ANTICANCER RESEARCH 28: 2907-2912 (2008)
A New Diagnostic Method for Early Gastric Cancer: Volume Measurement by 3-Dimensional Endoscopic Ultrasonography in Early Gastric Cancer and Its Clinical Significance NOBUE FUTAWATARI1, SHIRO KIKUCHI1, SHINICHI SAKURAMOTO1, MITSUHIRO KIDA2 and MASAHIKO WATANABE1
1Department
2Department
of Surgery, School of Medicine, Kitasato University, Sagamihara-shi, Kanagawa 228; of Gastroenterology, Kitasato University East Hospital, Sagamihara-shi, Kanagawa 228, Japan
Abstract. Background: The objective of the present study
was to measure the volume of early gastric cancer using 3dimensional endoscopic ultrasonography (3D-EUS) and to ascertain the clinical significance of this new diagnostic method. Patients and Methods: The study comprised 100 patients with early gastric cancer who underwent preoperative 3D-EUS followed by surgical resection. The relationships of lymph node metastasis to 10 clinicopathological factors (gender, age, tumor location, ulcer, depth, macroscopic type, tumor histology, lymphatic invasion and venous invasion) and preoperative tumor volume (log tumor volume) as measured by 3D-EUS were determined. Results: Median tumor volume was 414.75 mm3 (range, 7.8-2,683.8 mm3) and median log tumor volume was 2.617 (range, 1.444-3.429). Univariate analyses showed that three factors (lymphatic invasion, p=0.0001; venous invasion, p=0.0216; log tumor volume, p=0.0121) correlated significantly with lymph node metastasis. Multivariate analysis showed only two factors (lymphatic invasion, p=0.011, regression coefficient=0.104; log tumor volume, p=0.020, regression coefficient=30.414) representing independent predictors for lymph node metastasis. Conclusion: Tumor volume as measured by 3D-EUS represents an independent risk factor for lymph node metastasis in early gastric cancer. This new method can be used as a reliable diagnostic tool for early gastric cancer.
Correspondence to: Nobue Futawatari, MD, Department of Surgery, School of Medicine, Kitasato University, 1-15-1 Kitasato, Sagamihara-shi, Kanagawa 228, Japan. Tel: +81 427489111, Fax: +81 427455582, e-mail:
[email protected] Key Words: Early gastric cancer, tumor volumetry, 3D endoscopic ultrasonography, lymph node metastasis.
0250-7005/2008 $2.00+.40
Although lymph node metastases are found in 5-20% of patients who undergo surgical resection for early gastric cancer, treatment results are generally favorable (1-6). The diagnosis and treatment of early gastric cancer thus requires selection of the proper therapy by considering not only local tumor extension, but also lymph node metastasis. In recent years, minimally invasive endoscopic treatments such as endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD) have been actively performed for early gastric cancer without lymph node metastasis (711). However, objective and accurate assessment of tumor depth and size is difficult using existing diagnostic methods and the indications for endoscopic treatment are very complicated, involving tumor histology, 2-dimensional (2D) growth and tumor depth. More convenient and rational diagnostic methods are needed for early gastric cancer. We previously measured the 3-dimensional (3D) structure and volume of gastric cancer using histopathological samples of gastric cancer, clarifying tumor volume as an important factor for regulating lymph node metastasis and tumor progression (12-16). In recent years, we have performed 3D endoscopic ultrasonography (3D-EUS) and multidetectorrow computed tomography (MD-CT) to ascertain the 3D shape and volume of gastrointestinal tumors preoperatively and have already reported the potential utility of this information in clinical applications (17-20). The aim of the present study was to measure the volume of early gastric cancer using 3D-EUS and to ascertain the clinical significance of this new diagnostic method.
Patients and Methods
A total of 107 patients with early gastric cancer underwent preoperative 3D-EUS followed by gastrectomy and lymph node dissection in the Department of Surgery at Kitasato University East Hospital over a 3-year period from January 2004 to December 2006. The study comprised 100 patients (93.5% ; 67 men, 33 women) in
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ANTICANCER RESEARCH 28: 2907-2912 (2008)
Figure 1. Distribution of tumors according to tumor diameter. Open column, tumors with no lymph node metastasis; closed column, tumors with lymph node metastasis.
Figure 2. Distribution of tumors according to logarithmic tumor volume. Open column, tumors with no lymph node metastasis; closed column, tumors with lymph node metastasis.
whom the volume of gastric cancer could be measured by 3D-EUS. Mean age was 60.0 years (range, 31-84 years). A total of 3,226 lymph nodes were excised (mean, 32.3 nodes/patient; range, 8-74 nodes/ patient). Lymph node metastases were confirmed in 23 lymph nodes. The 3D-EUS was performed according to previously reported methods (17, 20), using a 3D-EUS probe (20 MHz, UM-DP20-25R; Olympus, Tokyo, Japan) inserted into the stomach through the lateral hole of a conventional flexible endoscope. The tumor was serially scanned using a mechanical spiral technique (40 mm/procedure) to obtain continuous ultrasonographic images. Furthermore, using a computer image analysis system (Endoecho system; Olympus, Tokyo, Japan), the outline of the lesion was visually traced on ultrasonographic radial images at 2-mm intervals. Based on 2D data, the 3D structure and volume of the lesion were measured. Lesions larger than 40 mm were scanned in stages to measure volume (Figures 1 and 2). Each lesion was scanned 3 times and the average of the 3 measurements was used for analysis. Clinicopathological findings were classified according to the Japanese Classification of Gastric Carcinoma (21). In the present study, based on macroscopic data, types I and IIa were reclassified as elevated tumors and IIb, IIc and III as depressed tumors. Based on histological findings, papillary adenocarcinoma and tubular adenocarcinoma were reclassified as differentiated tumors, while poorly differentiated adenocarcinoma, signet ring cell adenocarcinoma and mucinous carcinoma were classified as undifferentiated tumors. Relationships of lymph node metastasis to 10 clinicopathological factors (gender, age, tumor location, ulcer, depth, macroscopic type, tumor histology, lymphatic invasion, and venous invasion) and preoperative tumor volume (log tumor volume) as measured by 3D-EUS were ascertained. Tumor diameter and tumor volume (log tumor volume) were analyzed as continuous variables, while all other clinicopathological factors were analyzed as categorical data. Univariate analysis was conducted using the χ2 test and Mann-Whitney’s U-test, while multivariate analysis was conducted using logistic regression analysis with the level of significance set at p
