Circulating tumour cells in gastrointestinal cancers: food for thought?

Abstract

Gastrointestinal (GI) cancers account for 35% of cancer-related deaths, predominantly due to their ability to spread and generate drug-tolerant metastases. Arising from different locations in the GI system, the majority of metastatic GI malignancies colonise the liver and the lungs. In this context, circulating tumour cells (CTCs) are playing a critical role in the formation of new metastases, and their presence in the blood of patients has been correlated with a poor outcome. In addition to their prognostic utility, prospective targeting of CTCs may represent a novel, yet ambitious strategy in the fight against metastasis. A better understanding of CTC biology, mechanistic underpinnings and weaknesses may facilitate the development of previously underappreciated anti-metastasis approaches. Here, along with related clinical studies, we outline a selection of the literature describing biological features of CTCs with an impact on their metastasis forming ability in different GI cancers.

Fig. 1. Circulating tumour cells (CTCs) in gastrointestinal (GI) cancer metastasis.

Primary tumours originating in various GI organs are complex entities consisting of heterogeneous tumour cell populations entangled with tumour microenvironment (TME) components like stromal cells, immune cells and microbiota. During the process of metastasis, cancer cells intravasate into circulation as various CTC entities, including single cells, homotypic clusters and heterotypic clusters. The liver and the lungs are the predominant metastatic sites, compared to peritoneum, bones and brain. Illustrations were created with BioRender.