Correlation Between Fluorodeoxyglucose (FDG) and FLT Uptake and Gene-Expression Oncotype Assay in Patients With Breast Cancer

Several publications have addressed the role of PET imaging for biological characterization of breast cancer. A modest but significant correlation was reported between tumor grading and FDG uptake. Few studies reported a positive correlation between SUV and the Ki-67 labeling index of malignant breast tumors. Others have correlated p53 expression in breast cancer and FDG uptake. F18-Fluoro-3'-deoxythymidine (FLT) has been developed as a PET marker for cellular proliferation has been developed for imaging cell proliferation and findings correlate strongly with the Ki-67 labeling index in breast cancer. A 10-minute FLT-PET scan acquired two weeks after the end of the first course of chemotherapy, has been shown in two recent studies to be useful for predicting longer-term efficacy of chemotherapy regimens for women with breast cancer.

In the current study FDG and FLT uptake and their ratios will be correlated with the risk score results of the Oncotype gene-expression assay in patients with clinically negative nodal disease planned for surgical removal of the tumor. It is our hypothesis that since high uptake of these tracers implies aggressive behavior and rapid tumor growth, it might well be that patients with high risk score on Oncotype will have high uptake of the PET tracers and those with low risk score will show low-intensity uptake values. If this will be the case, it might well be that in patients with non-conclusive oncotype results (intermediate score) FDG and FLT uptake measurement will allow further dichotomy to 1. Patients with intermediate score on Oncotype and high uptake of the PET tracers, suggestive of aggressive behavior and 2. Patients with intermediate score on Oncotype and low uptake of the PET tracers suggesting a less aggressive behavior.