Somatostatin receptor (SSTR) PET has become a mainstay in the diagnosis of neuroendocrine tumors (NETs) and for selecting patients for SSTR-based therapy; however, no consensus has yet been reached in terms of prognosis. A systematic review and meta-analysis was performed on the prognostic value of the maximum standardized uptake value (SUVmax) for 68Ga-SSTR PET in patients with NETs.
We performed a systematic search using the following keywords: PET, SSTR, NET, and prognosis. The inclusion criteria were the use of 68Ga-SSTR PET as an imaging tool, studies limited to NETs, studies that reported progression-free survival (PFS) and/or overall survival (OS), and studies that included SUVmax as a prognostic parameter. The effect of SUVmax on PFS and OS was measured in terms of the hazard ratio (HR).
Eight eligible studies with 474 patients were finally included and analyzed. The combined HR of SUVmax on PFS was 2.31 with significance (95% confidence interval [CI], 1.34–4.00; P = 0.003). The trim and fill adjusted analysis for SUVmax on PFS demonstrated the combined HR as 1.81 with significance (95% CI, 1.11–2.95; P = 0.017), as the publication bias was found (Egger P = 0.004). The combined HR of SUVmax on OS was 2.97 with significance (95% CI, 1.71–5.15; P = 0.0001), without publication bias (Egger P = 0.929). The subgroup analysis revealed that well-differentiated NETs (grade 1 or 2) on PFS showed significance (P = 0.03); however, all grades of NETs (including grade 3) on PFS did not reach significance (P = 0.11). Tumor site and type of radiotracer did not affect the prognostic value of SUVmax.
Low SUVmax of 68Ga-SSTR PET was associated with a worse prognosis for PFS and OS in patients with NETs. Well-differentiated NETs had more prognostic value compared with all grades of NETs. The SUVmax of 68Ga-SSTR PET could be used as an objective prognosis predictor.
From the Department of Nuclear Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea.
Conflicts of interest and sources of funding: none declared.
Received for publication April 11, 2019; revision accepted May 18, 2019.
Correspondence to: Yong-il Kim, MD, PhD, Department of Nuclear Medicine, Asan Medical Center, University of Ulsan College of Medicine, 88, Olympic-ro 43-gil, Songpa-gu, Seoul 05505, Republic of Korea. E-mail: firstname.lastname@example.org.
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Online date: July 8, 2019