Non-invasive neoplasia of the stomach.

Invasive gastric cancer is the final step of a cascade of genomic and phenotypic changes, which have been defined as multistep oncogenesis. This process includes a continuum of progressively dedifferentiated phenotypes, which may result in a biologically new (i.e., nuepsilonomega = neo) cell characterized by autonomous, potentially metastatic, growth (i.e., pilambdaalphazetaomega = plasia). The clinico-pathological characterization of the advanced gastric precancerous lesions has important implications for both primary and secondary cancer prevention. The WHO agency has recently redefined dysplasia as intraepithelial [i.e., non-invasive neoplasia (NiN)]; such a proposal is consistent with the biological profile of dysplasia, which shares with invasive cancer some significant molecular attributes. Long-term follow-up studies have demonstrated that, in the natural history of gastric cancer, NiN precedes invasive adenocarcinoma. In this review, the morphological features of gastric NiN are described, also illustrating differences and similarities between the current and the previously adopted histological diagnostic criteria. The molecular profile of NiN is summarized and the spectrum of the options in the clinical management of gastric NiN are reported.