Tumour specificity of 11C-acetate and 18F-FDG positron emission tomography in prostate cancer patients


Tumour specificity of 11C-acetate and 18F-FDG positron emission tomography in prostate cancer patients

Fricke, E.; Machtens, S.; Hofmann, M.; van den Hoff, J.; Bergh, S.; Brunkhorst, T.; Meyer, G. J.; Karstens, J. H.; Knapp, W. H.; Boerner, A. R.

Visualisation of primary prostate cancer and its metastases remains a clinical important problem, state-of-the-art methods like CT, MRI, TRUS (transrectal ultrasound) and 18F-FDG PET notwithstanding. The difficulties are even more pronounced in case of local recurrence as 18F-FDG PET, while useful in the detection of metastases, is not considered helpful in the investigation of relapse. The aim of this study was to evaluate the efficacy of 11C-acetate and 18F-FDG-PET in the detection of prostate cancer and its metastases in patients treated with or without hormonal ablation.
25 patients (age: 54 to 82 years) were investigated during follow-up of a primary prostate cancer, suspected relapse, or metastatic disease using 11C-acetate PET and 15 with 18F-FDG PET additionally. 14 Patients had antiandrogen treatment at the time of the investigation, the other 11 patients were drug-naive.
Primary tumours were detected in 20/24 (83%) patients using 11C-acetate PET and in 10/15 (75%) patients using 18F-FDG PET. Based on the results of both PET scans, one patient was diagnosed with a lung cancer as second malignancy. Median 18F-FDG uptake exceeded that 11C-acetate in distant metastases (SUV=3.2 vs. 2.3, respectively). 11C-acetate uptake, however, was higher in local recurrence and in local lymph node metastases (median SUVs = 2.9 and 3.8) compared to 11C-acetate (median SUVs = 1.0 and 1.1, respectively). 11C-acetate and 18F-FDG uptake was lower in patients on antiandrogen therapy compared with the drug-naïve patients but 11C-acetate uptake was not significantly impaired. A close correlation of serum PSA level and Gleason score on the one hand and both 11C-acetate uptake and 18F-FDG uptake on the other hand was observed.
These data confirm that 11C-acetate is more useful than 18F-FDG in the detection of local recurrences and localised lymph node metastases. 18F-FDG, however, appears to be more accurate in visualising distant metastases. Antiandrogen therapy reduces tumour metabolic activity and therefore overall PET accuracy but detection of local recurrences by 11C-acetate is not severly compromised. Ultimately, there may be a role for combined 11C-acetate/18F-FDG PET in the follow-up of patients with prostate cancer and persisting or increasing PSA.

Keywords: 11C-acetate PET; 18F-FDG PET; prostate cancer; antiandrogen therapy monitoring

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Publ.-Id: 5338