Calculated prostate cancer volume: the optimal predictor of actual cancer volume and pathologic stage.

Objectives: A new clinical pretreatment quantity called the calculated prostate cancer volume has been defined. The correlation between the calculated parameter and the actual prostate cancer volume, and its ability to predict for pathologic Stage T3 disease in patients with clinically localized disease, is tested.

Methods: Prostate cancer volume measurements were obtained using a 3-dimensional computerized morphometric reconstruction technique on 104 whole-mounted radical prostatectomy specimens. The calculated prostate cancer volume was determined based on pretreatment clinical parameters (prostate-specific antigen [PSA], biopsy Gleason score, and prostate ultrasound volume). Linear regression was used to determine the Pearson correlation coefficients (r) between the PSA, the calculated prostate cancer volume, and the measured prostate cancer volume. Logistic regression multivariable analysis evaluating the predictive value of the pretreatment PSA, biopsy Gleason score, clinical stage, and calculated prostate cancer volume in predicting pathologic Stage T3 disease in patients with clinically organ-confined disease was performed.

Results: The calculated prostate cancer volume (r 0.71 to 0.96) was superior to PSA (r 0.12 to 0.67) in predicting the measured prostate cancer volume over a wide range (0.02 to 9.5 cm3) of cancer volumes. The calculated prostate cancer volume was the only significant predictor (P = 0.02) of pathologic Stage T3 disease in patients with clinical Stage T1 to T2 disease on multivariable analysis.

Conclusions: The calculated volume of prostate cancer is superior to PSA in predicting both the pathologic prostate cancer volume and pathologic Stage T3 disease in patients with clinical Stage T1 and T2 disease. Therefore, it may be useful in determining the optimal candidates for radical prostatectomy.