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The treatment of patients with metastatic castration-resistant prostate cancer (CRPC) has undergone a dramatic change in the past 5 years with the approval of multiple new agents. However, these agents are primarily approved for patients with M1 disease, placing enhanced interest on the detection of metastases in patients with a rising PSA, explains Raoul S. Concepcion, MD.
A baseline bone and CT scan should be conducted for patients on hormonal therapy with a rising PSA, notes Kenneth M. Kernen, MD. If scans fail to show evidence of metastases, a sodium fluoride-enhanced PET scan can also be utilized. If neither of these approaches detects M1 disease, there are clinical trials currently available for patients with M0 CRPC.
For patients that convert from M0 to M1 disease, there is level 1 evidence in both the AUA and NCCN guidelines for treatment, notes Neal D. Shore, MD. For asymptomatic patients, immunotherapy, an oral hormonal agent, or chemotherapy can be administered. Additionally, for patients with symptomatic disease, radium-223 is a reasonable option, notes Shore.
For patients with CRPC, with a testosterone level less than 50, and a rising PSA, following baseline scans, the frequency of repeat imaging can be tailored based on PSA kinetics, Shores says. For patients with PSA doubling times of less than 6 months, repeat imaging should be conducted in order to detect M1 disease early. However, for a PSA doubling time of greater than 6 months, scans can safely be conducted annually, Shore believes.
The baseline scan is essential once the PSA begins to increase, notes Michael E. Williams, MD. In many situations, this early scan finds M1 disease 20-30% of the time. Moreover, in patients with a rapidly increasing PSA, scanning should become more aggressive, especially if the PSA climbs from 2 to 40 in a short timeframe.
Having baseline scans allows for comparison from scan-to-scan, making the detection of changes easier, notes Philippa J. Cheetham, MD. Moreover, ascertaining the best information from imaging requires collaboration between medical oncologists and radiologists, Cheetham suggests. Adding to this, Kernen notes that it is important to advise the radiologists exactly what to look for in the scans. If radiology knows that findings M1 disease will make a big difference in terms of treatment, they may be more aggressive in finding metastatic lesions.