Background: Liver metastasis from colorectal carcinoma is an important problem in surgical treatment and profoundly affects the prognosis of patients. If it were possible to identify characteristic features in the primary lesion strongly related to liver metastasis, these could be used as prognostic markers for liver metastasis. To search for such features, the primary lesions of patients with colorectal carcinoma with liver metastasis were investigated.
Methods: Three groups of colorectal carcinoma were examined: Group A with synchronous liver metastases; Group B with only lymph node metastases without recurrence for 5 years; and Group C with recurrence of liver metastases. Groups A and B included 24 cases and Group C, 20. We focused on cancer cell morphology at the invasive front and expression of sialyl Lewis X (sialyl Lex) in the primary cancer.
Results: At the invasive front in Group A it was frequently found that polygonal, not columnar, cancer cells with a single or solitary trabecular form with indistinct polarity, showed an infiltrative growth pattern. This type of morphology was termed "focal dedifferentiation" and graded four levels. Eleven of 24 cases (46%) had severe focal dedifferentiation in Group A, 1 of 24 (4%) in Group B, and 6 of 20 (30%) in Group C. Sialyl Lex staining was positive in 12 of 24 cases (50%) in Group A, in 3 of 24 cases (13%) in Group B, and in 7 of 20 cases (35%) in Group C in the primary carcinoma. In respect to the staining of (sialyl Lex) at focal dedifferentiation, it was positive in 17 of 24 cases (71%) in Group A, in 4 of 24 cases (17%) in Group B and in 11 of 20 cases (55%) in Group C. Focal dedifferentiation and sialyl Lex staining in the primary cancer showed a significant difference between Groups A and B. Sialyl Lex staining at focal dedifferentiation showed a significant difference between Groups A and B and Groups B and C. Other adhesion related molecules, sialyl LeA and CEA, showed no difference among Groups A, B, and C.
Conclusions: Both focal dedifferentiation and expression of sialyl Lex antigen in the primary lesion are considered good markers for assessing the metastatic proclivity of colorectal cancer.