The inhibitory effect of ¹¹¹In-DTPA⁰-octreotide on intrahepatic tumor growth after partial hepatectomy

The aim of this animal study was to evaluate whether peptide receptor radionuclide therapy with ¹¹¹In -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 μg/kg subcutaneously twice daily or with 370 MBq ¹¹¹In-DTPA⁰-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 ¹¹¹In-DTPA⁰-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. ¹¹¹In-DTPA⁰-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). ¹¹¹In-DTPA⁰-octreotide was also effective on SS-R-negative tumors after PHx (P = 0.01) but not after sham operation. Furthermore, ¹¹¹In-DTPA⁰-octreotide therapy did not influence liver regeneration or liver function after PHx. Conclusion: Peptide receptor radionuclide therapy with ¹¹¹In-DTPA⁰octreotide 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.