Background: Fludeoxyglucose positron emission topography ((18)F-FDG PET) is insufficiently sensitive at detecting small or low-grade breast tumors. The characterization of somatostatin receptors (SSTR) in tumors and the development of (68)Ga-DOTATOC PET for imaging could be of interest. The aim of this study was to validate an animal model expressing SSTR2 and to correlate the immunohistochemical (IHC) analysis with (18)F-FDG and (68)Ga-DOTATOC uptake in vivo.
Materials and methods: Ten nude mice were xenografted with the ZR-75-1 breast tumor cell line. Imaging was performed with (68)Ga-DOTATOC and (18)F-FDG and correlated to IHC analysis of SSTR2.
Results: IHC analyses showed that the tumors expressed SSTR2. On PET imaging, the tumors were barely visible with (18)F-FDG, whereas with (68)Ga-DOTATOC, specific two-fold higher uptake was observed (p<0.005).
Conclusion: Our results suggest that (68)Ga-DOTATOC PET could be used for detection of breast tumors not detected with (18)F-FDG. SSTR2 status should be assessed to allow for individual treatment.
Keywords: 18F-FDG; 68Ga-DOTATOC; PET; SSTR2; immunohistochemistry; somatostatin analogs.