Prostate Cancer and Seminal Vesicles Cancer – Lessons Learned from the Commonest and the Rarest Malignancy Types in Men

Purpose: The prostate and the seminal vesicles (SVs) are analogous in terms of pelvic location, function, and response to hormones; however, prostate cancer (PC) is the most common cancer in men, whereas adenocarcinoma of the SVs is one of the rarest cancer types. This manuscript studies the similarities and dissimilarities between these organs and through them attempts to provide insights into the pathogenesis of PC.

Views: The number of prostatic luminal (the origins cells of PC) and SV cells is similar (1.5 × 10⁹ and 1.9 × 10⁹ cells), and so is the number of daily mitotic cycles in these organs (3 × 10⁶ in the prostate and 3.8 × 10⁶ in the SVs). Thus, numerical differences cannot account for the difference in cancer incidence. Nevertheless, remarkable anatomical and physiological differences can be noted. The SVs are surrounded by loose connective tissue, whereas the prostate is surrounded by a non-expandable collagenous-muscular capsule. The SVs excrete into two thin and long ducts, whereas the prostate into multiple short ducts. The prostate is subjected to the high pressure generated by the contractions of the levator ani muscle on which it lies. By the end of the contraction, the intra-prostatic pressure drops, and urine is sucked from the urethra to the acini, exposing them to high concentrations of pro-inflammatory substances, such as monosodium-urate. Repeated exposures to high pressure and to urine initiate prostatic inflammation, commonly observed in prostate biopsies, but exceedingly rare in SVs. Inflammation promotes proliferative inflammatory atrophy which can degenerate into prostatic intraepithelial neoplasia and to PC. Neutralizing the deleterious components of urine could possibly prevent PC.

Conclusions: The prostate and SVs are similar in number of cells and in daily mitotic cycles. The prostate with its non-expandable capsule and short excretory ducts is repeatedly exposed to urine at high pressures. This offence initiates a chain of events that starts with inflammation and continues with proliferative inflammatory atrophy and PC. The SVs are not exposed to these insults.