PET efficacious for early treatment assessment of breast cancer type

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Non-invasive imaging can measure how well patients with the most common form of breast cancer--estrogen receptor positive type--respond to standard aromatase inhibitor therapy after only two weeks and shows similar findings that more invasive needle sampling identifies, according to a study to be presented at the 2009 American Society of Clinical Oncology (ASCO) meeting in Orlando, Fla., May 29 - June 2.

Using FDG-PET, a research team led by Hannah Linden, MD, and David Mankoff MD, of the Seattle Cancer Care Alliance and the University of Washington in Seattle, scanned 21 patients before and after two weeks of aromatase inhibitor therapy. Many of the patients also underwent a needle biopsy as a control measure to compare the two techniques, according to the investigators.

The results, 16 of the 21 patients had a greater than 20 percent decline in FDG values, paralleled perfectly "earlier work done by U.K.-based researchers who used needle biopsies to measure whether the proliferation of cancer cells was slowed by therapy," according to Linden, who is a breast cancer oncologist.

"Our findings are exciting because they suggest that we can measure a patient's response to therapy noninvasively, and PET scanning provides us simultaneous quantitative metabolic measurements at multiple tumor sites," she said. "PET has the potential to be a powerful tool to help doctors make important treatment decisions in as little as two weeks instead of two or more months."

It is common for patients with estrogen receptor positive cancer to a bone-dominant type yet they have remained largely unstudied in clinical trials because they are very difficult to image, according to Linden.

"Our work allowed us to study a common problem in a way that's not been done before and to help more people," she said. "More work needs to be done but in my mind this was a homerun," Linden said.

The study was funded by a Progress for Patients grant from the National Cancer Institute (NCI) and the Avon Foundation.