Secondary hormonal therapy in men with castration-resistant prostate cancer

Background: Androgen receptor (AR) signaling remains important in castration-resistant prostate cancer (CRPC) and sequential responses to hormonal therapies are observed. Little is known about the factors associated with responsiveness to secondary hormone therapy (HT). Methods: We retrospectively identified patients with CRPC who were treated with secondary HT. Patient characteristics and types and duration of secondary HT were analyzed. Selected clinical characteristics and their association with duration of secondary HT were evaluated. Results: Of 436 eligible patients, 321 (74%) and 87 (20%) received at least two or four secondary HT regimens, respectively. Median duration of time on primary androgen deprivation therapy alone (ADT) and secondary HT were 24.0 months (range, 1.5 to 171.8 months) and 30.3 months (range, 0.6 to 156.1+ months), respectively. Patients who received primary ADT < 24 months received secondary HT for a median duration of 40.0 months, whereas men who received ADT < 24 months had a median duration of 18.4 months on secondary HT (P <.0001). Metastatic disease at secondary HT initiation was associated with a shorter time on secondary HT (P =.0001). Patients who received the first secondary HT for < 6 months were more likely to have a longer duration on subsequent secondary HT compared with the men who received the first secondary HT < 6 months (P =.0001). Conclusions: Treatment durations of secondary HT are variable. Longer duration of primary ADT was associated with longer duration of secondary HT. These results imply that AR signaling remains an important therapeutic target in CRPC.