Factors associated with improved biochemical response to neoadjuvant androgen deprivation therapy before definitive radiation therapy in prostate cancer patients

Background:In prostate cancer patients treated with androgen deprivation therapy (ADT) and radiation therapy (RT), a pre-RT PSA level ≥0.5 ng ml-1, determined after neoadjuvant ADT and before RT, predicts for worse survival measures. The present study sought to identify patient, tumor and treatment characteristics associated with the pre-RT PSA in prostate cancer patients.Methods:We reviewed the charts of all patients diagnosed with intermediate-and high-risk prostate cancer and treated with a combination of neoadjuvant (median, 2.2 and 2.5 months, respectively), concurrent, and adjuvant ADT and RT between 1990 and 2011.Results:A total of 170 intermediate-and 283 high-risk patients met inclusion criteria. On multivariate analysis, both intermediate-and high-risk patients with higher pre-treatment PSA (iPSA) were significantly less likely to achieve a pre-RT PSA <0.5 ng ml-1 (iPSA 10.1-20 ng ml-1: P=0.005 for intermediate risk; iPSA 10.1-20 ng ml-1: P=0.005, iPSA >20 ng ml-1: P<0.001 for high risk). High-risk patients undergoing total androgen blockade were more likely to achieve a pre-RT PSA <0.5 ng ml-1 (P=0.031). We observed an interaction between race and type of neoadjuvant ADT (P=0.074); whereas African-American men on total androgen blockade reached pre-RT PSA <0.5 ng ml-1 as frequently as other men on total androgen blockade (P=0.999), African-American men on luteinizing hormone-releasing hormone (LH-RH) agonist monotherapy/orchiectomy were significantly less likely to reach pre-RT PSA <0.5 ng ml-1 compared with other men on LH-RH monotherapy/ orchiectomy (P=0.001).Conclusions:Our findings suggest that total androgen blockade in the neoadjuvant period may be beneficial compared with LH-RH monotherapy for achieving a pre-RT PSA <0.5 ng ml-1 in African-American men with high-risk prostate cancer. In addition, men with higher iPSA are more likely to have a pre-RT PSA greater than 0.5 ng ml-1 in response to neoadjuvant ADT and are therefore candidates for clinical trials testing newer, more aggressive hormone-ablative therapies.