Prognostic Value of 16α-<sup>18</sup>F-Fluoro-17β-Estradiol PET as a Predictor of Disease Outcome in Endometrial Cancer: A Prospective Study
Shizuka Yamada, Hideaki Tsuyoshi, Makoto Yamamoto, Tetsuya Tsujikawa, Yasushi Kiyono, Hidehiko Okazawa, Yoshio Yoshida
Abstract
The purpose of this study was to evaluate the potential of 16α-<sup>18</sup>F-fluoro-17β-estradiol (<sup>18</sup>F-FES) PET to predict prognosis in patients with endometrial cancer (EC). <b>Methods:</b> In total, 67 patients with International Federation of Gynecology and Obstetrics (FIGO) stage I–IV EC underwent <sup>18</sup>F-FES and <sup>18</sup>F-FDG PET/CT before treatment. The SUV<sub>mean</sub> of the primary tumor was compared with the clinical characteristics, and the relationships between SUV and progression-free survival (PFS) or overall survival were analyzed. <b>Results:</b><sup>18</sup>F-FES SUV was significantly associated with stage, histology, lymphovascular space involvement (LVSI), and lymph node metastasis, and <sup>18</sup>F-FDG SUV was significantly associated with stage, myometrial invasion, tumor size, and lymph node metastasis. Receiver-operating characteristic curve analysis revealed that <sup>18</sup>F-FES SUV could significantly detect tumor progression and survival, with areas under the curve of 0.813 and 0.790, respectively, whereas <sup>18</sup>F-FDG SUV could detect them with areas under the curve of 0.557 and 0.635, respectively. The Kaplan–Meier survival curve showed that patients with a low <sup>18</sup>F-FES SUV had significantly poor PFS (<i>P</i> < 0.001) and overall survival (<i>P</i> = 0.001) compared with patients with a high SUV, whereas <sup>18</sup>F-FDG showed no significant differences. In a subanalysis of 27 patients with a low risk of recurrence (FIGO stage IA endometrioid carcinoma [grade 1 or 2] without LVSI), those with a low <sup>18</sup>F-FES SUV also had poorer PFS than those with a high SUV (<i>P</i> = 0.002). In multivariate analysis, an <sup>18</sup>F-FES SUV of less than 2.63 (<i>P =</i> 0.037; hazard ratio, 10.727; 95% CI, 1.16–99.35) and FIGO stages III and IV (<i>P =</i> 0.042; hazard ratio, 8.838; 95% CI, 1.09–71.84) were significantly associated with PFS. <b>Conclusion:</b> A low <sup>18</sup>F-FES for the primary tumor was strongly associated with prognostic factors of EC such as LVSI and lymph node metastasis, and a low <sup>18</sup>F-FES SUV was an independent prognostic factor for PFS in patients with EC. These data suggest that pretreatment <sup>18</sup>F-FES PET might be useful in determining the appropriate treatment for patients with EC.