Development of a new nomogram for predicting the probability of a positive initial prostate biopsy in Japanese patients with serum PSA levels less than 10 ng/mL.

OBJECTIVES

Although several nomograms for prostate cancer detection have been developed for Western populations, the models constructed on Japanese data would be more useful for the Japanese population because of various differences between Western and Asian populations. We previously developed a model for predicting the probability of a positive initial prostate biopsy using clinical and laboratory data from Japanese males. In the present study, a predictive model for Japanese males with a prostate-specific antigen (PSA) < 10 ng/mL was developed to guide decision-making for prostate biopsies.

METHODS

The age, total PSA level, free to total PSA ratio, prostate volume, and the digital rectal examination findings of 1037 Japanese males with a PSA < 10 ng/mL undergoing initial prostate biopsy as part of individual screening were analyzed. For study validation, 20% of these data was randomly reserved. Logistic regression analysis estimated relative risk, 95% confidence intervals, and P-values.

RESULTS

Age and the independent predictors of a positive biopsy result (elevated PSA, decreased free to total PSA ratio, small prostate volume, and abnormal digital rectal examination findings) were used to develop a predictive nomogram. The area under the receiver operating characteristic curve was significantly higher for the model (73.0%) than for PSA alone (55.0%). If externally validated, the use of this nomogram could reduce unnecessary biopsies by 26% and overall prostate biopsies by 7.8%.

CONCLUSIONS

This predictive nomogram could provide more precise risk-analysis information for individual Japanese patients with PSA levels less than 10 ng/mL and may help to identify patients who need a prostate biopsy.