Benign Prostatic Hyperplasia

Urinary obstruction resulting from benign prostatic disease was described in the earliest days of medicine. Initially formalized by Riolan in the 17th century, the relationship between BPH and urinary obstruction was further elucidated by Morgani in the mid-18th century; he provided one of the earliest descriptions of BPH and its sequelae (23). More specific recognition of the pathologic process has been credited to Virchow in the last quarter of the 19th century. Despite a greater understanding of benign prostate growth, however, identification of its cause remains elusive.

Incidence

Autopsy studies have repeatedly demonstrated an association between BPH and aging based on histologic criteria, prostate weight, and prostate volume. Randall found histologic evidence that the incidence of BPH exceeded 50% in men over 50 yr of age and rose to 75% as men entered their 80s (24). The age-related prevalence of histologic BPH found at autopsy is similar in several countries despite population diversity (Fig. 5; 25). Mass producing BPH, however, occurs in approximately half of men with presumed histologic BPH and is clinically manifested in only half of those (25). Its reported clinical incidence varies appreciably in different parts of the world (26). Based on the combined

Prevalence Bph 2012
Fig. 5. This graph illustrates the strikingly similar age-specific prevalence of histologic BPH among different populations (From 25, with permission.)

data from 10 autopsy studies, Berry et al. constructed curves for the prevalence of BPH with age (Fig. 6; 27). Their analysis implies that BPH begins before the age of 30. Their calculated doubling time for BPH weight varies with age: 4.5 yr in the 31- to 50-yr age group, 10 yr in the 51- to 70-yr age group, and more than 100 yr in the greater than 70-yr age group. The autopsy finding of increased weight of glands requiring surgical intervention compared with the weight of those glands with hyperplasia only reinforces the potential role of prostate mass in BPH voiding dysfunction, as suggested in the Olmsted county male voiding pattern studies (28).

Although the literature on the racial and regional impact of BPH is difficult to interpret critically because of variable sampling and evaluation criteria, it clearly indicates an increasing but quantitatively variable incidence of pathologic and clinical BPH with aging (29-31). The studies suggest that black and white populations in the United States have a similar incidence of BPH, although symptoms most likely develop earlier in blacks (32). Blacks in the United States have a higher prevalence of adenomatous hyperplasia than blacks on the African continent. Moreover, data from the first half of the 20th century indicated a much lower prevalence of BPH in native Chinese and Japanese than in white populations (31,33). These results were reaffirmed by a recent mass screening in Japan, which reported a 9.9 and 11.6% prevalence of

Fig. 6. This graph demonstrates the relationship between age-related changes in histologic BPH and prostate size. The increasing prevalence of BPH is far more apparent than the increase in prostate weight. (From 27, with permission.)

BPH in men 70-79 and more than 80 yr of age, respectively (31). Prospective ultrasound evaluation of monozygotic and dizygotic twins coupled with historic assessments of twins and of families with a high incidence of prostatectomy in men under age 64 support possible genetic factors in development of BPH (34-36). Meikle et al., who studied twins, suggested that hereditary factors contributed substantially to symptomatology, but that nongenetic factors have more influence on zonal volumes of the prostate (34,37). Overall, the data suggest that race and genetics have a limited role in the prevalence of histologic BPH, and that the environment, dietary intake, and genetic factors play a greater role in the rate and degree of development of mass-producing BPH.

Natural History of Anatomic BPH

The first pathologic evidence of BPH occurs in less than 10% of men in the 31- to 40-yr-old group (Table 1). Thus, either the initiating factor is present in most men of this age and only clinically evident in a few, or young men with recognizable BPH have a discrepancy between physiologic and chronologic aging. Evidence of histologic and anatomic BPH increases with age; by the ninth decade approx 90% of men have histologic evidence of BPH, and more than half have anatomic evidence of BPH (38). The initial lesion of BPH typically occurs in the periurethral

Table 1

Prevalence of Pathologic BPH with Age in 1075 Human Prostates Collected at Autopsy

Autopsy studies Combined data

Table 1

Prevalence of Pathologic BPH with Age in 1075 Human Prostates Collected at Autopsy

Autopsy studies Combined data

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