FES-PET in the Care of Patients With Breast Cancer: Clinical Case 1

Jeremy Force, DO: For the first case, we have a 48-year-old female. She was newly diagnosed with de novo stage IV ER+ [estrogen receptor-positive], PR+ [progesterone receptor-positive], HER2 [human epidermal growth factor receptor 2]-negative disease. It was clinically T1C, grade 2 invasive ductal carcinoma. She presented to her primary care physician with difficulty walking and hip pain. The primary breast mass was biopsied, and a CT scan showed a left acetabular lesion, but the patient was hesitant about biopsy. She was initiated on a CDK4/6 inhibitor and aromatase inhibitor with her local oncologist and came to see me at Duke [Cancer Institute] for a second opinion. We subsequently reviewed the imaging that was done at the outside hospital, but I thought there may be utility to identify is this lesion in the left acetabulum estrogen receptor-positive or not. Dr Ulaner spoke pretty eloquently about the need to determine ER positivity and the potential benefit, especially from the Netherlands study showing that there were even subsets of this disease that may respond better or worse to CDK4/6 inhibition combined with endocrine therapy.

Indeed, this patient, when looking at the left acetabular lesion, you can see quite nicely on the right that the FES [F-18 fluoroestradiol] is negative for the estrogen receptor, while it is FDG [fluorodeoxyglucose] positive, so it is an active cancer but FES negative. I did express to her that we really needed to get a biopsy to confirm this diagnosis because it would change her prognostic components and also potential therapeutic interventions. Thankfully, we have a very robust interventional radiology group here. We discussed her case at our spine metastasis center. It was decided that we would not only biopsy the left acetabulum, but also simultaneously use cryoablation.

That biopsy did show that it was triple-negative breast cancer. It was 1+ score by HER2, so we did double check with fluorescence in situ hybridization. That was not amplified. We also sent out for genomic sequencing, and there was no actionable mutation. We did feel that given she was at a younger age, it would be reasonable to perform a lumpectomy with sentinel lymph node biopsy. That confirmed the ER+ primary breast cancer with now a triple-negative isolated bone lesion. She wished to avoid chemotherapy at all costs, and there were various reasons for that. Through a shared informed decision-making process, she decided to continue with the CDK4/6 inhibitor and aromatase inhibition. She did stay on this for about a year before there was progression in her lungs. While I don’t have that imaging, we did follow up with another FES-PET [positron emission tomography], and those lung lesions were also negative. She has now moved on to chemotherapy at this point.

Transcript Edited for Clarity