The invasion-MTT assay as a predictor of liver metastasis using human gastrointestinal carcinomas transplanted in nude mice.

The invasion-3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide (MTT) assay, which evaluates invasive potential into the reconstituted basement membrane, Matrigel, was performed on 49 human gastrointestinal carcinomas transplanted in nude mice. There were 19 colorectal carcinomas, 10 pancreatic carcinomas, 10 gastric carcinomas, 8 esophageal carcinomas, and 2 bile duct carcinomas. The percent invasion (PI) value of each tumor by the invasion-MTT assay expresses the invasive rate of tumor cells into the Matrigel as a percentage. There were no significant differences in correlations between the PI values and primary tumor site, clinicopathological findings, tumor doubling time, or DNA index; however, the PI values of primary tumors and lymph nodes with liver metastases were significantly higher than those of primary tumors without liver metastasis (P < 0.05). Furthermore, the primary tumors with synchronous (P < 0.05) or asynchronous (P < 0.01) liver metastases showed significantly higher PI values compared with the primary tumors without liver metastases. These results suggest that PI is not only an independent factor to predict liver metastasis, but it also correlates closely with liver metastasis. Thus, the invasion-MTT assay for primary tumors might be clinically useful to predict liver metastasis in patients following surgery for gastrointestinal carcinomas.