PMC3715690_01
Scatterplots of %freePSA (in percent) and [-2]proPSA (in pg/mL) for the 227 SABOR prostate cancer cases and 247 SABOR controls.
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F1
Figure 1 shows a joint scatterplot of the two markers for the 227 prostate cancer cases and 247 controls on the logarithmic scale. These are seen on the left side of Figure 1, with the four prostate cancer cases with [-2]proPSA values exceeding 100 pg/mL, a handful of controls with %freePSA very low and one with an outlying low [-2]proPSA value in addition.
Contour plots of estimated likelihood ratios for a 65-year old man with psa value 2.0 ng/mL (a) and 5.0 ng/mL(b).
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F2
Figure 2, where the axes have been chosen to reflect contours of the marker pairs near values of LRs of 1, meaning no preference for cancer case versus control assignment. For both scenarios, LRs are highest for low %freePSA and high [-2]proPSA values, but specific pairs of %freePSA and [-2]proPSA will yield different LRs for lower versus higher PSA values as seen by comparison of Figures 2a and b.
ROCs for the EDRN validation set
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F3
Figure 3 shows ROCs for updated posterior PCPTRC risks (AUC=0.698, 95% CI=0.655 to 0.741), %freePSA (AUC=0.693, 95% CI=0.649 to 0.736), PCPTRC risks (AUC=0.677, 95% CI=0.634 to 0.721), PSA (AUC=0.663, 95% CI=0.619 to 0.707), and [-2]proPSA (AUC=0.648, 95% CI=0.604 to 0.693) evaluated on the EDRN validation set.
Net benefit curves for the EDRN validation set.
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F4
The net benefit curves in Figure 4 indicated benefit of using both the PCPTRC prior and posterior risks over the blanket rule of referring all men in the EDRN cohort to prostate biopsy for thresholds exceeding 20%, but no clear benefit of the more complicated posterior PCPTRC risks over the prior PCPTRC risks in the region of risks between 10 and 40%, of most clinical relevance to men deciding on whether to pursue prostate biopsy as referenced by Steyerberg and Vickers (2008).