Prognostic significance of serosal invasion and free intraperitoneal cancer cells in gastric cancer

Survival rates after curative gastrectomy for advanced gastric cancer among 238 patients in whom the cancer was invading the serosa were compared with 283 patients without serosal invasion. Generalized Wilcoxon estimates for 5-year survival rate were 47.1 per cent for patients exhibiting serosal invasion and 75.9 per cent for patients without serosal invasion. The frequency of lymph node metastasis increased proportionately with the extent of serosal invasion: 18.4 per cent in cases of S0; 53.8 per cent in cases of S1; 80.0 per cent in cases of S2; and 91.4 per cent in cases of S3. The higher the aggregate total of S (serosal invasion) and n (lymph node metastasis) factors, the lower the 5-year survival rate. In addition, patients with serosal invasion had a propensity for peritoneal dissemination of cancer cells; the percentage of cases with intraperitoneal free cancer cells increased with the extent of serosal invasion. It is worth noting that when cancer infiltration proceeded to the deeper layers and was accompanied by nodal metastasis, cancerous invasion of the perinodal fatty tissue was frequently evident. Therefore, unfavourable prognosis after curative resection in gastric cancer patients with serosal invasion may be largely dependent on whether or not the cancer has invaded the peritoneal cavity and the perinodal fatty tissue.