Discussion
tumor, CRC, micro-thrombi, malignancy, tumors
PATHOLOGY, TUMOR, METASTASIS, LYMPHATIC VESSELS, MALIGNANT TUMORS, SETTLE, PRIMARY TUMOR, TUMORS, INVASION
CRC is one of the most common malignant tumors globally, accounting for 10% of newly diagnosed cases of malignancy [The distant metastasis of tumors, including CRC, is thought to comprise a multistep process of three phases: (1) Invasion phase: in situ tumor cells increase their invasiveness through epithelial–mesenchymal transition (EMT) processes, penetrating the surrounding tissues and migrating to the blood vessels or lymphatic vessels, creating circulating tumor cells (CTCs); (2) circulation phase: platelets adhere directly to the surface of CTCs, creating micro-thrombi structures that reduce the recognition and clearance of the immune system; (3) settlement phase: CTCs settle in distant organs, forming a pre-metastatic niche, a microenvironment characterized by immune suppression, enabled by the secretion of cytokines or exosomes from the primary tumor site [The relationship between tumor size and prognosis of CRC patients has long been of great concern to clinicians. This study, based on a large-scale clinical data analysis, found that tumor size is an independent prognostic factor for mCRC patients. Nevertheless, certain limitations of the study could not be overlooked. Despite the large size of SEER database, our stratification by tumor size and metastatic site resulted in relatively small subgroups, reducing statistical power to detect small differences. This may help explain why we failed to detect significant associations between tumor size and metastatic site in the subgroups of bone and brain metastatic patients. In addition, information on missing molecular characteristics such as BRAF mutation status, microsatellite status, adjuvant therapy, or pathology techniques was not included in the SEER database. Furthermore, although this study was conducted in large populations, the proportion of Asian patients was still too small, thus necessitating further multicentral research to validate the results of this study.