Neoadjuvant chemotherapy (NACT) followed by interval debulking surgery (IDS) is an alternative treatment approach to primary surgery for primarily inoperable advanced epithelial ovarian cancer (EOC) patients with a poor diagnosis. A clinical challenge has been a lack of reliable noninvasive NACT response assessment methods. Evaluation of the total tumor burden changes with the serum tumor marker HE4 and metabolic 18F-FDG-PET/CT imaging provide novel opportunities for studying NACT response. 

A total of 54 advanced EOC patients were recruited in the study; 32 patients treated with NACT followed by IDS and 22 patients referred to primary surgery. Serum HE4 and CA125 were determined at baseline and before each NACT and postoperative chemotherapy cycles. The HE4 and CA125 percentual changes during NACT were determined. In addition to CT imaging, 18F-FDG-PET/CT was performed before and after NACT. The metabolical response to NACT was estimated by using omentum as a reference lesion and by calculating the total metabolic tumor volume (MTV). 

The HE4 and CA125 profiles during NACT did not correspond with the anatomical CT response. An HE4 decrease of >80% during NACT associated with longer survival. The postoperative serum HE4 levels corresponded with the residual tumor in surgery, whereas the same observation was not noted for CA125. In 18F-FDG-PET/CT, the omental SUVmax change during NACT associated with omental histopathological response. The total MTV decrease during NACT corresponded with the primary therapy outcome. The changes in serum HE4 and in 18F-FDG-PET/CT during NACT could be used to identify the patients not responding to NACT.