Recent data demonstrated a high sensitivity (>90%) in the visualization of primary/recurrent pancreatic cancer as well as metastases by means of 123I-labeled vasoactive intestinal peptide (VIP). The aim of this study was to investigate the diagnostic value of radioiodinated VIP in patients suffering from adenocarcinoma of the exocrine pancreas.
Methods: Sixty consecutive patients (26 women, 34 men; mean age 59 yr) with histologically verified pancreatic cancer were investigated in this study. Twenty-one patients presented with organ-confined malignancy (19 at study entry and 2 during follow-up after initial surgery developed tumor recurrence), while 25 patients had distant metastases along with the local malignancy, and 7 patients had liver metastases after resection of the primary lesion (6 on study entry and 1 during follow-up showed tumor development). In 5 of these patients, abdominal lymph node metastases were present at the time of scanning. Of 10 patients, who had undergone potentially curative surgery for their cancer, 7 remained free of disease during follow-up until death or for at least 6 mo. Iodine-123-VIP (150-200 MBq; approximately 1 microg VIP) was administered to all patients. Scintigraphic results were evaluated as compared to conventional radiologic imaging methods and surgical exploration.
Results: Primary pancreatic tumors were visualized by 123I-VIP in 19/21 patients (90%) with disease confined to the pancreas and in 8/25 patients (32%) suffering both from locoregional and disease metastatic to the liver. The overall 123I-VIP scan sensitivity for primary pancreatic adenocarcinomas was 58% (27/46 scans). Liver metastases were imaged in 29/32 patients (scan sensitivity 90%) and abdominal lymph node metastases in 4/5 patients. In 5 patients, the VIP receptor scan indicated the malignant lesion before CT. In vitro results confirmed specific binding of 123I-VIP to primary pancreatic tumor cells as well as to PANC1 adenocarcinoma cells.
Conclusion: Iodine-123-VIP receptor scanning has the potential to offer additional information to augment diagnostic standard methods and could influence the decision-making process in the treatment of pancreatic cancer.