Effects of prostacyclin on hepatic metastases from human pancreatic cancer in the nude mouse.

Human pancreatic cancer is an aggressive malignancy, with systemic metastases ultimately accounting for its grave prognosis. Arachidonic acid metabolites known to affect platelet function also interfere with tumor growth and metastases. We evaluated the effect of prostacyclin on the hepatic metastases of a human pancreatic cancer in a nude mouse model. The mean surface area of tumor on the liver was significantly reduced in all treatment groups. In the control group 485 mm2 of tumor was present on the liver surface. Animals treated with 200 micrograms of prostacyclin 0.5 hr prior to the injection of tumor cells had 21 mm2 of tumor present on the liver surface (P = 0.004). Similarly, 400 micrograms of prostacyclin caused a reduction of tumor surface area to 20 mm2 (P = 0.004). The maximal reduction of tumor surface area, 11 mm2, was observed when 200 micrograms of prostacyclin was given 0.5 hr prior to and 4.0 hr after the injection of tumor cells (P = 0.003). For the group given 200 micrograms of prostacyclin 4.0 hr after the injection of tumor, the surface area of tumor was 85 mm2 (P = 0.017). The number of tumor colonies on the liver surface was significantly reduced from 20 to 11 when 200 micrograms of prostacyclin was administered intraperitoneally 0.5 hr before and 4.0 hr after the injection of tumor cells (P = 0.047). These results indicate that prostacyclin has antimetastatic activity on hepatic metastases from a human pancreatic adenocarcinoma in the nude mouse.