OBJECTIVETo explore whether cancer cells abide by the mechanism of epithelial-mesenchymal transition (EMT) in the process of invasion and metastasis by comparing histology and protein expression of E-cadherin and vimentin among primary, metastatic carcinomas and their emboli.

METHODSA total of 68 tissue specimens in 59 cases of primary adenocarcinoma or squamous cell carcinoma and their lymphatic metastasis were collected, of which there were 13 well differentiated, 11 moderately differentiated, 30 poorly differentiated tumors and 14 lymphatic metastases. The morphology and the expression of E-cadherin and vimentin proteins were assessed by H-E stain and immunohistochemistry.

RESULTSThe overall morphology of the primary cancers and their tumor emboli was similar. Among 54 primary cancers, 50 cases were positive for E-cadherin and 22 cases were positive for vimentin. Fifty-one cases were positive for E-cadherin and 22 cases were positive for vimentin in the tumor emboli, with no statistical difference (P = 0.804, P = 0.842). Among 14 cases of lymphatic metastasis, 12 cases were positive for E-cadherin and 6 cases were positive for vimentin, and the tumor emboli in 12 cases were positive for E-cadherin and 7 cases were positive for vimentin, with statistical difference (P = 0.084, P = 0.878). There were no significant difference of E-cadherin and vimentin protein expression between the cancer tissue and its emboli (P = 0.410, P = 0.824). A subset of tumor cells in cancer emboli expressed E-cadherin at a high level without vimentin expression, whereas other cells in tumor emboli showed an opposite expression pattern.

CONCLUSIONSThere is no significant difference of EMT characteristics among primary cancer, lymphatic metastases and their cancer emboli. Cancer thrombus contains both EMT and non-EMT cells. Further studies are required to elucidate the role of EMT in the processes of tumor invasion and metastasis.