In vivo uptake of [11C]choline does not correlate with cell proliferation in human prostate cancer

PURPOSE

Prostate cancer is the second leading cause of death from cancer among US men. Positron emission tomography (PET) with [(11)C]choline has been shown to be useful in the staging and detection of prostate cancer. The background of the increased uptake of choline in human prostate cancer is not completely understood. The aim of this study was to prospectively investigate the relationship between the [(11)C]choline uptake and the cell proliferation in human prostate cancer.

METHODS

Prostate cancer tissue from 18 patients who had undergone a radical prostatectomy for histologically proven disease was studied. An [(11)C]choline PET scan was performed prior to surgery. Post-prostatectomy specimens were prepared and stained with the antibody MIB-1 for Ki-67, which depicts proliferation. Two independent observers counted the amount of stained nuclei per specimen.

RESULTS

Prostate cancer showed Ki-67 staining and high uptake of [(11)C]choline. Statistical analysis showed no significant correlation between [(11)C]choline uptake and Ki-67 staining (R=0.23; P=0.34). No significant relationships were found between the uptake of [(11)C]choline (SUV) and either preoperative PSA (R=0.14; P=0.55) or Gleason sum score (R=0.28; P=0.25).

CONCLUSION

In vivo uptake of [(11)C]choline does not correlate with cell proliferation in human prostate cancer as depicted by Ki-67. Our results suggest that a process other than proliferation is responsible for the uptake of [(11)C]choline in prostate cancer.

Highly efficient automated synthesis of [(11)C]choline for multi dose utilization

[(11)C]Choline has been under investigation as a PET ligand for imaging tumor tissue, especially prostate cancer. An improved, automated synthesis of the tracer now was established. [(11)C] Choline was produced by labeling 2-(dimethylamino)-ethanol (DMAE) with [(11)C]CH(3)I in a Tefzel tube at room temperature without solvent. The product was purified using a cation exchange cartridge. Reaction conditions were optimized with respect to synthesis time and amount of DMAE, resulting in radiochemical yields higher than 80% using 60 microl of DMAE in 20 min, radiochemical purity was >99% and residual DMAE was below 10 ppm. After (11)C-production of 1h at 50 microA [(11)C]choline activities of 30.0+/-5.6 GBq (n = 29) were obtained in sterile solution ready for intravenous administration.