Can serial FCH-PET/CT scans predict the response to treatments in castrate resistant prostate cancer?

Abstract

Abstract.To evaluate the use of serial 18 F-choline (FCH) PET/CT scans in order to monitor the response to chemotherapy in patients (pts) with metastatic castrate-resistant prostate cancer (mCRPCa). Materials and methods. We collected FCH-PET/CT data from a consecutive series of 21 mCRPCa pre-treated pts (median age:73years) who met the inclusion criteria: such as visceral and non-visceral metastasis with clear uptake on a baseline FCH-PET/CT scan and no fewer than two scans separated by at least one month and by no more than 12 months whilst receiving chemotherapy. Eighteen pts were treated by taxanes and 3 with abiraterone. Change in FCH uptake (SUVmax of the index lesion; ΔSUVmax) during the course of treatment was compared with the clinical assessment response and PSA change (ΔPSA). The correlations were evaluated by using non-parametric tests, as appropriate. Results. The median interval time between PET/CT scans was 5 months (interquartile range-IQR: 3-7). Median (IQR) PSA value and SUVmax were 25(7.22-141) ng/mL, 15.7(11.3-17.83), 22.9(7.7-92.5) ng/mL and 5.5(7.21-19.1) ng/mL respectively at the time of baseline and 2 nd PET/CT. The median ΔPSA and ΔSUVmax were -49.9% and 8.3%, respectively. No correlation between ΔPSA and ΔSUVmax was found (r=0.046; p=0.843). In accordance with the clinical assessment, 8 pts were responders, 4 had a stable and 9 a progressive disease. A significant overlap was reported for ΔPSA and clinical categories of response (p=0.685). Conversely, ΔSUVmax was significantly different in pts with a response to chemotherapy as compared to those with stable and progressive disease (p=0.005). Conclusions. ΔSUVmax, rather than ΔPSA, represents an important measure of response to chemotherapy and should be useful to stratify the prognosis of mCRPCa pts. A large multicenter prospective study is necessary to confirm these findings.