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Published on: April 17, 2019
Assessment of Neuroendocrine Features Using 99mTc-Octreotide Scintigraphy in Patients with Metastatic
Mehrdad Tavakoli1, Elahe Pirayesh1, Sepide Khoshbakht1
1Nuclear Medicine Department, Shohada'e Tajrish Medical Centre, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
Purpose:
Neuroendocrine differentiation is a recognized phenotypic change in advanced prostate cancer. Neuroendocrine-like cells may lack androgen receptor or prostate-specific membrane antigen expression, potentially contributing to treatment resistance. This study evaluated octreotide scan positivity as a surrogate marker of neuroendocrine differentiation and its association with response to 177Lu-prostate-specific membrane antigen radioligand therapy in patients with metastatic castration-resistant prostate cancer.
Materials And Methods:
Thirty-six patients with metastatic castration-resistant prostate cancer who were candidates for 177Lu-prostate-specific membrane antigen radioligand therapy were enrolled. Whole-body octreotide scintigraphy was performed after intravenous administration of 750 MBq of 99mTc-octreotide. Abnormal uptake was classified as mild, moderate, or severe relative to liver uptake. All patients subsequently received standard 177Lu-prostate-specific membrane antigen radioligand therapy and were followed for treatment response after at least two treatment cycles.
Results:
Of the 36 enrolled patients, 8 who died within 2 months after the first treatment cycle were excluded from response assessment; therefore, 28 patients were included in the final response analysis. Among these 28 patients, 19 (67.9%) responded to treatment and 9 (32.1%) did not. Eight patients (28.6%) had negative octreotide scans, whereas 20 (71.4%) had positive scans, all showing mild uptake. Positive scans were observed in 13 of 19 responders (68.4%) and 7 of 9 non-responders (77.8%). No significant association was observed between octreotide scan positivity and treatment response (P = 1.00).
Conclusion:
Octreotide scan positivity was relatively common in patients with metastatic castration-resistant prostate cancer but was not significantly associated with response to 177Lu-prostate-specific membrane antigen radioligand therapy. Larger studies are needed to confirm these findings.
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