The biological behaviour of gastric cancer.

A characterisation of the biological behaviour of gastric carcinoma was attempted by relating the histological classification to the mean number of metastases for each case (metastatic index). The material was chosen from a consecutive series of 294 gastric cancer autopsies in which only conservative therapy had been given or in which the cancer was first diagnosed at autopsy. According to the extent of metastasis it was possible to divide the nine histological types into two groups of limited invasiveness and generalised invasiveness. Unfavourable biological behaviour of the cancer was determined by the presence of the latter group of histological types in the primary site even in cases where this histological type formed the minor component of the tumour. The variation in histology within the primary tumour and between the primary site and the metastatic sites was related both to histological affinities and to the metastatic index associated with the primary site histology. It is suggested that this dual classification system adds significantly to our understanding of the natural history of gastric cancer.