Report from SNM: FDG-PET predicts response of ovarian cancer to chemotherapy

Ovarian cancer is one of the more pernicious and aggressive human neoplastic diseases. The condition could be more manageable if oncologists knew before the completion of chemotherapy whether treatment was having the desired effect.

A study presented Monday at the Society of Nuclear Medicine meeting strongly suggests that FDG-PET will be the tool that could provide that information. Dr. Stefanie Sassen and colleagues at the Technical University of Munich demonstrated that changes in FDG uptake rates after one cycle of neoadjuvant therapy can predict long-term patient survival. Standard uptake value measures were even more accurate when FDG-PET was performed after three cycles.

A preliminary trial involving 33 patients, along with experience with other cancers suggesting that a 20% decline in FDG uptake indicates a positive response to therapy, formed the basis for these findings. FDG-PET imaging covering the abdomen and pelvis was performed before treatment and after the first and third cycles of carboplatin-based chemotherapy. Patients received three cycles of chemotherapy before debulking surgery. Results were monitored for three years.

Sassen and the nuclear medicine laboratory of Dr. Markus Schwaiger found significant correlation between changes in FDG-PET uptake and patient survival after the first (p = 0.008) and third (p = 0.005) cycles of therapy. Patients classified as responders survived 38.3 months compared with 23.1 months for patients classified with PET as nonresponders. Using a 55% decrease in SUV as a positive response threshold, the researchers found the overall survival of patients classified as responders with FDG-PET to be 38.9 months. It was 19.7 months for predicted nonresponders.

The study laid the foundation for larger trials to confirm the results and to apply the protocol to treatment modifications to improve patient outcomes, Sassen said.

"We found that we can predict survival by performing baseline PET and PET again after one cycle of chemotherapy. This change in metabolic activity will predict outcomes," she said.

For further information from Diagnostic Imaging:

Reducing uncertainty: PET identifies early response to therapy

PET could become go-to modality for gauging response to therapy

Targeted PET agents fulfill valuable diagnostic roles