Abstract
1400
Objectives Positron emitters may irradiate surrounding tumor cells by beta- and gamma emissions. A few commercially available postron emitters have short half-lives that deliver most radiation within hours and allow simplied radiation protection. This study evaluate tumor suppression abilities of 3 commercially available positron-emitting radiopharmaceuticals (F-18 FDG, Cu-64 chloride and Ga-68 Chloride) when used intratumorally at dose range of 0.5-3 mCi.
Methods Two established tumor models were tested in 13762 rat mammary tumor and B16-OVA melanoma in C57BL/6 mice respectively. Tumors were inoculated subcutaneously. Tumor growth was observed manually and by serial microCT (Seimens Inveon) until palpable. Intratumoral injection was performed using F-18 FDG, Ga-68 Cl (pH 6) and Cu-64 (pH 6) between 0.5-3 mCi in 0.1-0.5 ml volumes. Immediate serial images were acquired for dosimetry. Tumor growth curves were observed until euthanasia. Serial F-18 FDG PET-CT was conducted with 0.4 mCi iv injection using PET-CT in selected animals over 4 weeks. In the rat model, intratumoral injection was also compared with interstititial injection using F-18 FDG or Ga-68 Cl before tumor was formed.
Results Tumor volume by manual measurement correlated well with microCT measured volumes which is about 50% lower. There was significant tumor suppression with for all 3 positron-emitting radiopharmaceuticals. Suppression of melanoma in mice is illustrated in Figure 1. Intratumoral injection is more effective than interstitial injection with 4 of 6 rats treated with 1.8-3 mCi of F-18 FDG undergoing complete regression in 2 weeks.
Conclusions Intratumoral positron emission cancer therapy may be a feasible means of locoregional cancer treatment and could be readily applied to human disease with further studies.
Research Support MDACC University Cancer Fund; DOD BC020808