Associations of Transitional Zone Volume with Intraprostatic Chronic Inflammation and Prostate Cancer Risk in Patients Undergoing a First Random Biopsy Set

Abstract

Objectives: To investigate associations of the transitional zone volume (TZV) with intraprostatic chronic inflammatory infiltrate (CII) and prostate cancer (PCa) risk in patients undergoing a first random biopsy set.

Materials and methods: The study included a homogenous population of 596 patients. The volume of the prostate and TZV were separately measured. Independent associations were investigated by multivariate logistic regression analysis.

Results: The median TZV was 18 ml, CII was detected in 157 cases (26.3%), and PCa was present in 292 patients (49%). TZV was the only independent clinical factor associated with CII risk (OR = 1.014). After correcting for CII (OR = 0.276; p < 0.0001), independent factors associated with PCa risk included age (OR = 1.066), prostate specific antigen (OR = 1.177), TZV (OR = 0.919), and an abnormal digital rectal exam (OR = 2.024).

Conclusion: In a patient population undergoing a first random prostate biopsy set because of suspected cancer, independent associations were detected among TZV, CII, and PCa. The association between TZV and CII was direct, but the relation between TZV and PCa was inverse. The measurement of the volume of the transitional zone was a useful parameter for evaluating chronic intraprostatic inflammation and PCa risk.

Keywords: Chronic prostate inflammation; Prostate biopsy; Prostate cancer; Prostate volume; Prostate-specific antigen; Transitional zone volume.

Fig. 1

Association between TZV and CII in patients undergoing the first random biopsy set because of suspected cancer. The probability of detecting CII in the biopsy cores is directly associated with increasing measurements of TZV.

Fig. 2

Association of TZV and age with PCa risk in patients electing a first random biopsy set. The probability of PCa is directly associated with age. However, when we stratified the population into 4 groups of increasing TZV quartiles, the risk of PCa was decreased at the same age levels because of the inverse association between TZV and PCa. The patient population was clustered in 4 groups according to ranking TZV quartiles as follows: (i) group 1: TZV within the first quartile, (ii) group 2: TZV above the first quartile but within the median (second quartile), (iii) group 3: TZV above the median and within the third quartile, and (iv) group 4: TZV above the third quartile.

Fig. 3

Association of TZV and PSA with PCa risk in patients electing a first random biopsy set. The probability of PCa is associated with increasing PSA levels. However, when we stratified the population into 4 groups of increasing TZV quartiles, the PCa risk was decreased at the same PSA levels because of the inverse association between TZV and PCa. Patients presenting with the same PSA level of 5 ng/ml might show different probabilities of PCa by TZV measurements. PCa risk is about 0.10 in group 4, close to 0.30 in group 3, about 0.45 in group 2, and just above 0.60 in group 1. As a result, the model stratifies the risk of detecting PCa in the different groups having the same PSA levels.

Fig. 4

The diagram illustrates the independent relations among PCa, TZV, and intraprostatic CII. The risk of detecting PCa is decreased by both TZV and intraprostatic CII.