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Detection of occult gastrinomas with iodine 125-labeled lanreotide and intraoperative gamma detection
E A Woltering1, R Barrie, T M O'Dorisio
1Department of Surgery, Louisiana State University, New Orleans.
Background:
Surgical exploration for gastrinoma has a high failure rate because of small primary tumors and occult metastasis. Despite extensive preoperative and intraoperative tumor localization, only 30% to 40% of patients with gastrinoma are cured by surgery. Two patients with unlocalized gastrinomas were studied with intraoperative gamma detection of an iodine 125-labeled somatostatin analog, lanreotide, to localize their tumors.
Methods:
Both patients were challenged before operation with 100 micrograms of octreotide acetate, and both had circulating gastrin levels suppressed by greater than 50%. Iodine 125-labeled lanreotide (100 to 150 muCi) was injected during exploration, and an intraoperative gamma detector was used to detect tumor binding of the analog.
Results:
In patient 1 a single source of increased counts was discovered in a retroduodenal lymph node, which was excised; no other tissue was removed. Histologic study of this node failed to demonstrate tumor; however, the patient's gastrin level was normal (63 pg/ml) 4 months after operation. In patient 2 five areas of increased counts were discovered and excised. Three of these five areas had visible tumor on microscopic examination. Three months after operation the patient's fasting gastrin level was 103 pg/ml.
Conclusions:
Intraoperative gamma detection of radiolabeled peptides may allow the localization of occult tumors that contain specific peptide receptors.
Insights
Intraoperative gamma detection using radiolabeled somatostatin analogs successfully located occult gastrinomas in two patients. This technique aids in identifying tumors missed by conventional methods, improving surgical outcomes for gastrinoma patients.
Area of Science:
- Endocrinology
- Nuclear Medicine
- Surgical Oncology
Background:
- Surgical exploration for gastrinoma (a neuroendocrine tumor) has limited success due to small tumor size and metastasis.
- Current localization methods often fail, with only 30-40% of gastrinoma patients achieving a cure via surgery.
Observation:
- Two patients with unlocalized gastrinomas underwent exploration using intraoperative gamma detection.
- Iodine 125-labeled lanreotide, a somatostatin analog, was administered, and its tumor binding was detected using a gamma probe.
Findings:
- In one patient, a lymph node with increased radiotracer uptake was removed, leading to normalized gastrin levels post-surgery.
- In the second patient, five areas of uptake were excised, with three confirmed to contain gastrinoma upon microscopic examination.
Implications:
- Intraoperative gamma detection of radiolabeled peptides offers a promising method for localizing occult tumors expressing specific peptide receptors.
- This technique has the potential to improve the detection and surgical management of challenging gastrinoma cases.
