Invasive squamous cell carcinoma (ISCC) represents 5 to 15% of breast cancers. Despite the rarity of this pathology, the number of patients with Invasive squamous cell carcinoma treated at HCL is significant. Patients at risk of metastasis are usually referred to the HCL Nuclear Medicine departments to perform positron emission tomography - computed tomography (PET/CT) with \[18\]F-FDG as an extension assessment. The investigators know that \[18\]F-FDG PET/CT has limited diagnostic performance for assessing the extent of breast cancer with a sensitivity of 66-96% for all histologies combined. For the ISCC, these performances are even lower with average Standard Uptake Value (SUV) values of 3.4 \[2.8-3.9\] versus 6.6 \[4.8-9.7\] for the others histological types of breast cancer. False negatives in \[18\]F-FDG PET/CT are due to an insufficient osteoblastic and immune response in the tumor stroma. Avril \& al. showed 65.2% false negatives with \[18\]F-FDG PET/CT for ISCC. This is why the search for new imaging techniques in this indication is particularly relevant. Targeting fibroblast activation protein (FAP), a type II membrane glycoprotein belonging to the dipeptidyl peptidase-4 family, is a promising strategy for imaging tumor stroma, particularly in epithelial carcinomas . The investigators would like to compare the \[18\]F-FDG PET/CT technique currently used to this new emerging modality. The investigators hypothesize superior diagnostic performance of \[68\]Ga-FAPI PET/CT compared to \[18\]F-FDG PET/CT for the assessment of ISCC extension, with a gold standard histological. The investigators translate this into the hypothesis of finding 30% of positive FAPI PET when the \[18F\]FDG PET/CT is negative or doubtful. The advantage of this project and this new imaging modality is to not undertreat patients wrongly classified as non-metastatic. The investigators therefore wish to offer \[68\]Ga-FAPI PET/CT to patients with negative \[18\]F-FDG PET/CT. The FAPICL project constitutes a seed project before a larger structuring study.
Study Type
INTERVENTIONAL
Allocation
NA
Purpose
DIAGNOSTIC
Masking
NONE
Enrollment
45
Realization of a \[68\]GA-FAPI-46 PET scan to detect at least one \[68\]GA-FAPI positive lesion (confirmed by histology)
Lyon sud Hospital center - Hospices Civils de Lyon
Lyon, France
Percentage of patients for whom at least one secondary lesion is demonstrated in [68]Ga-FAPI and confirmed by histology, when [18]F-FDG PET/CT is negative
Time frame: 6 weeks
Average number per patient of lesions demonstrated in [68]Ga-FAPI, not seen in [18F]-FDG
This criteria will be collected when the imaging is read by a nuclear physician.
Time frame: 6 weeks
Number of lesions positive on histology, among the lesions visualized on PET/CT with [68]Ga-FAPI (and in the case of negative histology, identify the differential diagnoses)
This criteria will be collected at the time of publication of the histological report of the suspicious lesion detected.
Time frame: 6 weeks
Evaluate the Positive Predictive Value of [68]Ga-FAPI PET/CT at the patient level, in patients negative on [18]F-FDG PET/CT
This criterion will be collected at the time of publication of the histological report of the suspicious lesion detected.
Time frame: 6 weeks
Analyze the semi-quantitative values of the PET signal by describing the [68Ga]-FAPI lesional SUVs, compared to the vascular and hepatic background
SUVmax bw lesion, SUVmax liver, SUVmax aorta will be collected at the time of reading the imaging by a nuclear physician, for each suspicious lesion
Time frame: 6 weeks
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