Post FDA approval analysis of 200 gallium-68 DOTATATE imaging: A retrospective analysis in neuroendocrine tumor patients
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Aman Chauhan1,*, Riham El-Khouli2,*, Timothy Waits2, Rohitashva Agrawal1, Fariha Siddiqui3, Zachary Tarter3, Millicent Horn3, Heidi Weiss4, Elizabeth Oates2, B. Mark Evers5 and Lowell Anthony1
1 Department of Internal Medicine-Medical Oncology and the Markey Cancer Center, University of Kentucky, Lexington, KY, USA
2 Department of Radiology, University of Kentucky, Lexington, KY, USA
3 College of Medicine, University of Kentucky, Lexington, KY, USA
4 Department of Biostatistics and the Markey Cancer Center, University of Kentucky, Lexington, KY, USA
5 Department of Surgery and the Markey Cancer Center, University of Kentucky, Lexington, KY, USA
* Co primary authors
Keywords: gallium-68 DOTATATE; neuroendocrine diagnosis; NET
Received: June 27, 2020 Accepted: June 30, 2020 Published: August 11, 2020
Gallium-68 DOTATATE provides physiologic imaging and assists in disease localization for somatostatin receptor (SSTR) positive neuroendocrine tumor (NET) patients. However, questions regarding usefulness of gallium- 68 DOTATATE imaging in identifying the primary site in neuroendocrine tumors (NETS) of unknown primary, correlation of NET grade with median Standardized Uptake Value (SUV) and effects of long acting somatostatin analog on gallium-68 DOTATATE imaging quality needs to be evaluated.
A single institution retrospective review of the first 200 NET patients with gallium-68 DOTATATE imaging from Dec 2016 to Dec 2017 was conducted. Questions related to NETs of unknown primary, correlation of Standardized Uptake Value (SUV) to Ki-67 (which signifies proliferation rate), the effects of long-acting systemic somatostatin analog (SSA) on SUV were part of our data analysis.
From these 200 patients, 59.5% (119) were females, 40.5% (81) were males; the median age was 62 years. The following primary tumor sites were identified: small bowel-37.5%; pancreas-18.5%; bronchial-14%; colon-3.5%; rectum-2%; appendix-1.5%; adrenal-0.5%; prostate-0.5%; others-3% and unknown primary-19%. Mean hepatic SUV of the lesion with the greatest radiolabeled uptake in 96 patients was similar irrespective to exposure to long acting SSA. Patients exposed to long acting SSA had mean SUV of 31.3 vs 27.8 for SSA naïve patients. The difference was not statistically significant.
Gallium-68 DOTATATE imaging seems to distinguished G3 NET from G1/G2 based on mean SUV, and also identified the primary tumor site in 17 of 38 (45%) patients with unknown primary. Systemic exposure to long acting SSA does not appear to influence mean SUV of gallium-68 DOTATATE scan.
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