Effect of dutasteride on the detection of prostate cancer in men with benign prostatic hyperplasia

Effect of dutasteride on intraprostatic androgen levels in men with benign prostatic hyperplasia or prostate cancer

OBJECTIVES

Dutasteride exerts its beneficial effects on the prostate through suppression of intraprostatic dihydrotestosterone (DHT). The aim of this analysis was to assess the effects of the approved dose of dutasteride (0.5 mg/d), given for 2 weeks to 4 months, on the serum and intraprostatic DHT and testosterone levels in 3 randomized studies.

METHODS

Intraprostatic androgen levels were measured in benign prostatic tissue collected during transurethral resection of the prostate (benign prostatic hyperplasia studies, n = 256) or radical prostatectomy (prostate cancer study, n = 51), performed after 2 weeks, or 1, 3, or 4 months of treatment with dutasteride or with placebo or surgery alone. The serum androgen levels were assessed at the same points during treatment. Data from the control groups were pooled to provide 1 comparison group.

RESULTS

Dutasteride reduced the intraprostatic DHT levels by 83%, 90%, 92%, and 93% after 2 weeks and 1, 3, and 4 months of treatment, respectively, compared with placebo/surgery alone. Dutasteride reduced the serum DHT levels from baseline by 84% at 2 weeks and by approximately 90% at 1, 2, 3, and 4 months compared with a 5.2% increase in the control group. The decrease in DHT levels with dutasteride was accompanied by a reciprocal increase in the serum and intraprostatic testosterone levels. However, the intraprostatic testosterone levels in the dutasteride groups generally remained lower than the intraprostatic DHT levels in the control group.

CONCLUSIONS

The results of our study have shown that dutasteride provides near-maximal suppression of both serum and intraprostatic DHT levels in men with benign prostatic hyperplasia or prostate cancer at all points assessed.

The REDUCE trial: chemoprevention in prostate cancer using a dual 5alpha-reductase inhibitor, dutasteride

Dutasteride, a dual 5alpha-reductase inhibitor, is used in the treatment of benign prostatic hyperplasia (BPH). It reduces serum prostate-specific antigen levels by approximately 50% at 6 months and total prostate volume by 25% after 2 years. Randomized placebo-controlled trials in BPH patients have shown the efficacy of dutasteride in symptomatic relief, improvements in quality of life and peak urinary flow rate. Side effects occurring with dutasteride are decreased libido, erectile dysfunction, ejaculation disorders and gynecomastia. Preliminary data from placebo-controlled BPH trials have shown a decrease in the detection of prostate cancer in patients treated with dutasteride, although these studies were not designed to look at this issue. Dutasteride differs from finasteride in that it inhibits both isoenzymes of 5alpha-reductase, type I and type II. The landmark Prostate Cancer Prevention Trial at the end of the 7-year study demonstrated a 24.8% reduction in the incidence of prostate cancer in the finasteride group compared with placebo. However, a 25.5% increase in the prevalence of high-grade Gleason tumors has been observed, the clinical significance of which has been debated. Preliminary data suggest a decrease in prostate cancer incidence in dutasteride-treated patients and demonstrate type I alphareductase enzyme expression in prostate cancer. As a result, dutasteride is being investigated for prostate cancer prevention in the ongoing Reduction by Dutasteride of Prostate Cancer Events (REDUCE) trial, which is discussed here.

Five-alpha-reductase Inhibitors for prostate cancer prevention

BACKGROUND

Five-alpha-reductase inhibitors (5ARI) are frequently used to treat bothersome lower urinary tract symptoms associated with benign prostatic hyperplasia and male androgenic alopecia. They have potential as chemopreventive agents.

OBJECTIVES

We sought to estimate the effectiveness and harms of 5ARI in preventing prostate cancer.

SEARCH STRATEGY

MEDLINE, PreMEDLINE, and the Cochrane Collaboration Library were searched through April 2007 to identify randomized trials.

SELECTION CRITERIA

For prostate cancer outcomes we included randomized controlled trials of at least 1 year in duration published after 1984. For non-prostate cancer outcomes, randomized trials were included if: they were at least 6 months in duration published after 1999.

DATA COLLECTION AND ANALYSIS

The primary outcome was prostate cancer period-prevalence "for-cause." "For-cause" was defined as prostate cancer clinically detected based on symptoms, an abnormal digital rectal exam, or detected as a result of an abnormal prostate specific antigen value. Trials were categorized as long (> 2 year), mid (1-2 years) and short (< 1 year) term.

MAIN RESULTS

Nine trials reported prostate cancer period-prevalence. Three trials using finasteride lasted 4 years or longer but only one (the Prostate Cancer Prevention Trial) was specifically designed to assess the impact of 5ARI on prostate cancer period-prevalence. The mean age of enrollees was 64.6 years, 91% were white, mean PSA was 2.1 ng/mL. For-cause prostate cancers comprised 54% of all cancers detected. Finasteride was associated with a 26% relative risk reduction in prostate cancers detected for-cause among all randomized subjects (relative risk 0.74 [95% CI 0.67 to 0.83]; absolute risk reduction = 1.4% (3.5% versus 4.9%). Six trials assessed prostate cancers detected overall with a pooled 26% relative reduction favoring 5ARI (relative risk 0.74 [95% CI 0.55 to1.00]; 2.9% absolute reduction (6.3% versus 9.2%). Reductions were observed regardless of age, race or family history of prostate cancer but not among men with baseline PSA > 4.0 ng/mL. A greater number of high Gleason score tumors (7-10 or 8-10) occurred in men on finasteride in the PCPT. Impaired sexual or erectile function or endocrine effects were more common with finasteride than placebo.

AUTHORS' CONCLUSIONS

5ARI reduce prostate cancer risk but may increase the risk of high-grade disease in men who are undergoing regular screening for prostate cancer using prostate specific antigen and digital rectal examination. Effects are consistent across race, family history and age and possibly 5ARI but were limited to men with baseline PSA values <4.0 ng/mL. The impact of 5ARI on absolute or relative rates of prostate cancer in men who are not being regularly screened is not clear. Information is inadequate to assess the impact of 5ARI on mortality.

5alpha-reductase inhibitors in benign prostatic hyperplasia and prostate cancer risk reduction

Androgens play an essential role in prostatic development and function, but are also involved in prostate disease pathogenesis. The primary prostatic androgen, dihydrotestosterone (DHT), is synthesized from testosterone by 5alpha-reductase types 1 and 2. Inhibition of the 5alpha-reductase isoenzymes therefore has potential therapeutic benefit in prostate disease. The two currently approved 5alpha-reductase inhibitors (5ARIs), finasteride and dutasteride, have demonstrated long-term efficacy and safety in the treatment of benign prostatic hyperplasia. Finasteride, a type-2 5ARI, has also been studied for its ability to reduce the incidence of biopsy-detectable prostate cancer in the Prostate Cancer Prevention Trial. Treatment with dutasteride, a dual 5ARI, has been shown to result in a greater degree and consistency of DHT suppression compared with finasteride. Two large-scale studies of dutasteride are currently investigating the role of near-maximal DHT suppression in the settings of prostate cancer risk reduction and expectant management of localized prostate cancer.

The rationale for inhibiting 5alpha-reductase isoenzymes in the prevention and treatment of prostate cancer

PURPOSE

Androgens are essential for prostatic growth and development but they also have a significant role in prostate disease pathogenesis. Dihydrotestosterone, the primary prostatic androgen, is transformed from testosterone by types 1 and 2 5alpha-reductase and, thus, a potential therapeutic benefit could be achieved through the inhibition of 5alpha-reductase.

MATERIALS AND METHODS

A literature review was performed using PubMed/MEDLINE and congress abstracts to examine evidence supporting the potential of 5alpha-reductase inhibitors in the primary prevention of prostate cancer and in limiting the progression of diagnosed disease.

RESULTS

Prostate disease development is associated with increased expression of each 5alpha-reductase isoenzyme with over expression of type 1 of particular importance in prostate cancer development and progression. The 2 5alpha-reductase inhibitors currently clinically available are finasteride, a type 2 5alpha-reductase inhibitor, and dutasteride, a dual 5alpha-reductase inhibitor. Dual inhibition by dutasteride has been shown to translate into a greater degree and consistency of dihydrotestosterone suppression compared with finasteride. The Prostate Cancer Prevention Trial showed that finasteride significantly decreased the 7-year risk of prostate cancer in men with prostate specific antigen 3.0 ng/ml or less, while the ongoing Reduction by Dutasteride of Prostate Cancer Events study is assessing whether dutasteride decreases the risk of biopsy detectable prostate cancer in men with prostate specific antigen 2.5 to 10 ng/ml and a previous negative biopsy. Small-scale studies have demonstrated potential effects of 5alpha-reductase inhibition in prostate cancer treatment that warrant further investigation, while dutasteride use in men undergoing expectant treatment is also being examined.

CONCLUSIONS

The inhibition of 5alpha-reductase represents a valid target for prostate cancer risk reduction and treatment strategies. The greater suppression of dihydrotestosterone observed with agents that inhibit each 5alpha-reductase isoenzyme may translate into enhanced outcomes and studies are under way to test this hypothesis.

The effects of dutasteride, tamsulosin and combination therapy on lower urinary tract symptoms in men with benign prostatic hyperplasia and prostatic enlargement: 2-year results from the CombAT study

PURPOSE

We investigated whether combination therapy with dutasteride and tamsulosin is more effective than either monotherapy alone for improving symptoms and long-term outcomes in men with moderate to severe lower urinary tract symptoms and prostatic enlargement (30 cc or greater). We report preplanned 2-year analyses.

MATERIALS AND METHODS

The CombAT study is an ongoing, multicenter, randomized, double-blind, parallel group study. Men 50 years or older with a clinical diagnosis of benign prostatic hyperplasia, International Prostate Symptom Score 12 points or greater, prostate volume 30 cc or greater, total serum prostate specific antigen 1.5 ng/ml or greater to 10 ng/ml or less and peak urinary flow greater than 5 to 15 ml per second or less with a minimum voided volume of 125 ml or greater were randomized to 0.5 mg dutasteride, 0.4 mg tamsulosin or the combination once daily for 4 years. Symptoms were assessed every 3 months and peak urinary flow was assessed every 6 months. The primary end point at 2 years was the change in International Prostate Symptom Score from baseline.

RESULTS

Combination therapy resulted in significantly greater improvements in symptoms vs dutasteride from month 3 and tamsulosin from month 9, and in benign prostatic hyperplasia related health status from months 3 and 12, respectively. There was a significantly greater improvement from baseline in peak urinary flow for combination therapy vs dutasteride and tamsulosin monotherapies from month 6. There was a significant increase in drug related adverse events with combination therapy vs monotherapies, although most did not result in the cessation of therapy.

CONCLUSIONS

In men with moderate to severe lower urinary tract symptoms and prostate enlargement (30 cc or greater) combination therapy provides a significantly greater degree of benefit than tamsulosin or dutasteride monotherapy.

Delay in the progression of low-risk prostate cancer: Rationale and design of the Reduction by Dutasteride of Clinical Progression Events in Expectant Management (REDEEM) trial

PURPOSE

Men with prostate cancer may live as long as men their age without prostate cancer. Those with low-risk disease may benefit from expectant management, which actively monitors disease progression. Dutasteride, a dual 5alpha-reductase inhibitor (5ARI), may delay prostate cancer progression or extend the time to initiation of more aggressive therapy.

MATERIALS AND METHODS

The Reduction by Dutasteride of Clinical Progression Events in Expectant Management (REDEEM) trial will evaluate whether dutasteride decreases time to prostate cancer progression. Three hundred candidates for expectant management with biopsy-proven, low-risk, localized prostate cancer will receive dutasteride 0.5 mg/day or placebo for 3 years. Eligible men are between 50 and 80 years of age, have clinical stage T1c-T2a prostate cancer, a Gleason score of less than or equal to 6, and serum prostate-specific antigen (PSA) less than or equal to 10 ng/mL. Entry biopsy of at least 10 cores had to be performed within 6 months of screening and will be repeated at 1.5 and 3 years. Men will complete questionnaires to measure symptoms, quality of life (QOL), and anxiety. Because PSA is an important monitoring tool in expectant management that may impact patients' comfort levels, actual PSA values will be provided to physicians and subjects. Time-to-disease progression (primary therapy for prostate cancer or pathologic progression), positive cores, change in Gleason score, and QOL assessments will be compared between groups.

RESULTS

The trial completed recruitment of 302 subjects in March 2007. The study will be completed in 2010.

CONCLUSIONS

The REDEEM study will evaluate the potential for dutasteride to delay disease progression in men with low-risk, localized prostate cancer. This study will better define which patients with prostate cancer can be managed with less invasive and potentially less debilitating therapy.

Effects of dutasteride on prostate growth in the large probasin-large T antigen mouse model of prostate cancer

PURPOSE

We evaluated the effects of dutasteride for preventing or delaying prostate growth and neoplastic changes in a transgenic model of prostate cancer.

MATERIALS AND METHODS

Large probasin-large T antigen mice were treated for 4 or 8 weeks with dutasteride. The prostate and seminal vesicles were compared with those from intact and castrated large probasin-large T antigen mice and WT mice.

RESULTS

Dutasteride greatly decreased the transgene induced increase in prostate weight but castration caused greater reduction. Dutasteride inhibited type 1 and 2, 5alpha-reductase activities, decreased DNA and protein, and increased apoptotic bodies and TUNEL staining in the dorsolateral prostate. No evidence of poorly differentiated cancer was seen. Dutasteride did not decrease the weight of the androgen dependent levator ani or bulbocavernosus muscle.

CONCLUSIONS

Dutasteride inhibited type 1 and 2, 5alpha-reductase activities, and decreased DNA and protein content of the dorsolateral prostate without affecting androgen responsive muscle weight in large probasin-large T antigen mice. These studies provide support for the hypothesis that a 5alpha-reductase inhibitor inhibits the initiation and/or progression of clinical prostate cancers.

Chemoprevention of prostate cancer: agents and study designs

PURPOSE

With the completion of the Prostate Cancer Prevention Trial and the ongoing performance of several additional large-scale prostate cancer prevention trials interest in this intervention has increased. We review promising agents for prostate cancer prevention, clinical trial designs and how these agents may be used clinically.

MATERIALS AND METHODS

We reviewed current and completed randomized chemoprevention trials for prostate cancer as well as the most promising agents for which evidence suggests that a decreased prostate cancer risk may result from their use.

RESULTS

Evidence suggests that lycopene, decreased dietary fat, antioxidants such as alpha-tocopherol and selenium, nonsteroidal anti-inflammatory drugs and selective estrogen receptor modulators such as toremifene and 5alpha-reductase inhibitors may prove useful for decreasing the risk of prostate cancer in a man. Ongoing studies are examining these agents in the 3 general scenarios of 1) general population studies (finasteride, alpha-tocopherol and selenium), 2) increased prostate specific antigen with negative biopsy (dutasteride) and 3) prostatic intraepithelial neoplasia (toremifene and selenium).

CONCLUSIONS

There are many agents that may decrease the risk of prostate cancer. It requires careful study of the agents in specific populations to determine whether risk is reduced, the magnitude of the risk reduction and the spectrum of side effects associated with the agent. Physicians caring for men entering the range of age of prostate cancer risk must be aware of these preventive opportunities.

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.

Prevention of benign prostatic hyperplasia disease

PURPOSE

We reviewed the evidence that benign prostatic hyperplasia is a progressive condition and men at risk for benign prostatic hyperplasia disease can be identified, treated and protected to a meaningful extent regardless of symptom status.

MATERIALS AND METHODS

The MEDLINE database was searched in 4 areas of interest relating to benign prostatic hyperplasia, including 1) progression of clinical manifestations with age, especially in regard to baseline symptom status, 2) the incidence of complications due to disease progression, 3) the use of predictive factors that may help identify men at risk for disease progression and 4) the prevention of benign prostatic hyperplasia disease with medical therapy.

RESULTS

Tissue changes in the prostate (benign prostatic hyperplasia) are inevitable consequences of aging. However, benign prostatic hyperplasia disease, which we define as a life altering urinary condition requiring medical intervention, is predictable and preventable. Benign prostatic hyperplasia disease progression is associated with increasing prostate volume, decreasing urinary flow, symptomatic deterioration often to the point of major life-style interference and serious complications, eg acute urinary retention and the need for surgery. The risk of benign prostatic hyperplasia disease progression was found to be directly related to prostate volume and its surrogate marker, serum prostate specific antigen, after prostate cancer is excluded. Other factors, eg baseline symptoms and the flow rate, were found to be less relevant compared with prostate specific antigen greater than 1.5 ng/ml for predicting benign prostatic hyperplasia disease morbidity.

CONCLUSIONS

Men at risk for benign prostatic hyperplasia disease can be identified using prostate specific antigen greater than 1.5 ng/ml as a surrogate marker of prostate volume. In men at risk with prostate specific antigen greater than 1.5 ng/ml 5alpha-reductase inhibitors have potential value for benign prostatic hyperplasia disease prevention regardless of symptom status.

Should finasteride be used to prevent prostate cancer?

Prostate cancer is an important public health problem. Chemoprevention offers an attractive solution because it may lead to decreased disease-specific mortality. Furthermore, because many men are treated radically for prostate cancers that pose little or no threat to life, chemoprevention may also provide an excellent strategy for diminishing treatment-related costs and adverse effects such as erectile and urinary dysfunction. The Prostate Cancer Prevention Trial was a 7-year randomized study of finasteride versus placebo among men aged older than 55 years. All men were intended to have a prostate biopsy at study conclusion. At trial's end, there was a 25% reduction in period prevalence in all prostate cancers (24.4% for placebo vs 18.4% for finasteride). This represents a 6% absolute risk reduction. A larger number of higher-grade cancers were noted among men randomized to finasteride, which post hoc analyses and studies suggest are almost certainly related to previously unrecognized biases in trial design. There continues to be great debate as to the clinical significance of the cancers prevented. It is our opinion that among men who warrant 5-alpha reductase inhibitors (5ARIs) as part of their benign prostatic hyperplasia regimen, cancer prevention should be recognized as an additional benefit of treatment. Furthermore, men with high risk of clinically significant prostate cancer, such as significant family history, abnormal prostate biopsy histologies, and African descent, should be made aware of these findings. Men with significant anxiety or concern about prostate cancer should also be made aware of the risks and benefits of this therapy. Additional trials of antiestrogens, micronutrients, and other 5ARIs, which will mature over the next 2 to 5 years, will better define the role of 5ARIs in prostate cancer chemoprevention.

The effects of 5alpha-reductase inhibitors on the natural history, detection and grading of prostate cancer: current state of knowledge

PURPOSE

The Prostate Cancer Prevention Trial (PCPT) showed that the 5alpha-reductase inhibitor (5ARI) finasteride significantly decreased the 7-year period prevalence of prostate cancer vs placebo. However, Gleason score 7-10 tumors were significantly more common in the finasteride vs the placebo group. We considered data on the effects of 5ARIs on prostate cancer natural history and detection.

MATERIALS AND METHODS

A detailed review was performed of the literature identified from the MEDLINE database examining the effects of 5ARIs on prostate cancer prevalence and tumor histopathology.

RESULTS

In PCPT there were fewer biopsies performed for cause in the finasteride vs the placebo group and the proportion of high grade tumors in the treatment groups did not diverge with time. Given that finasteride has an effect on prostate specific antigen and prostate volume, which are key factors in triggering prostate biopsies, they may be significant confounders of Gleason score results. Prostate shrinkage in the finasteride treated group may minimize biopsy sampling error. Furthermore, histological studies have shown that 5ARIs have a significant effect on prostate architecture, which can make the interpretation of prostate specimens in men treated with 5ARIs difficult. Further evaluation of PCPT findings will help determine the true nature of these observations.

CONCLUSIONS

5ARIs decrease the risk of prostate cancer but also alter the detection of disease through effects on prostate specific antigen, and prostate volume and histology. The weight of evidence suggests an artifactual effect of finasteride on Gleason grading in the PCPT. The role of 5ARIs for prostate cancer chemoprevention needs further examination before it can be considered for wide recommendation.

Use of 5α-reductase inhibitors to prevent benign prostatic hyperplasia disease

A histologic change in the prostate, benign prostatic hyperplasia (BPH), is a normal part of aging. However, BPH disease, defined here as a life-altering urinary condition caused by BPH requiring prompt medical intervention, is a serious medical disorder associated with major complications, surgical intervention, and severe lifestyle interference. BPH disease is preventable. The rationale for BPH disease prevention rests on four pillars of evidence: (1) BPH disease generally is a progressive disorder; (2) complications and severe lifestyle interference from BPH disease are common and serious; (3) men at greatest risk of BPH disease can be identified using prostate-specific antigen (PSA) level higher than 1.5 ng/mL as a surrogate marker for an enlarged prostate; and (4) 5alpha-reductase inhibitors (5ARIs) reduce the primary androgen responsible for prostate growth (dihydrotestosterone), shrink the prostate, and arrest the disease process regardless of symptom status. Thus, we now can identify men with an enlarged prostate at risk for BPH disease who may be candidates for preventive therapy with 5ARIs, regardless of urinary symptoms or bother.

Chemoprevention of prostate cancer

Prostate cancer is an attractive target for chemoprevention because of its ubiquity, treatment-related morbidity, long latency between premalignant lesions and clinically evident cancer, and defined molecular pathogenesis. The Prostate Cancer Prevention Trial has provided the first firm evidence that this cancer can be prevented by a relatively nontoxic oral agent. Additional agents, many of which are antioxidants with antiandrogenic effects, are being tested (or soon will be) in large clinical trials. The current body of evidence is insufficient to make a routine recommendation of any dietary or nutritional supplement for the prevention of prostate cancer.

[The role of PSA in diagnosis of prostate cancer and its recurrence]

Prostate specific antigen is the most important tumor marker of prostate cancer. PSA, in conjunction with digital rectal examination, is the first-line clinical tool for detection of prostate cancer. To improve its specificity PSA-density, PSA-ratio (fPSA/tPSA), PSA-velocity, and complexed PSA have been introduced into clinical praxis. The treatment of lower stage disease in younger men has resulted in a longer period of post-treatment cancer surveillance. Biochemical recurrence is an early indicator for clinical disease recurrence. PSA doubling time allows to distinguish between local and systemic progression and is also a valid predictor for distant metastasis and death of disease.

Dutasteride: a dual 5-alpha reductase inhibitor for the treatment of symptomatic benign prostatic hyperplasia

OBJECTIVE

To review the pharmacology, pharmacokinetics, efficacy, safety, drug interactions, and dosing recommendations of dutasteride, a 5-alpha reductase inhibitor for benign prostatic hyperplasia (BPH).

DATA SOURCES

A MEDLINE search (1966-February 2006) was conducted to extract human research data in the English language on dutasteride. Search terms included benign prostatic hyperplasia, dutasteride, and finasteride. The reference lists of articles identified through this search process, the manufacturer's Web site, and dutasteride prescribing information were also examined.

STUDY SELECTION AND DATA EXTRACTION

All published studies and clinical data from the manufacturer were included, with emphasis placed on randomized, controlled trials.

DATA SYNTHESIS

Dutasteride is approved for the treatment of symptomatic BPH in men with an enlarged prostate to improve urinary symptoms, reduce the risk of acute urinary retention, and reduce the need for BPH-related surgical interventions. Compared with placebo, dutasteride has been shown to significantly improve BPH symptoms, reduce the incidence of acute urinary retention and BPH-related surgery, and improve BPH-related quality of life. Few published data exist comparing dutasteride with finasteride. The most common adverse effects of dutasteride include ear, nose, and throat infection; malaise; headache; dizziness; and musculoskeletal pain.

CONCLUSIONS

Clinical trials, sponsored primarily by the manufacturer, have shown dutasteride to be an effective treatment of BPH compared with placebo and to likely possess efficacy similar to that of finasteride. Further studies are needed to gain a more clear understanding of any clinically significant differences between dutasteride and finasteride.

Long-term therapy with the dual 5alpha-reductase inhibitor dutasteride is well tolerated in men with symptomatic benign prostatic hyperplasia

OBJECTIVE

To examine the long-term (4-year) safety and tolerability of dutasteride in the treatment of symptomatic benign prostatic hyperplasia (BPH).

PATIENTS AND METHODS

Patients who completed the double-blind phase of three dutasteride Phase III studies were eligible to enter a 2-year open-label extension, during which all patients received dutasteride 0.5 mg. Safety was assessed, including adverse-event reporting, clinical laboratory assessments, yearly physical examinations, and vital sign assessments.

RESULTS

In all, 2340 patients entered the open-label phase, 1188 of whom previously received dutasteride during the double-blind phase of the study. The most common drug-related adverse events (occurring in > or = 1%) were effects on sexual function, which decreased with a longer duration of therapy. Gynaecomastia was reported in a small percentage of men throughout the 4-year study period. The incidence of individual sexual functional adverse events that led to withdrawal was < or = 1% (0.3-1.0%) during the 4-year study period. Dutasteride had no relevant effects on vital signs or clinical laboratory variables.

CONCLUSION

These data show that dutasteride is well tolerated during long-term use for the treatment of symptomatic BPH.

Testosterone replacement therapy for late onset hypogonadism: what is the risk of inducing prostate cancer?

Prescription sales of testosterone have risen considerably over the last decade and are likely to continue to grow as further preparations become available. Testosterone promotes existing prostate cancer; however, concern does exist as to whether or not testosterone therapy induces prostate cancer. The aim of this article is to review the evidence for such a link.

Dutasteride: a novel dual inhibitor of 5α-reductase for benign prostatic hyperplasia

Dutasteride is a new dual 5alpha-reductase inhibitor for the treatment of benign prostatic hyperplasia. It differs from finasteride as it inhibits both isoenzymes of 5alpha-reductase and results in near-complete suppression of serum dihydro-testosterone. Similar to finasteride, it reduces serum prostatic specific antigen by approximately 50% at 6months and total prostate volume by 25% in 2years. Randomised, placebo-controlled trials conducted over 2years have shown the efficacy of dutasteride in symptomatic relief, improvements in quality of life and peak urinary flow rate, and reduction of acute urinary retention events and the need for surgery. The main side effects are erectile dysfunction, decreased libido, gynaecomastia and ejaculation disorders. However, long-term usage for > 4years did not reveal increased new onset of sexual side effects. In addition, the combination of dutasteride and tamsulosin is well-tolerated and has the added advantage of rapid symptomatic relief. Finally, dutasteride has been shown to possess tumour regression properties invitro and its role in chemoprevention of prostate cancer will be confirmed in the ongoing Reduction by Dutasteride of Prostate Cancer Events (REDUCE) trial.

The Role of 5αR Inhibitors in the Early Growth of Pca Cells

Aim of this study is to investigate the efficacy of Finasteride (MK906), a selective 5α reductase type 2(5αR2) inhibitor, and of MK386, a selective 5α reductase type 1 (5αR1), on the cellular proliferation of primary cell cultures derived from patients with prostatic diseases.

Methods

We evaluated the effects of Finasteride and MK386 in 30 primary cultures obtained from prostatic carcinoma (PCa), 6 from high grade intraepithelial neoplasia (HGPIN) and 10 from benign prostatic hyperplasia (BPH).

Results

Primary cultures require testosterone (T) for optimal growth and both 5αR inhibitors decreased cell proliferation of primary cultures of PCa cells. IC50 values of Finasteride were lower when compared to those of MK386. In particular, Finasteride was more active in cultures derived from Gleason 2–6 PCa, compared to those derived from Gleason 7–10 PCa. On the contrary, we observed higher effectiveness of MK386 in Gleason 7–10 PCa derived cultures compared to those derived from Gleason 2–6 PCa tissues. The growth of PCa primary cultures was down-modulated by MK386 through a direct inhibition of the epithelial 5αR1, whereas the anti-proliferative activity of Finasteride seems to be mediated by stromal cells present in the primary cultures.

Conclusions

We found biological evidence for an important role of 5αR inhibitors in the early growth of PCa cells and for the necessity of combining anti-hormonal treatment for a sustained inhibition of PCa through the inhibition of stromal cell function even in advanced and androgen-resistant tumor progression phases.

Can prostate cancer be prevented?

The goal of primary chemoprevention is to decrease the incidence of a given cancer, simultaneously reducing both treatment-related adverse events and mortality. Prostate cancer is an attractive and appropriate target for primary prevention because of its incidence, prevalence, and disease-related mortality; its long latency and molecular pathogenesis; and epidemiologic data indicating that modifiable environmental factors may decrease risk. The Prostate Cancer Prevention Trial (PCPT) demonstrated that finasteride can prevent prostate cancer, albeit with an apparently increased risk of high-grade disease. A substantial amount of epidemiologic, molecular, and clinical evidence suggests that both selenium and vitamin E might also prevent prostate cancer, and this combination is being tested in the Selenium and Vitamin E Cancer Prevention Trial (SELECT). Ultimately, the adoption of a preventive strategy hinges on its potential benefits weighed against the potential risks of the specific agents used.

[Use of 5-alpha-reductase inhibitors in the prevention of prostate cancer]

5-alpha-reductase inhibitors are now in widespread use for the treatment of benign prostatic hyperplasia (BHP) and these molecules have recently come under the spotlight in prostate cancer. Their peripheral "hormonal" action inducing reduced intraprostatic DHT synthesis seems to involve them in this hormone-dependant disorder. Finasteride evaluated in the treatment of BPH (PLESS study) was found to have a preventive effect on the incidence of cancer and this activity was assessed in a specific trial (PCPT study). Nevertheless, in the latter randomized study with a 7-year follow-up period, a reduction in the global incidence of the number of cases of cancers was associated with an increase in the number of high-grade cancers. A slight reduction in prostate cancer was also noted in the studies with dutasteride in BPH (ARIA3001, ARIA3002 and ARIB3003). An international multicenter study (REDUCE) is currently being conducted to confirm the preventive value of this molecule which has a more complete activity than finasteride with its inhibitory action on the two 5-alpha-reductase iso-enzymes, and may therefore have a clearer efficiency and rule out the risk of onset of high-grade cancer.