Quantifying the Impact of Prostate Volumes, Number of Biopsy Cores and 5α-Reductase Inhibitor Therapy on the Probability of Prostate Cancer Detection Using Mathematical Modeling

Abstract

Purpose: Previous studies demonstrated a negative correlation between prostate volume and biopsy yield. By decreasing prostate volume 5␣-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. Materials and 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, 5␣-reductase inhibitor therapy could lead to excess cancer detection, including high grade tumors.

Metabolic abnormalities linked to an increased cardiovascular risk are associated with high-grade prostate cancer: a single biopsy cohort analysis

“…These data were similar to previous experiences from our centre and from other studies demonstrating a negative correlation between prostate volume and PCa diagnosis at biopsy. [12][13] Overall, PCa detection rate (40.4%) was the same as in other series in the extended biopsy protocol era. 14 Furthermore, our patients presented at least one metabolic abnormality among obesity, abnormal waist circumference and MS.…”

The Influence of Prostate Volume on Prostate-Specific Antigen Performance: Implications for the Prostate Cancer Prevention Trial Outcomes

“…In other words, with decreasing prostate size, an increase in biopsy accuracy would occur given that cancer was present. Serfling et al (8), using a mathematical modeling system, suggested that given a baseline prostate size of 40 cm 3 and assuming a tumor volume of 1 cm 3 , a 25% decrease in prostate size would lead to an increase in tumor diagnosis of 21% using sextant biopsy. However, this study was unable to take into account low-grade versus high-grade tumors.…”

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“…This can increase the sensitivity of the biopsy and increase the likelihood of finding high-grade disease. Serfling et al 131 showed that a decrease of 25% in prostate volume (as occurs after finasteride treatment) can increase cancer detection by 23%.…”