Tumor Response Assessment to Treatment with [Lu-177-DOTA(0),Tyr(3)]Octreotate in Patients with Gastroenteropancreatic and Bronchial Neuroendocrine Tumors: Differential Response of Bone Versus Soft-Tissue Lesions

Esther Vliet, John Hermans, Maria de Ridder, JJ Teunissen, BL Kam, Ronald de Krijger, Eric Krenning, Dik Kwekkeboom

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We have noted that bone lesions on CT respond differently from soft-tissue lesions to treatment with [Lu-177-DOTA(0),Tyr(3)]octreotate (Lu-177-octreotate). We therefore compared the response of bone lesions with that of soft-tissue lesions to treatment with Lu-177-octreotate in patients with gastroenteropancreatic and bronchial neuroendocrine tumors (NETs). Methods: Forty-two patients with well-differentiated NETs who had bone metastases that were positive on [In-111-DTPA(0)]octreotide somatostatin receptor scintigraphy (SRS) before treatment, and who had soft-tissue lesions, were studied. All patients had had a minimum of 1 follow-up CT scan. Lesions were scored on CT and bone lesions also on SRS before and after treatment. Tumor markers (chromogranin A and 5-hydroxyindoleacetic acid) before and after treatment were compared. Results: Because bone lesions were not visible on CT before treatment in 11 of 42 patients (26%), bone and soft-tissue lesions were evaluated in 31 patients. Whereas bone lesions increased in size, soft-tissue lesions decreased in size. The percentage change in bone and soft-tissue lesions was significantly different at all time points up to 12 mo of follow-up (P < 0.001). The intensity or number of bone lesions on SRS decreased after treatment in 19 of 23 patients (83%) in whom SRS after treatment was available. The tumor markers also decreased significantly after treatment. In 1 patient, bone lesions became visible on CT after treatment, mimicking progressive disease with "new" bone lesions, although there was an overall treatment response. Conclusion: In patients with NETs, the apparent increase in size of bone lesions or the appearance of new bone lesions on CT after treatment with Lu-177-octreotate should be interpreted cautiously, as this finding may be therapy-related rather than indicative of tumor progression.
Original languageUndefined/Unknown
Pages (from-to)1359-1366
Number of pages8
JournalJournal of Nuclear Medicine
Issue number9
Publication statusPublished - 2012

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