CT evaluation of response in advanced gastroenteropancreatic neuroendocrine tumors treated with long-acting-repeatable octreotide: what is the optimal size variation threshold?
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To identify a reliable early indicator of deriving progression-free survival (PFS) benefit in patients with advanced gastroenteropancreatic neuroendocrine tumors (GEP-NETs) treated with octreotide long-acting repeatable (LAR).
We investigated the images of 50 patients with well-differentiated advanced GEP-NETs treated with LAR octreotide and underwent baseline and follow-up thoracic, abdominal, and pelvic computed tomography. Receiver-operating characteristic (ROC) analysis and the Kaplan-Meier method were used to identify the optimal threshold to distinguish between those with and without significant improvement of PFS.
The optimal threshold for determining a response to octreotide LAR was -10% ΔSLD, with a sensitivity and specificity of 85.7% and 80%, respectively. At this threshold, 19 patients were responders and 31 were non-responders; the median PFS was 20.2 and 7.6 months in responders and non-responders (hazard ratio, 2.66; 95% confidence interval, 1.32–5.36).
A 10% shrinkage in tumor size is an optimal early predictor of response to octreotide LAR in advanced GEP-NETs.
• Octreotide LAR can significantly prolong PFS among patients with well-differentiated advanced GEP-NETs.
• No optimal tumor size-based response criteria are reported in GEP-NETs with octreotide.
• Ten percent tumor shrinkage is a reliable indicator of the response to octreotide for advanced GEP-NETs.
KeywordsNeuroendocrine tumors Octreotide Progression-free survival Response Evaluation Criteria in Solid Tumors Tomography, spiral computed
Gastroenteropancreatic neuroendocrine tumors
- Octreotide LAR
Octreotide long-acting repeatable
Response Evaluation Criteria in Solid Tumors
- ROC curve
Receiver-operating characteristic curve
Sum of the longest diameters
Transhepatic arterial chemotherapy and embolization
Well-differentiated advanced gastroenteropancreatic neuroendocrine tumors
Change in the sum of the longest tumor diameters
National Natural Science Foundation of China (81771908,81571750, 81770654), National Key Research and Development Program of China (2017YFC0113402), Guangzhou Science and Technology Foundation (201804010078). Natural Science Foundation of Guangdong Province (2015A030313043).
Compliance with ethical standards
The scientific guarantor of this publication is Dr. Shi-Ting Feng.
Conflict of interest
The authors of this manuscript declare no relationships with any companies, whose products or services may be related to the subject matter of the article.
Statistics and biometry
Ms. Fangjing Zhou (expert in statistics, Sun Yat-Sen University) kindly provided statistical advice for this manuscript.
Written informed consent was obtained from all subjects (patients) in this study.
Institutional Review Board approval was obtained.
• diagnostic or prognostic study
• performed at one institution
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