Predictive factors of peritoneal metastasis in gastric cancer

Preoperative radiological diagnosis of gastric cancer with peritoneal metastasis is still incomplete. Staging laparoscopy is performed for patients who are diagnosed T3 or T4 preoperatively. The aim of this study is to establish a method for predicting peritoneal metastasis.

236 gastric cancer patients who were determined histologically at the final staging were studied. We evaluated whether the parameters of preoperative evaluation such as maximum tumor size, circumferential involvement, macroscopic type, number of metastatic lymph nodes and histological differentiation could predict a peritoneal metastasis.

The patients with maximum tumor size > 50 mm in diameter, all 4 cross-sectional parts in circumference involved, Type IV tumor, number of metastatic lymph nodes > 3 and histologically undifferentiated type had a significantly higher incidence of peritoneal metastasis, compared with those with other types. Maximum tumor size > 50 mm, all 4 cross-sectional parts involved and type IV were confirmed as independent risk factors by multivariate analysis. A predictive equation "y = 0.018+0.171 (Maximum tumor size > 50 mm)+0.387 (all 4 cross-sectional parts involved)+0.183 (type IV)" was established. When y value was set to 0.5, sensitivity and specificity were 78.3%, 88.5%, respectively.

The predictive equation of peritoneal metastasis revealed satisfactory results and can be regarded as useful in diagnosing peritoneal metastasis.