Prognostic Significance of the Nadir Prostate Specific Antigen Level after Hormone Therapy for Prostate Cancer Patients

Kwak, Cheol; Jeong, Seong Jin; Lee, Chang ho; Jin, Ren Jie; Park, Tae Hee; Lee, Sang Eun

Abstract

PURPOSE: We tried to find out whether the nadir PSA level after hormone therapy affected the progression into hormone-refractory prostate cancer (HRPC).
MATERIALS AND METHODS
We reviewed the progressive status and the survival of the 177 patients with stage C or D prostate cancer who had received hormone therapies. The relative efficacy of the nadir PSA level for predicting the progression into HRPC was evaluated by the receiver operating characteristic (ROC) analysis.
RESULTS
85.4% of patients responded to the treatment and 78% of responders progressed into HRPC. Median time to nadir PSA level after hormone therapy and to HRPC were 8.1 and 24.0 months, respectively. The nadir PSA levels were under 0.2ng/ml in 31%, 0.2-1.0ng/ml in 23%, 1.1-10ng/ml in 42%, and over 10ng/ml in 5% of the responders (n=151). As the nadir PSA levels were lower, pretreatment PSA levels, Gleason score and the number of cases progressing into HRPC were significantly lower (p<0.05). In addition, the nadir PSA level was inversely correlated with the interval to the establishment of HRPC (r= 0.465, p<0.05). By univariate analysis, the bone metastasis, the nadir PSA level, PSA level at six months after treatment and pretreatment PSA level were associated with the progression into HRPC. Only the nadir PSA level was an independent factor by multivariate analysis. ROC analysis disclosed an accuracy of 86.2% for the nadir PSA level to predict the progression into HRPC after two years. By setting the lower limit of the nadir PSA level to 1.1ng/ml, the sensitivity was 80.3% and the specificity was 83.8%, being most adequate.
CONCLUSIONS
The nadir PSA level after hormone therapy may be the most important factor that can predict the progression into HRPC. Also, in consideration of sensitivity and specificity, it would be adequate to set the lower limit of the nadir PSA level to 1.1ng/ml.