PT  - JOURNAL ARTICLE
AU  - Gary A. Ulaner
AU  - Komal Jhaveri
AU  - Sarat Chandarlapaty
AU  - Vaios Hatzoglou
AU  - Christopher C. Riedl
AU  - Jason S. Lewis
AU  - Audrey Mauguen
TI  - Head-to-Head Evaluation of <sup>18</sup>F-FES and <sup>18</sup>F-FDG PET/CT in Metastatic Invasive Lobular Breast Cancer
AID  - 10.2967/jnumed.120.247882
DP  - 2021 Mar 01
TA  - Journal of Nuclear Medicine
PG  - 326--331
VI  - 62
IP  - 3
4099  - http://jnm.snmjournals.org/content/62/3/326.short
4100  - http://jnm.snmjournals.org/content/62/3/326.full
SO  - J Nucl Med2021 Mar 01; 62
AB  - Invasive lobular carcinoma (ILC) demonstrates lower conspicuity on 18F-FDG PET than the more common invasive ductal carcinoma. Other molecular imaging methods may be needed for evaluation of this malignancy. As ILC is nearly always (95%) estrogen receptor (ER)–positive, ER-targeting PET tracers such as 16α-18F-fluoroestradiol (18F-FES) may have value. We reviewed prospective trials at Memorial Sloan Kettering Cancer Center using 18F-FES PET/CT to evaluate metastatic ILC patients with synchronous 18F-FDG and 18F-FES PET/CT imaging, which allowed a head-to-head comparison of these 2 PET tracers. Methods: Six prospective clinical trials using 18F-FES PET/CT in patients with metastatic breast cancer were performed at Memorial Sloan Kettering Cancer Center from 2008 to 2019. These trials included 92 patients, of whom 14 (15%) were of ILC histology. Seven of 14 patients with ILC had 18F-FDG PET/CT performed within 5 wk of the research 18F-FES PET/CT and no intervening change in management. For these 7 patients, the 18F-FES and 18F-FDG PET/CT studies were analyzed to determine the total number of tracer–avid lesions, organ systems of involvement, and SUVmax of each organ system for both tracers. Results: In the 7 comparable pairs of scans, there were a total of 254 18F-FES–avid lesions (SUVmax, 2.6–17.9) and 111 18F-FDG–avid lesions (SUVmax, 3.3–9.9) suggestive of malignancy. For 5 of 7 (71%) ILC patients, 18F-FES PET/CT detected more metastatic lesions than 18F-FDG PET/CT. In the same 5 of 7 patients, the SUVmax of 18F-FES–avid lesions was greater than the SUVmax of 18F-FDG–avid lesions. One patient had 18F-FES–avid metastases with no corresponding 18F-FDG–avid metastases. There were no patients with 18F-FDG–avid distant metastases without 18F-FES–avid distant metastases, although in one patient liver metastases were evident on 18F-FDG but not on 18F-FES PET. Conclusion: 18F-FES PET/CT compared favorably with 18F-FDG PET/CT for detection of metastases in patients with metastatic ILC. Larger prospective trials of 18F-FES PET/CT in ILC should be considered to evaluate ER-targeted imaging for clinical value in patients with this histology of breast cancer.