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

Purpose: 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. Methods and Materials: 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 18. Gy with 50.4. Gy in 28 fractions of EBRT. Treatment took place between December 1999 and March2006. Results: 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). Conclusion: 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.