Quantifying the impact of prostate volumes, number of biopsy cores and 5alpha-reductase inhibitor therapy on the probability of prostate cancer detection using mathematical modeling.
OBJECTIVE
Previous studies demonstrated a negative correlation between prostate volume and biopsy yield. By decreasing prostate volume 5alpha-reductase inhibitors may enhance cancer detection, which may explain the greater detection of high grade tumors in the finasteride arm of the Prostate Cancer Prevention Trial.


METHODS
A mathematical model was constructed to analyze the effects of prostate and tumor volumes, and biopsy core number on cancer detection. The effects of the volume reduction observed with finasteride in the Prostate Cancer Prevention Trial were also modeled, as was the potential reduction in tumor volume needed to explain the observed difference in prostate cancer detection. The model was also applied to the Reduction by Dutasteride of Prostate Cancer Events study.


RESULTS
A higher number of biopsies are required to ensure a detection probability of 0.90 or greater in larger glands or with smaller tumors. In the Prostate Cancer Prevention Trial for a tumor volume of 1 cc a 17% increase in the detection rate in the finasteride arm would be predicted if there was no change in tumor volume, likewise the rate would be 11% to 17% for the dutasteride arm of the Reduction by Dutasteride of Prostate Cancer Events study. The calculated reduction in tumor volume needed to explain the difference in cancer detection between the finasteride and placebo arms of the Prostate Cancer Prevention Trial would be 51% to 66%.


CONCLUSIONS
This model provides guidance on the optimal number of biopsy cores that accord with an earlier model. These findings also suggest that, if there were no reduction in tumor volume, 5alpha-reductase inhibitor therapy could lead to excess cancer detection, including high grade tumors.
Serfling
Robert
R
Department of Mathematical Sciences, University of Texas at Dallas, Richardson, TX 75083, USA. serfling@utdallas.edu
Shulman
Michael
M
Thompson
G L
GL
Xiao
Zhiyao
Z
Benaim
Elie
E
Roehrborn
Claus G
CG
Rittmaster
Roger
R
D058891:5-alpha Reductase Inhibitors; D001706:Biopsy / Q000379:methods*; D018120:Finasteride / Q000627:therapeutic use*; D006801:Humans; D008297:Male; D008962:Models, Theoretical; D009929:Organ Size; D011237:Predictive Value of Tests; D011471:Prostatic Neoplasms / Q000188:drug therapy* / Q000473:pathology*; D047368:Tumor Burden
D058891:5-alpha Reductase Inhibitors; D018120:Finasteride