I-123 LABELED VASOACTIVE-INTESTINAL-PEPTIDE RECEPTOR SCINTIGRAPHY IN PATIENTS WITH COLORECTAL-CANCER

Recent studies have shown that various gastrointestinal tumours expres s substantial amounts of vasoactive intestinal peptide (VIP) receptors . Based on these observations, we have developed a receptor scintigrap hy using [I-123]VIP as a radioligand. An initial series performed at o ur institution showed promising potential for visualization of various gastrointestinal adenocarcinomas by means of [I-123]VIP. In this arti cle, we now report the results obtained in 80 consecutive patients wit h colorectal adenocarcinoma. Eighty consecutive patients with histolog ically verified colorectal cancer underwent scanning by means of [I-12 3]VIP (1 mu g, approximately 150 MBq). Thirteen patients were free of tumour after complete resection of Dukes' C cancer. eight patients pre sented with primary and 14 with locally recurrent tumours but were fre e of metastases. Ten patients had locally recurrent disease and liver, lung or lymph node metastases. Disease confined to organ metastases ( i.e. liver, lung or lymph nodes) was present in 35 patients. The size of the primary or recurrent tumours ranged between 3 and 6 cm, and the size of metastases was between 1 and 13 cm in diameter. Scan results were evaluated independently by two nuclear medicine physicians in a b linded way, and results were then compared with computerized tomograph y (CT)scans not older than 4 weeks. Seven out of eight primary (87%) a nd 21 out of 24 (82%) locally relapsing cancers were imaged with [I-12 3]VIP. Negative VIP scans were obtained in all 13 patients in whom the cancers had been curatively resected. All patients with lymph node me tastases showed positive VIP scans (four out of four), and positive sc ans were obtained in 25 out of 28 (89%) patients with liver metastases and in two out of three cases with lung metastases. in four patients with relapsing cancer, the VIP scan indicated the presence of disease before CT, and in two patients the diagnosis of scar tissue instead of a local recurrence of rectal cancer as suggested by GT could be estab lished. We conclude that [I-123]VIP receptor scanning is a sensitive m ethod for radioimaging of colorectal cancer with the potential to prov ide valuable additional information to conventional radiological metho ds.