Does prostate-specific antigen nadir predict longer-term outcomes of prostate cancer after neoadjuvant and adjuvant androgen deprivation therapy in conjunction with brachytherapy?

Abstract

To evaluate whether nadir prostate-specific antigen (nPSA), time to nPSA (TnPSA), and nPSA 3-years post-treatment are prognostic for prostate cancer (PC) in patients treated with temporary brachytherapy plus external beam radiation therapy (EBRT) and hormonal manipulation. We retrospectively analyzed our database of 253 patients with Stage T1-T3 N0M0 PC who underwent brachytherapy with temporary brachytherapy plus EBRT. All patients received neoadjuvant androgen deprivation for a median of 6 months. Treatment consisted of three pulses of pseudo pulsed-dose-rate brachytherapy to a median dose of 18Gy with 50.4Gy in 28 fractions of EBRT. Treatment took place between December 1999 and March 2006. At a median of 6-years followup, nPSA value was a predictor of biochemical control. Rising nPSA categories of <0.01, 0.01-<0.05, 0.05-≤0.1, 0.1-≤ 1.0, or >1.0 ng/mL correlated with a deteriorating 5-year biochemical control (nBED) by the Phoenix definition of 100%, 90.0%, 82.5%, 64.3%, and 10%, respectively. A highly statistically significant relationship between nPSA value and subsequent clinical failure is also demonstrated. The relationship between TnPSA and nBED was strongly significant (p<0.0001), with a significantly longer nPSA for patients who had Phoenix nBED. A PSA of <1.5 ng/mL achieved 3-year post radiation therapy was prognostic for biochemical and clinical disease control (p<0.0001). The nPSA, TnPSA, and reaching a PSA cutoff level of <1.5 ng/mL at 3 years post-treatment can provide useful prognostic information on long-term biochemical and clinical control of PC in patients treated with pseudo PDR, EBRT, and hormone manipulation.