Identification and classification of serosal invasion, as it relates to cancer cell shedding and surgical treatment in gastric cancer.

Surgery to the extent of R+1 [gastric resection plus removal of group 1 lymph nodes (N1) and part of group 2 lymph nodes (N2)] is adequate for cancer confined to the mucosa when the serosa is normal, while operation at the R2 level is adequate for cancer confined to the submucosa (SM) or the muscularis propria (PM) when the serosa is of the reactive type. As the status of serosal involvement advances from normal to reactive, nodular, tendonoid and colour diffused, the lymph node metastatic rate soars and the 5-year survival rate declines in that order. There were no peritoneally shed cancer cells in cases with normal or reactive serosa over the lesion. Shed cancer cells increased significantly when the serosal involvement exceeded 30 cm2. The 2-year survival rate of the patients who had serosal involvement increased by 23.1% when peritoneal lavage with 43 degrees C distilled water was done.