The extent of breast cancer is an important prognostic factor in patients diagnosed with this disease. Therefore, adequate staging at diagnosis is a requisite for optimal treatment. In all patients diagnosed with locally advanced breast cancer (LABC), distant staging using 18F-FDG PET/CT is recommended. However, the degree of metabolic uptake in the primary breast tumor is significantly lower in the ER+ subtype compared to HER2+ and triple negative breast cancer (TNBC). As a consequence, a suboptimal 18F-FDG uptake in ER+ breast cancer patients can potentially lead to missed distant metastases. Fibroblast-activating protein inhibitor (FAPI) is a recently developed radiotracer that binds to FAP, a stromal antigen overexpressed in more than 90% of epithelial-derived tumors and their metastases. Previous studies all show 68Ga-FAPI PET/CT to have a higher detection rate compared to 18F-FDG PET/CT. However, all previous studies were performed without considering breast cancer subtype. If the metabolic uptake by 68Ga-FAPI-46 is higher in ER+ breast cancer patients, more lesions will be detected, resulting in a more appropriate treatment for these patients. Therefore, in this pilot study, the investigators aim to compare the diagnostic performance of 18F-FDG with 68Ga-FAPI-46 as PET-tracer in ER+ breast cancer patients.
Study Type
INTERVENTIONAL
Allocation
NA
Purpose
DIAGNOSTIC
Masking
NONE
Enrollment
20
All participating patients will undergo an additional 68Ga-FAPI- 46 PET/CT and 68Ga-FAPI-46 PET/MRI scan prior to their breast cancer treatment.
Maastricht University Medical Center+
Maastricht, Netherlands
RECRUITINGTo determine essential input parameters for an adequate sample size calculation for a diagnostic study that compares the diagnostic accuracy of 18F-FDG and 68Ga-FAPI-46 as PET tracer in patients with ER+ breast cancer.
To investigate the proportion of discordant pairs: the number of lesions detected on 18F-FDG PET but not on 68Ga-FAPI-46 PET and the number of lesions detected on 68Ga-FAPI-46 PET but not on 18F-FDG PET.
Time frame: Patients will be followed from diagnosis until the additional imaging exams are performed, within 20 working days both PET exams will be performed.
To explore the feasibility of taking biopsies in test-positive patients.
The proportion of 68Ga-FAPI-46-positive 18F-FDG-negative lesions for which performing a biopsy is not feasible.
Time frame: Patients will be followed from diagnosis until the additional imaging exams are performed, within 20 working days both PET exams will be performed.
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