Authors
Aman Chauhan1, Millicent Horn2, Riham El-Khouli3, Timothy Waits3, Lowell Brian Anthony1; , 1 Division of Medical Oncology, Markey Cancer Center, University of Kentucky Lexington, KY; 2 University of Kentucky, School of Medicine, 3 Department of Radiology, University of Kentucky. Lexington.
Introduction
On June 1, 2016, FDA approved use of Gallium 68 DOTATE scan for localization of somatostatin positive neuroendocrine tumors. Since the FDA approval, many questions regarding utility of Ga 68 DOTATATE in monitoring of the disease, effect of systemic somatostatin analog on quality of imaging and most importantly, whether Ga 68 DOTATATE scan alters clinical decision making remains to be answered. We review our single center experience with Ga DOTATATE scan post FDA approval.
Methods
Retrospective review of 200 patients who had undergone Ga-68 DOTATE scanning at Markey cancer center between Nov 2016 and Jan 2018.
Results
Of these 200 patients, 59.5% were females and the median age was 62 (30-84 years). The study cohort was comprised of following primary tumor sites: 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%. Ga-68 DOTA scan influenced clinical decisions in 39% (n = 78) pts. Ga-68 DOTA scanning was able to locate primary tumors in 17 of 38 pts who were classified as NET of unknown primary based on CT imaging. Seventeen patients had comparative Ga-68 DOTA scans. Ten of 17 (58%) patients had discordant results between Ga-68 DOTA vs IV contrasted CT scan. Five progressed on CT but had stable disease or no evidence of disease on Ga-68 DOTA scan. Two demonstrated stable disease on CT but had progression on Ga-68 DOTA scanning. Subgroup analysis of mean SUV for hepatic metastatic lesions revealed 37.3 for G1 (n = 20) as compared to 32.3 for G2 (n = 37) and 17.46 for G3 (n = 4). Mean hepatic SUV of the hottest lesion in 96 patients was similar irrespective of exposure to SSA LAR. 31.3 vs 27.8 for SSA vs no SSA cohorts.
Conclusion
Ga-68 DOTA scanning impacted clinical decision making in 39% of NET pts (n = 200), identified the primary site in 38 pts and assisted with differentiating G3 NET from G1/G2 based on mean SUV in a subgroup analysis (n = 61). Serial Ga-68 DOTA monitoring disease progression in our subset analysis (n = 17) revealed a 58% discordancy between anatomical vs physiologic imaging. Systemic exposure to long acting SSA does not seem to impact quality of Ga-68 DOTA scan.