PET imaging with fluorine-18 fluoroestradiol may help predict breast cancer response to hormone therapy: early research.(Gynecology)

NEW ORLEANS -- Physicians may now have a tool to help predict which patients with recurrent or metastatic breast cancer will respond to hormone therapy, early research suggests.

PET imaging-using fluorine-18 fluoroestradiol (FES) appears to indicate treatment response, Dr. David A. Mankoff said at the annual meeting of the Society of Nuclear Medicine.

In a study of 34 patients with recurrent metastatic breast cancer, all 10 patients responding to treatment had high levels of FES uptake as revealed in PET images, said Dr. Mankoff of the University of Washington, Seattle.

Previous studies have shown that FES uptake corresponds to levels of estrogen receptor (ER) expression, which in turn has been linked to response to therapy by in vitro studies.

"We know from prior studies that only those tumors that express hormone receptors--ER being the most predictive--respond to hormonal therapy," Dr. Mankoff said. Patients are currently selected for hormonal therapy based on the ER expression of the primary tumor. More recent studies, however, have shown that ER expression in recurrent or metastatic disease may not be the same as in the primary tumor.

The researchers set out to determine which patients with recurrent or metastatic breast cancer with an ER-positive primary tumor are most likely to respond to hormonal therapy. They hypothesized that noninvasive measurement of ER expression using FES-PET would predict that response.

For the study, dynamic imaging using FES-PET focused on the areas with the most lesions. Based on torso surveys, patients were ...