Dual time point imaging fluorine-18 flourodeoxyglucose positron emission tomography for evaluation of large loco-regional recurrences of breast cancer treated with electrochemotherapy

Abstract

Background: Electrochemotherapy is a local anticancer treatment very efficient for treatment of small cutaneous metastases. The method is now being investigated for large cutaneous recurrences of breast cancer that are often confluent masses of malignant tumour with various degrees of inflammation. To this end 18-Flourine-Flourodeoxyglucose-Positron Emission Tomography/Computed Tomography (FDG-PET/CT) could be a method for response evaluation. However, a standard FDG-PET/CT scan cannot differentiate inflammatory tissue from malignant tissue. Dual point time imaging (DTPI) FDG-PET has the potential of doing so. The purpose of this study was to investigate if DTPI FDG-PET/CT could assess response to electrochemotherapy and to assess the optimal timing of imaging.

Patients and methods: Within a phase II clinical trial 11 patients with cutaneous recurrences had FDG-PET/CT scans at three time points: 60 min, 120 min and 180 min after FDG injection. The scans were performed before and 3 weeks after electrochemotherapy.

Results: A significant reduction in maximum standard uptake value at 60 min post injection was seen after treatment. Furthermore a change in the FDG uptake pattern was observed; from increasing uptake in up to 180 min post injection before treatment to stabilization of FDG uptake at 120 min post injection after treatment. The change in FDG uptake pattern over time lead to change of response in three target lesions; two lesions changed from stable metabolic disease to partial metabolic response and one lesion changed from partial metabolic response to stable metabolic disease. To ensure detection of the change in uptake pattern, scanning 60 and 180 min post injection seems optimal.

Conclusions: The present study shows that FDG-PET/CT 60 and 180 min after tracer injection is a promising tool for response evaluation of cutaneous recurrences of breast cancer treated with electrochemotherapy.

Keywords: breast cancer; cutaneous metastases; dual time point FDG PET; electrochemotherapy; response assessment.

FIGURE 1.

Large recurrence with varying depth and inflammation on the left chest wall of 68 y female. Left column shows from the top clinical presentation, CT-scan, PET scan at 60 min p.i., PET scan at 120 min p.i. and PET scan 180 min p.i. Right column. Same patients after one treatment. Change in SUVmax in target lesion at baseline compared to follow up was 29.7% at 60 min p.i., 71.2% at 120 min p.i., and 83.1% at 180 min p.i.

FIGURE 2.

Change in SUVmax over time in target lesions and background. There was significant increase in mean SUVmax over time in target lesions before treatment wheras the mean SUVmax in target lesions after treatment stabilized at 120 min after FDG injection. Mean SUVmax in background (measused in the aortic arch) did not increase over time.