The inhibitory effect of (111)In-DTPA(0)-octreotide on intrahepatic tumor growth after partial hepatectomy.

The aim of this animal study was to evaluate whether peptide receptor radionuclide therapy with (111)In-diethylenetriaminepentaacetic acid (DTPA)(0)-octreotide was able to reduce tumor growth even under tumor growth-stimulating conditions induced by partial hepatectomy (PHx). METHODS: Rats underwent 70% PHx or sham operation. The development of hepatic metastases was determined 21 d after direct injection of somatostatin receptor (SS-R)-positive or SS-R-negative tumor cells into the portal vein. Groups of 8 or 9 animals that underwent PHx or sham operation were treated with octreotide 50 micro g/kg subcutaneously twice daily or with 370 MBq (111)In-DTPA(0)-octreotide intravenously on days 1 and 8. Both treatments were compared with control treatment. Forty non-tumor-bearing rats were used to determine the influence of (111)In-DTPA(0)-octreotide therapy on liver regeneration after PHx. RESULTS: PHx induced an increase in tumor growth in all experiments (P < 0.01). Octreotide treatment did not influence tumor growth after PHx or sham operation. (111)In-DTPA(0)-octreotide could effectively reduce tumor growth in the liver of SS-R-positive tumors also under conditions of increased tumor growth as generated by PHx (P < 0.01). (111)In-DTPA(0)-octreotide was also effective on SS-R-negative tumors after PHx (P = 0.01) but not after sham operation. Furthermore, (111)In-DTPA(0)-octreotide therapy did not influence liver regeneration or liver function after PHx. CONCLUSION: Peptide receptor radionuclide therapy with (111)In-DTPA(0)-octreotide is effective in SS-R-positive tumors. During liver regeneration, the growth of SS-R-negative tumors is also reduced. This effect is not induced by impairment of liver regeneration or liver function. Radionuclide therapy could therefore be a promising treatment modality for patients with symptomatic liver metastases of neuroendocrine tumors in combination with liver resection.