Overall Survival of Well-Differentiated Neuroendocrine Tumors Evaluated by F-18-FDG-PET.

Introduction: Today, grading, and thereby choice of treatment strategy for patients with neuroendocrine (NE) tumors, is mainly based on the proliferation index, Ki-67. As a supplement to this pathological evaluation, a whole body image analysis could be of value. Aim(s): To investigate the prognostic value of FDG-PET in patients with WHO grade I and IINE tumors. Materials and methods: Eighty-one prospectively enrolled patients with NE tumors grade I and II underwent FDG-PET imaging. The prognostic value of the FDG-PET scan was evaluated. There were 47 grade I tumors (Ki-67 index2<20). Follow-up time after the FDG-PET scan was 31 ± 12.6 months (mean + SD). Results: FDG-PET identified pathological loci in 42 of 81 patients, giving an overall modest sensitivity of 52%. During the 3-year follow-up, 22 of the 81 patients died, and of these 22 events, 19 were FDG-PET positive and three were FDG-PET negative. Thus, in the FDG-positive group, 45% died, compared to 7.7% of the FDG-negative. A positive FDG-PET scan was associated with a significantly higher risk of death (p<0.001), with an HR of 7.3 (95% confidence interval: 2.1 - 24.6) in these low-grade NE tumors. Conclusion: FDG-PET predicts survival of grade I and IINE tumors. We therefore propose that FDG-PET can be a valuable prognostic tool even in NE tumors classified as low-grade. [ABSTRACT FROM AUTHOR]