Correlation of Somatostatin Receptor Expression by Qualitative and Quantitative Analysis of ¹⁸F-FDG PET and Tumor Grading in Neuroendocrine Tumors and Their Association With Treatment Response to PRRT: A Prospective Observational Cross-Sectional Study
DOI:
https://doi.org/10.51168/v56s3909Keywords:
Fluorodeoxyglucose positron emission tomography/computed tomography, Maximum standardized uptake value, Peptide receptor radionuclide therapy, Ki-67 proliferation index, Neuroendocrine tumorsAbstract
Abstract
Background:
Although peptide receptor radionuclide therapy (PRRT) has become an established treatment for advanced neuroendocrine tumors (NETs), treatment response varies considerably among patients. Fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) reflects tumor glucose metabolism and biological aggressiveness and may provide prognostic information beyond conventional histopathological grading.
Objective:
To evaluate the correlation between pretreatment FDG PET/CT maximum standardized uptake value (SUVmax), tumor grade, and treatment response following PRRT in patients with metastatic or unresectable NETs.
Materials and Methods:
This prospective observational cross-sectional study included 50 histopathologically confirmed NET patients undergoing ^177Lu-DOTATATE/DOTANOC PRRT. Pretreatment FDG PET/CT was performed, and SUVmax was measured for representative lesions. Histopathological grading was determined using mitotic count and Ki-67 proliferation index. Patients were followed after PRRT and evaluated for symptomatic, biochemical, and objective imaging responses.
Results:
Among 41 patients with available histological grading, 19 (46%) had Grade 1, 17 (42%) Grade 2, and 5 (12%) Grade 3 tumors. Mean pretreatment SUVmax increased with increasing proliferation index and was highest in tumors with Ki-67 >20%. Patients with high SUVmax demonstrated poorer objective treatment responses. Low proliferation index was generally associated with better symptomatic and imaging outcomes, whereas patients with both high proliferation index and high SUVmax demonstrated the poorest treatment outcomes.
Conclusion:
Pretreatment FDG PET/CT SUVmax is a useful imaging biomarker of tumor aggressiveness and treatment response following PRRT. Combining metabolic imaging with histopathological grading may improve risk stratification.
Recommendation:
Pretreatment FDG PET/CT may be considered as a complementary tool for risk assessment and individualized treatment planning in patients undergoing PRRT.
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