Evaluation of androgen-induced effects on the uptake of [18F]FDG, [11C]choline and [11C]acetate in an androgen-sensitive and androgen-independent prostate cancer xenograft model

Background: Androgen deprivation (AD) is generally used as a first-line palliative treatment in prostate cancer (PCa) patients with rising prostate-specific antigen (PSA) after primary therapy. To acquire an accurate detection of tumour viability following AD with positron emission tomography (PET), an androgen-independent uptake of tracers would be advantageous. Several metabolic PET tracers are employed for detecting recurrent PCa. We evaluated the effect of AD on the uptake of 2-deoxy-2-[F-18]fluoro-D-glucose ([F-18] FDG), [C-11]choline and [C-11]acetate in vivo. Methods: An [F-18] FDG, [C-11]choline and [C-11]acetate baseline micro(mu) PET/mu computed tomography (CT) scan was subsequently performed in xenografts of androgen-sensitive (LAPC-4) and androgen-independent (22Rv1) tumours in nude mice. An untreated control group was compared to a surgical castration group, i.e. androgen-deprived group. mu PET/mu CT imaging with the above-mentioned tracers was repeated 5 days after the start of treatment. The percentage change of SUVmax and SUVmeanTH in the tumours was calculated. Results: AD did not significantly affect the uptake of [F-18] FDG and [C-11]choline in LAPC-4 tumours as compared with the uptake of both tracers in untreated tumours. In control 22Rv1 tumours, [C-11]choline and [F-18] FDG uptake increased over time. However, compared with the uptake in control tumours, AD significantly decreased the uptake of [C-11] choline and tended to decrease [F-18] FDG uptake. [C-11]acetate uptake remained unaffected by AD in both PCa xenograft models. Conclusions: [F-18] FDG and especially [C-11]choline PET, which is currently used for the detection of recurrent PCa, could miss or underestimate the presence of local recurrent PCa following AD therapy. [C-11]acetate uptake occurs independently of androgens and thus may be more favourable for detecting tumour viability during or following AD.