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Emerging data suggests that many patients with M0 castration-resistant prostate cancer (CRPC) may actually have M1 disease that has not yet been detected, suggests Evan Y. Yu, MD. During the enrollment process for a phase III trial, approximately a third of patients thought to have M0 disease actually tested positive for radiographically detectable metastatic disease, Yu notes. Patients with early metastatic CRPC are ideal candidates for less toxic treatments, such as sipuleucel-T and abiraterone acetate.
Unfortunately, the case report forms from this phase III trial did not indicate characteristics to help detect patients that have transitioned from M0 to M1 disease, Yu points out. However, another trial was able to find a correlation between the time to the first bone metastasis and PSA doubling time. In this analysis, for the entire population the median time to metastasis was over 2 years, Yu notes. However, for men with short PSA doubling times the first bone metastasis occurred in less than 7.7 months. To help gain a better understanding of metastases, Yu images patients following a continued rise in PSA levels and before changing therapies.
If bone metastases are not present but the PSA is rising, a switch to a secondary hormonal therapy may be warranted. In some cases, these agents may include older treatments, such as ketoconazole, bicalutamide addition, or bicalutamide withdrawal, but the utilization of these agents is decreasing dramatically, due to the efficacy of new agents, notes Leonard G. Gomella, MD. Overall, the panel agrees with this sentiment, noting that limited use remains for first-generation anti-androgens, given the far superior efficacy of newer agents.