Tuesday, December 3 | 5:00 p.m.-5:10 p.m. | T8-SSNMMI04-4 | Room S405
A mid-study analysis presented during this session suggests that F-18 fluoroestradiol (FES) PET/CT may detect unsuspected stage IV invasive lobular carcinoma (ILC). Yet FES-PET may fail to identify multiple metastatic axillary lymph nodes in comparison to sentinel lymph node biopsy, researchers found.
Overall, the primary endpoint of the study will likely be met, according to presenter Matthew Covington, MD, of the University of Utah in Salt Lake City, and colleagues. The study determined changes in clinical staging for patients with ILC when using FES-PET/CT. The primary endpoint is that FES-PET/CT will change clinical staging in at least 20% of patients, compared with standard-of-care imaging.
A positive shift in clinical staging was noted in six out of 21 (29%) cases. In three instances (14%), FES-PET/CT revealed unexpected distant metastatic disease in two patients with clinical stage 2A disease and another patient with stage 3A disease, which was subsequently confirmed through additional imaging or biopsy. All three had concurrent FDG-PET/CT that did not indicate stage IV disease, the group noted. Also, in two separate cases, FES-PET/CT detected axillary metastatic disease in patients who showed no abnormalities in axillary lymph nodes based on standard imaging. In one case, FES-PET/CT showed more axillary disease than seen on MRI and ultrasound, resulting in upstaging from stage 3A to 3C.
However, the group observed a false-negative assessment of axillary lymph nodes in pathologic staging in 5 out of 21 (25%). All five involved small nodal metastases identified on sentinel lymph node biopsy with no abnormal axillary FES uptake, the group noted.
“The mid-study analysis indicates a positive shift in clinical staging in up to 29% of cases, suggesting the primary study endpoint will be met,” the researchers concluded.
