Author(s): Michael Pinkawa, Richard Holy, Marc D Piroth, Jens Klotz, Sandra Nussen, Thomas Krohn
Purpose: To report the own experience with 66 patients who received 18F-choline PET-CT (positron emission tomography-computed tomography) for treatment planning. Patients and Methods: Image acquisition followed 1 h after injection of 178–355 MBq 18F-choline. An intraprostatic lesion (GTVPET [gross tumor volume]) was defined by a tumor-to-background SUV (standard uptake value) ratio > 2. A dose of 76 Gy was prescribed to the prostate in 2-Gy fractions, with a simultaneous integrated boost up to 80 Gy. Results: A boost volume could not be defined for a single patient. One, two and three or more lesions were found for 36 (55%), 22 (33%) and seven patients (11%). The lobe(s) with a positive biopsy correlated with a GTVPET in the same lobe in 63 cases (97%). GTVPET was additionally defined in 33 of 41 prostate lobes (80%) with only negative biopsies. GTVPET, SUVmean and SUVmax were found to be dependent on well-known prognostic risk factors, particularly T-stage and Gleason Score. In multivariate analysis, Gleason Score > 7 resulted as an independent factor for GTVPET > 8 cm3 (hazard ratio 5.5; p = 0.02) and SUVmax > 5 (hazard ratio 4.4; p = 0.04). Neoadjuvant hormonal treatment (NHT) did not affect SUV levels. The mean EUDs (equivalent uniform doses) to the rectum and bladder (55.9 Gy and 54.8 Gy) were comparable to patients (n = 18) who were treated in the same period without a boost (54.3 Gy and 55.6 Gy). Conclusion: Treatment planning with 18F-choline PET-CT allows the definition of an integrated boost in nearly all prostate cancer patients – including patients after NHT – without considerably affecting EUDs for the organs at risk. GTVPET and SUV levels were found to be dependent on prognostic risk factors, particularly Gleason Score.