BERKELEY, CA (UroToday.com) - Biochemical relapse (BCR) is a hot topic in patients after primary treatment for prostate cancer. About 40% of all patients who undergo radical prostatectomy with pelvic lymph node dissection develop BCR, but only 10-20% harbor a clinically detectable recurrence. BCR is defined by clearly increasing PSA kinetics after radical treatment, and it always precedes the disease progression. It usually takes place in the prostatic bed, pelvic or retroperitoneal lymph nodes (following a centripetal pattern from the obturator fossa to the retroperitoneum), and bones, especially the spine (maybe due to both an osteotropism, according to the “fertile soil hypothesis,” and veins connecting the prostate to the spine, as postulated by Batson, et al.) Many nomograms are already present in the clinical practice to assist clinicians in the diagnosis of the site of recurrence.
Many diagnostic tools are presently being used to assess BCR, but they are affected by several limits. TRUS-biopsy has low accuracy in the detection of the recurrence: a negative biopsy does not exclude local relapse, and multi-parametric magnetic resonance imaging (MRI), especially if integrated with dynamic contrast enhancement (DCE) and Spectroscopy, may be indicated in some cases because of its better accuracy. For the evaluation of bone metastases, conventional CT or MRI are not accurate enough, particularly if PSA is lower than 20 ng/mL or PSA velocity is inferior to 20/ng/mL/year; thus they are currently been replaced by choline PET/CT. This technique has shown better sensitivity and specificity than FDG PET/CT, especially for its ability to visualize disease relapse even in the presence of low PSA level. The main limit of this tool is the relatively short half-life of the tracer (about 20 min), which limits is use to centers with an on-site cyclotron. Anyway, choline PET/CT scan can find bone metastases in about 15% of patients with a negative bone scan, showing more lesions in about 50% of patients harboring bone metastases already detected by bone scan. Furthermore, hormonal therapy interruption can increase the detection rate of Choline PET/CT, but the overall accuracy of this technique remains low. To overcome this limit, a novel radiotracer is currently being investigated, the 18F–FACBC, a synthetic L-leucine analogue, which has less kidney uptake, no activity in the urinary tract, and a longer half life (109 min). All these features have been proven to improve sensitivity of 20-25%, if compared with Choline-PET/CT; thus the 18F-FACBC may be considered the potential radiotracer for the future in prostate cancer imaging.
PCa restaging still remains a thrilling topic; many tools are currently used and are under evaluation. Considering that every radiological restaging condition should have therapeutic consequences, more than one exam (for local and systemic relapse at the same time), is typically needed to complete the assessment of patients, keeping an eye on their costs, availability of technologies, and confirmation of results.
Written by:
R. Schiavina,a E. Brunocilla,a M. Borghesi,a V. Vagnoni,a P. Castellucci,a C. Nanni,b F. Ceci,b M. Gacci,c G. Martorana,a D. Romagnoli,a and S. Fantia as part of Beyond the Abstract on UroToday.com. This initiative offers a method of publishing for the professional urology community. Authors are given an opportunity to expand on the circumstances, limitations etc... of their research by referencing the published abstract.
a Dept. of Urology, University of Bologna, S. Orsola-Malpighi Hospital, Bologna, Italy.
b Dept. of Nuclear Medicine, University of Bologna, S. Orsola-Malpighi Hospital, Bologna, Italy.
c Dept. of Urology, University of Florence, Careggi Hospital, Florence, Italy
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