Variable Growth Patterns of Transition vs. Peripheral Zones of Prostate - Implications for BPH Therapy
Christina Sharkey, MLA, Xingbo Long, MD, Zongwei Wang, PhD, Ra'ad Al-Faouri, MD, Boris Gershman, MD, Leo L. Tsai, MD, PhD, Aria F. Olumi, MD.
Beth Israel Deaconess Medical Center, Boston, MA, USA.
BACKGROUND: As men age, the prostate gland continues to grow at around 2.9% per year depending on the initial prostate size. While the variable growth rate of the total prostate gland is recognized, the growth rate patterns of the different prostate zones among adult males remain largely unclear. The continuous prostate growth leads to the development of Benign Prostatic Hyperplasia (BPH) in elderly men. 5-alpha reductase inhibitors (5ARIs) are one of the main medical therapies for BPH and are known to reduce the total prostate size. Here, we evaluated the growth rate patterns of different prostate zones and measured the effect of 5ARI treatment on zonal growth rates. METHODS: Prostate MRI data and clinical information were obtained retrospectively on 160 patients who had a history of BPH or low-grade prostate cancer and underwent at least three prostate MRIs between 2003 and 2018. Prostate volume was measured and calculated for the central gland, peripheral gland, and total prostate. The outcome was analyzed using linear regression. RESULTS: We observed that prostate growth rates vary depending on age, the prostate zone, and 5ARI use. Body mass index (BMI) and Transition zone index (TZI) are associated with the growth rate of the peripheral zone (p=0.027, p<0.001 respectively), but not the central zone growth rate. 5ARI use is significantly associated with the reduction in the central zone growth rate (Regression coefficient [RO]: -0.123 to -0.005; p=0.035), not the peripheral zone. In addition, patients with TZI greater than 60% had the most significant reduction in the central zone growth rate while taking 5ARI (RO: -0.151 to -0.063; p<0.001). CONCLUSIONS: The growth pattern of the prostate varies between the central and peripheral zones and is dependent on age and BMI. In addition, reduction of the prostate size as a result of the 5ARI treatment occurs mainly in the central zone. Patients with TZI greater than 60% had the greatest reduction of the central zone growth rate with 5ARI treatment.
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