Angiotensin alteration of drug uptake in an experimental model of hepatic metastases

Angiotensin-II administration is useful for the detection of liver metastasis from pancreatic cancer during pharmacoangiographic computed tomography

AIM: To improve the preoperative diagnosis of liver metastasis from pancreatic cancer, we estimated computed tomography during arterial angiography (CTA) with/without administration of angiotensin-II (AT-II).

METHODS: Thirty-five patients with pancreatic cancer were examined in this study. After conventional CTA was performed, pharmacoangiographic CTA was performed with a 1-3 microgram/5 mL solution of angiotensin  IIinjected through a catheter into the celiac artery during spiral computed tomography. We prospectively analyzed the relative region of interest (ROI) ratio of tumor to liver with/without AT-II.

RESULTS: In all patients, the relative ratio of each computed tomography (CT) number in the ROI was larger at pharmacoangiographic CT than at conventional angiographic CT. Administration of angiotensin-II enhanced the metastatic liver tumor as compared with normal tissue. Intratumoral blood flow increased in all patients with malignant tumors due to the pressure effect of AT-II. Furthermore, the metastatic lesions in the liver of three patients were represented by only pharmacoangiographic CT, not by conventional CT and conventional CT angiography. In even peripheral and central areas of metastatic liver tumor, the lesions were enhanced after administration of AT-II.

CONCLUSION: These results support that high detection rate of liver metastasis revealed by pharmacoangiographic CT suggests the improvement of diagnosis on preoperative staging. Moreover, chemotherapy under AT-II induced hypertension may have a better effect on the treatment of metastatic liver tumors.

Vasopressin selectively increases 5-fluorouracil uptake by colorectal liver metastases following hepatic artery bolus infusion

BACKGROUND

Poor drug uptake secondary to the hypovascularity of colorectal liver metastases may partially explain their limited response to hepatic artery chemotherapy. Vasoconstrictors can increase tumor perfusion but their effect on drug uptake has not been well-characterized. The aim of this study was to determine whether vasopressin could selectively increase tumor uptake of 5-FU.

MATERIALS AND METHODS

A syngeneic rat model of colorectal liver metastases was used. Control group rats underwent a 60-s hepatic artery infusion of 14C-5-FU (30 mCi/150 microL). Treatment group rats had vasopressin (60 mIU/kg, dose determined in pilot study) added to the 14C-5-FU infusion. Mean systemic arterial pressure was minimally affected. Tumor:liver (T/L UR) and tumor center:periphery (C/P UR) 5-FU uptake ratios were determined using quantitative autoradiography techniques. Differences in tumor size (< or > 4 mm) and location (superficial vs deep) were accounted for. Statistical analysis was by repeated measures ANOVA (P = 0.01 significant).

RESULTS

A total of 161 tumors in 18 rats was analyzed. T/L URs were significantly higher in the treatment group compared to controls for tumors <4 mm (1.72 +/- 0.14 vs 0.70 +/- 0.16, P <0.001), tumors >4 mm (0.99 +/- 0.15 vs 0.45 +/- 0.16, P = 0.01), deep tumors (1.17 +/- 0.13 vs 0.68 +/- 0.15, P = 0.01), and superficial tumors (1.54 +/- 0. 15 vs 0.47 +/- 0.17, P <0.001). C/P URs did not differ significantly between the groups.

CONCLUSIONS

The results of this study show that vasopressin selectively enhances the uptake of 5-FU by colorectal liver metastases in a rat model of hepatic artery infusion. This may represent a promising strategy for improving tumor response rates and patient survival.