Natural course of human benign prostatic hyperplasia with relation to urinary disturbance

[Morphologic course of prostatic hyperplasia]

OBJECTIVE

To find a morphologic model of the development of prostate hyperplasia.

METHODS

Study of the transitional zone in 60 patients (30 with infravesical obstruction, 30 with no obstructive symptoms) and quantification of the involved surface, number of pure stromal and glandular-stromal nodes, node area for each of them, and non-nodular area of the transitional zone, correlating each parameter to age based on clinical status.

RESULTS

The greater transitional zone area is seen in patients with obstruction: 1376.83 +/- 408.17 mm2 vs 321.39 +/- 151.49 mm2 in asymptomatic patients, mainly due to a higher number of glandular-stromal nodes (17 vs 2.2) and their size, with a correlation to age (p = 0.03). Moderate increases of non-nodular areas are also found.

CONCLUSIONS

These findings suggest that onset of prostate hyperplasia may be due to a consistent increase of the transitional area, and that in some patients, probably because of local factors, nodular development occurs as a result of both an increase in nodes number and size.

Androgen receptor CAG repeat length polymorphism in benign prostatic hyperplasia (BPH): correlation with adenoma growth

BACKGROUND

The androgen receptor (AR) gene has a polymorphic CAG microsatellite encoding variable-length glutamine repeats in the AR protein. The purpose of this study was to evaluate the association between the growth of benign prostatic hyperplasia (BPH) and the AR gene CAG repeat length.

METHODS

We determined CAG repeat lengths in 176 BPH patients who underwent simple prostatectomy and in 41 control subjects without benign prostatic enlargement (non-BPE group).

RESULTS

A statistically significant (P < 0.02) trend for large adenoma size with short CAG repeat length was found among the adenoma quartiles. CAG repeat length in the fourth quartile (large adenoma, 21.5 +/- 2.7) was significantly shorter than in the first quartile (small adenoma, 23.3 +/- 2.1, P < 0.02). It tended to be shorter than in the non-BPE group (23.1 +/- 2.4), but CAG repeat lengths in the entire BPH (22.4 +/- 2.5) and non-BPE groups did not significantly differ. The relative risk of large BPH (the fourth quartile) was 2.75 (95% confidence interval, 1.05-7.24; P < 0.05) on comparing CAG repeats of < or = 22-> or = 23.

CONCLUSIONS

Shorter CAG alleles may be a genetic factor that promotes the growth of BPH.

Heritability of the symptoms of benign prostatic hyperplasia and the roles of age and zonal prostate volumes in twins

OBJECTIVES

Both benign prostatic hyperplasia and lower urinary tract symptoms (LUTS) have been shown to increase with age in men, but a causal relationship between prostate volume and symptoms has not been established. This study had two aims, to investigate the inter-relationships of age, symptoms, and various zonal measurements in the prostate and to assess the impact of heritable influences on symptom score.

METHODS

Eighty-three monozygotic twin pairs and 83 dizygotic twin pairs were studied to determine age and LUTS as assessed by the American Urological Association symptom score. Their prostate volumes (total, transition zone, and peripheral zone) were measured by transrectal ultrasound.

RESULTS

There was significant evidence of pairwise correlation between transition zone and symptom score (P = 0.04) and between age and symptom score (P = 0.03). Age also showed significant correlation with all volume measurements. Heritability appears to account for 82.6% of the variability in symptom score in men older than 50 years.

CONCLUSIONS

This study provides evidence that age and transition zone volume play a role in LUTS, but also that their influence is not strong. Estimates of heritability suggest that hereditary factors contribute substantially to LUTS.

Variability in urinary flow rate and prostate volume: an investigation using the placebo arm of a drug trial

PURPOSE

We analyzed a large data set to study reproducibility of peak urinary flow rates and prostate volumes in benign prostatic hyperplasia patients.

MATERIALS AND METHODS

Longitudinal data were analyzed from 284 placebo treated patients in a double-blind, placebo controlled benign prostatic hyperplasia drug trial.

RESULTS

A statistically significant increase in mean maximum flow rate was seen in the initial 3 measurements, as well as after adjusting for voided volume and time between uroflows. The mean maximum flow rate increased from 8.61 to 9.36 ml. per second at measurement 4 (8.7%). Of the patients 43% had 2 consecutive prostate volume determinations within +/- 10%. Within patient variability accounted for 7% of total prostate volume variability.

CONCLUSIONS

With subsequent voidings maximum flow rate increases in a large group of patients. At least 4 uroflows must be performed to reach a plateau for maximum flow rate. Explanations for this finding may be the increasing experience of the patient and regression to the mean. These findings may impact on comparison of large trials of treatment efficacy. Within patient variability of prostate volume is substantial and, in addition to measurement method and lack of reader blinding to time and patient identity, may be caused by other yet unknown factors.

Relationship among symptom score, prostate volume, and urinary flow rates in 543 patients with and without benign prostatic hyperplasia

BACKGROUND

Studies on the relationship among symptom score, urinary flow rate, and prostate volume in men with lower urinary tract symptoms (LUTS) continue to be of great interest.

METHODS

A total of 2,418 men, aged 30-86 years, agreed to participate in an interview and to complete a questionnaire regarding voiding patterns. All subjects answering positively to one or more of the questions were submitted to a diagnostic assessment, based on the algorithm outlined by the guidelines of the International Consultation on Benign Prostatic Hyperplasia (BPH). Five hundred forty-three out of the 2,418 participants (22.45%) were evaluated. At the end of the diagnostic evaluation, 400 men with LUTS but without concomitant conditions (except BPH) known to interfere with normal voiding were selected. Descriptive statistics were used to characterize age, symptom score (International Prostate Symptom Score), prostate volume, and urinary flow rate distribution in these patients. Correlations among the aforementioned parameters were evaluated by means of a multivariate, multiple linear regression and logistic regression model.

RESULTS

As reported in other studies, only weak or modest correlations were found. Moreover, the 400 cases were classified according to four age decades. The decrease in peak and mean flow rate per decade of age was similar (0.5 and 0.4 ml/sec); the increase in prostate volume and in total symptom score per decade was 3.3 cc and 0.6, respectively. In patients less than 50 years old, most of the correlations were stronger than those observed in the entire population of 400 men (age and prostate volume, c.c. 0.2864; age and peak flow rate, c.c. -0.2689; age and mean flow rate, c.c. -0.3034). However, symptom score continued to be weakly correlated with age and prostate volume (c.c. 0.0498 and 0.1966, respectively). In the last part of the study, men were assigned to different treatment strategies. Patients who were assigned to surgical treatment had higher prostate volume and IPSS and lower urinary flow rate than those assigned to nonsurgical treatment.

CONCLUSIONS

We believe that the reason for the weak statistical association frequently reported in the literature is mainly the urology clinic-based population from which the patient samples were drawn. Data emerging from this analysis support the hypothesis that age is one of the principal factors influencing the relationship among symptom score, urinary flow rate, and prostate volume.

Effect of age and outlet resistance on rabbit urinary bladder emptying

PURPOSE

To investigate the influence of age and effect of increased outlet resistance on the ability of rabbit bladders to empty in response to various methods of stimulation.

MATERIALS AND METHODS

Bladders from six-month-old (young) and three-year-old rabbits (aged) were mounted in an in vitro whole organ bath system and filled with 15 ml. saline. The ability of the bladders to empty against low outlet resistance (LOR) and high outlet resistance (HOR) in response to field stimulation, bethanechol, and KCl was measured. The following parameters were measured: intravesical pressure and volume emptied. From these, flow rate, power, and external mechanical work were calculated.

RESULTS

Maximum isometric pressure did not change with age. All bladders emptied with increased pressure and decreased flow rate at HOR. The young bladders generated a greater maximum power in response to bethanechol and KCl than the aged bladders at both outlet resistances, and maximum power did not change with increased resistance. The aged bladders did less work and emptied significantly less than the young bladders at the HOR.

CONCLUSIONS

The aged rabbit bladders were unable to maintain the bladder contraction long enough to empty completely through an increased outlet resistance. Because maximum power remained constant when the outlet resistance was increased, it might be useful clinically to determine the emptying ability of the urinary bladder, independent of changes in outlet resistance. In addition, bladder work could be used to evaluate bladder function if the volume emptied is also taken into consideration.

Prostate-specific antigen levels from a mass screening program using highly sensitive RIA kits

BACKGROUND

This study was designed to evaluate the distribution of prostate-specific antigen (PSA) levels of men in a mass screening program for prostatic disease.

METHODS

A total of 763 men over 40 years of age underwent mass screening for prostatic disease in a Japanese prefecture using the highly sensitive Eiken kit and the Hybritech (Tandem-R) kit. The screening tests consisted of serum PSA determination, digital rectal examination, a questionnaire on symptoms, evaluation of prostate volume, and determination of the obesity rate.

RESULTS

Serum PSA levels of all subjects were measured with both kits. The correlation between the values obtained by the Eiken kit and those of the Tandem-R kit was high (r = 0.990), but the values of the former were slightly higher than those of the latter. Serum PSA weakly correlated with age, however, when estimated within decade age brackets, the levels of PSA showed significant differences among only 1 pair of groups stratified by age. In contrast, the levels of PSA showed significant differences among 9 pairs of groups stratified by prostate volume.

CONCLUSION

A highly sensitive assay kit is useful to evaluate both the distribution of PSA levels and the relationship of PSA values to age and prostate volume of men in mass screening programs for prostatic disease, since approximately 40% of the subjects who underwent the present mass screening showed PSA values under 1.0 ng/mL, which have been the the lower limit of detection of many PSA kits.