FDG-PET predicts ovarian cancer response to chemotherapy

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

A study presented at the Society of Nuclear Medicine meeting in June strongly suggests that FDG-PET could be the tool that will provide that information. Dr. Stefanie Sassen and colleagues at the Technical University of Munich demonstrated that changes in FDG uptake in advanced stages of ovarian cancer can predict long-term patient survival after one cycle of neoadjuvant therapy. 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 after the first cycle of chemotherapy indicates a positive response to therapy, formed the basis for these findings.

FDG-PET imaging of 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 Prof. 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 after the third cycle of chemotherapy, the researchers found the overall survival to be 38.9 months for patients classified as responders with FDG-PET and 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.