UCSF

Introduction: Breast cancer is prevalent health issue in women. Currently PET scanning is used as a noninvasive means to provide physiological information the uptake of glucose and its metabolism. This is performed by using the 18F-FDG tracer, which is a glucose analog. Currently, in vitro experiments are executed to understand the metabolism and glucose uptake of breast cancer cell lines in order to develop novel therapeutics. However, the in vitro glucose uptake data on breast cancer cell lines contradicts our speculation of how the trend should look, which is based off our understanding of cell line's characteristics in human models. The aim of our study is to ensure if glucose uptake in vitro correlates with in vivo glucose uptake (FDG tracer).

Methods: 7 breast cancer cell lines were bilaterally implanted with the same cell line in the mammary fat pad of immunodeficient mice (SCID and NSG). The mice were monitored for volume growth and were imaged by microPET/CT when the tumors reached about 200 mm3. The mice were injected with about 200 μCi/0.1 ml concentrations.

Results and Discussions: Small correlation (R2 = 0.08394) was between the comparisons of glucose uptake in vitro and FDG uptake in vivo. Imaging was seen as inconsistent for two different cell lines. No correlation (R2 = 0.00666) was observed in the comparison between volume (in all instance) and their corresponding FDG uptake. Volume growth was an issue with all the animals and it is speculated that the implantation procedure is not optimal. Low correlation (R2 = 0.0352) is observed in the overall comparison between FDG uptakes and volume growth rate. A comparison was done to clarify if %ID/gmax can be used instead of SUVmax, which resulted in a strong correlation (as expected). Further studies are needed due to small sample size

Conclusion: At the end of the study, it was observed that glucose uptake in vitro does not correlate with FDG uptake in vivo. This has a strong implication that in vitro studies for glucose uptake might not be translated to in vivo uptake.