Who Underwent Operation
Sensitivity | Specificity | Accuracy | Positive predictive value | |
---|---|---|---|---|
CT | 69.8 | 69.6 | 71.2 | 54.4 |
Tumor SUVmax >3.75 | 73.5 | 74.5 | 74.1 | 60.0 |
Tumor SUVmax >3.75 & lymph node uptake(+) | 47.2 | 94.1 | 96.2 | 80.6 |
Table 5.
Prediction of Non-curative Surgery in Patients Who Underwent Operation
Sensitivity | Specificity | Accuracy | Positive predictive value | |
---|---|---|---|---|
CT | 45.8 | 93.9 | 86.5 | 57.9 |
Tumor SUVmax >4.35 | 83.3 | 78.0 | 78.8 | 40.8 |
Tumor SUVmax >4.35 & lymph node uptake(+) | 58.8 | 91.6 | 86.5 | 56.0 |
Table 6.
Role of CT and 18F-FDG PET/CT in Detecting Distant Metastasis and Peritoneal Carcinomatosis