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Use of sequential FDG-PET to predict patient outcome after neoadjuvant chemotherapy in advanced stage ovarian cancer.
Chemotherapy is a quite toxic treatment with significant side effects and a substantial number of patients do not respond to chemotherapy. Currently, treatment is continued over several cycles before anatomical imaging modalities (CT or MRI) identify that tumors are not responding. FDG-PET measures the increased glucose metabolism of cancer and changes in tumor glucose metabolism occur early after the first dose of chemotherapy and precede changes in tumor size. The aim of our study was to evaluate the use of sequential FDG-PET to predict patient outcome after the 1st and 3rd cycle of neoadjuvant chemotherapy in advanced stage (FIGO IIIC and IV) ovarian cancer. We observed a significant correlation between FDG-PET metabolic response after the 1st (p=0.008) and 3rd (p=0.005) cycle of chemotherapy and overall survival. When using a previously defined threshold for decrease in FDG uptake from baseline of 20% after the 1st cycle of chemotherapy the median overall survival of metabolic responders was 38.3 months compared to 23.1 months in metabolic non-responders. At a threshold of 55% decrease in SUV after the 3rd cycle of chemotherapy median overall survival was 38.9 months in metabolic responders compared to 19.7 months in non-responders. There was no correlation between clinical response criteria (p=0.7) or CA125 response criteria (p=0.5) and overall survival and there was only a weak correlation (p=0.09) between histopathological response criteria and overall survival. We found that no change in tumor glucose metabolism after initiation of treatment predicts poor response. Sequential FDG-PET predicted patient outcome as early as after the 1st cycle of chemotherapy. The potential clinical application of FDG-PET is the individual tailoring of treatment (not only chemotherapy). Prediction of response by FDG-PET might be helpful in the stratification for surgery vs. continued chemotherapy and might also serve as surrogate endpoint in chemotherapy for recurrent ovarian cancer. FDG-PET could also reassure oncologists that the treatment is working and let them consider alternatives if FDG-PET, in conjunction with other clinical parameters, suggests that the treatment is not working. Patients would therefore have less ineffective treatments which would also save substantial cost.
Reference:
Norbert Avril Department of Nuclear Medicine, Queen Mary, University of London, Barts and The London School of Medicine, London
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