Comparison between F-18 fluorodeoxyglucose and Ga-68 DOTATOC in metastasized melanoma

Abstract

Somatostatin binding to somatostatin receptors (SSTRs) is known to have an antiproliferative effect in neuroendocrine tumours. Melanoma cells are derived from the neural crest and thus express SSTR. Treatment options in metastasized melanomas are limited. Therefore, we aimed to investigate whether there is a relevant uptake of the SSTR analogue DOTATOC in metastasized melanoma patients, which could be used for therapy with radiolabelled SSTR analogues. We investigated 18 patients (nine men and nine women; mean age 61 years) with metastasized melanoma using PET/CT, first with F-18 fluorodeoxyglucose ((18)F-FDG) and then with Ga-68 DOTATOC. The number of (18)F-FDG-positive or DOTATOC-positive lesions and the maximum standardized uptake value (SUV(max)) for an index lesion were determined for each patient. DOTATOC could reveal metastatic lesions in 11 of 18 patients (61%). However, on a lesion-by-lesion basis only 59 of 263 (22%) (18)F-FDG-avid metastases were seen with DOTATOC. Further, DOTATOC uptake was only faint. The mean SUV(max) was 3.1 (range, 1.2-4.2) for DOTATOC, in contrast to 28.2 (range, 2.3-115) for (18)F-FDG. Radiolabelled DOTATOC does not seem to be a promising agent for treatment of metastasized melanoma.