Onkológia 3/2015
18F-choline PET/CT in evaluation of therapeutic response of castration-resistant prostate cancer
Castration-resistant prostate cancer (CRPC) is a progressive disease with rising serum PSA levels, with progression of metastatic involvement and of clinical symptoms in spite of castrate serum testosterone levels. Also at this stage of disease, several therapeutic options are available. The aim of these treatments is to achieve a disease control, to relief or eliminate symptoms present at initiation of treatment and to prevent or delay the appearance of new symptoms of the disease. Detection of progression of CRPC during potentially toxic and expansive or innovative treatment investigated in a clinical trial is of interest since it may warn the need for its eventual change, particularly if several therapeutic options remain open. In this situation, it is important to identify a reliable diagnostic that could in clinical trials replace the progression free survival and overall survival as an end point. Monitoring the variations of serum PSA levels as a measure of therapeutic response of CRPC is useful, but its significance is not clearly defined and decrease in serum PSA levels itself does not permit to accept an innovative treatment as effective. Morphologic criteria RECIST 1.1 are in CRPC of limited applicability. Indirect visualisation of bone metastases with bone scintigraphy or PET/ CT is not suitable for early evaluation of therapeutic effect due to possible flare-up phenomenon. More convenient is a direct visualisation of CRPC lesions. 18F-choline (FCH) PET/CT is accepted for staging and restaging of prostate cancer and shows a better sensitivity for CRPC lesions than 18F-deoxyglucose (FDG) PET/CT. FCH PET/CT seems also to be useful in early evaluation of therapeutic response of CRPC when it can also provide with useful prognostic information. However, its acceptance for routine use warrants further prospective studies. Present article summarise available data on use of FCH PET/CT as a potential method for early evaluation of therapeutic response of CRPC.
Keywords: castration-resistant prostate cancer, PET/CT, 18F-choline, therapeutic effect, PSA.
