Value of¹⁸F-FES PET in Solving Clinical Dilemmas in Breast Cancer Patients: A Retrospective Study

Abstract

Breast cancer (BC) is a heterogeneous disease in which estrogen receptor (ER) expression plays an important role in most tumors. A clinical dilemma may arise when a metastasis biopsy to determine the ER status cannot be performed safely or when ER heterogeneity is suspected between tumor lesions. Whole-body ER imaging, such as 16a-18 F-fluoro-17b-estradiol ( 18 F-FES) PET, may have added value in these situations. However, the role of this imaging technique in routine clinical practice remains to be further determined. Therefore, we assessed whether the physician's remaining clinical dilemma after the standard workup was solved by the 18 F-FES PET scan. Methods: This retrospective study included 18 F-FES PET scans of patients who had (or were suspected to have) ER-positive metastatic BC and for whom a clinical dilemma remained after the standard workup. The scans were performed at the University Medical Center of Groningen between November 2009 and January 2019. We investigated whether the physician's clinical dilemma was solved, defined either as solving the clinical dilemma through the 18 F-FES PET results or as basing a treatment decision directly on the 18 F-FES PET results. In addition, the category of the clinical dilemma was reported, as well as the rate of 18 F-FES-positive or -negative PET scans, and any correlation to the frequency of solved dilemmas was determined. Results: One hundred 18 F-FES PET scans were performed on 83 patients. The clinical dilemma categories were inability to determine the extent of metastatic disease or suspected metastatic disease with the standard workup (n 5 52), unclear ER status of the tumor (n 5 31), and inability to determine which primary tumor caused the metastases (n 5 17). The dilemmas were solved by 18 F-FES PET in 87 of 100 scans (87%). In 81 of 87 scans, a treatment decision was based directly on 18 F-FES PET results (treatment change, 51 scans; continuance, 30 scans). The frequency of solved dilemmas was not related to the clinical dilemma category (P 5 0.334). However, the frequency of solved dilemmas was related to whether scans were 18 F-FES-positive (n 5 63) or 18 F-FES-negative (n 5 37; P , 0.001). Conclusion: For various indications, the 18 F-FES PET scan can help to solve most clinical dilemmas that may remain after the standard workup. Therefore, the 18 F-FES PET scan has added value in BC patients who present the physician with a clinical dilemma.

18F-FES PET-CT Scan in Patients of Histopathologically Proven Estrogen Receptor Positive Breast Carcinoma at a Tertiary Care Facility

“…Our limited data demonstrates that 18 F-FES PET-CT imaging can be performed successfully in a PET-CT and cyclotron facility using standard radio-pharmacy techniques for labeling and production of 18 F-FES followed by PET-CT imaging in appropriately selected patients. The technique may be considered in patients with ER-pos BCa for metastatic work-up, inconclusive ER status, identifications of unknown primary with ER-pos histology and solving clinical dilemma [12], particularly in the regions with high incidence of BCa.…”

Non-conventional and Investigational PET Radiotracers for Breast Cancer: A Systematic Review

“…All [ 18 F]F-FDG-positive lesions were also [ 18 F]F-FES-positive. Boers et al ( 104 ) evaluated whether [ 18 F]F-FES PET/CT could resolve the remaining physician's clinical dilemma in 83 BC patients with suspected heterogeneous ER expression. The dilemmas were as follows: inability to determine the extent of metastatic disease or suspected metastatic disease with standard work-up ( n = 52), unclear ER status of the tumor ( n = 31), and inability to determine which primary tumor was responsible for the metastases ( n = 17).…”

Chemotherapy Shows a Better Efficacy Than Endocrine Therapy in Metastatic Breast Cancer Patients with a Heterogeneous Estrogen Receptor Expression Assessed by 18F-FES PET

“…Novel methods of detection for ER heterogeneity are warranted because multiple pathological punctures are often infeasible, especially for metastatic patients. 18 F-fluoroestradiol ( 18 F-FES) positron emission tomography/computed tomography (PET/CT) is a noninvasive, molecular imaging technique to observe and quantify ER status in vivo [7]. 18 F-FES is now widely used in the diagnosis and treatment prediction of breast cancer patients [8,9].…”

“…Moreover, studies have demonstrated that 18 F-FES uptake correlates well with ICH scoring for ER [10,11]. It has been reported that a conspicuous number of patients present with discordant ER expression between primary tumor and metastasis, and 18 F-FES PET/CT is used to reveal the existence and prognostic effects of ER heterogeneity [7,[12][13][14].…”