Long-term clinical impact of PSA surge in castration-resistant prostate cancer patients treated with abiraterone

Background: Early changes in PSA have been evaluated in association to treatment outcome. The aim of this study was to assess PSA surge phenomenon in castration-resistant prostate cancer (CRPC) patients treated with abiraterone and to correlate those variations with long-term treatment outcome.

Patients and methods: We retrospectively evaluated 330 CRPC patients in 11 Italian hospitals, monitoring PSA levels at baseline and every 4 weeks. Other clinical, biochemical and molecular parameters were determined at baseline. We considered PSA surge as PSA increase within the first 8 weeks from starting abiraterone more than 1% from baseline followed by a PSA decline. The log-rank test was applied to compare survival between groups of patients according to PSA surge. The impact of PSA surge on survival was evaluated by Cox regression analyses.

Results: A total of 330 patients with CRPC, median age 74 years (range, 45-90), received abiraterone (281 chemotherapy-treated and 49 chemotherapy-naïve). PSA surge was observed in 20 (7%) post-chemotherapy and 2 (4%) chemotherapy-naïve patients. For overall patients presenting PSA surge, timing of PSA peak from baseline was 5 ± 1.8 weeks and PSA rise from baseline was 21 ± 18.4%. The overall median follow-up was 23 months (range 1-62). No significant differences in progression-free survival and overall survival were observed between patients with and without PSA surge (P = 0.16 and =0.86, respectively). In addition, uni- and multivariate analyses showed no baseline factors related to PSA surge.

Conclusion: PSA surge occurs in both chemotherapy-treated and chemotherapy-naïve patients treated with abiraterone resulting, however, in no long-term impact on outcome. Physicians and patients should be aware of PSA surge challenge to prevent a premature discontinuation of potentially effective therapy with abiraterone. Further larger and prospective studies are warranted to investigate this not infrequent phenomenon.