Abstract
Simple Summary[68Ga]RM2 positron emission tomography (PET)/computed tomography (CT) has shown to be a promising imaging method for primary breast cancer (BC) with positive estrogen receptor (ER) status, but it has not been tested for visualization of metastasized recurrent or progressive BC. The aim of this pilot study was to assess tumor visualization using [68Ga]RM2 PET/CT in patients with pre-treated ER-positive BC and suspected metastases. Eight female patients with initial ER-positive, pre-treated BC were included in this retrospective study. Strong RM2 binding was found in all metastatic lesions of six patients, whereas two patients were rated RM2-negative. Our data suggest that RM2 binding is maintained in the majority of patients with advanced disease stage of pre-treated ER-positive BC. Thus, [68Ga]RM2 PET/CT could support treatment decision in these patients, radiotherapy planning in oligometastatic patients or selection of patients for RM2 radioligand therapy.Background: Positron emission tomography (PET)/computed tomography (CT) using the gastrin-releasing peptide receptor antagonist [68Ga]RM2 has shown to be a promising imaging method for primary breast cancer (BC) with positive estrogen receptor (ER) status. This study assessed tumor visualization by [68Ga]RM2 PET/CT in patients with pre-treated ER-positive BC and suspected metastases. Methods: This retrospective pilot study included eight female patients with initial ER-positive, pre-treated BC who underwent [68Ga]RM2 PET/CT. Most of these patients (seven out of eight; 88%) were still being treated with or had received endocrine therapy. [68Ga]RM2 PET/CTs were visually analyzed by two nuclear medicine specialists in consensus. Tumor manifestations were rated qualitatively (i.e., RM2-positive or RM2-negative) and quantitatively using the maximum standardized uptake value (SUVmax). SUVmax values were compared between the two subgroups (RM2-positive vs. RM2-negative). Results: Strong RM2 binding was found in all metastatic lesions of six patients (75%), whereas tracer uptake in all metastases of two patients (25%) was rated negative. Mean SUVmax of RM2-positive metastases with the highest SUVmax per patient (in lymph node and bone metastases; 15.8 ± 15.1 range: 3.7–47.8) was higher than mean SUVmax of the RM2-negative metastases with the highest SUVmax per patient (in bone metastases; 1.6 ± 0.1, range 1.5–1.7). Conclusions: Our data suggest that RM2 binding is maintained in the majority of patients with advanced disease stage of pre-treated ER-positive BC. Thus, [68Ga]RM2 PET/CT could support treatment decision in these patients, radiotherapy planning in oligometastatic patients or selection of patients for RM2 radioligand therapy. Further studies with larger patient cohorts are warranted to confirm these findings.
Highlights
Breast cancer (BC) still represents the most common type of cancer in women worldwide [1]
Our data suggest that RM2 binding is maintained in the majority of patients with advanced disease stage of pre-treated estrogen receptor (ER)-positive breast cancer (BC)
Two patients were excluded as they presented with older sclerotic bone lesions which could not be confirmed as vital metastases by either tumor growth on current computed tomography (CT) or by a distinct appearance on other imaging modalities
Summary
Breast cancer (BC) still represents the most common type of cancer in women worldwide [1]. Oligometastatic disease is considered an intermediate stage between localized and systemic metastatic disease [8] It typically includes a maximum of five metastases [9] and is diagnosed by imaging alone [10]. In analogy to highly accurate molecular imaging techniques in other tumor entities (e.g., prostate cancer) [6,11], [68Ga]RM2 positron emission tomography (PET)/computed tomography (CT) targeting the gastrin-releasing peptide receptor (GRPR) could help detecting the oligometastatic stage in patients with BC and might, improve accurate stratification of this patient group. Methods: This retrospective pilot study included eight female patients with initial ER-positive, pre-treated BC who underwent [68Ga]RM2 PET/CT Most of these patients (seven out of eight; 88%) were still being treated with or had received endocrine therapy. Further studies with larger patient cohorts are warranted to confirm these findings
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
