Simple risk assessment in prostate cancer patients treated with primary androgen deprivation therapy: The Korean Cancer Study of the Prostate risk classification.

OBJECTIVES

To investigate the progression to castration-resistant prostate cancer after primary androgen deprivation therapy, and to build a simple risk prediction model for primary androgen deprivation therapy patients based on the Japan Cancer of the Prostate Risk Assessment criteria.

METHODS

A total of 602 patients who received primary androgen deprivation therapy were entered into the Korean Cancer Study of the Prostate database. The effect of prognostic factors was determined by multivariate analysis. For each patient, the weight of all factors was totaled to give Korean Cancer Study-prostate scores; patients were divided into three risk groups according to their score. The probability of castration-resistant prostate cancer, cancer-specific survival and overall survival was estimated by Kaplan-Meier analysis.

RESULTS

On multivariate analysis for castration-resistant prostate cancer, the significant variables were initial prostate-specific antigen (>40 ng/mL; 1 point), biopsy Gleason score (≥9; 1 point), clinical N1 (1 point), and non-regional lymph node (1 point), bone (1 point) and visceral (1 point) metastasis. The Korean Cancer Study-prostate scoring model was calculated on a scale of 0-6 (0: low, 1-2: intermediate, ≥3: high risk). The risk groups stratified castration-resistant prostate cancer (P < 0.0001), cancer-specific survival (P < 0.0001) and overall survival (P < 0.0001) by Kaplan-Meier curve. The Korean Cancer Study-prostate model predicted castration-resistant prostate cancer with a c-index of 0.7242, cancer-specific survival with a c-index of 0.7036 and overall survival with a c-index of 0.5890. The 5-year estimated castration-resistant prostate cancer/cancer-specific death rates were 10.3%/6.3% in the low-risk group, 48.4%/22.2% in the intermediate-risk group and 81.7%/53.1% in the high-risk group.

CONCLUSIONS

The Korean Cancer Study-prostate risk classification, a modified Japan Cancer of the Prostate Risk Assessment model, is a simple scoring model for predicting oncological outcomes after primary androgen deprivation therapy.