(111)-INDIUM-DTPA-OCTREOTIDE-SCINTIGRAPHY FOR COLORECTAL LIVER METASTASES

The somatostatin analogue octreotide is effective in the treatment of neuroendocrine and other tumours. (111)-In-labelled DTPA-octreotide sc intigraphy is successful in localizing primary neuroendocrine rumours and metastases and other rumours containing somatostatin receptors. An antiproliferative effect of octreotide was also demonstrated for colo rectal carcinoma. Since only about 40% of colorectal carcinomas expres s somatostatin receptors. we tried to establish whether (111)-In-Iabel led DTPA-octreotide scintigraphy is able to reveal the receptor status of liver metastases in patients with colorectal liver metastases. Thi s would be useful in selecting patients for adjuvant therapy studies w ith octreotide. We performed (111)-In-labelled DTPA-octreotide scintig raphy in ten patients with nonresectable liver metastases of colorecta l origin and curatively resected primary. In nine of ten patients the liver metastases were somatostatin receptor negative, in one patient s omatostatin receptor positive. In the patient with somatostatin recept or-positive liver metastases after resection of a rectal carcinoma, th e histological examination of the biopsies from the liver metastases s howed a solid tumour of neuroendocrinal differentiation. Tn the repeat ed histological examination of the specimen of the rectal primary, a s mall solid tumour with neuroendocrinal differentiation was found betwe en formations of adenocarcinoma (adenoendocrine carcinoma). In our stu dy (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 autoradiographi c investigation on tissue biopsies are still necessary. In patients wi th adenoendocrine carcinomas (111)-In-labelled DTPA-octreotide scintig raphy may help to histologically differentiate the metastases.