Can serial FCH-PET/CT scans predict the response to treatments in castrate resistant prostate cancer?
Journal of Diagnostic Imaging in Therapy
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
... 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.