Long-term (7 to 8-year) experience with finasteride in men with benign prostatic hyperplasia

Finasteride delays atherosclerosis progression in mice and is associated with a reduction in plasma cholesterol in men

Finasteride is commonly prescribed to treat benign prostate hyperplasia and male-pattern baldness in cis men and, more recently, trans individuals. However, the effect of finasteride on cardiovascular disease remains elusive. We evaluated the role of finasteride on atherosclerosis using low-density lipoprotein (LDL) receptor-deficient (Ldlr-/-) mice. Next, we examined the relevance to humans by analyzing the data deposited between 2009 and 2016 in the National Health and Nutrition Examination Survey. We show that finasteride reduces total plasma cholesterol and delays the development of atherosclerosis in Ldlr-/- mice. Finasteride reduced monocytosis, monocyte recruitment to the lesion, macrophage lesion content, and necrotic core area, the latter of which is an indicator of plaque vulnerability in humans. RNA sequencing analysis revealed a downregulation of inflammatory pathways and an upregulation of bile acid metabolism, oxidative phosphorylation, and cholesterol pathways in the liver of mice taking finasteride. Men reporting the use of finasteride showed lower plasma levels of cholesterol and LDL-cholesterol than those not taking the drug. Our data unveil finasteride as a potential treatment to delay cardiovascular disease in people by improving the plasma lipid profile.

Post-finasteride syndrome: a surmountable challenge for clinicians

Post-finasteride syndrome (PFS) is a constellation of serious adverse side effects manifested in clinical symptoms that develop and persist in patients during and/or after discontinuing finasteride treatment in men with pattern hair loss (androgenetic alopecia) or benign prostatic hyperplasia. These serious adverse side effects include persistent or irreversible sexual, neurological, physical and mental side effects. To date, there are no evidence-based effective treatments for PFS. Although increasing number of men report persistent side effects, the medical community has yet to recognize this syndrome nor are there any specific measures to address this serious and debilitating symptoms. Here we evaluate the scientific and clinical evidence in the contemporary medical literature to address the very fundamental question: Is PFS a real clinical condition caused by finasteride use or are the reported symptoms only incidentally associated with but not caused by finasteride use? One key indisputable clinical evidence noted in all reported studies with finasteride and dutasteride was that use of these drugs is associated with development of sexual dysfunction, which may persist in a subset of men, irrespective of age, drug dose or duration of study. Also, increased depression, anxiety and suicidal ideation in a subset of men treated with these drugs were commonly reported in a number of studies. It is important to note that many clinical studies suffer from incomplete or inadequate assessment of adverse events and often limited or inaccurate data reporting regarding harm. Based on the existing body of evidence in the contemporary clinical literature, the author believes that finasteride and dutasteride induce a constellation of persistent sexual, neurological and physical adverse side effects, in a subset of men. These constellations of symptoms constitute the basis for PFS in individuals predisposed to epigenetic susceptibility. Indeed, delineating the pathophysiological mechanisms underlying PFS will be of paramount importance to the understanding of this syndrome and to development of potential novel therapeutic modalities.

The effects of Pueraria mirifica extract, diadzein and genistein in testosterone-induced prostate hyperplasia in male Sprague Dawley rats

Pueraria mirifica (PM) is a medicinal plant native to Thailand contained high amount of phytoestrogen and possesses anticancer activity. This study reports the effect of P. mirifica extract, phytoestrogen of diadzein and genistein for its benign prostate hyperplasia properties in testosterone-induced prostate hyperplasia in male Sprague Dawley rats. The P. mirifica extract was evaluated for its total phenols, flavonoid and antioxidant activity using DPPH, FRAP and metal chelating assay. The assessment of P. mirifica, diadzein and genistein against benign prostate hyperplasia was determined in testosterone-induced prostate hyperplasia in male Sprague Dawley rats. The total phenol was higher than flavonoid but showed low antioxidant activity of DPPH, FRAP and metal chelating. The aqueous PM extract at 1000 mg/kg significantly increased testosterone levels in testosterone-induced rats by 13% while diadzein and genistein increased it by 11% and 17% respectively. However, levels of FSH, LH, triglyceride and HDL are not affected by the oral administration of PM, diadzein and genistein to the rats. Similarly, total protein, albumin, globulin, total bilirubin, conjugated bilirubin, alkaline phosphatase, alanine aminotransferase, AST, and G-glutamyltransferase showed no significant difference as compared with negative control rats. The body weight of the rats, testis, kidney and liver showed no toxic effect. The zinc content increased significantly and the zinc transporter gen of ZnT4 and ZIP4 highly expressed suggesting that the PM, diadzein and genistein plays essential role in modulating prostate zinc homeostasis. Similarly, the expression of IL-6, AR and ER was significantly reduced indicating functioning in regulation of prostate growth and acts as anti-inflammatory role in preventing BPH. In conclusion, the results indicated that PM reduced BPH and contributed to the regulation in the zinc transport expression of the prostate cells in the benign prostate hyperplasia (BPH).

Hormone-dependent medial preoptic/lumbar spinal cord/autonomic coordination supporting male sexual behaviors

Testosterone (T) can act directly through neural androgen receptors (AR) to facilitate male sexual behavior; however, T's metabolites also can play complicated and interesting roles in the control of mating. One metabolite, dihydrotestosterone (DHT) binds to AR with significantly greater affinity than that of T. Is that important behaviorally? Another metabolite, estradiol (E), offers a potential alternative route of facilitating male mating behavior by acting through estradiol receptors (ER). In this review we explore the roles and relative importance of T as well as E and DHT at various levels of the neuroaxis for the activation of male sex behavior in common laboratory animals and, when relevant research findings are available, in man.

Ethanol Extract of Evodia rutaecarpa Attenuates Cell Growth through Caspase-Dependent Apoptosis in Benign Prostatic Hyperplasia-1 Cells

The dried fruits of Evodia rutaecarpa Bentham have been used widely as a herbal medicine for the treatment of inflammatory disorders and abdominal pain. Benign prostatic hyperplasia (BPH) is a nonmalignant disease characterized by overgrowth of prostates. Despite the pharmacological efficacy of the fruits of E. rutaecarpa against various diseases, their effects against BPH have not been reported. Here, we investigated the inhibitory activity of a 70% ethanol extract of E. rutaecarpa (EEER) against BPH, and its underlying mechanisms regarding cell growth of BPH using BPH-1 cells. An in vitro 5α-reductase activity assay showed that EEER exhibited inhibitory activity against 5α-reductase. In BPH-1 cells, EEER treatment inhibited cell viability and reduced the expression of the proliferating cell nuclear antigen proliferating cell nuclear antigen (PCNA), cyclin D1, and phosphor-ERK1/2 proteins. Moreover, EEER also induced apoptosis, with chromatin condensation, apoptotic bodies, and internucleosomal DNA fragmentation. Regarding its underlying mechanisms, EEER exacerbated the activation of caspase-8 and caspase-3 in a concentration-dependent manner and eventually caused the cleavage of PARP. Taken together, these data demonstrated that EEER had a potent 5α-reductase inhibitory activity and that EEER treatment in BPH-1 cells inhibited cell viability via caspase-8- and caspase-3-dependent apoptosis. Therefore, EEER may be a potential phytotherapeutic agent for the treatment of BPH.

Atorvastatin attenuates testosterone-induced benign prostatic hyperplasia in rats: role of peroxisome proliferator-activated receptor-γ and cyclo-oxygenase-2

Diabetes and obesity have been reported to alter sex steroid hormone metabolism. In this study, an attempt was made to investigate the protective effect of atorvastatin (ATR) in combination with celecoxib (CEL) or pioglitazone (PIO) on testosterone-induced BPH in rats. Male Wistar rats (200-250 g) were randomly divided into nine groups (n = 8) and orally treated as follows for 28 consecutive days: group 1: vehicle control (10 mL/kg); group 2: vehicle testosterone (10 mL/kg); groups 3 - 5: ATR (0.5, 2.5, and 5 mg/kg, respectively); group 6: CEL (20 mg/kg); group 7: PIO (20 mg/kg); and groups 8-9: ATR 0.5 mg/kg, and 15 min later, animals were given CEL (20 mg/kg) or PIO (20 mg/kg), respectively. One hour post-treatment, animals in groups 2-9 were given testosterone propionate (3 mg/kg, s.c.). Twenty-four hours after last treatment on day 28, blood was collected for serum testosterone and prostate-specific antigen (PSA) analysis. Prostate was harvested for biochemical and histological assays. Subcutaneous injection of testosterone increased serum levels of testosterone and PSA which was ameliorated by pretreatments of rat with ATR, celecoxib, or pioglitazone. Similarly, testosterone-induced increase in MDA and reduction in the activity of GSH, superoxide dismutase (SOD), and catalase were attenuated by ATR. Conversely, celecoxib or pioglitazone treatment failed to affect the activity of antioxidant enzymes. The histology of the prostate showed significant improvement in prostatic cells of ATR, celecoxib, or pioglitazone treated. Findings from the study showed that atorvastatin attenuated testosterone-induced BPH. Moreover, synergistic effect was observed when atorvastatin was combined with celecoxib.

Apoptotic Pathways Linked to Endocrine System as Potential Therapeutic Targets for Benign Prostatic Hyperplasia

Benign prostatic hyperplasia (BPH) is a chronic condition common in older men that can result in bothersome lower urinary tract symptoms. The molecular mechanisms and networks underlying the development and the progression of the disease are still far from being fully understood. BPH results from smooth muscle cell and epithelial cell proliferation, primarily within the transition zone of the prostate. Apoptosis and inflammation play important roles in the control of cell growth and in the maintenance of tissue homeostasis. Disturbances in molecular mechanisms of apoptosis machinery have been linked to BPH. Increased levels of the glycoprotein Dickkopf-related protein 3 in BPH cause an inhibition of the apoptosis machinery through a reduction in B cell lymphoma (Bcl)-2 associated X protein (Bax) expression. Inhibitors of apoptosis proteins influence cell death by direct inhibition of caspases and modulation of the transcription factor nuclear factor-κB. Current pharmacotherapy targets either the static component of BPH, including finasteride and dutasteride, or the dynamic component of BPH, including α-adrenoceptor antagonists such as tamsulosin and alfuzosin. Both these classes of drugs significantly interfere with the apoptosis machinery. Furthermore, phytotherapic supplements and new drugs may also modulate several molecular steps of apoptosis.

Effect of 5α-Reductase Inhibitors on Sexual Function: A Meta-Analysis and Systematic Review of Randomized Controlled Trials

INTRODUCTION

5α-Reductase inhibitors (5ARIs) are widely used for the treatment of benign prostatic hyperplasia (BPH) and androgenetic alopecia (AGA).

AIM

To review all the available data on the effect of 5ARIs on sexual function and assess whether 5ARIs increase the risk of sexual dysfunction.

METHODS

A systematic search of the literature was conducted using the Medline, Embase, and Cochrane databases. The search was limited to articles published in English and up to October 2015. Article selection proceeded according to the search strategy based on Preferred Reporting Items for Systematic Reviews and Meta-analyses criteria. Data were analyzed using Stata 12.0. A fixed- or a random-effects model was used to calculate the overall combined risk estimates. Publication bias was assessed using Begg and Egger tests.

MAIN OUTCOME MEASURES

Sexual dysfunction, erectile dysfunction, and decreased libido.

RESULTS

After screening 493 articles, 17 randomized controlled trials with 17,494 patients were included. Nine studies evaluated the efficacy of 5ARIs in men with BPH. The other eight reported using 5ARIs in the treatment of men with AGA. The mean age of participants was 60.10 years across all studies. We included 10 trials (6,779 patients) on the efficacy and safety of finasteride, 4 trials (6,222 patients) on the safety and tolerability of dutasteride, and 3 trials (4,493 patients) using finasteride and dutasteride for AGA. The pooled relative risks for sexual dysfunction were 2.56 (95% CI = 1.48-4.42) in men with BPH and 1.21 (95% CI = 0.85-1.72) in men with AGA; those for erectile dysfunction were 1.55 (95% CI = 1.14-2.12) in men with BPH and 0.66 (95% CI = 0.20-2.25) in men with AGA; and those for decreased libido were 1.69 (95% CI = 1.03-2.79) in men with BPH and 1.16 (95% CI = 0.50-2.72) in men with AGA. Estimates of the total effects were generally consistent with the sensitivity analysis. No evidence of publication bias was observed.

CONCLUSION

Evidence from the randomized controlled trials suggested that 5ARIs were associated with increased adverse effects on sexual function in men with BPH compared with placebo. However, the association was not statistically significant in men with AGA. Well-designed randomized controlled trials are indicated to study further the mechanism and effects of 5ARIs on sexual function.

Rice Hull Extract Suppresses Benign Prostate Hyperplasia by Decreasing Inflammation and Regulating Cell Proliferation in Rats

Even though rice hull has various physiological functions with high antioxidant potential, the molecular mechanism(s) underlying the effects of rice hull on benign prostatic hyperplasia (BPH) have not been evaluated. The aim of this study was to determine the protective effect of rice hull water extract (RHE) against BPH, which is a common disorder in elderly men and involves inflammation that induces an imbalance between cell proliferation and cell death. In this study, RHE-treated mice exhibited lower prostate weights and ratios of prostate weight to body weight compared to those for the BPH-induced group. In addition, RHE-treated mice had lower serum levels of dihydrotestosterone, mRNA expression of 5α-reductase2, and protein expressions of proliferating cell nuclear antigen (PCNA). Furthermore, RHE treatment significantly decreased cell proliferation by regulating the expression levels of inflammatory-related proteins (iNOS and COX-2) and apoptosis-associated proteins (Fas, FADD, procaspase-8, -3, and Bcl-2 family proteins). These results suggest that RHE could protect against the development of BPH through its anti-inflammatory and apoptotic properties and has good potential as a treatment for BPH.

Living with a 100 ml prostate: Outcomes over a decade

Objective:

The objective of this article is to determine outcomes and guide the management of patients with a prostate volume of 100 ml or greater.

Patients and methods:

A database of patients undergoing transrectal ultrasound (TRUS)-guided biopsy from 1994 to 1999 was analysed. Records of those with a prostate of 100 ml or greater were reviewed.

Results:

A total of 63 patients were included in the study with a mean follow-up of 11 years. Initial TRUS-guided biopsy yielded prostate cancer (CaP) in six of 63 (10%). Twenty-six of 63 (41%) underwent repeat biopsies. CaP was ultimately diagnosed in 13/63 (21%). Prostate-specific antigen (PSA) levels were erratic over time, making monitoring difficult. The PSA coefficient of variation in benign prostates ranged from 8.9% to 48.6% in the year following biopsy. Twenty-one of 50 (42%) with benign prostates experienced acute urinary retention (AUR), 31/50 (62%) haematuria and 43/50 (86%) received treatment for lower urinary tract symptoms (LUTS). Twenty-six of 50 (52%) received 5-alpha reductase inhibitors (5ARI), 11/50 (22%) α-blockers and 28/50 (56%) surgery. Thirteen of 15 (87%) experienced further symptoms when treated for less than two years with 5ARI versus five of 16 (31%) receiving long-term treatment (mean duration 8.1 years). Fifteen of 25 (60%) experienced haematuria following TURP and 14/25 (56%) required further treatment.

Conclusion:

Large prostates cause considerable symptoms prompting multiple medical consultations and investigations. PSA monitoring in this group is difficult, leading to repeated biopsies of benign prostates. Long-term 5ARI treatment should be considered to reduce progression to AUR, the incidence of haematuria and to facilitate PSA monitoring. Newer treatment modalities such as holmium laser enucleation (HoLEP) should be considered ahead of TURP. When TURP is performed, 5ARI treatment should be considered post-operatively. This group of men should have close urological follow-up.

5α-Reductase inhibitors in androgenetic alopecia

PURPOSE OF REVIEW

The authors will review the current literature on efficacy and safety of 5-alpha reductase inhibitors (5αRIs) for androgenetic alopecia (AGA).

RECENT FINDINGS

The 5αRI finasteride and dutasteride are effective in treating AGA and promoting hair regrowth. 5αRI can be given orally, topically and more recently through mesotherapy. However, there has been an increasing concern about permanent sexual adverse events such as impotence and infertility. Most of these reports are published as case reports, and two studies reporting persistent sexual side-effects after discontinuation of finasteride had serious method limitations, as patients were recruited from a website. To our knowledge, permanent sexual adverse events have yet to be published in higher quality studies, such as randomized controlled trials. Although patients treated with 5αRIs have an increased incidence of sexual adverse events, these events decrease if discontinued or over time with continued therapy.

SUMMARY

Sexual side-effects are uncommon and resolve spontaneously in most patients even without discontinuing therapy. Significant effort is underway to find delivery systems that optimize delivery and reduce systemic absorption of topical 5αRs including hydroxypropyl chitosan and liposomal and nanoparticulate systems.

Steroidal 5α-reductase and 17α-hydroxylase/17,20-lyase (CYP17) inhibitors useful in the treatment of prostatic diseases

The role of steroidal inhibitors of androgen biosynthesis as potential weapons in the treatment of prostatic diseases, such as benign prostatic hyperplasia and prostatic cancer will be reviewed. Two enzymes have been targeted in the development of inhibitors that potentially could be useful in the management of such conditions. 5α-Reductase is primarily of interest in benign prostatic disease, though some role in the chemoprevention of prostatic carcinoma have been considered, whereas the 17α-hydroxylase/17,20-lyase (CYP17) enzyme is of interest in the treatment of malignant disease. An overview of the main achievements obtained during the past years will be presented, however special focus will be made on steroidal molecules that reached clinical trials or have been commercially launched. Relevant examples of such drugs are finasteride, dutasteride, abiraterone acetate and galeterone (TOK-001, formerly known as VN/124-1). This article is part of a Special Issue entitled "Synthesis and biological testing of steroid derivatives as inhibitors".

Advances in the design and discovery of drugs for the treatment of prostatic hyperplasia

INTRODUCTION

Benign prostatic hyperplasia (BPH) is a common medical problem in nearly 80% of geriatric male population severely affecting the quality of life. Several strategies has been suggested in the past for the management of BPH, but only α-blockers and 5α-reductase inhibitors are in clinical use. This review aims to give deep insight into advances in the design and discovery of newer chemical entities as 'druggable' molecule for the management of BPH.

AREAS COVERED

In this review, the authors cover various classes of drugs that have shown their potential for management of BPH. These drugs include α-adrenergic antagonists, 5α-reductase inhibitors, phytochemical agents, phosphodiesterase inhibitor, luteinizing hormone releasing hormone antagonists and muscarinic receptor antagonists. Literature searches were carried out using Google Scholar, SciFinder and PubMed.

EXPERT OPINION

The exact etiology of BPH is unknown; however, several mechanisms may be involved in the progression of the disease. Beside surgery and watchful waiting, medical therapies to treat BPH include α-adrenergic antagonist and 5α-reductase inhibitors. Phytotherapeutic agents are also used in some countries. Various other chemical classes of drugs are proposed for the treatment of the disease, but none of them have reached the clinic. Many classes of drugs are currently undergoing clinical trials such as phosphodiesterase inhibitors, luteinizing hormone releasing hormone antagonists and muscarinic receptor antagonists. The current need is to develop a potent, efficacious and highly selective drug for the treatment of BPH.

Anticancer steroids: linking natural and semi-synthetic compounds

Steroids, a widespread class of natural organic compounds occurring in animals, plants and fungi, have shown great therapeutic value for a broad array of pathologies. The present overview is focused on the anticancer activity of steroids, which is very representative of a rich structural molecular diversity and ability to interact with various biological targets and pathways. This review encompasses the most relevant discoveries on steroid anticancer drugs and leads through the last decade and comprises 668 references.

Associations of serum sex steroid hormone and 5α-androstane-3α,17β-diol glucuronide concentrations with prostate cancer risk among men treated with finasteride

BACKGROUND

Finasteride, an inhibitor of 5α-reductase (type II), lowers intraprostatic dihydrotestosterone (DHT), which is reflected in serum as reduced 5α-androstane-3α,17β-diol glucuronide (3α-dG). It also modestly increases serum testosterone (T), estrone (E(1)), and estradiol (E(2)). In this altered hormonal milieu, it is unknown whether serum concentrations of these hormones are associated with prostate cancer risk.

METHODS

In this nested case-control study of men in the finasteride arm of the Prostate Cancer Prevention Trial, sex steroid hormones and sex hormone binding globulin were measured at baseline and approximately 3-year posttreatment in 553 prostate cancer cases and 694 controls.

RESULTS

Median posttreatment changes in concentrations of 3α-dG, T, E(1), and E(2) were -73.8%, +10.1%, +11.2%, and +7.5% (all P < 0.001), respectively. Neither the pre- nor posttreatment concentrations of 3α-dG, nor its change, were associated with risk. Pretreatment, high concentrations of E(1) and low concentrations of T were associated with increased cancer risk [OR; 95% confidence interval (CI) quartile 4 vs. 1: 1.38 (0.99-1.93) P(trend) = 0.03; 0.64 (0.43-0.93) P(trend) = 0.07, respectively]. Posttreatment, high concentrations of both E(1) and E(2) were associated with increased cancer risk [OR; 95% CI quartile 4 vs. 1: 1.54 (1.09-2.17) P(trend) = 0.03; 1.49 (1.07-2.07) P(trend) = 0.02, respectively].

CONCLUSIONS

Among finasteride-treated men, concentrations of 3α-dG were not associated with total or Gleason grades 2 to 6, 7 to 10, or 8 to 10 cancer. High serum estrogens may increase cancer risk when intraprostatic DHT is pharmacologically lowered.

IMPACT

Low posttreatment serum estrogens may identify men more likely to benefit from use of finasteride to prevent prostate cancer.

Effects of Melandrium firmum methanolic extract on testosterone-induced benign prostatic hyperplasia in Wistar rats

Benign prostatic hyperplasia (BPH) is an age-related disease of unknown aetiology characterized by prostatic enlargement coincident with distinct alterations in tissue histomorphology. Instead of therapeutic agents that can cause severe side effects, plant extracts are frequently used to treat BPH. In this study, we investigated whether the Melandrium firmum methanolic extract (MFME) improves BPH, using the testosterone propionate (TP)-induced BPH rat model. Castration was performed via the scrotal route under sodium pentobarbital anaesthesia. BPH in castrated rats was generated via daily subcutaneous injections of TP (3 mg kg(-1)) dissolved in corn oil, for 4 weeks. MFME was administered daily by oral gavage at a dose of 200 mg kg(-1) for 4 weeks, along with the TP injections. The control group received injections of corn oil subcutaneously. At the scheduled termination of the experiment, all rats were killed and their prostates weighed; the relative prostate weight (prostate/body weight ratio) was calculated, and histomorphological changes in the prostate were examined. Additionally, we measured the levels of testosterone and dihydrotestosterone (DHT) in the serum and the prostate. Experimentally induced BPH led to marked decreases in the relative prostate weight and the DHT levels in the serum and the prostate. Histologically, BPH was evident in the ventral lobe of the prostate, and MFME treatment suppressed the severity of the lesions. These results indicate that MFME effectively inhibits the development of BPH induced by testosterone in a rat model. Further studies will be needed to identify the compound(s) responsibility for inducing the protective effect against BPH and determine its mechanism of action.

Bloodless management of benign prostatic hyperplasia: medical and minimally invasive treatment options

Benign prostatic hyperplasia (BPH) is a medical condition affecting a wide range of the aging male population resulting in various degrees of lower urinary tract symptoms (LUTS). Today, a variety of medical therapies and minimally invasive BPH treatment modalities are available. Medical therapy includes α(1) blockers, 5()α reductase inhibitors and combination therapy. When these options fail, surgery is indicated. Transurethral resection of the prostate (TURP) is still considered the gold standard surgical treatment for BPH. Nevertheless, numerous minimally invasive treatment alternatives are available that are comparable in effectiveness to TURP, with significantly less morbidity. In this article, current treatment options for BPH are reviewed with respect to their indications, long-term safety and efficacy in relieving BPH related LUTS. The selection of the type of BPH treatment should be based on the physician's experience, patient's co-morbidities as well as the prostate size and clinical disease progression.

Targeting 5α-reductase for prostate cancer prevention and treatment

Testosterone is the most abundant circulating androgen, and can be converted to dihydrotestosterone (DHT), a more potent androgen, by the 5α-reductase enzymes in target tissues. Current treatments for prostate cancer consist of reducing androgen levels by chemical or surgical castration or pure antiandrogen therapy that directly targets the androgen receptor (AR). Although these therapies reduce tumor burden and AR activity, the cancer inevitably recurs within 18-30 months. An approach targeting the androgen-AR axis at different levels could, therefore, improve the efficacy of prostate cancer therapy. Inhibition of 5α-reductase is one such approach; however, the two largest trials to investigate the use of the 5α-reductase inhibitors (5ARIs) finasteride and dutasteride in patients with prostate cancer have shown that, although the incidence of cancer was reduced by 5ARI treatment, those cancers that were detected were more aggressive than in patients treated with placebo. Thus, the best practice for using these drugs to prevent and treat prostate cancer remains unclear.

Steroid 5 α-reductase inhibitors targeting BPH and prostate cancer

Steroid 5 alpha-reductase inhibitors (5ARIs) have been approved for use clinically in treatment of benign prostate hyperplasia (BPH) and accompanying lower urinary tract symptoms (LUTS) and have also been evaluated in clinical trials for prevention and treatment of prostate cancer. There are currently two steroidal inhibitors in use, finasteride and dutasteride, both with distinct pharmacokinetic properties. This review will examine the evidence presented by various studies supporting the use of these steroidal inhibitors in the prevention and treatment of prostate disease. Article from the Special issue on Targeted Inhibitors.

Finasteride for benign prostatic hyperplasia

BACKGROUND

Benign prostatic hyperplasia (BPH), a non-malignant enlargement of the prostate in aging men, can cause bothersome urinary symptoms (intermittency, weak stream, straining, urgency, frequency, incomplete emptying). Finasteride, a five-alpha reductase inhibitor (5ARI), blocks the conversion of testosterone to dihydrotestosterone, reduces prostate size, and is commonly used to treat symptoms associated with BPH.

OBJECTIVES

To compare the clinical effectiveness and harms of finasteride versus placebo and active controls in the treatment of lower urinary tract symptoms (LUTS).

SEARCH STRATEGY

We searched The Cochrane Library (which includes CDSR (Cochrane Database of Systematic Reviews), DARE (Database of Abstracts of Reviews of Effects), HTA (Heath Technology Assessments), and CENTRAL (Cochrane Central Register of Controlled Trials, and which includes EMBASE and MEDLINE), LILACS (Latin American and Caribbean Center on Health Sciences Information) and Google Scholar for randomized, controlled trials (RCTs). We also handsearched systematic reviews, references, and clinical-practice guidelines.

SELECTION CRITERIA

Randomized trials in the English language with placebo and/or active arms with a duration of at least 6 months.

DATA COLLECTION AND ANALYSIS

JT extracted the data, which included patient characteristics, outcomes, and harms. Our primary outcome was change in a validated, urinary symptom-scale score, such as the AUA/IPSS. A clinically meaningful change was defined as 4 points. We also categorized outcomes by trial lengths of ≤ 1 year (short term) and > 1 year (long term).

MAIN RESULTS

Finasteride consistently improved urinary symptom scores more than placebo in trials of > 1 year duration, and significantly lowered the risk of BPH progression (acute urinary retention, risk of surgical intervention, ≥ 4 point increase in the AUASI/IPSS). In comparison to alpha-blocker monotherapy, finasteride was less effective than either doxazosin or terazosin, but equally effective compared to tamsulosin. Both doxazosin and terazosin were significantly more likely than finasteride to improve peak urine flow and nocturia, versus finasteride. Versus tamsulosin, peak urine flow and QoL improved equally well versus finasteride. However, finasteride was associated with a lower risk of surgical intervention compared to doxazosin, but not to terazosin, while finasteride and doxazosin were no different for risk of acute urinary retention. Two small trials reported no difference in urinary symptom scores between finasteride and tamsulosin. Finasteride + doxazosin and doxazosin monotherapy improved urinary symptoms equally well (≥ 4 point improvement).For finasteride, there was an increased risk of ejaculation disorder, impotence, and lowered libido, versus placebo. Versus doxazosin, finasteride had a lower risk of asthenia, dizziness, and postural hypotension, and versus terazosin, finasteride had a significant, lower risk of asthenia, dizziness, and postural hypotension.

AUTHORS' CONCLUSIONS

Finasteride improves long-term urinary symptoms versus placebo, but is less effective than doxazosin. Long-term combination therapy with alpha blockers (doxazosin, terazosin) improves symptoms significantly better than finasteride monotherapy. Finasteride + doxazosin improves symptoms equally - and clinically - to doxazosin alone. In comparison to doxazosin, finasteride + doxazosin appears to improve urinary symptoms only in men with medium (25 to < 40 mL) or large prostates (≥ 40 mL), but not in men with small prostates (25 mL).Comparing short to long-term therapy, finasteride does not improve symptoms significantly better than placebo at the short term, but in the long term it does, although the magnitude of differences was very small (from < 1.0 point to 2.2 points). Doxazosin improves symptoms better than finasteride both short and long term, with the magnitude of differences ∼2.0 points and 1.0 point, respectively. Finasteride + doxazosin improves scores versus finasteride alone at both short and long term, with mean differences ∼2.0 points for both time points. Finasteride + doxazosin versus doxazosin improves scores equally for short and long term.Drug-related adverse effects for finasteride are rare; nevertheless, men taking finasteride are at increased risk for impotence, erectile dysfunction, decreased libido, and ejaculation disorder, versus placebo. Versus doxazosin, which has higher rates of dizziness, postural hypotension, and asthenia, men taking finasteride are at increased risk for impotence, erectile dysfunction, decreased libido, and ejaculation disorder. Finasteride significantly reduces asthenia, postural hypotension, and dizziness versus terazosin. Finasteride significantly lowers the risk of asthenia, dizziness, ejaculation disorder, and postural hypotension, versus finasteride + terazosin.

Self-organizing molecular field analysis on pregnane derivatives as human steroidal 5alpha-reductase inhibitors

Normal growth and development of human prostate is regulated by the androgens which balances cell proliferation and apoptosis. Testosterone (T) and dihydrotestosterone (DHT) are the two key androgens that stimulate most of the androgen action in prostate. Testosterone is converted to DHT by the membrane bound NADPH-dependent 5alpha-reductase enzyme. As a consequence of the important observation that progesterone and deoxycortisone inhibits the synthesis of DHT by competing with 4-en-3-one function of the testosterone for the 5alpha-reductase enzyme a number of pregnane derivatives were synthesized and have been reported as inhibitors of human 5alpha-reductase enzyme. Due to lack of information on the crystal structure of human 5alpha-reductase, ligand-based 3D-QSAR study has been performed on pregnane derivatives using self-organizing molecular field analysis (SOMFA) for rationalizing the molecular properties and human 5alpha-reductase inhibitory activities. The statistical results having good cross-validated r(cv)(2) (0.881), non-cross-validated r(2) (0.893) and F-test value (175.527), showed satisfied predictive ability r(pred)(2) (0.777). Analysis of SOMFA models through electrostatic and shape grids provide useful information for the design and optimization of steroidal structure as novel human 5alpha-reductase inhibitors.

Therapeutic options in the treatment of benign prostatic hyperplasia

Current theraputic options for the treatment of symptomatic benign prostatic hyperplasia (BPH) are reviewed. Therapeutic options for mild lower urinary tract symptoms (LUTS), as defined by the American Urological Association, are generally treated medically. Moderate to severe LUTS can be treated medically or with surgical therapy. Current medical and surgical treatments for LUTS secondary to BPH are reviewed and evolving treatments are explored.

[Conservative treatment of benign prostatic hyperplasia]

Medical treatment of benign prostatic hyperplasia is reviewed by the author. Experiences with herbal extracts have been known for more than 2 decades. Treating benign prostatic hyperplasia with these extracts is recommended in initial phase. Prostate volume is decreased and mechanical component of dysuria is improved by treating for a long time (months, years) with 5-alpha-reductase finasteride which contains hormone. This drug is indicated when volume of the prostate is over 40 g. Dynamical component of benign prostatic hyperplasia is treated with alpha-receptor blockers which act on the bladder neck. These medicines have effects earlier and are recommended for all patients with benign prostatic hyperplasia independently of prostate volume. These might have some side effects like hypotension. The improving effects of 5-phosphodiesterase inhibitors on BPH have been discovered recently. The same effect has been described of alpha-blockers on sexual activity.

Inhibitory effect of traditional Chinese medicine Zi-Shen Pill on benign prostatic hyperplasia in rats

In the present study, we investigate the effects of an extract isolated from traditional Chinese medicine Zi-Shen Pill (ZSPE) on benign prostatic hyperplasia (BPH) in rats induced by testosterone after castration. A total of 50 rats were equally divided into five groups: Group 1 served as control (sham-operated group); Group 2 was model group; Group 3 and Group 4 animals were administered with ZSPE at dose levels of 300 mg/kg and 600 mg/kg; Group 5 was served as positive control group and treated with finasteride at a dose of 1 mg/kg. The drugs were administered orally once a day for 28 days consecutively. The prostate weight, prostatic index, and serum dihydrotestosterone (DHT) levels were significantly reduced and the pathological changes in BPH were also by ameliorated ZSPE. Immunohistochemical examination revealed that the expressions of vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) in prostate were inhibited by ZSPE treatment, whereas the levels of transforming growth factor-beta1 (TGF-beta1) were increased. These results suggest that ZSPE has a definite inhibitory effect on BPH and might be an alternative medicine for treatment of human BPH.

Advances in the development of hormonal modulators for the treatment of benign prostatic hyperplasia

Benign prostatic hyperplasia (BPH) is a leading disorder of the ageing male population and is characterized by a progressive enlargement of the prostate, resulting in the obstruction of the proximal urethra and hence the disturbance in normal urinary flow and further quality of life of the patients. Therefore, there is an imperative need to develop a therapeutic modality to combat the overgrowth of the prostate with improvements in both the urinary flow rate and the quality of life of the patients. At present, alpha-blockers, which act on the dynamic component of the disease to regulate the increased adrenergic tone of the lower urinary tract smooth muscles, and 5-alpha-reductase inhibitors, which control the overgrowth of the prostate and hence static component by regulating the levels of androgens, are the mainstay of therapies for the treatment of BPH and associated lower urinary tract symptoms. However, each target class has its own limitations in terms of compromised efficacy or tolerability. Therefore, it is pertinent to have an effective and safe therapeutic modality for the further improvement of life of the geriatric male population. Hormone modulators, which regulate the overgrowth of the prostate, represent one of the important categories that have been explored and that is still undergoing certain investigations towards the development of a therapeutic entity for the treatment of BPH. The key lies in achieving the differentiation in terms of improved tolerability with comparable or better efficacy over the existing class of drugs. Gonadotropin receptor modulators and vitamin D receptor agonists may represent promising druggable targets in this therapeutic area, due to the availability of proof of principles and concepts in preclinical animal models and human subjects.

Finasteride and doxazosin alone or in combination for the treatment of benign prostatic hyperplasia

Benign prostatic hyperplasia is an increasingly prevalent condition affecting > 50% of men > 65 years of age. Although it is a condition that is unlikely to be life threatening, it can significantly affect quality of life with distressing lower urinary tract symptoms. Increasingly, medical therapy is being used as first-line treatment for men with moderate-to-severe lower urinary tract symptoms. Two main pharmacological classes of drugs are used: 5alpha-reductase inhibitors and alpha-1 selective blockers. Both these classes of drugs have shown good tolerability and clinical efficacy. This article examines the potential benefit of the use of combination therapy. In particular, what is the evidence for using doxazosin and finasteride therapy together?

Diagnosis of prostatic carcinoma after therapy

CONTEXT

Prostate cancer is the most common cancer of men in the United States and is third only to lung and colon cancer as a cause of cancer death. In 2006, 27,350 Americans will die of prostate cancer, and 234,460 new cases will be diagnosed. Treatment changes in the benign and cancerous prostate create diagnostic challenges in pathologic interpretation, particularly in needle biopsy specimens and in evaluation of extraprostatic metastases.

OBJECTIVE

To summarize therapy-related pathologic findings in the prostate with emphasis on recognition of treated adenocarcinoma.

DATA SOURCES

Extensive review of published literature and the authors' experience.

CONCLUSIONS

Following therapy for prostate cancer, it is critical that the clinician provide the pertinent history of androgen deprivation or radiation therapy to assist the pathologist in rendering the correct diagnosis.

Dutasteride Improves Objective and Subjective Disease Measures in Men With Benign Prostatic Hyperplasia and Modest or Severe Prostate Enlargement

PURPOSE

We determined whether the effect of dutasteride for benign prostatic hyperplasia is influenced by baseline prostate volume using data from 3 phase III clinical trials.

MATERIALS AND METHODS

Patients randomized to dutasteride or placebo in the double-blind portion of the phase III studies were eligible to receive 0.5 mg dutasteride daily in a 2-year open label extension in dutasteride/dutasteride and placebo/dutasteride groups. Patients were prospectively stratified according to baseline prostate volume 30 to less than 40 and 40 cc or greater.

RESULTS

In patients treated with dutasteride throughout the study (dutasteride/dutasteride group) the mean reduction in prostate volume from baseline to month 48 was 30.3% in those with a baseline prostate volume of 30 to less than 40 cc and 26.2% in those with a prostate volume of 40 cc or greater. Mean improvements in peak urinary flow from baseline to month 48 were 2.7 ml per second regardless of baseline prostate volume. Improvements in the American Urological Association symptom index score were 6.3 in men with a prostate volume of 30 to less than 40 cc and 6.5 in those with a prostate volume of 40 cc or greater. No significant relationships between treatment effect and baseline prostate volume were observed for these parameters. In dutasteride/dutasteride treated patients the risk of acute urinary retention was decreased by 60% in those with a prostate volume of 30 to less than 40 cc and 55% in those with a prostate volume of 40 cc or greater vs values in placebo/dutasteride treated patients (p = 0.036 and <0.001, respectively). The corresponding values for benign prostatic hyperplasia related surgery were 27% and 48% (p = 0.35 and <0.001, respectively).

CONCLUSIONS

This analysis demonstrates that dutasteride significantly improves objective (prostate volume and peak urinary flow) and subjective (symptom scores) measures even in patients with only a slightly enlarged prostate (30 to less than 40 cc). The risks of acute urinary retention and benign prostatic hyperplasia related surgery were decreased regardless of baseline prostate volume.

Saw palmetto and lower urinary tract symptoms: What is the latest evidence?

The use of dietary supplements for treating a wide range of health conditions has grown rapidly in the United States. In the field of men's health, the most common dietary supplement used is an extract of the berry of the saw palmetto plant, with which men commonly self-medicate in order to treat lower urinary tract symptoms. Throughout the past two decades, substantial literature has emerged examining the biologic and clinical effects of saw palmetto extracts. Several lines of evidence suggest that saw palmetto may exert physiologic effects consistent with a beneficial clinical effect on the mechanisms of benign prostatic hyperplasia. Although most clinical studies tend to suggest a modest efficacy benefit of saw palmetto, more recent studies are less consistent and the precise clinical value of saw palmetto for treating lower urinary tract symptoms remains undefined. Overall, there appear to be few safety concerns with short-term use of this herbal medicine, although large-scale and longer-term safety studies have not been performed. Higher-quality studies are currently underway to better define the potential benefits and risks of plant-based extracts for treating symptoms related to benign prostatic hyperplasia.

Finasteride targets prostate vascularity by inducing apoptosis and inhibiting cell adhesion of benign and malignant prostate cells

BACKGROUND

This study investigated the effects of finasteride, a 5alpha-reductase inhibitor, clinically used for the treatment of benign prostatic hyperplasia (BPH) on prostate tumor vascularity, apoptosis, and cell adhesion in situ and in vitro.

METHODS

Prostate specimens from BPH patients treated with finasteride for 1-12 months (n = 13), or without finasteride treatment (n = 14), were evaluated for apoptosis (TUNEL assay), microvessel density (Factor VIII), and prostate specific antigen (PSA) immunoreactivity. In vitro, the effect of finasteride was investigated in benign prostate cells, BPH-1, and its tumorigenic derivatives, CAFTD-01 and CAFTD-03, using Hoechst staining and cell adhesion assays.

RESULTS

A significant increase in the apoptotic index, and reduced microvessel density and PSA expression were detected in prostates from finasteride-treated patients, compared to controls (P < 0.01). In vitro finasteride led to a significant decrease in prostate epithelial cell adhesion (P < 0.05).

CONCLUSIONS

Finasteride can induce prostate apoptosis and reduce tissue vascularity by inhibiting epithelial cell adhesion. This evidence supports that finasteride has apoptotic and anti-angiogenic effects against benign and malignant prostate.

Combination therapy for the pharmacological management of benign prostatic hyperplasia: rationale and treatment options

The management of symptomatic benign prostatic hyperplasia (BPH) continues to evolve, with new techniques and forms of medical management being introduced and traditional surgical techniques being used less frequently. Medical management of BPH has evolved from nonspecific alpha-adrenoceptor antagonists to uroselective alpha-adrenoceptor antagonists and 5-alpha reductase inhibitors. Traditionally, alpha-adrenoceptor antagonists have been used for relief of lower urinary tract symptoms (LUTS) as a result of BPH and are known for their quick onset of action. 5-alpha Reductase inhibitors have proven useful for the prevention of BPH progression as measured by prostate volume, disease progression, incidence of acute urinary retention and the need for subsequent BPH-related surgery. Recent studies have shown that the combination of an alpha-adrenoceptor antagonist and a 5-alpha reductase inhibitor has significantly better efficacy than either drug alone or placebo. Currently, alpha-adrenoceptor antagonists are used in the acute setting or for short-term relief of LUTS. The combination of an alpha-adrenoceptor antagonist and a 5-alpha reductase inhibitor is used for the longer term management of BPH symptoms and to prevent progression of BPH and perhaps avoid surgical intervention.

Patients with a large prostate show a higher prevalence of androgenetic alopecia

Androgenetic alopecia (AGA) and benign prostatic hyperplasia (BPH) are both androgen-dependent disorders, displaying in situ high levels of dihydrotestosterone with a good therapeutic response to finasteride. Embryological development of both the hair follicle and the prostate depends on mesenchymal-epithelial interaction, which is influenced by the expression of type 2 5alpha-reductase. The aim of this study was to elucidate the association between the size of the prostate gland and the prevalence and severity of AGA. A total of 46 patients age between 56 and 87 years were retrospectively recruited. They fulfilling the clinical diagnosis of BPH defined as (1) prostate volume > 30 cm3, measured by transrectal ultrasound, (2) maximal urine flow rate < 15 ml/s and mean urine flow rate < 10 ml/s, and (3) prostate serum albumin < 10 ng/ml. The control group comprised 34 patients aged between 49 and 81 years with urogenital infection, cystitis or urolithiasis. The expression and severity of AGA were evaluated by dermatologists using modified Norwood/Hamilton classification. Patients with a prostate volume > 30 cm3 had a higher prevalence of AGA than patients with a smaller prostate (< 30 cm3) (83.3% vs 61.3%; P < 0.05). The prostate size, however, did not correlate with the severity of AGA in either group or in the whole patient group. The prevalence of AGA was not significantly different in patients with or without BPH (85.7% vs 70.6%). The prostate was slightly larger among patients with AGA than among those without AGA (mean+/-SD 42.7+/-17.4 vs 35.4+/-14.9 cm3), but this was not statistically significant. There was no significant correlation between the age of onset of AGA and the development of BPH. Our results suggest that a larger prostate is associated with a higher prevalence of AGA. It remains to be seen if long-term use of finasteride in AGA patients will prophylactically lower the incidence of BPH.

Prevention of Hormone-Related Cancers: Prostate Cancer

Androgens are known to play an important role in normal prostate development, benign prostatic hyperplasia, established prostate cancer, and in prostate carcinogenesis. However, despite convincing experimental and clinical evidence, the epidemiologic data correlating sex steroid levels with disease risk is inconsistent. More recent work has focused on studies of polymorphisms in germ-line DNA in an effort to develop polygenic models of prostate cancer susceptibility and prognosis. Such models have the potential to aid in the selection of men for specific chemopreventive interventions and to help determine which men with localized prostate cancer are most likely to benefit from aggressive therapy. In this review, we will provide a brief summary of androgen metabolic pathways followed by an assessment of the epidemiology literature addressing the relationship between androgens and prostate cancer. Finally, we will address the two major questions that have arisen in response to the recently published results from the Prostate Cancer Prevention Trial: Who are the best candidates for finasteride chemoprevention, and what are the clinical implications of the high prevalence of prostate cancer that was detected in men with prostate-specific antigen levels in the so-called “normal” range?

The dual 5-alpha-reductase inhibitor dutasteride induces atrophic changes and decreases relative cancer volume in human prostate

OBJECTIVES

To perform the first evaluation of the effects of the 5-alpha-reductase inhibitor class of drugs on cancer histopathologic features at radical prostatectomy in a placebo-controlled multicenter trial.

METHODS

We analyzed prostatectomy slides in a blinded manner from 17 men treated with dutasteride, an inhibitor of types 1 and 2 isoenzymes of 5-alpha-reductase, and 18 men treated with placebo for 5 to 11 weeks before radical prostatectomy. The histopathologic features of benign epithelium, high-grade prostatic intraepithelial neoplasia, and cancer were recorded, and the treatment effect was scored. Digital imaging analysis was used to measure the stroma/epithelium ratio and epithelial height, as well as the nuclear area in cancer.

RESULTS

In benign epithelium, treatment caused distinctive cytoarchitectural changes of atrophy and a decrease in the epithelial height (P = 0.053). The peripheral zone showed the most marked response to treatment. In cancer tissue, the tumor volume was significantly lower in the dutasteride-treated men than in the placebo-treated men (mean 15% versus 24%, respectively, P = 0.025), the percentage of atrophic epithelium was increased (P = 0.041), and the stroma/gland ratio was doubled (P = 0.046). The treatment alteration effect score was doubled (P = 0.055) and did not correlate with any Gleason score changes.

CONCLUSIONS

After short-term dutasteride treatment, benign epithelium showed involution and epithelial shrinkage, and prostate cancer tissue demonstrated a decrease in epithelium relative to stroma. These findings indicate that dutasteride induces significant phenotypic alterations in both the benign and the neoplastic prostate, supportive of a chemopreventive or chemoactive role.

Benign prostatic hyperplasia

Benign prostatic hyperplasia (BPH) is a common condition, which increases with increasing age. Although not a life-threatening condition, BPH can significantly affect quality of life. BPH manifests clinically with lower urinary tract symptoms (LUTS) and may be associated with sexual dysfunction. As many as 60% of men aged 60 years have some degree of clinical BPH. With the projected increases in the distribution of people over the age of 60, BPH isset to become an even greater problem in men's health.

Efficacy and Safety of Long-Term Treatment with the Dual 5α-Reductase Inhibitor Dutasteride in Men with Symptomatic Benign Prostatic Hyperplasia

OBJECTIVES

Dutasteride, a dual inhibitor of Type 1 and Type 2 5 alpha-reductase, has been shown to improve disease measures in patients with symptomatic benign prostatic hyperplasia (BPH) in three randomised, placebo-controlled, large-scale, 2-year Phase III clinical studies. This paper reports the pooled results of a 2-year open-label extension of the three randomised studies assessing the long-term efficacy and safety of dutasteride.

METHODS

Patients randomised to dutasteride or placebo in the double-blind portion of the Phase III studies were eligible for a 2-year open-label extension, where all patients received dutasteride 0.5mg daily (dutasteride/dutasteride [D/D] group and placebo/dutasteride [P/D group]).

RESULTS

Significant improvements in AUA-SI score and Q(max) were observed from Month 24 to 48 in both study groups. At Month 48, patients in the D/D group had significantly greater improvements in AUA-SI score and Q(max), and significantly greater reductions in prostate volume, than those in the P/D group. Acute urinary retention and BPH-related surgery occurred in a small percentage of patients during the open-label phase. No new safety issues were noted with long-term therapy. Onset of new drug-related adverse events were reported most frequently at the start of therapy and declined over time in patients receiving dutasteride.

CONCLUSIONS

Long-term treatment with dutasteride results in continuing improvements in urinary symptoms and flow rate, and further reductions in TPV, in men with symptomatic BPH. The reduction in risk of AUR and BPH-related surgery, seen in the double-blind phase, was durable over 4-year treatment. Dutasteride was also well tolerated in long-term use.

Does Finasteride Alter the Pathology of the Prostate and Cancer Grading?

All forms of androgen-deprivation therapy, including finasteride, induce distinctive histologic changes in benign and neoplastic prostatic epithelial cells, including cytoplasmic clearing, nuclear and nucleolar shrinkage, and chromatin condensation. Treated cancer has a significantly higher architectural (Gleason) grade, lower nuclear grade, and smaller nucleolar diameter than untreated controls, creating the potential for grading bias. Recognition of these changes may be difficult in needle biopsies and lymph node metastases with treated cancer because of the subtle infiltrative pattern and inconspicuous nucleoli. The effects of finasteride may be less pronounced than other forms of therapy with variable distribution throughout the prostate; further, there may be greater sensitivity of low and intermediate-grade cancer than high-grade cancer. The Gleason grading system for cancer should not be used after finasteride treatment as it is not validated in this setting and is likely to overestimate the biologic potential of high-grade cancer observed after therapy. Chemoprevention trials with agents such as finasteride that alter morphology should not rely on cancer grading as a secondary endpoint owing to grading bias.