Studies have suggested an association between PSA kinetics and outcome to AA. In order to identify p with resistance to AA, we assessed potential factors associated with overall survival (OS) in p with mCRPC treated with AA after progression to docetaxel.
We included 104 p with mCRPC treated with AA plus prednisone after progression to docetaxel at three centers of the Catalan Institute of Oncology from August 2011 to October 2014. All p were assessed monthly to check PSA levels and hematological parameters. We used a multivariable Cox proportional hazards model to explore the association of baseline characteristics and PSA parameters with OS.
Median OS was 16.4 months (m) and the median of duration of treatment was 7.54 m. In the univariate analysis, 14 factors were significantly associated with OS: ECOG PS, metastatic site, hemoglobin, alkaline phosphatase, lactate dehydrogenase (LDH), baseline PSA levels (classified by terciles), neutrophil-lymphocyte ratio (NLR), interval between end of docetaxel and start of AA, early PSA response (decrease >30% at week 4), PSA nadir, time to PSA nadir, PSA decrease >50%, end-of-treatment (EOT) PSA levels, and EOT PSA doubling time (PSADT). The multivariate analysis identified lymph node metastases (P = 0.016), NLR <4 (P = 0.038), baseline PSA levels <43 ng/ml (P = 0.026), normal LDH (P = 0.035), early PSA response (P = 0.001), and EOT PSADT >1.5 m (P < 0.001) as independent markers of longer OS.
Our results suggest an association between PSA kinetics, primarily early PSA response, with outcome to AA after progression to docetaxel. Taken together with other factors, lack of an early PSA response could identify patients that will probably not obtain a benefit from AA and who might be considered for alternative therapies.
Clinical trial identification
Legal entity responsible for the study
Catalan Institute of Oncology, Hospital Universitary Germans Trias i Pujol.
Has not received any funding.
All authors have declared no conflicts of interest.