Early detection of prostate cancer relapse by biochemistry and diagnostic imaging

Prostate cancer (PCa) is a common malignancy in men associated with an increase in the incidence rate. Radical prostatectomy (RP) or external beam radiotherapy (EBRT) represents the most employed treatments for the local control of disease. However, 10-50% of patients who experienced a recurrence of disease after primary treatments can benefit from salvage or palliative therapies. To date, prostate specific antigen (PSA) is usually used in clinical practice to monitor the status of disease and to early detect the recurrence of PCa. Nevertheless, PSA cannot discriminate the presence of local vs. distant metastatic disease. Circulating tumor cells are considered as a sign of disease widespread, but their correlation with metastatic PCa and local recurrence of disease is still indeterminate. Digital rectal exploration and transrectal ultrasonography are considered the first clinical and diagnostic approach to identify the local recurrence of PCa, but are associated with a low detection rate and low diagnostic accuracies. Conversely, magnetic resonance imaging (MRI) has gained a great importance in this setting of disease, being able to determine the presence of local recurrence with high sensitivity, also in the presence of low serum PSA levels. Lastly, the introduction of positron emission tomography/computed tomography (PET/CT) with radiolabeled choline agents let to improve the management of patients with early recurrence of disease, although its accuracy is linked to the PSA and PSA dynamic values. New radiopharmaceutical agents, like 68Ga-PSMA or 18F-FACBC and others could improve the diagnostic accuracy of PET/CT, but the data is still preliminary. In the present review we will discuss both clinical and diagnostic instrumentations, actually available in clinical practice, able to early identify the presence of recurrent PCa and to differentiate between local and distant relapse of tumor.