Figure 3: (a) Plasma CAI levels in patients with prostate cancer ( ), BPH ( ), prostatitis ( ), and RCC ( ) and healthy controls ( ) were , , , , and μg/mL (mean ± SD), respectively. There was a significant difference between prostate cancer patients and healthy controls ( , Mann-Whitney test). Horizontal lines represented the average levels. (b) Scatter plot correlating PSA and CAI levels in prostate cancer patients (red) and healthy controls (black). The dotted lines were added to indicate the PSA gray zone. Serum PSA levels were measured using the Tandem-R kit before the first treatment in each patient. (c) ROC curve of PSA plus CAI (red line) and PSA alone (blue line) confined to the cases with PSA levels in the gray zones. ROC curves were created using a composite index of the 2 markers generated from the results of multivariate logistic regression analysis. As a reference, ROC curves of CAI (black line) for all cases were included.