[111-indium DTPA octreotide scintigraphy in colorectal liver metastases]

The somatostatin analogue octreotide is effective in the treatment of neuroendocrine and other tumours. 111-In-labelled DTPA-octreotide scintigraphy is successful in localizing primary neuroendocrine tumours and metastases and other tumours containing somatostatin receptors. An antiproliferative effect of octreotide was also demonstrated for colorectal carcinoma. Since only about 40% of colorectal carcinomas express somatostatin receptors, we tried to establish whether 111-In-labelled DTPA-octreotide scintigraphy is able to reveal the receptor status of liver metastases in patients with colorectal liver metastases. This would be useful in selecting patients for adjuvant therapy studies with octreotide. We performed 111-In-labelled DTPA-octreotide scintigraphy in ten patients with nonresectable liver metasoffes of colorectal origin and curatively resected primary. In nine of ten patients the liver metastases were somatostatin receptor negative, in one patient somatostatin receptor positive. In the patient with somatostatin receptor-positive liver metastases after resection of a rectal carcinoma, the histological examination of the biopsies from the liver metastases showed a solid tumour of neuroendocrinal differentiation. In the repeated histological examination of the specimen of the rectal primary, a small solid tumour with neuroendocrinal differentiation was found between formations of adenocarcinoma (adenoendocrine carcinoma). In our study 111-In-labelled DTPA-octreotide scintigraphy did not indicate the receptor status of liver metastases from colorectal carcinoma and was not useful in the planning of therapeutic regimens. For the diagnosis of the receptor status of colorectal liver metastases autoradiographic investigation on tissue biopsies are still necessary. In patients with adenoendocrine carcinomas 111-In-labelled DTPA-octreotide scintigraphy may help to histologically differentiate the metastases.