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.

Visualisation of bladder cancer using (11)C-choline PET: first clinical experience.

Fluorine-18 fluorodeoxyglucose (FDG), the most widely used radiopharmaceutical in positron emission tomography (PET) for oncological purposes, is unsuitable for imaging of bladder cancer owing to high excretion into the urine. More specific PET radiopharmaceuticals which are not excreted into urine would be welcome. Carbon-11 labelled choline (CHOL) is a new radiopharmaceutical potentially useful for tumour imaging and is not excreted into the urine. We prospectively studied the visualisation of bladder cancer using CHOL PET. Eighteen patients with bladder cancer and five healthy volunteers were included. Bladder cancer was first diagnosed by transurethral resection or by biopsy of the tumour. Next, PET images were performed before surgical treatment by cystectomy. The histopathological findings after cystectomy were used as the gold standard. PET images were performed on either an ECAT 951/31 or an ECAT Exact HR+ system. Attenuation-corrected PET images were obtained after injection of 400 MBq CHOL. PET images were analysed by two independent physicians using visual analysis and calculation of the standardised uptake value (SUV). In the normal bladder wall, the uptake of CHOL was low, and the bladder margin was only outlined by minimal urinary radioactivity, if present. In ten patients the tumour was detected correctly by CHOL PET, with an SUV of 4.7+/-3.6 (mean+/-SD). One false positive CHOL PET scan was seen in a patient with an indwelling catheter for 2 weeks prior to the PET scan. In two patients, lymph node metastases were detected by CHOL PET. A micrometastasis <5 mm was not visualised with CHOL PET. In seven patients, no residual tumour was found after surgery. In six of seven patients CHOL PET imaging was negative. In situ carcinoma, dysplasia and a non-invasive urothelial tumour (pTa) remained undetected in three of these six patients. Minimal to no urinary tract radioactivity was seen in 22/23 subjects. Non-specific uptake of CHOL was observed in the small bowel, rectum and prostate gland. CHOL uptake in bladder cancer was avid, visualising the tumour in the virtual absence of urinary radioactivity. No uptake of CHOL was seen in pre-malignant lesions or in small non-invasive tumours. Our results warrant further research into the value of CHOL PET in the clinical management of patients with bladder cancer.