No decline in tumor blood flow plus a high metabolism on PET, seen during neoadjuvant treatment, is associated with high disease recurrence rates in women with locally advanced breast cancer.

No decline in tumor blood flow plus a high and unchanging tumor metabolism on positron emission tomography, seen during neoadjuvant treatment, is associated with high disease recurrence rates in women with locally advanced breast cancer.

The finding, from a study of 53 women, is reported by Dr. David A. Mankoff of the University of Washington in Seattle and colleagues in the September 20 issue of the Journal of Clinical Oncology.

"The study implies a new way of thinking about measuring tumor response," Dr. Mankoff commented to Reuters Health.

The study subjects underwent dynamic PET scanning with the radiotracers fluorine-18 fluorodeoxyglucose (FDG) and oxygen-15 water before and at midpoint of neoadjuvant chemotherapy.

The team estimated tumor blood flow with the O-15 water PET study and calculated the FDG metabolic rate (MRFDG) and transport (FDG K1) parameters.

They report that "patients with persistent or elevated blood flow and FDG K1 from baseline to mid-therapy had higher recurrence and mortality risks than patients with reductions."

Blood flow and transport parameters "remained independent prognosticators of disease-free survival and overall survival," the researchers found. "For example, in the association between blood flow and mortality, a patient with a five per cent increase in tumor blood flow had a 67 per cent higher mortality risk compared with a patient with a five per cent decrease in tumor blood flow."

"The in vivo changes in breast cancer perfusion and metabolism in response to treatment are highly predictive of relapse and survival, and the imaging results add significantly to the ability to predict relapse and survival," Dr. Mankoff said. "These results suggest that this type of imaging measurement is valuable in evaluating the efficacy of treatment, and predicting how that treatment will impact patient survival."

The study uncovered "risk factors for tumor recurrence and death that have not been identified before, namely, an imbalance between tumor metabolism and perfusion (too much metabolism per unit perfusion) and a failure to diminish tumor perfusion with treatment," Dr. Mankoff said.

"This points to future research to understand the biologic basis of these findings and also suggests new treatment directed at tumor metabolism and/or tumor vasculature in patients with resistant tumors," the researcher concluded.

J Clin Oncol 2008;26:4449-4457