Presentation Effectiveness of Short-term Repeated 131I metaiodobenzylguanidine (MIBG) Radiotherapy for Preventing Disease Progression in Patients with Malignant Neuroendocrine Tumors

Yoshinaga, Keiichiro  ,  Okamoto, Shozo  ,  Shiga, Tohru  ,  Shinohara, Nobuo  ,  Abe, Takashige  ,  Uchiyama, Yuuko  ,  Tamaki, Nagara

Background: Single high dose I-131 metaiodobenzylguanidine (MIBG) radiotherapy (12mCi/kg) has revealed slightly better outcome in patients with malignant neuroendocrine tumors (NECT). However, this protocol still shows 35% progressive disease (PD) within 1 year and increases adverse effects. Thus, it requires alternative therapeutic approaches. The aim of this study was to evaluate the effects of relatively short term repeated MIBG therapy for preventing PD in patients with metastatic NECT using computed tomography (CT).Methods: Nineteen patients with metastatic NECT prospectively had repeated 150 mCi of MIBG therapy within 6 months intervals. Total 46 treatments were performed. Patients were subdivided into 2 groups such as positive MIBG scan after the treatment (Group P: N=13) and negative MIBG (Group N, N-6). Mean treatments were 2.7 ±0.5 vs. 1.8 ±0.8times, .Cumulative MIBG dose was 404±72 mCi (7.0 mCi/kg) vs. 275 ± 112 mCi (4.4 mCi/kg) The tumor responses were evaluated by CT with RECIST criteria 6 months after final MIBG therapy and follow-up period from the first MIBG therapy was also observed.Results: The within 1 year PR or SD ratio was significantly higher in Group P (85% vs. 17%, P=0.043). Group P prevented increasing tumor size compared to Group N (% change of total sum longest diameter: -0.8±51.6% vs. 59.5±43.5%, P=0.024). Group P had trend to longer follow-up period compared to Group N (34.8±37.5 vs 15.3±13.7 months, P=0.24). Conclusions: Eighty-five percent metastatic NECT with MIBG positive patients effectively achieved PR or SD disease by relatively short term repeated MIBG therapy. MIBG positive patients were significantly lower within 1 year PD ratio and prevented increasing tumor size than MIBG negative patients using repeated MIBG therapy. Thus, this relatively short period of repeated MIBG treatment may have a potential to be one of therapeutic protocols for metastatic NECT.
62nd Society of Nuclear Medicine and Molecular Imaging

Number of accesses :  

Other information