Changes in the Expression of Somatostatin Receptor Imaging Following Y-90 Lanreotide Therapy for Carcinoid Tumor: A Flare Response?

A 53-year-old man with In-111 octreotide-positive metastatic hepatic carcinoid was referred for Y-90 lanreotide therapy. A diagnostic In-111 lanreotide scan, performed to assess suitability for therapy, showed less uptake in lesions compared with In-111 octreotide. After 3 therapy doses of Y-90 lanreotide, a repeat In-111 lanreotide scan showed intense uptake in old lesions, appearance of new lesions, and uptake in the spleen. This was associated with improvement in flushing and regression of liver size. Computed tomography scan showed stable disease. Increased expression of somatostatin receptors has been observed with In-111 octreotide but not with In-111 lanreotide. If this is a flare response, then pretreatment with “cold” lanreotide may be beneficial before Y-90 lanreotide therapy.