Absent malignancy, most tissues in the body shrink as we age. Why does the prostate expand as men grow old?
—Kishan Agarwal, MD, Edison, N.J.

What a great question. The size of any organ will be dependent on the equilibrium between cell division and cell death. It turns out that androgens not only are required for normal prostatic cell proliferation but also actively inhibit cell death. Thus the normal male aging process induces a block in the progression of normal prostatic cells to terminally differentiated cells and thereby reduces the overall rate of cell death. This leads to increasing gland size. It is interesting to note that patients who are castrated before puberty or who have a genetic disorder that impairs androgen action or synthesis do not develop benign prostatic hyperplasia (Walsh PC, Retik AB, Vaughan ED, et al, eds. Campbell’s Urology. 8th ed. Philadelphia, Pa.: WB Saunders; 2002:1297-1303).
—David T. Noyes, MD