Detection bias due to the effect of finasteride on prostate volume: a modeling approach for analysis of the Prostate Cancer Prevention Trial

Risks and side effects in the medical management of benign prostatic hyperplasia

Benign prostatic hyperplasia affects up to 80% of men in their lifetime. It causes bladder outflow obstruction, leading to lower urinary tract symptoms, which can have a large impact on quality of life. Lifestyle modifications and pharmacotherapy are often offered as first-line treatments for patients. These include alpha blockers, 5-alpha-reductase inhibitors, phosphodiesterase-5 inhibitors, anticholinergics, B3-agonists, and desmopressin. While often well tolerated, these pharmacotherapies do have significant side effects, which both clinicians and patients should understand and discuss in order to make an informed treatment decision among alternatives. The purpose of this review is to provide a current overview of the risks and side effects of commonly used medications in benign prostatic hyperplasia management.

Clinical and histological predictive factors of reclassification of prostate cancer patients on active surveillance

INTRODUCTION AND OBJECTIVE

Active surveillance (AS) has been established as a therapeutic strategy in patients with low-risk prostate cancer. Demographic and anatomopathological factors that increase the probability of reclassifying patients have been identified.

MATERIALS AND METHODS

Laboratory and histopathological data were collected from 116 patients included on AS since 2014. Univariate analysis was performed with Chi-square, t-student and Kendall's Tau, multivariate analysis according to logistic regression and Kaplan-Meier curves were calculated.

RESULTS

Of the 116 patients in AS, the median age at diagnosis was 66 years and the median follow-up was 13 months (2-72). Of these, 61 (52.6%) are still on surveillance, while 55 (47.4%) have left the program, mostly due to histological progression (52 patients (45.2%)); radical prostatectomy was performed in 27 (49.1%). Prostate volume (PV)≤60cc and the number of positive cylinders >1 in diagnostic biopsy (P=.05) were associated with higher reclassification rate in univariate analysis (P<.05). Multivariate analysis showed that these two variables significantly correlated with higher reclassification rate (PV 60 cc: OR 4.39, P=.04; >1 positive cylinder at diagnostic biopsy: OR 2.48, P=.03).

CONCLUSIONS

It has been shown that initial ultrasound volume and the number of positive cylinders in the diagnostic biopsy are independent risk factors for reclassification. Initial PSA, laterality of the affected cylinders and PSA density were not predictive factors of progression in our series.

Circulating free testosterone and risk of aggressive prostate cancer: Prospective and Mendelian randomisation analyses in international consortia

Previous studies had limited power to assess the associations of testosterone with aggressive disease as a primary endpoint. Further, the association of genetically predicted testosterone with aggressive disease is not known. We investigated the associations of calculated free and measured total testosterone and sex hormone-binding globulin (SHBG) with aggressive, overall and early-onset prostate cancer. In blood-based analyses, odds ratios (OR) and 95% confidence intervals (CI) for prostate cancer were estimated using conditional logistic regression from prospective analysis of biomarker concentrations in the Endogenous Hormones, Nutritional Biomarkers and Prostate Cancer Collaborative Group (up to 25 studies, 14 944 cases and 36 752 controls, including 1870 aggressive prostate cancers). In Mendelian randomisation (MR) analyses, using instruments identified using UK Biobank (up to 194 453 men) and outcome data from PRACTICAL (up to 79 148 cases and 61 106 controls, including 15 167 aggressive cancers), ORs were estimated using the inverse-variance weighted method. Free testosterone was associated with aggressive disease in MR analyses (OR per 1 SD = 1.23, 95% CI = 1.08-1.40). In blood-based analyses there was no association with aggressive disease overall, but there was heterogeneity by age at blood collection (OR for men aged <60 years 1.14, CI = 1.02-1.28; Phet  = .0003: inverse association for older ages). Associations for free testosterone were positive for overall prostate cancer (MR: 1.20, 1.08-1.34; blood-based: 1.03, 1.01-1.05) and early-onset prostate cancer (MR: 1.37, 1.09-1.73; blood-based: 1.08, 0.98-1.19). SHBG and total testosterone were inversely associated with overall prostate cancer in blood-based analyses, with null associations in MR analysis. Our results support free testosterone, rather than total testosterone, in the development of prostate cancer, including aggressive subgroups.

Initial Findings from a High Genetic Risk Prostate Cancer Clinic

OBJECTIVE

To improve prostate cancer screening for high-risk men, we developed an early detection clinic for patients at high genetic risk of developing prostate cancer. Despite the rapidly growing understanding of germline variants in driving aggressive prostate cancer and the increased availability of genetic testing, there is little evidence surrounding how best to screen these men.

METHODS

We are reporting on the first 45 patients enrolled, men between the ages of 35-75, primarily with known pathogenic germline variants in prostate cancer susceptibility genes. Screening consists of an intake lifestyle survey, PSA, DRE, and SelectMDx urine assay. A biopsy was recommended for any of the following indications: 1) abnormal DRE, 2) PSA above threshold, or 3) SelectMDx above threshold. The primary outcomes were number needed to screen, and number needed to biopsy to diagnose a patient with prostate cancer.

RESULTS

Patients enrolled in the clinic included those with BRCA1 (n=7), BRCA2 (n=16), Lynch Syndrome (n=6), and CHEK2 (n = 4) known pathogenic germline variants. The median age and PSA were 58 (range 35-71) and 1.4 ng/ml (range 0.1-11.4 ng/ml), respectively. 12 patients underwent a prostate needle biopsy and there were 4positive biopsies for prostate cancer.

CONCLUSION

These early data support the feasibility of opening a dedicated clinic for men at high genetic risk of prostate cancer. This early report on the initial enrollment of our long-term study will help optimize early detection protocols and provide evidence for personalized prostate cancer screening in men with key pathogenic germline variants.

Association of 5-alpha-reductase inhibitor and prostate cancer incidence and mortality: a meta-analysis

Background

5-Alpha-reductase inhibitors (5-ARIs) have been suggested as potential chemopreventive agents for prostate cancer (PCa). This study was conducted to evaluate the effect of 5-ARIs on the incidence and mortality of PCa.

Methods

The PubMed, Embase and Cochrane Library databases were searched comprehensively from database inception to October 2019. The clinical outcomes included the incidence of overall PCa, high-grade (Gleason8-10) PCa, metastatic PCa, overall survival (OS), and cancer-specific survival (CSS).

Results

Overall, 23 studies were included in the present study, representing 11 cohort studies, 5 case-control studies, and 8 randomized controlled trials. The use of 5-ARIs was associated with a decreased risk of overall PCa [relative risk (RR) =0.77; 95% CI: 0.67–0.88; P<0.001] and increased risk of Gleason 8–10 PCa (RR=1.19; 95% CI: 1.01–1.40; P=0.036). In terms of metastatic PCa, there were no significant between-group differences (RR=1.23; 95% CI: 0.69–2.18; P=0.487). Furthermore, we found that prediagnostic 5-ARI usage was not associated with an increased risk of overall or prostate cancer mortality, with HRs of 1.00 (95% CI: 0.92–1.08; P=0.938) and 0.98 (95% CI: 0.80–1.21; P=0.881), respectively.

Conclusions

In conclusion, while male 5-ARI users were associated with a decreased risk of overall prostate cancer and increased risk of high-grade prostate cancer (Gleason 8–10), they were not associated with an increased risk of overall or prostate cancer mortality. 5-ARIs should be recommended carefully for use as chemopreventive agents.

A review of the treatment of male pattern hair loss

Introduction: Androgenetic alopecia is a common hair loss disorder affecting up to 80% of males by the age of 80. It is characterized by androgen related progressive thinning of hair in a defined pattern. It results in diminished self-esteem, reduced confidence and distress in affected men, irrespective of age or stage of baldness. An effective treatment for hair baldness is needed.Areas covered: In androgenetic alopecia, hair follicles undergo progressive miniaturization. Genetic factors and androgens are key role-players in disease pathogenesis. Herein the authors review the pharmacologic treatment of androgenetic alopecia, which involves 5 alpha reductase inhibitors, minoxidil and prostaglandins. Non-pharmacologic approaches are also explored.Expert opinion: Androgenetic alopecia progresses over time and although the current available medical treatments like finasteride and minoxidil are effective in arresting the progression of the disease, they allow only partial regrowth of hair at its best. Early treatment achieves a more optimal outcome. Non-pharmacologic treatments like PRP can be considered in patients refractory to medical treatment.Abbreviations: MPHL: male pattern hair loss; AGA: androgenetic alopecia; DHT: dihydrotestosterone; 5AR: 5-alpha-reductase; VEGF: vascular endothelial growth factor; PG's: prostaglandins (PG's); PGD2R: prostaglandin D2 receptor; VPA: valproic aid; SR: Serenoa Repens; PRP: platelet-rich plasma; PDGF: platelet derived growth factor; TGF: transforming growth factor; ERK: extracellular signal-regulated kinase; PKB: protein kinase B; LLLT: low-level laser therapy; ROS: reactive oxygen species; RCT: randomized control trial; SFRP1: secreted frizzled related protein 1; DP: dermal papilla; PDE5: phosphodiesterase 5.

Association between 5α-reductase inhibitors therapy and incidence, cancer-specific mortality, and progression of prostate cancer: evidence from a meta-analysis

5α-reductase inhibitors (5-ARI) are widely employed for the treatment of benign prostatic hyperplasia. It has been noted that 5-ARI exhibit the potential to attenuate the risk of prostate cancer, but consistent agreement has not been achieved. Moreover, the effect of 5-ARI on cancer-specific mortality and progression of prostate cancer remains unclear. Therefore, the goal of the current meta-analysis was to elucidate the impact of 5-ARI on the incidence and progression of prostate cancer. We searched for all studies assessing the effect of 5-ARI on risk of prostate cancer in PubMed, Embase, Medline, and Cochrane Library databases. Pooled relative risk (RR) and corresponding 95% confidence intervals (CIs) were accepted to evaluate the association between 5-ARI and the risk of prostate cancer. Synthetic results implied that subjects who accepted 5-ARI compared with the placebo group experienced a distinctly weakened overall incidence of prostate cancer (RR = 0.74; 95% CI: 0.66–0.82; P < 0.001). Subgroup analyses further revealed that 5-ARI reduction of the incidence of prostate cancer was limited to low-grade (Gleason score 2–6; RR = 0.68; 95% CI: 0.57–0.81; P < 0.001) and intermediate-grade tumors (Gleason score 7; RR = 0.81; 95% CI: 0.67–0.97; P = 0.023), but not high-grade tumors (Gleason score >7; RR = 1.19; 95% CI: 0.98–1.43; P = 0.069). The results also showed that 5-ARI treatment did not significantly alter prostate cancer-specific mortality (RR = 1.0; 95% CI: 0.95–1.05; P = 0.916). In addition, it was worth noting that 5-ARI treatment acted in a protective role that presented a dramatic benefit to delay the progression of low-risk tumors (RR = 0.58; 95% CI: 0.43–0.78; P < 0.001).

Low Free Testosterone and Prostate Cancer Risk: A Collaborative Analysis of 20 Prospective Studies

BACKGROUND

Experimental and clinical evidence implicates testosterone in the aetiology of prostate cancer. Variation across the normal range of circulating free testosterone concentrations may not lead to changes in prostate biology, unless circulating concentrations are low. This may also apply to prostate cancer risk, but this has not been investigated in an epidemiological setting.

OBJECTIVE

To examine whether men with low concentrations of circulating free testosterone have a reduced risk of prostate cancer.

DESIGN, SETTING, AND PARTICIPANTS

Analysis of individual participant data from 20 prospective studies including 6933 prostate cancer cases, diagnosed on average 6.8 yr after blood collection, and 12 088 controls in the Endogenous Hormones, Nutritional Biomarkers and Prostate Cancer Collaborative Group.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Odds ratios (ORs) of incident overall prostate cancer and subtypes by stage and grade, using conditional logistic regression, based on study-specific tenths of calculated free testosterone concentration.

RESULTS AND LIMITATIONS

Men in the lowest tenth of free testosterone concentration had a lower risk of overall prostate cancer (OR=0.77, 95% confidence interval [CI] 0.69-0.86; p<0.001) compared with men with higher concentrations (2nd-10th tenths of the distribution). Heterogeneity was present by tumour grade (phet=0.01), with a lower risk of low-grade disease (OR=0.76, 95% CI 0.67-0.88) and a nonsignificantly higher risk of high-grade disease (OR=1.56, 95% CI 0.95-2.57). There was no evidence of heterogeneity by tumour stage. The observational design is a limitation.

CONCLUSIONS

Men with low circulating free testosterone may have a lower risk of overall prostate cancer; this may be due to a direct biological effect, or detection bias. Further research is needed to explore the apparent differential association by tumour grade.

PATIENT SUMMARY

In this study, we looked at circulating testosterone levels and risk of developing prostate cancer, finding that men with low testosterone had a lower risk of prostate cancer.

Chemoprevention in Prostate Cancer: Current Perspective and Future Directions

Chemoprevention of prostate cancer aims to reduce the mortality as well as the public burden of overdetection, which increases anxiety, cost, and morbidity related to the disease. The role of 5-α-reductase inhibitors has been well investigated and shown to decrease the risk of prostate cancer. No current evidence exists to encourage the use of nutrients or vitamins as chemopreventive agents. The modulation of inflammation is one of the most promising targets for chemoprevention of prostate cancer.

Computer vision detects subtle histological effects of dutasteride on benign prostate

OBJECTIVE

To determine whether a computer vision-based approach applied to haematoxylin and eosin (H&E) prostate biopsy images can distinguish dutasteride-treated tissue from placebo, and identify features associated with degree of responsiveness to 5α-reductase inhibitor (5ARI) therapy.

SUBJECTS AND METHODS

Our study population comprised 100 treatment-adherent men without prostate cancer assigned to dutasteride or placebo in the REDUCE trial, who had slides available from mandatory year-4 biopsies. Half of the men also provided slides from a year-2 biopsy. We obtained 20× whole-slide images and used specialized software to generate a library of 1 300 epithelial and stromal features from objects comprising superpixels and several types of nuclei, including spatial relations among objects between and within each hierarchical level. We used penalized logistic regression and fivefold cross-validation to find optimal combinations of histological features in the year-4 biopsies. Feature data from the year-2 biopsies were fitted to a final model for independent validation. Two pathologists, blinded to treatment, scored each image for focal atrophy and histological features previously linked to 5AR1 treatment.

RESULTS

Consensus classification by pathologists obtained a discrimination accuracy equivalent to chance. A 21-feature computer vision model gave a cross-validation area under the curve of 0.97 (95% confidence interval [CI] 0.95-0.99) in the year-4 biopsies and 0.79 (95% CI: 0.65-0.92) in the set-aside year-2 biopsies. Histology scores were not correlated with change in prostate-specific antigen level, serum dihydrotestosterone level or gland volume. Key features associated with dutasteride treatment included greater shape and colour uniformity in stroma, irregular clustering of epithelial nuclei, and greater variation in lumen shape.

CONCLUSION

The present findings show that a computer vision approach can detect subtle histological effects attributable to dutasteride, resulting in a continuous measure of responsiveness to the drug that could eventually be used to predict individual patient response in the context of BPH treatment or cancer chemoprevention.

5-Alpha Reductase Inhibitors and the Risk of Prostate Cancer Mortality in Men Treated for Benign Prostatic Hyperplasia

OBJECTIVE

To compare the risk of prostate cancer mortality among men treated with 5- alpha reductase inhibitors (5-ARIs) with those treated with alpha-adrenergic blockers (ABs) in community practice settings.

PATIENTS AND METHODS

A retrospective matched cohort (N=174,895) and nested case-control study (N=18,311) were conducted in 4 regions of an integrated health care system. Men 50 years and older who initiated pharmaceutical treatment for benign prostatic hyperplasia between January 1, 1992, and December 31, 2007, and had at least 3 consecutive prescriptions were followed through December 31, 2010. Adjusted subdistribution hazard ratios, accounting for competing risks of death, and matched odds ratios were used to estimate prostate cancer mortality associated with 5-ARI use (with or without concomitant ABs) as compared with AB use.

RESULTS

In the cohort study, 1,053 men died of prostate cancer (mean follow-up, 3 years), 15% among 5-ARI users (N= 25,388) and 85% among AB users (N=149,507) (unadjusted mortality rate ratio, 0.80). After accounting for competing risks, it was found that 5-ARI use was not associated with prostate cancer mortality when compared with AB use (adjusted subdistribution hazard ratio, 0.85; 95% CI, 0.72-1.01). Similar results were observed in the case-control study (adjusted matched odds ratio, 0.95; 95% CI, 0.78-1.17).

CONCLUSION

Among men being pharmaceutically treated for benign prostatic hyperplasia, 5-ARI use was not associated with an increased risk of prostate cancer-specific mortality when compared with AB use. The increased prevalence of high-grade lesions at the time of diagnosis noted in our study and the chemoprevention trials may not result in increased prostate cancer mortality.

JNCI and cancer prevention

The Journal of the National Cancer Institute (JNCI), with its broad coverage of bench research, epidemiologic studies, and clinical trials, has a long history of publishing practice-changing studies in cancer prevention and public health. These include studies of tobacco cessation, chemoprevention, and nutrition. The landmark Breast Cancer Prevention Trial (BCPT)-the first large trial to prove efficacy of a preventive medication for a major malignancy-was published in the Journal, as were key ancillary papers to the BCPT. Even when JNCI was not the publication venue for the main trial outcomes, conceptual and design discussions leading to the trial as well as critical follow-up analyses based on trial data from the Prostate Cancer Prevention Trial (PCPT) and the Selenium and Vitamin E Chemoprevention Trial (SELECT) were published in the Journal. The Journal has also published important evidence on very charged topics, such as the purported link between abortion and breast cancer risk. In summary, JNCI has been at the forefront of numerous major publications related to cancer prevention.

Extended followup and risk factors for disease reclassification in a large active surveillance cohort for localized prostate cancer

PURPOSE

Active surveillance to manage prostate cancer provides an alternative to immediate treatment in men with low risk prostate cancer. We report updated outcomes from a long-standing active surveillance cohort and factors associated with reclassification.

MATERIALS AND METHODS

We retrospectively reviewed data on all men enrolled in the active surveillance cohort at our institution with at least 6 months of followup between 1990 and 2013. Surveillance consisted of quarterly prostate specific antigen testing, repeat imaging with transrectal ultrasound at provider discretion and periodic repeat prostate biopsies. Factors associated with repeat biopsy reclassification and local treatment were determined by multivariate Cox proportional hazards regression. We also analyzed the association of prostate specific antigen density and outcomes stratified by prostate size.

RESULTS

A total of 810 men who consented to participate in the research cohort were followed on active surveillance for a median of 60 months. Of these men 556 (69%) met strict criteria for active surveillance. Five-year overall survival was 98%, treatment-free survival was 60% and biopsy reclassification-free survival was 40%. There were no prostate cancer related deaths. On multivariate analysis prostate specific antigen density was positively associated with the risk of biopsy reclassification and treatment while the number of biopsies and time between biopsies were inversely associated with the 2 outcomes (each p <0.01). When stratified by prostate volume, prostate specific antigen density remained significantly associated with biopsy reclassification for all strata but prostate specific antigen density was only significantly associated with treatment in men with a smaller prostate.

CONCLUSIONS

Significant prostate cancer related morbidity and mortality remained rare at intermediate followup. Prostate specific antigen density was independently associated with biopsy reclassification and treatment while on active surveillance.

A tale of two trials: The impact of 5α-reductase inhibition on prostate cancer (Review)

The use of 5α-reductase inhibitors (5α-RIs) as prostate cancer chemoprevention agents is controversial. Two large randomized trials, the Prostate Cancer Prevention Trial (PCPT) and the Reduction by Dutasteride of Prostate Cancer Events (REDUCE) Trial, have both shown a decreased incidence of prostate cancer in patients administered with 5α-RIs. Both studies showed, however, an increased risk of higher-grade prostate cancer. Numerous studies have since analyzed the inherent biases in these landmark studies and have used mathematical modeling to estimate the true incidence of prostate cancer and the risk for high-grade prostate cancer in patients undergoing 5α-RI treatment. All primary publications associated with the PCPT and REDUCE studies were reviewed in detail. Pertinent references from the above publications were assessed and a literature search of all published articles associated with PCPT, REDUCE or 5α-RIs as chemopreventative agents through October 2013 was performed using Pubmed/Medline. PCPT and REDUCE both showed a significant decrease in the incidence of prostate cancer following the administration of 5α-reductase inhibitor, as compared with placebo, suggesting that 5α-RIs may be effective agents for prostate cancer chemoprevention. Inherent biases in the design of these two studies may have caused an artificial increase in the number of high-grade cancers reported. Mathematical models, that integrated data from these trials, revealed neither an increased nor decreased risk of high-grade disease when taking these biases into consideration. Moderately strong evidence exists that 5α-RIs may reduce the risk of prostate cancer. PCPT and REDUCE showed a decreased prevalence of prostate cancer in patients taking 5α-RIs. Urologists should have a working knowledge of these studies and discuss with patients the risks and benefits of 5α-RI treatment. Further studies to evaluate the cost-effectiveness of chemoprevention with 5α-RIs and appropriate patient selection are warranted.

Nonsurgical therapy for hair loss

This article is an update of the currently available options for medical therapies to treat androgenetic alopecia in men and women. Emerging novel therapeutic modalities with potential for treating these patients are discussed. Because androgenetic alopecia is progressive in nature, stabilization of the process using medical therapy is an important adjunct to any surgical hair-restoration plan.

Androgens and prostate disease

A growing body of literature has established the anabolic benefi ts of testosterone (T) therapy in hypogonadal men. However, there remains a paucity of data regarding the risks of exogenous androgen use in older men and the potential for adverse effects on the prostate gland. Whether T therapy in older, hypogonadal men might worsen lower urinary tract symptoms or exacerbate, unmask, or even incite prostate cancer development has tempered enthusiasm for T therapy, while known prostatic disease has served as a relative contraindication to T therapy. Androgens are necessary for the development and maintenance of the prostate gland. However, epidemiologic studies do not consistently fi nd a positive relationship between endogenous serum androgen concentrations and the risk of prostate disease. Recent data demonstrate that 5α-reductase inhibitors decrease the risk of low-grade prostate cancer, suggesting that modifying androgen metabolism may have beneficial effects on prostate health, yet similar reductions in high-grade disease have not been observed, thereby questioning the true clinical benefits of these agents for chemoprevention. Knowing how to best investigate the relationship between androgens and the development of prostate disease given the lack of large, randomized trials is difficult. Accumulating data challenges the assumption that alterations in serum androgens have parallel effects within the prostate hormonal environment or change androgen-regulated processes within the gland. Long-term intervention studies are needed to truly ascertain the effects of androgen manipulation on prostate tissue and disease risk. However, available data do not support the notion that restoring serum androgens to normal physiologic ranges drives prostate disease.

Five-alpha reductase inhibitor influences expression of androgen receptor and HOXB13 in human hyperplastic prostate tissue

OBJECTIVES

Five-alpha reductase inhibitors (5ARIs) are known as chemopreventive agents in prostate cancer with a risk of high-grade disease. This study evaluated the effects of 5ARI on androgen receptor (AR) and proteins involved in prostate cell growth such as HOXB13 expression in human prostate tissue and LNCaP prostate cancer cells.

MATERIALS AND METHODS

We retrospectively selected 21 patients who underwent TURP between March 2007 and February 2010 for previously confirmed BPH by prostate biopsy. They were grouped into control (group 1, n = 9) and 5ARI treatment (group 2, n = 12) before TURP. AR and HOXB13 expression in prostate tissue was evaluated by immunohistochemical staining. We tested the effect of 5ARI on the expression of AR, prostate specific antigen (PSA) and HOXB13 in LNCaP cells. Cells were assessed by Western blot analysis, MTT in vitro proliferation assay, and ELISA.

RESULTS

Group 2 showed stronger reactivity for AR and HOXB13 than those of the group 1. MTT assay showed death of LNCaP cells at 25uM of 5ARI. At the same time, ELISA assay for PSA showed that 5ARI inhibited secretion of PSA in LNCaP cells. Western blot analysis showed that 5ARI did not greatly alter AR expression but it stimulated the expression of HOXB13.

CONCLUSIONS

These results demonstrated that 5ARI influences AR and HOXB13 expression in both LNCaP cells and human prostate tissue. In order to use 5ARI in chemoprevention of prostate cancer, we still need to clarify the influence of 5ARI in ARs and oncogenic proteins and its regulation pathway.

The strategies to control prostate cancer by chemoprevention approaches

Prostate cancer (PCA) is the most commonly diagnosed cancer in men in the United States with growing worldwide incidence. Despite intensive investment in improving early detection, PCA often escapes timely detection and mortality remains high; this malignancy being the second highest cancer-associated mortality in American men. Collectively, health care costs of PCA results in an immense financial burden that is only expected to grow. Additionally, even in cases of successful treatment, PCA is associated with long-term and pervasive effects on patients. A proactive alternative to treat PCA is to prevent its occurrence and progression prior to symptomatic malignancy. This may serve to address the issue of burgeoning healthcare costs and increasing number of sufferers. One potential regimen in service of this alternative is PCA chemoprevention. Here, chemical compounds with cancer preventive efficacy are identified on the basis of their potential in a host of categories: their historical medicinal use, correlation with reduced risk in population studies, non-toxicity, their unique chemical properties, or their role in biological systems. PCA chemopreventive agents are drawn from multiple broad classes of chemicals, themselves further subdivided based on source or potential effect, with most derived from natural products. Many such compounds have shown efficacy, varying from inhibiting deregulated PCA cell signaling, proliferation, epithelial to mesenchymal transition (EMT), invasion, metastasis, tumor growth and angiogenesis and inducing apoptosis. Overall, these chemopreventive agents show great promise in PCA pre-clinical models, though additional work remains to be done in effectively translating these findings into clinical use.

Utility of 5-alpha-reductase inhibitors in active surveillance for favourable risk prostate cancer

INTRODUCTION

This retrospective review compares prostate-specific antigen (PSA) doubling time (DT) prior to the initiation of a 5-alpha-reductase inhibitor (pre-5-ARI) to after the PSA nadir (post-nadir) has been reached for patients on active surveillance for favourable-risk prostate cancer.

METHODS

Between 1996 and 2010, a total of 100 men with a history of 5-ARI use were captured from our active surveillance database. Twenty-nine patients had a sufficient number of PSA values to determine both pre-5-ARI and post-nadir DTs. PSADT was calculated using the general linear mixed-model method.

RESULTS

The median follow-up was 69.5 months. The median pre-5-ARI PSADT was 55.8 (range: 6-556.8) months, while the post-nadir value was 25.2 (range: 6-231) months (p = 0.0081). Six patients were reclassified after an average of 67.7 (range: 59-95) months, due to progression in PSADT (n = 2) or Gleason score (n = 4). The median pre-5-ARI and post-nadir DTs for this group were 42.3 (range: 32.4-91.1) and 21.1 (range: 6-44.3) months, respectively.

CONCLUSION

5-ARIs significantly decreased PSADT compared to prior to their initiation. This effect may be due to preferential suppression of benign tissue following PSA nadir. The resulting PSADT would then represent a more accurate depiction of the true cancer-related DT. If validated with a larger cohort, 5-ARIs may enhance the utility of PSADT as a biomarker of disease progression in active surveillance.

Prostate cancer chemoprevention

Prostate cancer is a leading cause of morbidity and mortality in men and has significant treatment-associated complications. Prostate cancer chemoprevention has the potential to decrease the morbidity and mortality associated with this disease. Chemoprevention research to date has primarily focused on nutrients and 5 alpha-reductase inhibitors (5ARIs). A large randomized trial (SELECT) found no favorable effect of selenium or vitamin E on prostate cancer prevention. Two large randomized placebo controlled trials (the PCPT and REDUCE trials) have been published and have supported the role of 5ARIs in prostate cancer chemoprevention; however, these trials also have prompted concerns regarding the increase in high-grade disease seen with treatment and have not been approved by the US Food and Drug Administration (FDA) for chemoprevention. Conclusive evidence for the chemopreventive benefit of nutrients or vitamins is lacking, whereas the future role of 5ARIs remains to be clarified.

Use of 5α-reductase inhibitors for lower urinary tract symptoms and risk of prostate cancer in Swedish men: nationwide, population based case-control study

OBJECTIVE

To assess the association between 5α-reductase inhibitor (5-ARI) use in men with lower urinary tract symptoms and prostate cancer risk.

DESIGN

Nationwide, population based case-control study for men diagnosed with prostate cancer in 2007-09 within the Prostate Cancer data Base Sweden 2.0.

SETTING

The National Prostate Cancer Register, National Patient Register, census, and Prescribed Drug Register in Sweden, from which we obtained data on 5-ARI use before date of prostate cancer diagnosis.

PARTICIPANTS

26,735 cases and 133,671 matched controls; five controls per case were randomly selected from matched men in the background population. 7815 men (1499 cases and 6316 controls) had been exposed to 5-ARI. 412 men had been exposed to 5-ARI before the diagnosis of a cancer with Gleason score 8-10.

MAIN OUTCOME MEASURES

Risk of prostate cancer calculated as odds ratios and 95% confidence intervals by conditional logistic regression analyses.

RESULTS

Risk of prostate cancer overall decreased with an increasing duration of exposure; men on 5-ARI treatment for more than three years had an odds ratio of 0.72 (95% confidence interval 0.59 to 0.89; P<0.001 for trend). The same pattern was seen for cancers with Gleason scores 2-6 and score 7 (both P<0.001 for trend). By contrast, the risk of tumours with Gleason scores 8-10 did not decrease with increasing exposure time to 5-ARI (for 0-1 year of exposure, odds ratio 0.96 (95% confidence interval 0.83 to 1.11); for 1-2 years, 1.07 (0.88 to 1.31); for 2-3 years, 0.96 (0.72 to 1.27); for >3 years, 1.23 (0.90 to 1.68); P=0.46 for trend).

CONCLUSIONS

Men treated with 5-ARI for lower urinary tract symptoms had a decreased risk of cancer with Gleason scores 2-7, and showed no evidence of an increased risk of cancer with Gleason scores 8-10 after up to four years' treatment.

Rank-based principal stratum sensitivity analyses

We describe rank-based approaches to assess principal stratification treatment effects in studies where the outcome of interest is only well-defined in a subgroup selected after randomization. Our methods are sensitivity analyses, in that estimands are identified by fixing a parameter and then we investigate the sensitivity of results by varying this parameter over a range of plausible values. We present three rank-based test statistics and compare their performance through simulations, and provide recommendations. We also study three different bootstrap approaches for determining levels of significance. Finally, we apply our methods to two studies: an HIV vaccine trial and a prostate cancer prevention trial.

An introduction to acinar pressures in BPH and prostate cancer

Intra-acinar and peri-acinar pressures in the prostate might be key factors in the evolution of its zonal morphology and the pathogenesis of BPH and cancer. Herein, I hypothesize that intra-acinar pressures lead to a decrease in apoptosis by distending or stretching acinar epithelium and its surrounding stroma. Increased prostatic smooth muscle content and tone might generate peri-acinar pressures, which could, in the long-term, counteract intra-acinar pressures and decrease epithelial stretch. Thus, it is proposed that BPH (characterized by increased prostatic smooth muscle and, therefore, raised peri-acinar pressures) might decrease the risk of prostate cancer progression by counteracting intra-acinar pressures. In the context of this theory, the transition zone might have evolved as a specialized region within the prostate that can mount a concerted stromal-epithelial response to increased urethral and intra-acinar pressures (BPH), and the urethral angulation, anterior stroma and the prostatic capsule have an adjunctive evolutionary role in this phenomenon.

Selenium and prostate cancer prevention: insights from the selenium and vitamin E cancer prevention trial (SELECT)

The Selenium and Vitamin E Cancer Prevention Trial (SELECT) was conducted to assess the efficacy of selenium and vitamin E alone, and in combination, on the incidence of prostate cancer. This randomized, double-blind, placebo-controlled, 2 × 2 factorial design clinical trial found that neither selenium nor vitamin E reduced the incidence of prostate cancer after seven years and that vitamin E was associated with a 17% increased risk of prostate cancer compared to placebo. The null result was surprising given the strong preclinical and clinical evidence suggesting chemopreventive activity of selenium. Potential explanations for the null findings include the agent formulation and dose, the characteristics of the cohort, and the study design. It is likely that only specific subpopulations may benefit from selenium supplementation; therefore, future studies should consider the baseline selenium status of the participants, age of the cohort, and genotype of specific selenoproteins, among other characteristics, in order to determine the activity of selenium in cancer prevention.

Projecting prostate cancer mortality in the PCPT and REDUCE chemoprevention trials

BACKGROUND

Two recent chemoprevention trials demonstrated significant reductions in overall prostate cancer incidence. However, a possible increase in high-grade disease has raised concerns that the harms of the drugs, including mortality because of high-grade disease, may outweigh the benefits. The authors attempted to estimate the effect of these drugs on prostate cancer mortality to be able to better evaluate the cost-benefit tradeoff.

METHODS

The authors analyzed prostate cancer incidence in the Prostate Cancer Prevention Trial (PCPT) and Reduction by Dutasteride of Prostate Cancer Events (REDUCE) trial, which evaluated finasteride and the related compound dutasteride, respectively (both vs placebo). They used 13-year prostate cancer survival data from the Prostate, Lung, Colorectal and Ovarian (PLCO) trial to project prostate cancer mortality from incidence patterns; survival rates were applied to incident cancers according to prognostic strata, which were defined by Gleason score, prostate-specific antigen level, and clinical stage. For PCPT, the analysis was performed using both original trial results and previously published adjusted analyses that attempted to account for artifacts related to the drugs' effect on prostate volume.

RESULTS

For the PCPT trial, the estimated relative risk (RR) for prostate cancer mortality was 1.02 (95% confidence interval [95% CI], 0.85-1.23) using the original trial results and 0.87 (95% CI, 0.72-1.06) and 0.91 (95% CI, 0.76-1.09) based on the adjusted PCPT analyses. For the REDUCE trial, the RR for prostate cancer mortality was 0.93 (95% CI, 0.80-1.08).

CONCLUSIONS

Projecting a mortality outcome of the PCPT and REDUCE trials as an approach to weighing benefits versus harms suggests at most a small increase in prostate cancer mortality in the treatment arms, and possibly a modest decrease.

A multiscale, mechanism-driven, dynamic model for the effects of 5α-reductase inhibition on prostate maintenance

A systems-level mathematical model is presented that describes the effects of inhibiting the enzyme 5α-reductase (5aR) on the ventral prostate of the adult male rat under chronic administration of the 5aR inhibitor, finasteride. 5aR is essential for androgen regulation in males, both in normal conditions and disease states. The hormone kinetics and downstream effects on reproductive organs associated with perturbing androgen regulation are complex and not necessarily intuitive. Inhibition of 5aR decreases the metabolism of testosterone (T) to the potent androgen 5α-dihydrotestosterone (DHT). This results in decreased cell proliferation, fluid production and 5aR expression as well as increased apoptosis in the ventral prostate. These regulatory changes collectively result in decreased prostate size and function, which can be beneficial to men suffering from benign prostatic hyperplasia (BPH) and could play a role in prostate cancer. There are two distinct isoforms of 5aR in male humans and rats, and thus developing a 5aR inhibitor is a challenging pursuit. Several inhibitors are on the market for treatment of BPH, including finasteride and dutasteride. In this effort, comparisons of simulated vs. experimental T and DHT levels and prostate size are depicted, demonstrating the model accurately described an approximate 77% decrease in prostate size and nearly complete depletion of prostatic DHT following 21 days of daily finasteride dosing in rats. This implies T alone is not capable of maintaining a normal prostate size. Further model analysis suggests the possibility of alternative dosing strategies resulting in similar or greater effects on prostate size, due to complex kinetics between T, DHT and gene occupancy. With appropriate scaling and parameterization for humans, this model provides a multiscale modeling platform for drug discovery teams to test and generate hypotheses about drugging strategies for indications like BPH and prostate cancer, such as compound binding properties, dosing regimens, and target validation.

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.

Does variation in either age at start of therapy or duration of therapy make chemoprevention with finasteride cost-effective?

BACKGROUND

Incremental cost-effectiveness ratios (ICERs) of finasteride for prostate cancer prevention are consistent with estimates beyond $100 000 per quality-adjusted life-year (QALY). The majority of these analyses are based on chemoprevention starting in men aged 50-55 years. We sought to evaluate the impact of varying both age at commencement of therapy and length of therapy on the cost-effectiveness of finasteride.

METHODS

A probabilistic Markov model was designed to estimate lifetime prostate health-related costs and quality-adjusted survival for men receiving or not receiving chemoprevention with finasteride. ICERs across scenarios varying age at start of therapy and duration of chemoprevention were compared.

RESULTS

The ICER for men starting chemoprevention at age 50 and continuing to age 75 was $88 800 per QALY when assuming finasteride causes a constant risk reduction across all tumor grades (base case 1) and $142 300 per QALY when assuming a differential treatment effect according to Gleason score (base case 2). When starting age is increased, the ICERs trend downward and nadir at 65 years to $64 700 per QALY (base case 1) and $118 600 per QALY (base case 2). Altering duration of therapy had minimal impact. Patient-level experiences with finasteride and BPH significantly influenced the cost-effectiveness of chemoprevention.

CONCLUSIONS

Initiating chemoprevention at ages when prostate cancer incidence is higher improves its cost-effectiveness profile. Only when assuming a constant risk reduction for all tumor grades, did finasteride fall below $100 000 per QALY, but this finding was not upheld when accounting for side effects associated with the drug.

Epidemiology of prostate cancer and treatment remarks

Prostate cancer is one of the most common types of cancer and one of the leading causes of cancer death among men in the Western countries. The aim of the present analysis is to assess the cancer burden in order to ensure accurate strategies for chemoprevention and treatment, including the major therapeutic approaches for localized high-risk disease - surgery and radiation therapy - and quality of life issues related to each option.

The case for prostate cancer risk reduction by 5-alpha reductase inhibitors

Prostate cancer remains a significant public health problem. The current approach with prostate-specific antigen (PSA)-based screening has questionable effects on prostate cancer-specific mortality but is clearly associated with overdiagnosis of prostate cancer, especially relatively low-risk and low-volume tumors. Methods to decrease overdiagnosis include alterations in screening practices and, potentially, the use of 5-alpha reductase inhibitors. This article reviews the major trials that have evaluated 5-alpha reductase inhibitors in this setting: the Prostate Cancer Prevention Trial (PCPT) and the Reduction by Dutasteride Prostate Cancer Events Trial (REDUCE). Although these trials enrolled different patient populations, their findings are complementary and suggest a potential role for these agents in prostate cancer risk reduction. Use of 5-alpha reductase inhibitors results in an approximate 25% reduction in the detection of prostate cancer, reduces diagnosis of high-grade prostatic intraepithelial neoplasia (PIN), and improves benign prostatic hyperplasia (BPH)-related outcomes and the performance of PSA as a diagnostic test for aggressive prostate cancer. Side effects occur in a small percentage of men and consist of decreased sexual function and libido as well as gynecomastia. The risk of high-grade tumor development while receiving these agents is uncertain.

Chemoprevention of prostate cancer: Natural compounds, antiandrogens, and antioxidants - In vivo evidence

Prostate cancer is the leading non-skin malignancy detected in US males and the second cause of death due to male cancer, in the US. Interventions with drugs or diet supplements that slow down the growth and progression of prostate cancer are potentially very effective in reducing the burden of prostate cancer, particularly if these treatments also prevent the de novo development of new prostatic malignancies. Challenges to identify efficacious agents and develop them for chemopreventive application in men at risk for prostate cancer have included uncertainty about which preclinical models have the ability to predict efficacy in men and lack of consensus about which early phase clinical trial designs are the most appropriate and cost-effective to test promising agents. Efficacy studies in animal models have identified several agents with potential chemopreventive activity against prostate cancer, but few of these findings have been translated into clinical trials. This article identifies some of the major issues associated with prostate cancer chemoprevention research and summarizes the most significant current results from animal efficacy studies and human clinical prevention trials. This summary focuses on: (1) Naturally occurring agents and compounds derived from such agents, including green tea and its constituents, silibinin and milk thistle, and genistein and soy, (2) chemoprevention drugs including agents interfering with androgen action, and (3) antioxidants such as selenium, vitamin E, and lycopene. The general lack of activity of antioxidants is discussed, followed by considerations about translation of preclinical chemoprevention efficacy data, focusing on dose, form, bioavailability, and timing of administration of the agent, as well as discussion of study design of clinical trials and the predictive ability of preclinical models.

Finasteride upregulates expression of androgen receptor in hyperplastic prostate and LNCaP cells: implications for chemoprevention of prostate cancer

BACKGROUND

Although finasteride is recognized for its role as a chemopreventive agent for prostate cancer, higher grades of malignancy have been reported. It is questioned whether blocking of testosterone conversion to dihydrotestosterone (DHT) by finasteride in prostate tissue will change expression of androgen receptor (AR). Therefore, this study evaluated the effects of finasteride on AR expression in prostate tissue and in the LNCaP cell line.

METHODS

Between January and December 2006, we retrospectively selected and evaluated 47 cases of benign prostatic hyperplasia treated with variable duration of finasteride (5 mg QD) before transurethral resection of the prostate. AR expression in prostate tissue was semiquantified by immunostaining and compared with duration of finasteride treatment. An androgen-dependent prostate cancer cell line (LNCaP) was cultured in charcoal/dextran-treated FBS with DHT or testosterone, and treated with finasteride for 1-3 weeks. Samples of total RNA were collected to analyze expression of AR by real-time quantitative reverse transcription polymerase chain reaction.

RESULTS

Immunohistochemical study revealed significant upregulation of ARs by finasteride treatment for 30-180 days. In cell line study, quantitative real-time reverse transcription polymerase chain reaction revealed significant upregulation of ARs treated by finasteride.

CONCLUSIONS

In our study, finasteride influenced AR expression in benign prostate tissue and prostate cancer cell. Before we can use finasteride in chemoprevention with confidence, we still need to clarify the influence of finasteride in ARs and its regulation pathway.

Prevention strategies in prostate cancer

Prostate cancer (PCa) prevention has been an exciting and controversial topic since the results of the Prostate Cancer Prevention Trial (PCPT) were published. With the recently published results of the reduce (Reduction by Dutasteride of Prostate Cancer Events) trial, interest in this topic is at a peak. Primary pca prevention will be unlikely to affect mortality significantly, but the reduction in overtreatment and the effect on quality of life from the avoidance of a cancer diagnosis are important factors to consider.This review provides a comparative update on the REDUCE and PCPT trials and some clinical recommendations. Other potential primary preventive strategies with statins, selective estrogen response modulators, and nutraceutical compounds-including current evidence for these agents and their roles in clinical practice-are discussed. Many substances that have been examined in the primary prevention of pca and for which clinical data are either negative or particularly weak are not covered.The future of PCa prevention continues to expand, with several ongoing clinical trials and much interest in tertiary prostate cancer prevention.

Chemoprevention of prostate cancer

Over the past two decades, many more men are diagnosed with prostate cancer then die of the disease. This increase in diagnosis has led to aggressive treatment of indolent disease in many individuals and has been the impetus for finding a means of reducing the risk of prostate cancer. In the past decade, there have been eight large trials of prostate cancer risk reduction using dietary supplements, 5α-reductase inhibitors, or anti-estrogens. The only two trials which have demonstrated efficacy are those involving 5α-reductase inhibitors: the PCPT (finasteride) and REDUCE (dutasteride). This review examines prostate cancer risk reduction, with emphasis on conclusions that can be drawn from these two landmark studies.