TY - JOUR T1 - Tumor Response Assessment to Treatment with [<sup>177</sup>Lu-DOTA<sup>0</sup>,Tyr<sup>3</sup>]Octreotate in Patients with Gastroenteropancreatic and Bronchial Neuroendocrine Tumors: Differential Response of Bone Versus Soft-Tissue Lesions JF - Journal of Nuclear Medicine JO - J Nucl Med SP - 1359 LP - 1366 DO - 10.2967/jnumed.112.102871 VL - 53 IS - 9 AU - Esther I. van Vliet AU - John J. Hermans AU - Maria A. de Ridder AU - Jaap J. Teunissen AU - Boen L. Kam AU - Ronald R. de Krijger AU - Eric P. Krenning AU - Dik J. Kwekkeboom Y1 - 2012/09/01 UR - http://jnm.snmjournals.org/content/53/9/1359.abstract N2 - We have noted that bone lesions on CT respond differently from soft-tissue lesions to treatment with [177Lu-DOTA0,Tyr3]octreotate (177Lu-octreotate). We therefore compared the response of bone lesions with that of soft-tissue lesions to treatment with 177Lu-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 [111In-DTPA0]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 &lt; 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 177Lu-octreotate should be interpreted cautiously, as this finding may be therapy-related rather than indicative of tumor progression. ER -