Background: We have previously reported that, in models of mesenteric lymph vessel obstruction in rats, we observed lymphaticovenous communication. This suggested that cancer cells metastasized to the liver by a lymphatic route. In the present study, we investigated the relationship between liver metastasis and lymphatic involvement in gastric carcinoma by examining resected specimens.
Methods: Twenty gastric cancer patients who had synchronous liver metastasis and 17 who developed metachronous liver metastasis after gastrectomy, performed between 1985 and 1997, were included in this study. They were compared with 44 advanced gastric cancer patients who had neither synchronous nor subsequent liver metastasis, and who survived with a disease-free course for more than 5 years. We compared the patients' clinicopathological features; in particular, we investigated extranodal invasion in the resected lymph nodes. This invasion was classified according to the pattern of extranodal cancer invasion, with or without rupture of the lymph node capsule.
Results: Liver metastasis was more frequent in patients with extranodal invasion than in those without extranodal invasion (P < 0.002). Multivariate analysis revealed that the correlation between extranodal invasion and liver metastasis was significant (P < 0.024); the odds ratio was 4.412. Metastasis to the lymph nodes was the next most significant risk for liver metastasis.
Conclusion: We consider that the lymphatic system is closely related to the establishment of liver metastasis; in particular, extranodal invasion is a significant risk factor for liver metastasis in patients with gastric cancer.