Circulating tumor cells (CTCs) are a crucial contributor and
indicator for
cancer metastasis. The presence of CTCs and other two forms of occult disease including circulating
tumor microembolus (
CTMs) as well as disseminated
tumor cells (DTCs) as a sign for
micrometastasis has been associated with adverse survival of both localized and metastatic
cancers. However, their assignments in
micrometastasis are still not well understood. This mini-review is aimed to provide an overview of the
biological features and the clinical impact of CTCs, DTCs and CTM in
gastric cancer (GC), and to summarize the technical limitations of detection methods in addition to the significance of distinct migration modes in epithelial-mesenchymal transition (EMT) and gastric
micrometastasis. Although there are controversies over current CTC identification strategies, both single and collective migration modes as indispensable parts of
micrometastasis are influential participants in GC progression, diagnosis and prognosis. CTCs, CTM and DTCs are not separated forms of the occult disease; however available techniques fail to detect all subsets of them. Therefore, micrometastatic detection should be combined with conventional pathological examinations in order to make more accurate predictions of
tumor outcomes. Novel markers further defining the features of CTC subsets are warranted.