How far is the preoperative Kattan nomogram applicable for the prediction of recurrence after prostatectomy in patients presenting with PSA levels of more than 20 ng/ml? A validation study.

OBJECTIVE

We present an external validation study investigating the applicability of the preoperative Kattan nomogram for predicting recurrence after prostatectomy in a population of patients with serum prostate-specific antigen (PSA) levels exceeding 20 ng/ml.

MATERIALS

In the evaluation of clinical parameters pooled from a total of 191 patients presenting with PSA levels ranging between 20.1 and 100 ng/ml, the PSA-free survival rate 60 months after surgery was calculated according to Kattan nomograms. Subsequently, the results were statistically compared with the corresponding actual survival rates obtained from Kaplan-Meier analysis. For this purpose, the patients were assigned to one of four different risk groups according to predictions derived from the Kattan nomograms, enabling a direct comparison of expected (as predicted by Kattan nomogram) versus actual survival of each patient investigated in our study.

RESULTS

Predicted PSA-free survival rates were determined to be as follows: 83% (low risk group); 66% (intermediate risk group); 39% (intermediate-high risk group), and 10% (high risk group) in comparison with the actual survival rates determined to be 63, 62, 40 and 21%, respectively. For PSA levels ranging between 20.1 and 30 ng/ml, 30.1 and 50 ng/ml, and 50.1 and 100 ng/dl, PSA-free survival rates were found to be 57, 37, and 27% (p=0.0017), respectively, during a 5-year post-prostatectomy follow-up.

CONCLUSIONS

The Kattan nomogram shows good statistical concordance with actual survival rates in the mean risk quadrants, but considerable differences were demonstrated concerning individuals with either a high or with a low risk of cancer progression.