The Effect of Androgen-replacement Therapy on Prostate Growth: A Systematic Review and Meta-analysis

EUROPEAN UROLOGY 64 (2013) 811 822 available at www.sciencedirect.com journal homepage: www.europeanurology.com Review Benign Prostatic Enlargement The Effect of Androgen-replacement Therapy on Prostate Growth: A Systematic Review and Meta-analysis Yuanshan Cui, Yong Zhang * Department of Urology, Beijing Tian-Tan Hospital, Capital Medical University, Beijing, China Article info Article history: Accepted March 24, 2013 Published online ahead of print on April 3, 2013 Keywords: Androgens Prostate Meta-analysis Randomized controlled trial Abstract Context: Androgen-replacement therapy (ART) is a widely accepted form of treatment worldwide for aging men with late-onset hypogonadism syndrome. Urologists have been concerned about the possibility of ART causing prostate growth. Objective: To assess the relationship between ART and prostate growth. Evidence acquisition: A literature review was performed to identify all published randomized controlled trials (RCTs) of androgen treatment for hypogonadism. The search included the Medline, Embase, and Cochrane Controlled Trials Register databases. The reference lists of the retrieved studies were also investigated. A systematic review and meta-analysis were conducted. Evidence synthesis: Results of 16 RCTs involving a total of 1030 patients were analyzed. Seven RCTs were short-term (<12 mo) and nine were long-term (12 36 mo) comparisons of ART with a placebo; ART was administered transdermally, orally, or by injection. Respective p values for injection, transdermal administration, and oral administration of short-term ART were as follows: PSA level: 0.07, 0.01, and 0.95; prostate volume: 0.70, 0.79, and 0.32; IPSS: 0.78, 0.98, and no oral; Q max :0.92,no transdermal, and 0.10. Respective p values for injection, transdermal administration, and oral administration of long-term ART were as follows: PSA level: 0.42, 0.51, and 0.57; prostate volume: 0.35, 0.59, and 0.47; IPSS: 0.34, 0.32, and 0.97; Q max : 0.11, 0.63, and no oral. Neither short-term nor long-term ART showed significant changes in the four determinants of prostate growth investigated compared with placebo. Conclusions: This meta-analysis shows that regardless of the administration method, neither short-term nor long-term ART increases the risk of prostate growth. Further high-quality, prospective studies are required to confirm this observation. # 2013 European Association of Urology. Published by Elsevier B.V. All rights reserved. * Corresponding author. Department of Urology, Beijing Tian-Tan Hospital affiliated Capital Medical University, No. 6 Tiantan Xi Li, Dong cheng District, Beijing 100050, China. Tel. +86 10 67098393/ 67098394; Fax: +86 10 67096611. E-mail address: doctorzhy@126.com (Y. Zhang). 1. Introduction Androgen deficiency in the aging male has become a topic of increasing interest and debate worldwide. Cross-sectional and longitudinal data indicate that testosterone levels are reduced progressively with age and that a significant percentage of men aged >60 yr have serum testosterone levels that are below the lower limits of young adult men aged 20 30 yr [1 3]. Late-onset hypogonadism (LOH) is a clinical and biochemical syndrome associated with advancing age and is characterized by a deficiency in serum testosterone levels, among other signs and symptoms [4,5]. LOH may result in significant detriment to quality of life and may adversely affect the function of multiple organ systems. Androgen-replacement therapy (ART) is a widely accepted treatment to prevent or ameliorate many of the 0302-2838/$ see back matter # 2013 European Association of Urology. Published by Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.eururo.2013.03.042

812 EUROPEAN UROLOGY 64 (2013) 811 822 [(Fig._1)TD$FIG] symptoms and conditions associated with LOH in aging men. Studies over the past decade have reported evidence of benefit of androgen treatment for multiple target organs of hypogonadal men, including short-term beneficial effects of testosterone in older men that are similar to those seen in younger men [6]. ART is most commonly administered by injection, by transdermal application, or orally. Sometimes a gradual increase in prostate volume concomitant with the progressive decline in testosterone level that occurs in middle age reflects the evolution of benign prostatic hyperplasia (BPH) [7]. It is well known that androgen plays an important role in the development of BPH; therefore, it has been suggested that ART may potentially promote prostate growth [8 11]. Many urologists are concerned that ART may accelerate prostate growth not only in cancer but also in benign disease. 2. Evidence acquisition 146 articles were identified including: Medline: 96 articles Embase: 50 articles Cochrane Controlled Trials Register: 0 18 relevant articles were included. 16 RCTs were included in the analysis: 7 RCTs compared androgen with a placebo over the short term ( 12 mo) and 9 RCTs compared androgen with a placebo over the long term (12-36 mo). On the basis of titles and abstracts, 128 articles were excluded. 2 articles lacked useful data. Fig. 1 A flow diagram of the study selection process. RCT = randomized controlled trial. 2.1. Search strategy The Medline (1966 to October 2012), Embase (1974 to October 2012), and Cochrane Controlled Trials Register databases were searched to identify randomized controlled trials (RCTs) that referred to the impact of ART on the prostate. We also searched the reference lists of the retrieved studies. The following search terms were used: androgen, prostate, and randomized controlled trials. 2.2. Inclusion criteria and trial selection RCTs that met the following criteria were included: (1) The study design included ART; (2) the study provided accurate data that could be analyzed, including the total number of subjects and the values of each determinant of prostate growth, such as prostate-specific antigen (PSA) levels, prostate volume, International Prostate Symptom Score (IPSS), and maximum flow rate (Q max ); and (3) the full text of the study could be accessed. When the same study was published in various journals or in different years, the most recent publication was used for the meta-analysis. If the same group of researchers studied a group of subjects with multiple experiments, then each study was included. A flow diagram of the study selection process is presented in Figure 1. each study was rated and assigned to one of the three following quality categories: A: If all quality criteria were adequately met, the study was deemed to have a low risk of bias. B: If one quality criterion or more were only partially met or were unclear, the study was deemed to have a moderate risk of bias. C: If one criterion or more were not met or not included, the study was deemed to have a high risk of bias. Differences were resolved by discussion among the authors. 2.4. Data extraction The following information was collected for each study: (1) the name of the first author and the publication year; (2) the study design and sample size; (3) the therapy that the patients received; (4) the country in which the study was conducted; (5) data on the four determinants of prostate growth (ie, PSA levels, prostate volume, IPSS, Q max ); and (6) the ART administration method and dosage. 2.3. Quality assessment The quality of the retrieved RCTs was assessed using the Jadad scale [12]. All the identified RCTs were included in the meta-analysis, regardless of the quality score. The methodological quality of each study was assessed according to how patients were allocated to the arms of the study, the concealment of allocation procedures, blinding, and data loss due to attrition. The studies were then classified qualitatively according to the guidelines published in the Cochrane Handbook for Systematic Reviews of Interventions v.5.1.0 [13]. Based on the quality assessment criteria, 2.5. Statistical analysis and meta-analysis The meta-analysis of comparable data was carried out using RevMan v.5.1.0 (Cochrane Collaboration, Oxford, UK) [13]. Changes in all four determinants of prostate growth were determined as differences between baseline (study entry) and study completion. We estimated the relative risk for dichotomous outcomes and the standardized mean difference (SMD) for continuous outcomes pooled across studies by using the DerSimonian and Laird random-effects model [14]. We used a 95% confidence interval (CI). If the result of analysis showed p > 0.05, we considered the studies

EUROPEAN UROLOGY 64 (2013) 811 822 813 homogeneous and so chose a fixed-effect model for metaanalysis. Otherwise, a random-effect model was used. We quantified inconsistency using the I 2 statistic, which describes the proportion of heterogeneity across studies that is not due to chance, thus describing the extent of true inconsistency in results across trials [15]. I 2 <25% reflects a small level of inconsistency and I 2 >50% reflects significant inconsistency. 2.6. Subgroup and sensitivity analysis To explore causes of inconsistency and subgroup treatment interactions, subgroup analyses were specified a priori according to the following factors: Participants: aged <65 or 65 yr; total testosterone level at baseline (testosterone level was considered low if <350 ng/dl or 12 nmol/l); if total testosterone was not available, then the lower limit of normal for bioavailable or free testosterone levels was used; if neither total nor free testosterone levels were available, then studies were classified according to PSA levels Interventions: testosterone formulation, route of administration Outcome characteristic: duration of follow-up (<12 mo vs 12 mo) Study quality measure: proportion of patients lost to follow-up (10% vs >10%), concealment of allocation, and blinding of patients. 3. Evidence synthesis 3.1. Characteristics of the individual studies The database search found 146 articles that could have been included in our meta-analysis. Based on the inclusion and exclusion criteria, 128 articles were excluded after reading the titles and abstracts of the articles. Two articles lacked useful data. In all, 16 articles [16 31], reporting data from a total of 16 RCTs, were included in the analysis: 7 RCTs compared androgen with a placebo over the short term (<12 mo), and 9 RCTs compared androgen with a placebo over the long term (12 36 mo). Three different administration methods were used: oral, transdermal, and injection (Fig. 1). The baseline characteristics of the studies included in our meta-analysis are listed in Table 1. Only four of the included studies had as their end points the same determinants of prostate growth measured in the present analysis (ie, prostate volume, IPSS, PSA levels, and Q max ). All 16 RCTs included in our analysis involved rigorous, periodic monitoring of patients, and treatment was withdrawn when there were indications suspicious for prostate cancer or other serious complications. Few patients suffered serious complications, and all patients who withdrew from treatment had returned to normal at long-term assessment. Five of the 16 RCTs [18,21,23,25,26] reported that the few patients with increased PSA levels on follow-up had undergone prostate biopsy (Table 3), and pathologic examination of biopsy specimens revealed benign histology. All 16 RCTs provided baseline PSA levels, prostate volume, IPSS, and Q max, and only one patient from the studies [29] suffered from BPH symptoms (Table 3). In addition, for all 16 RCTs, no patient had prostate enlargement at baseline, all patients had normal PSA levels at baseline (Table 3), and no patient underwent prostate biopsy at study entry. 3.2. Quality of the individual studies All 16 RCTs were double blinded, and all described the randomization processes used. All except Kenny et al. [22] included a power calculation to determine the optimal sample size, and seven used intention-to-treat analysis (Table 2). The level of quality of each identified study was A (Table 2). The funnel plot provided a qualitative estimation of publication bias of the studies, and no evidence of bias was found (Fig. 4). 3.3. Short-term androgen replacement therapy versus placebo 3.3.1. Prostate-specific antigen levels Six RCTs, representing 345 participants (170 in the androgen group and 175 in the control group), included PSA data [16,22,23,26,30,31] (Fig. 2). Three studies used injection for administration [16,22,23]; two used transdermal application [26,30]; and in one, treatment was given orally [31]. No heterogeneity was found among the trials (Fig. 2). For the three RCTs using injected treatments, the fixed-effects estimate of the SMD was 0.50 (95% CI, 0.04 to 1.05; p = 0.07) (Fig. 2). For the RCTs using transdermal application, the SMD was 0.30 (95% CI, 0.07 0.54; p = 0.002) (Fig. 2). For the study in which treatment was given orally, the SMD was 0.02 (95% CI, 0.64 to 0.60; p = 0.95) (Fig. 2). This result suggests that ART was more likely to result in increased PSA levels than treatment with a placebo when administered transdermally. 3.3.2. Prostate volume changes Four RCTs [16,23,30,31], representing 103 participants (50 in the androgen group and 53 in the control group), included data on prostate volume changes (Fig. 2). Two trials used injection for administration [16,23], one used transdermal application [30], and one used oral delivery [31]. No heterogeneity was found between the RCTs in which treatment was given by injection (Fig. 2); the SMD was 0.95 (95% CI, 3.82 to 5.72; p = 0.70) (Fig. 2). For the study that used transdermal treatment application [30], the SMD was 0.40 (95% CI, 2.61 to 3.41; p = 0.79) (Fig. 2). For the study in which treatment was given orally [31], the SMD was 3.00 (95% CI, 2.96 to 8.96; p = 0.32) (Fig. 2). These results suggests that regardless of administration method, comparing androgen with a placebo revealed no apparent differences in prostate volume changes. 3.3.3. International Prostate Symptom Score changes Five RCTs [22 24,26,30], representing 346 participants (173 in the androgen group and 173 in the control group), included the data for changes in IPSS between groups (Fig. 2). Two trials used injection for administration of ART

814 Table 1 Study and patient characteristics Study Therapy in experimental group Therapy in control group Country Sample size T cut-off level for Experimental Control study entry Other inclusion criteria Exclusion of PSA levels, ng/ml Short-term or long-term ART Administration method Dosage Tenover, 1992 [16] T Placebo USA 6 7 TT 12.1 nmol/l Kenny et al., 2004 [22] T Placebo USA 6 5 BT 128 ng/dl Marks et al., 2006 [23] T Placebo USA 21 19 TT 300 ng/dl Chiang et al., 2007 [24] T Placebo Taiwan 20 17 TT 300 ng/dl Srinivas-Shankar et al., 2010 [26] T Placebo New Zealand 114 117 TT 12 nmol/l No history disease, BMI 22 29 kg/m 2 >4 Short-term I 100 mg/2 wk Folstein Mini-Mental State >4 Short-term I 200 mg/3 wk Exam scores 14 28 Men with late-onset >10 Short-term I 150 mg/2 wk hypogonadism symptoms T deficiency, never took ART >4 Short-term Tr 50 mg/d Men with late-onset hypogonadism symptoms Page et al., 2011 [30] DHT Placebo USA 12 15 TT normal IPSS <10 and a normal prostate TRUS Holmang et al., 1993 [31] T Placebo Sweden 11 12 TT normal Men without urinary tract symptoms Sih et al., 1997 [17] T Placebo USA 12 10 BT 60 ng/dl Snyder et al., 1999 [18] T Placebo USA 45 51 TT 475 ng/dl Kenny et al., 2001 [19] T Placebo USA 24 20 BT 4.44 nmol/l Normal liver function tests, PSA, and hematocrit Men with BMD of the lumbar spine below the mean for healthy young men Men with late-onset hypogonadism symptoms Wittert et al., 2003 [20] T Placebo Australia 33 25 TT normal Men with late-onset hypogonadism symptoms Amory et al., 2004 [21] T Placebo USA 17 18 TT 12.1 nmol/l Emmelot-Vonk et al., 2008 [25] T Placebo Netherlands 104 103 TT 13.7 nmol/l Men with late-onset hypogonadism symptoms Men with late-onset hypogonadism symptoms Idan et al., 2010 [28] DHT Placebo Australia 55 55 TT normal Men had no known prostate disease (cancer, disease requiring further treatment) Aversa et al., 2010 [27] T Placebo Italy 40 10 TT 11 nmol/l Shigehara et al., 2011 [29] T Placebo Japan 23 23 BT 11.8 pg/ml At least two symptoms of hypogonadism IPSS >7 and total prostate volume >20 ml >4 Short-term Tr 50 mg/d >2 Short-term Tr 7 mg/d >10 Short-term O 160 mg/d >4 Long-term I 200 mg/2 wk >4 Long-term Tr 6 mg/d >4 Long-term Tr 5 mg/d >5 Long-term O 80 mg 2/d >4 Long-term I 200 mg/2 wk >4.5 Long-term O 80 mg 2/d >4 Long-term Tr 70 mg/d >4 Long-term Tr 1000 mg/12 wk >2 Long-term I 250 mg/4 wk ART = androgen replacement therapy; BMD = bone mineral density; BMI = body mass index;dht = dihydrotestosterone; FTI = free testosterone index; I = injection; IPSS = International Prostate Symptom Score; O = oral; PSA = prostate-specific antigen; RCT = randomized controlled trial; SHBG = sex hormone-binding globulin; TT = total testosterone; BT = bioavailable testosterone; T = testosterone; Tr = transdermal; TRUS = transrectal ultrasound. EUROPEAN UROLOGY 64 (2013) 811 822

EUROPEAN UROLOGY 64 (2013) 811 822 815 Table 2 Quality assessment of individual studies Study Allocation sequence generation Allocation concealment Blinding Loss to follow-up Calculation of sample size Statistical analysis ITT analysis Level of quality Tenover, 1992 [16] B A A 0 Yes ANOVA No A Kenny et al., 2004 [22] B A A 0 No ANOVA No A Marks et al., 2006 [23] B A A 21 Yes Paired t tests No A Chiang et al., 2007 [24] A A A 3 Yes ANOVA Yes A Srinivas-Shankar et al., 2010 [26] A A A 31 Yes ANCOVA Yes A Page et al., 2011 [30] A A A 4 Yes Wilcoxon rank-sum tests No A Holmang et al., 1993 [31] B A A 2 Yes Student t test No A Sih et al., 1997 [17] A A A 10 Yes Student t test No A Snyder et al., 1999 [18] A A A 12 Yes ANOVA Yes A Kenny et al., 2001 [19] A A A 24 Yes Paired t tests No A Wittert et al., 2003 [20] A A A 18 Yes Fisher exact test Yes A Amory et al., 2004 [21] A A A 13 Yes Student t test Yes A Emmelot-Vonk et al., 2008 [25] A A A 16 Yes Unpaired t tests Yes A Idan et al., 2010 [28] A A A 33 Yes Fisher exact test Yes A Aversa et al., 2010 [27] A A A 0 Yes ANOVA No A Shigehara et al., 2011 [29] B A A 6 Yes Student t test No A A = all quality criteria met (adequate), low risk of bias; ANCOVA = analysis of covariance; ANOVA = analysis of variance; B = one quality criterion or more only partly met (unclear), moderate risk of bias; C = one criterion or more not met (inadequate or not used), high risk of bias; ITT = intention-to-treat analysis. or placebo [22,23], and three used a transdermal method [24,26,30]. No heterogeneity was found between the trials using the injection method [22,23] (Fig. 2); the SMD was 0.46 (95% CI, 3.74 to 2.82; p = 0.78) (Fig. 2). Nor was there heterogeneity among the trials using transdermal application [24,26,30] (Fig. 2); the SMD was 0.02 (95% CI, 1.01 to 1.04; p =0.98)(Fig. 2). These results demonstrate that ART and placebo were similar in terms of the IPSS changes whether administered by injection or transdermally. 3.3.4. Maximum urine flow rate changes Only two RCTs [23,31], involving a total of 63 participants (32 in the androgen group and 31 in the control group), included Q max data (Fig. 2). Treatment was given by injection in one study [23] and orally in the other [31]. No heterogeneity was found between the trials (Fig. 2). The SMD was 0.22 (95% CI, 4.35 to 4.79) for the study using delivery by injection and 5.00 (95% CI, 0.96 to 10.96) for the study using oral delivery ( p = 0.28) (Fig. 2). Therefore, for either an injection or an oral administration method, androgen did not decrease Q max compared with placebo. 3.4. Long-term androgen replacement therapy versus placebo 3.4.1. Prostate-specific antigen levels Nine RCTs [17 21,25,27 29] included PSA data for a total of 670 participants (255 in the androgen group and 315 in the control group) (Fig. 3). Three used injection [17,21,29] for administration, four used transdermal administration [18,19,27,28], and two gave treatments orally [20,25]. According to our analysis, no heterogeneity was found among the trials (Fig. 3). The SMDs were 0.15 (95% CI, 0.22 to 0.53; p = 0.42), 0.06 (95% CI, 0.23 to 0.12; p = 0.51), and 0.08 (95% CI, 0.36 to 0.20; p = 0.57) for ART administered by injection, transdermally, and orally, respectively (Fig. 3). These results indicate no apparent differences between ART and placebo in changes in PSA levels regardless of how the treatments were administered. 3.4.2. Prostate volume changes Four RCTs [21,25,27,28], representing a total of 402 participants (216 in the androgen group and 186 in the control group), included data on changes in prostate volume (Fig. 3). One study used injection [21] for administration, two used transdermal administration [27,28], and one administered treatment orally [25]. No heterogeneity was found among the trials (Fig. 3). Our analysis revealed that the SMD for injection was 4 (95% CI, 4.32 to 12.32; p =0.35), SMD for transdermal delivery was 0.42 (95% CI, 1.99 to 1.14; p = 0.59), and SMD for oral delivery was 1.20 ( 2.02 4.42; p = 0.47) (Fig. 3). The result clarified that there was no difference between ART and a placebo in terms of prostate volume changes for all three administration methods. 3.4.3. International Prostate Symptom Score changes Six RCTs [18 20,25,28,29], representing 563 participants (286 in the androgen group and 277 in the control group), included data on IPSS changes (Fig. 3). One trial delivered treatment by injection [29], three used transdermal application [18,19,28], and two used oral delivery [20,25]. No heterogeneity was found among the trials (Fig. 3), and a fixed-effects model was chosen for the analysis. The SMDs were 2.70 (95% CI, 2.88 to 8.28; p = 0.34), 0.42 (95% CI, 0.41 to 1.24; p = 0.32), and 0.02 (95% CI, 1.11 to 1.15; p = 0.97) for administration by injection, transdermally, and orally, respectively (Fig. 3). Therefore, we concluded that androgen and a placebo were nearly the same in terms of the IPSS changes for all three methods of administration. 3.4.4. Maximum urine flow rate changes Only two RCTs [18,29], representing a total of 142 participants (68 in the androgen group and 74 in the control

816 [(Fig._2)TD$FIG] EUROPEAN UROLOGY 64 (2013) 811 822 Fig. 2 Forest plots showing changes in (a) prostate-specific antigen levels, (b) prostate volume, (c) International Prostate Symptom Score, and (d) maximum urine flow rate in the short-term treatment studies. CI = confidence interval; IV = inverse; SD = standard deviation.

[(Fig._3)TD$FIG] EUROPEAN UROLOGY 64 (2013) 811 822 817 Fig. 3 Forest plots showing changes in (a) prostate-specific antigen levels, (b) prostate volume, (c) International Prostate Symptom Score, and (d) maximum urine flow rate in the long-term treatment studies. CI = confidence interval; IV = inverse; SD = standard deviation.

818 [(Fig._4)TD$FIG] EUROPEAN UROLOGY 64 (2013) 811 822 Fig. 4 Funnel plot of the studies represented in the meta-analysis. Although 16 articles are included, 15 symbols are shown because of overlap among the articles in reporting the determinants of prostate growth. MD = mean difference; SE = standard error. group), included Q max data (Fig. 3). One used an injection [29] method, and one used a transdermal method [18] of delivering treatment. No heterogeneity was found between the trials (Fig. 3). The SMD for the study using delivery by injection [29] was 3.70 (95% CI, 0.85 to 8.25) and 0.60 (95% CI, 3.04 to 1.84) for the study using transdermal application [18] ( p =0.74) (Fig. 3). Therefore, we concluded that for either an injection or a transdermal administration method, ART did not decrease the Q max compared with a placebo. 3.5. Subgroup analyses and sensitivity analysis According to the baseline data of PSA levels and the inclusion criteria for our studies, we divided the included studies into three groups for preplanned subgroup analyses: PSA 2 ng/ml, PSA 1 2 ng/ml, and PSA 1 ng/ml. There were no differences between the ART and placebo groups regarding the changes of the four determinants of prostate growth (Table 4). Subgroup analyses shows that all the results of determinants of prostate growth in the ART and placebo groups matched our findings (Table 4) except that ART using the transdermal administration method was more likely to increase PSA levels than treatment with a placebo ( p = 0.0005) in the group aged 65 yr (Table 4). Sensitivity analysis was performed by removing the studies for which generation of allocation sequence was inadequate. Our analysis indicated that short-term ART using the transdermal administration method was more likely to increase PSA levels than treatment with placebo ( p = 0.01) (Table 4). No differences were found between the ART and placebo groups in the long-term studies regarding changes in PSA levels ( p = 0.57), prostate volume ( p = 1.00), IPSS ( p = 0.41), or Q max ( p = 0.63) (Table 4). 3.6. Discussion Prostate growth is dependent on the presence of androgens; conversely, antiandrogen and orchidectomy can decrease prostate volume in patients with BPH [9]. It has been suggested that ART may potentially increase prostate volume. Urologists have been concerned about the use of androgen supplementation due to the possibility of fueling prostate growth not only in cancer but also in benign disease. Resolving this question will inform methods of treating LOH accompanied by prostatic problems. In our analysis, short-term ART delivered by transdermal application was more likely to increase PSA levels than treatment with a placebo; therefore, we can state that PSA levels increased slightly over 12 mo in patients receiving treatment transdermally. This is not in accord with clinical manifestation, however. There are two possible reasons for this discrepancy. One is that skin expresses high 5a-reductase activity; therefore, testosterone gel applied to the skin achieves much higher dihydrotestosterone levels than a comparable dose of testosterone enanthate [32 34], which may increase PSA levels. The other is that PSA is sensitive to changes in the level of testosterone at low concentrations, when unbound receptors are available to respond to an increase in testosterone. With an increase in testosterone to eugonadal levels in the clinical setting, the receptors become saturated, and increasing the testosterone level further has no real effect on the level of PSA [35]. Some urologists think that testosterone has a linear effect on prostate growth, and prostate dysfunction as an adverse effect of this was the dominant theory in the past. Now there is a new paradigm: the saturation model of testosterone and the prostate [36]. This theory holds that testosterone s effect on the prostate reaches a saturation point well below the physiologic testosterone levels encountered in the clinical setting, beyond which additional testosterone does not have an increased effect. This theory is gaining traction in modern studies. In the study by Page et al. [30], for example, the inclusion criteria for patients receiving treatment transdermally included PSA level <2 ng/ml, which was lower than in other short-term studies (Table 1). Perhaps due to the relatively low level of testosterone, unbound receptors are available to respond, leading to increased PSA levels in the short term. Combined with the long-term ART trial data, we recognized that the PSA levels exhibited small increases associated with ART. However, there was no significant difference between the PSA levels of the two groups at baseline compared with the end of the trial. Therefore, we hypothesize that the PSA level increases slightly in the early stage of ART and then decreases to a relatively low level that is still higher than baseline and remains relatively stable for a long period during ART. Our study also evaluated the safety of long-term ART (12 36 mo) for prostate growth. All 16 RCTs included in our analysis involved rigorous, periodic monitoring of patients, and treatment was withdrawn when there were indications suspicious for prostate cancer or other serious complications. In addition, for all 16 RCTs, no patient had prostate enlargement at baseline, all patients had normal PSA levels at baseline, and no patient underwent prostate biopsy at study entry (Table 3). Consequently, long-term ART is safe in terms of prostate growth, although rigorous monitoring is indispensable. Our conclusion is based on the fact that

Table 3 Baseline data in our study Age, yr, median PSA, ng/ml Prostate volume, ml IPSS Maximum flow rate, ml/s TG PG TG PG TG PG TG PG Prostate volume determination Prostate biopsy at study entry Prostate biopsy during follow-up Tenover, 1992 [16] 66.7 2.1 (0.4) 2.1 (0.4) 33 (4) 33 (4) Transabdominal US No No Kenny et al., 2004 [22] 79.5 0.88 (0.71) 1.30 (0.78) 6.6 (5.8) 8.8 (6.4) NA No No Marks et al., 2006 [23] 69 1.55 (0.89) 0.97 (1.55) 43.8 (9.94) 36.8 (6.51) 13.0 (8.14) 11.0 (7.74) 14.0 (7.48) 10.6 (7.27) Transabdominal US No Yes Chiang et al., 2007 [24] 52 8.6 (6.9) 8.8 (5.9) NA No No Srinivas-Shankar 73.8 1.5 (0.9) 1.5 (0.9) 7.0 (5.0) 5.9 (4.3) NA No Yes et al., 2010 [26] Page et al., 2011 [30] 43 0.7 (0.4) 1.1 (0.6) 20.3 (4.6) 21.5 (4.2) 2.3 (1.7) 2.5 (2.8) TRUS No No Holmang et al., 1993 [31] 52 1.28 (1.22) 0.72 (1.06) 24.6 (5.97) 22.1 (6.79) 15 (8.73) 17 (7.91) TRUS No No Sih et al., 1997 [17] 65 1.0 (0.82) 1.5 (1.16) NA No No Snyder et al., 1999 [18] 73 1.7 (1.1) 1.6 (1.0) 3.9 (2.5) 4.0 (2.3) 25.7 (5.4) 24.7 (6.1) NA No Yes Kenny et al., 2001 [19] 75.5 2.0 (1.3) 2.0 (1.2) 9.3 (6.5) 9.0 (5.2) NA No No Wittert et al., 2003 [20] 68.5 2.5 (0.8) 2.5 (1.2) 6.0 (4.0) 5.6 (5.1) NA No No Amory et al., 2004 [21] 71 0.9 (0.8) 1.4 (1.1) 29 (11) 32 (14) TRUS No Yes Emmelot-Vonk 67 1.6 (1.1) 1.7 (1.1) 28.3 (12.6) 28.0 (9.9) 6.3 (5.1) 6.7 (4.9) TRUS No Yes et al., 2008 [25] Idan et al., 2010 [28] 60.5 1.6 (1.1) 1.5 (1.1) 28.6 (10.4) 29.3 (16.2) 5.4 (4.2) 6.2 (5.0) TRUS No No Aversa et al., 2010 [27] 57 1.07 (0.4) 1.1 (0.5) 26 (3) 26.5 (2) TRUS No No Shigehara et al., 2011 [29] 70.5 1.06 (0.53) 1.06 (0.53) 15.7 (8.7) 14.0 (10.1) 12.9 (5.6) 11.4 (4.9) TRUS No No IPSS = International Prostate Symptom Score; NA = not available; PG = placebo group; PSA = prostate-specific antigen; TG = androgen group; TRUS = transrectal ultrasound; US = ultrasound. Baseline data are expressed as mean (standard deviation). Yes indicates that few patients with increased PSA levels on follow-up had undergone prostate biopsy. EUROPEAN UROLOGY 64 (2013) 811 822 819

820 EUROPEAN UROLOGY 64 (2013) 811 822 Table 4 The results of subgroup, sensitivity, and preplanned subgroup analysis PSA Prostate volume IPSS Maximum flow rate SMD (95% CI) p value SMD (95% CI) p value SMD (95% CI) p value SMD (95% CI) p value Age <65 yr 0.08 ( 0.24 to 0.08) 65 yr 0.23 (0.06 0.39) Testosterone level Lower 0.15 (0.01 0.29) Normal 0.10 ( 0.30 to 0.10) Testosterone assay types Gold standard * 0.05 ( 0.25 to 0.15) Not gold standard * 0.13 ( 0.01 to 0.27) Study quality (A level) ** Short-term 0.30 (0.07 0.54) Long-term 0.04 ( 0.18 to 0.10) Serum PSA level PSA 2 ng/ml 0.41 ( 0.36 to 1.18) PSA 1 2 ng/ml 0.06 ( 0.07 to 0.20) PSA 1 ng/ml 0.14 ( 0.11 to 0.39) Duration of ART Short-term 0.30 (0.09 0.50) Long-term 0.04 ( 0.17 to 0.10) 0.31 0.08 ( 1.43 to 1.27) 0.91 0.32 ( 0.59 to 1.23) 0.007 1.39 ( 1.15 to 3.93) 0.28 0.14 ( 0.54 to 0.83) 0.03 0.76 ( 1.21 to 2.73) 0.32 0.05 ( 1.55 to 1.44) 0.64 0.26 ( 1.74 to 2.26) 0.08 0.23 ( 1.26 to 1.72) 0.01 0.40 ( 2.61 to 3.41) 0.57 0.00 ( 1.39 to 1.39) 0.29 0.00 ( 12.55 to 12.55) 0.38 0.11 ( 1.52 to 1.29) 0.28 1.2 ( 1.09 to 3.49) 0.005 0.93 ( 1.41 to 3.27) 0.62 0.00 ( 1.39 to 1.39) 0.45 0.31 ( 0.28 to 0.9) 0.94 0.41 ( 1.84 to 1.03) 0.80 0.34 ( 0.59 to 1.27) 0.76 0.14 ( 0.54 to 0.81) 0.79 0.02 ( 1.01 to 1.04) 1 0.28 ( 0.39 to 0.95) 1 1.50 ( 4.30 to 1.30) 0.87 0.44 ( 0.19 to 1.07) 0.31 0.34 ( 1.90 to 1.23) 0.43 0.03 ( 1.00 to 0.95) 1.00 0.31 ( 0.35 to 0.98) 0.49 0.68 0.34 ( 1.61 to 2.28) 0.73 0.30 0.34 0.73 ( 1.61 to 2.28) 0.58 0.47 0.69 0.90 ( 1.13 to 2.92) 0.98 0.41 0.60 ( 3.04 to 1.84) 0.29 0.17 0.36 ( 1.79 to 2.52) 0.67 1.99 ( 1.64 to 5.62) 0.96 1.99 ( 1.64 to 5.62) 0.35 0.36 ( 1.79 to 2.52) 0.38 0.63 0.74 0.28 0.28 0.74 ART = androgen-replacement therapy; CI = confidence interval; IPSS = International Prostate Symptom Score; PSA = prostate-specific antigen; SMD = standardized mean difference. * Gold standard was tandem mass spectrometry and liquid chromatography. ** A level: all quality criteria were met (adequate), low risk of bias. ART has no adverse effect on prostate growth in patients without prostatic hyperplasia. Whether or not ART will increase the risk for prostate growth in patients with BPH needs further investigation in larger, high-quality studies. Current laboratory protocol to support a diagnosis of LOH is for a serum sample for total testosterone determination to be obtained between 7:00 AM and 11:00 AM [37]. It is generally agreed that a total testosterone level >12 nmol/l (350 ng/dl) does not require substitution [5], and that a free testosterone level <225 pmol/l (65 pg/ml) can provide supportive evidence for testosterone treatment [38]. The cohorts of 11 of the 16 studies in our meta-analysis were evaluated in accordance with the diagnosis standard (Table 1). Combined with our study, ART following this diagnosis standard dose not increase the risk of prostate growth. Inadequate data are available to determine the optimal serum testosterone level for efficiency and safety. For the present time, moderate to lower serum testosterone levels seem appropriate in young adult males and should be the therapeutic goal. Although different methods and dosages were used in the selected RCTs, supraphysiologic levels were avoided. This meta-analysis included findings from 16 doubleblinded RCTs. According to the quality-assessment scale that we developed, the quality of the individual studies in the meta-analysis was high. The results of this analysis are important from a scientific standpoint, and they apply to everyday clinical practice, particularly because data were analyzed by method of ART delivery. The results of the subgroup and sensitivity analyses are in accordance with our findings, indicating that our results are robust and reliable. Nevertheless, there are some limitations to our analysis. Data on prostate volume after short-term ART and on Q max were derived from a relatively small sample because cohort sizes of a few of the studies [16,17,22,31] were not large. Major limitations include heterogeneity in the populations examined (Table 1), androgen dosage used (Table 1), and baseline prostate status (with the exception of PSA levels) (Table 3). LOH is a clinical and biochemical syndrome that adversely affects the function of multiple organ systems. The presence of symptoms associated with LOH was not consistent across the included studies, and this may have contributed to the heterogeneous population. Although we

EUROPEAN UROLOGY 64 (2013) 811 822 821 conducted subgroup and sensitivity analyses to assess the quality of the studies, the problem of heterogeneity still could not be completely avoided. Only four of the included studies had as their end points the same determinants of prostate growth measured in the present analysis (ie, prostate volume, IPSS, PSA levels, and Q max ). Although 15 of the 16 RCTs drew morning blood samples to measure testosterone levels, 11 of the 15 studies reported 6 measurement assay methods included tandem mass spectrometry-liquid chromatography, mass spectroscopy, chemiluminescent immunoassay, radioimmunoassay, fluoroimmunoassay, and electrochemiluminescence. It is generally known that the first method is the gold standard. Although the results of subgroup analysis by testosterone assay types (gold standard and not gold standard) matched our findings, this made inclusion of studies using different testosterone assays problematic and potentially influenced the results of the meta-analysis. 4. Conclusions This meta-analysis shows that regardless of the administration method, neither short-term nor long-term ART increases the risk of prostate growth. Further highquality, prospective studies are required to confirm this observation. Author contributions: Yong Zhang had full access to all the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis. Study concept and design: Zhang. Acquisition of data: Zhang, Cui. Analysis and interpretation of data: Zhang, Cui. Drafting of the manuscript: Zhang, Cui. Critical revision of the manuscript for important intellectual content: Zhang, Cui. Statistical analysis: Zhang, Cui. Obtaining funding: None. Administrative, technical, or material support: Zhang. Supervision: Zhang. Other (specify): None. Financial disclosures: Yong Zhang certifies that all conflicts of interest, including specific financial interests and relationships and affiliations relevant to the subject matter or materials discussed in the manuscript (eg, employment/affiliation, grants or funding, consultancies, honoraria, stock ownership or options, expert testimony, royalties, or patents filed, received, or pending), are the following: None. Funding/Support and role of the sponsor: None. Acknowledgment statement: The authors thank Dragonfly Editorial for assisting in the preparation of this manuscript. References [1] Araujo AB, Esche GR, Kupelian V, et al. Prevalence of symptomatic androgen deficiency in men. J Clin Endocrinol Metab 2007;92: 4241 7. [2] Harman SM, Metter EJ, Tobin JD, Pearson J, Blackman MR. Longitudinal effects of aging on serum total and free testosterone levels in healthy men. 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