Diagnostic reliability of somatostatin receptor scintigraphy during continuous treatment with different somatostatin analogs

In order to evaluate the diagnostic reliability of somatostatin receptor scintigraphy (SRS) in patients treated with somatostatin analogs, ten patients with metastatic neuroendocrine tumors were investigated before and during continuous treatment. Different somatostatin analogs were used for therapy: five patients received octreotide (Sandostatin, Sandoz, Switzerland) and five were treated with BIM 23014 (Lanreotide, Ipsen Biotech, France) within the scope of a clinical phase II study. The SRS findings were analyzed in terms of biodistribution of the labeled somatostatin analogy and tumor visualization comparing the two studies in each patient. Whereas liver, spleen, and kidney uptake were decreased during octreotide treatment and increased on lanreotide therapy, tumor accumulation was intensified in all but one patient. Our results suggest that the diagnostic value of SRS is not necessarily restricted during treatment with somatostatin analogs. Indeed, tumor visualization may even be enhanced in this therapeutic setting. (orig.)