Predictors of prostate cancer evaluated by receiver operating characteristics partial area index: a prospective institutional study.

PURPOSE: To our knowledge we introduce the ROC partial area under the curve (AUC) index as a method of evaluating the discriminative power of different prostate cancer predictors. Peripheral zone volume and peripheral zone prostate specific antigen (PSA) density are introduced as potential predictors and compared with other known predictors of prostate cancer. MATERIALS AND METHODS: During 1999, 220 consecutive patients with suspected early prostate cancer were examined using total PSA, free PSA, total prostate volume, transition zone volume and transrectal ultrasonography guided sextant biopsy of the prostate. The free-to-total PSA ratio, PSA density, transition zone PSA density, peripheral zone volume and peripheral zone PSA density were calculated. Usually total AUC is used to evaluate the discriminative power of different parameters. In this study parameters were evaluated by the ROC partial area index, which includes only the AUC in highly sensitivity parts of the ROC curve. Explorative analysis using logistic regression analysis was performed to investigate the ability of combinations of parameters to predict cancer. RESULTS: Of the 220 patients 75 were diagnosed with cancer. In the subgroup of 160 patients with PSA less than 10 microg/l 44 had cancer. Transition zone PSA density and PSA density had significant discriminative power in the total group, while none of the parameters were discriminative in the subgroup of patients. CONCLUSIONS: When high sensitivity is demanded, the ROC partial area index seems to be meaningful for evaluating the discriminative power of potential predictors. In our study none of the evaluated parameters had discriminative power in patients with PSA less than 10 microg/l, while transition zone PSA density and PSA density showed discriminative power in the total group of patients.

Benign growth of different prostate zones in aging men with slightly elevated PSA in whom prostate cancer has been excluded: a prospective study of 510 patients.

OBJECTIVES: To study, in a selected series of patients, whether the peripheral/central zone volumes also change with age. The reported normal total prostate volume in the third decade seems not to exceed 25 to 30 cm(3). Benign prostatic hyperplasia is generally accepted to originate in the transition zone and periurethral tissue, which accordingly show substantial growth with age. METHODS: From January 1997 through December 2000, we performed transrectal ultrasound volume measurements of the different prostate zones in patients admitted for suspected prostate cancer. The information was registered according to a prospectively designed protocol. A total of 872 patients were examined, of whom 360 shown to have prostate cancer were excluded. Two more patients were excluded because of missing volume data, leaving 510 patients with noncancerous prostates for inclusion in this study. RESULTS: The mean age was 62.8 years and the mean total prostate-specific antigen level was 9.8 microg/L. It was found that 64.9% (331 of 510) had a peripheral/central zone volume larger than 30 cm(3), indicating that some form of growth had occurred also in this zone. A weak but significant correlation was found between age and the peripheral/central zone volume. CONCLUSIONS: The results of our study indicate that the peripheral/central zone may contribute to the benign growth of the prostate gland in men younger than 70 years old with slightly elevated total prostate-specific antigen levels.