RT Journal Article SR Electronic T1 A Randomized Feasibility Study of 18F-Fluoroestradiol PET to Predict Pathologic Response to Neoadjuvant Therapy in Estrogen Receptor–Rich Postmenopausal Breast Cancer JF Journal of Nuclear Medicine JO J Nucl Med FD Society of Nuclear Medicine SP 563 OP 568 DO 10.2967/jnumed.116.178368 VO 58 IS 4 A1 Sun Young Chae A1 Sung-Bae Kim A1 Sei Hyun Ahn A1 Hye Ok Kim A1 Dok Hyun Yoon A1 Jin-Hee Ahn A1 Kyung Hae Jung A1 Sangwon Han A1 Seung Jun Oh A1 Sang Ju Lee A1 Hee Jeong Kim A1 Byung Ho Son A1 Gyungyub Gong A1 Hyo Sang Lee A1 Dae Hyuk Moon YR 2017 UL http://jnm.snmjournals.org/content/58/4/563.abstract AB The aim of this study was to explore the ability of 18F-fluoroestradiol (18F-FES) PET/CT imaging to predict pathologic response to neoadjuvant therapy in postmenopausal women with estrogen receptor (ER)–rich breast cancer. Methods: This was a prospective, single-center study conducted as a substudy of the neoadjuvant study of chemotherapy versus endocrine therapy in postmenopausal patients with primary breast cancer (NEOCENT) trial. Patients with ER-rich breast cancer were randomized to neoadjuvant chemotherapy (NC) or neoadjuvant endocrine therapy (NET). The baseline SUVmax of 18F-FES PET/CT was measured. The pathologic response was assessed by the Miller–Payne system as nonresponse (grades 1 and 2) and response (grades 3–5). Results: Twenty-six patients were enrolled, with pathologic response achieved in 25 (NC, 12; NET, 13). Two patients achieved pathologic complete response after NC, but the remaining 23 patients had residual disease after NC or NET. Eight of 12 patients responded to NC, and 4 of 13 to NET; the difference was marginally significant (P = 0.07). In the NC group, the 2 patients with 18F-FES–negative tumors and none of the 10 patients with 18F-FES–avid tumors achieved pathologic complete response (P = 0.02). No difference in the SUVmax between responders and nonresponders was observed in either group. However, 5 of 7 NC patients with a baseline SUVmax of less than 7.3 achieved pathologic response, whereas none of the 5 NET patients with an SUVmax of less than 7.3 were responders (P = 0.03). The SUVmax values of the NC group were negatively correlated with percentage reduction of tumor cellularity (r = −0.63, P = 0.03), whereas those of the NET group showed positive correlation (r = 0.62, P = 0.02). During the median follow-up of 74 mo (range, 44–85 mo), recurrence occurred in only 4 NET patients. In patients with an SUVmax of less than 7.3, recurrence occurred in none of the 8 NC patients and 2 of the 5 NET patients (P = 0.13). Conclusion: Postmenopausal women who are ER-positive, but 18F-FES–negative, may benefit from NC rather than NET. 18F-FES PET/CT has the potential to predict response to neoadjuvant therapy in postmenopausal women with ER-rich breast cancer.