A systematic review on the role of imaging in early recurrent prostate cancer

Context: In patients treated for prostate cancer, a rising serum prostate-specific antigen (PSA) level is a first sign of relapse, but imaging is needed to determine the localization of the recurrence, which may be local, in lymph nodes, and/or metastatic. With the increasing success rate of earlier salvage therapy, the diagnosis has become pertinent when the recurrent PSA level is still very low. Objective: To systematically review the literature on the role of the existing imaging techniques in patients with early recurrent prostate cancer. Evidence acquisition: A systematic literature search across the MEDLINE and EMBASE databases was conducted in February 2018, searching for original studies reporting on imaging in a (sub)group of patients with recurrent PSA levels not higher than 5 ng/ml. This systematic review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. The methodological quality of the studies was assessed using the Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2) tool. Evidence synthesis: A total of 98 studies were included in this systematic review, reporting on the role of transrectal ultrasonography (TRUS), computed tomography (CT), bone scintigraphy (BS), single-photon emission CT, multiparametric magnetic resonance imaging (mpMRI), whole-body MRI (wbMRI), and positron emission tomography (PET)-CT/MRI using 18F fluoro-deoxy-glucose, 11C choline, 18F (fluoro)(methyl)choline, 11C acetate, 18F FACBC (fluciclovine) and prostate-specific membrane antigen (PSMA)-based tracers. CT and BS were not sufficiently sensitive in the early recurrence setting. For the detection of local recurrence, TRUS or mpMRI can be used; however, at the lowest PSA levels, few data were available, only after radical prostatectomy, showing a wide range of positivity. TRUS or mpMRI need to be combined with (PET)-CT to assess distant disease, but new techniques such as wbMRI, PET-MRI, or PET-CT allow for an all-in-one approach. At recurrent PSA levels <0.5 ng/ml, detection rates up to 31.3% were reported using 11C choline PET-CT and up to 65.0% using 68Ga PSMA-11 PET-CT. At recurrent PSA levels <0.2 ng/ml, detection rates of 68Ga PSMA-11 PET-CT ranged from 11.3% to as high as 58.3%. Conclusions: Detection rates of different imaging techniques depend on the PSA level at the time of imaging. Recent advanced imaging techniques may detect the localization of the recurrence, even when the PSA levels are still very low. Patient summary: In patients treated for prostate cancer, a rising serum prostate-specific antigen (PSA) level is a sign of recurrence of the disease. Advanced imaging techniques may demonstrate the localization of the recurrence, even when the PSA levels are still very low. We systematically reviewed the existing literature on the role of imaging in patients with early recurrent prostate cancer. Advanced imaging techniques may demonstrate the localization of the recurrence, even when the prostate-specific antigen values are still very low.