[F-18]FES-PET Assessment of ER Status in Metastases From Newly Diagnosed Patients With Metastatic Breast Cancer

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In a subanalysis from the Dutch IMPACT-MBC study reported in the Journal of Clinical Oncology, van Geel et al found that qualitative whole-body 16α-[fluorine F-18]fluoro-17β-estradiol positron-emission tomography/computed tomography ([F-18]FES-PET) was highly accurate in predicting estrogen receptor (ER) expression as determined by immunohistochemistry (IHC) in metastases from patients with newly diagnosed metastatic breast cancer.

The subanalysis of the multicenter study included 200 patients enrolled between August 2013 and May 2018. ER expression on IHC in biopsied metastases was compared with qualitative whole-body [F-18]FES-PET evaluation and quantitative local [F-18]FES uptake assessment in the corresponding metastases.

Key Findings

In 181 of 200 patients, ER status of the biopsied metastasis on IHC could be compared with whole-body [F-18]FES-PET assessment. In 156 of 200 patients, ER status on IHC could be compared with quantitative [F-18]FES uptake in the corresponding metastasis.

Qualitative whole-body [F-18]FES-PET assessment predicted ER expression in the biopsied metastasis with sensitivity of 95% (95% confidence interval [CI] = 89%–97%), specificity of 80% (95% CI = 66%–89%), positive predictive value of 93% (95% CI = 87%–96%), and negative predictive value of 85% (95% CI = 72%–92%). Among the 181 patients, ER status of the metastasis on IHC was positive in 132 and negative in 49. On whole-body [F-18]FES-PET, ER status was positive for 135, including 10 negative on IHC, and negative for 46, including 7 positive on IHC.

Quantitative local [F-18]FES uptake predicted ER expression with sensitivity of 91% (95% CI = 84%–95%), specificity of 69% (95% CI = 54%–81%), positive predictive value of 90% (95% CI = 83%–94%), and negative predictive value of 71% (95% CI = 55%–83%). For bone metastases, positive predictive value and negative predictive value were 92% and 81%. Among the 156 patients, ER status of the metastasis on IHC was positive in 117 and negative in 39. On quantitative [F-18]FES uptake, ER status was positive for 118, including 12 negative on IHC, and negative for 38, including 11 positive on IHC.   

When findings were included in a meta-analysis with 12 other studies, with a total population of 556 patients, qualitative assessment of [F-18]FES-PET had a pooled sensitivity of 84% (95% CI = 75%–90%) and specificity of 92% (95% CI = 64%–99%). Quantitative assessment of [F-18]FES-PET uptake had a pooled sensitivity of 89% (95% CI = 85­%–92%) and specificity of 78% (95% CI = 69%–84%).

The investigators concluded, “In this largest prospective series so far, we established the clinical validity of [F-18]FES-PET to determine tumor ER status in metastatic breast cancer. In view of the high diagnostic accuracy of qualitatively assessed whole-body [F-18]FES-PET, this noninvasive imaging modality can be considered a valid alternative to a biopsy of a metastasis to determine ER status in newly [diagnosed] metastatic breast cancer.”

Carolina P. Schröder, MD, PhD, of the Dutch Cancer Institute, Amsterdam, is the corresponding author for the Journal of Clinical Oncology article.

Disclosure: The study was supported by the Dutch Cancer Society. For full disclosures of the study authors, visit

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