Possible clinical implications of peripheral zone changes depending on prostate size.

Purpose: Although numerous studies have observed an inverse relationship between the size of benign prostate hypertrophy (BPH) and the incidence of prostate cancer (PCa), few studies have explored specific mechanisms by which BPH and PCa may influence one another. In a recent study, one possibility has been brought up that growth in the transition zone due to BPH may cause pressure-induced fibrotic changes in the peripheral zone, an area where 80% of cancer occurs, leading to gland atrophy and the thickening of the prostatic capsule. To shed more light on this phenomenon, we conducted a pilot study examining the quantitative and qualitative histo-anatomical changes that occur in the peripheral zone associated with BPH.

Methods: Thirty-nine prostate specimens of various sizes were selected from patients who had undergone radical prostatectomies. Each prostate was evaluated in six different locations along the dorsal aspect of the peripheral zone by measuring the thickness of the peripheral fibrotic zone (prostate capsule) and its association with gland atrophy. Multiple regression analysis was performed to determine the relationship between prostate size and the average thickness of the prostate capsule.

Results: Multiple regression analysis revealed a strong, positive relationship between prostate size and average capsule thickness with a Pearson coefficient of 0.707 (p < 0.05). Fibrotic histo-anatomical changes were spatially associated with gland atrophy: glands found within the peripheral fibrotic zone appeared elongated and atrophic.

Conclusion: The results suggest that BPH may be associated with the development of fibrotic material and atrophy of glands within the peripheral zone. Because this atrophy involves glands where 80% of prostate cancer originates, this potentially explains the inverse relationship between PCa and BPH.