Selenium and vitamin E for prostate cancer: post-SELECT (Selenium and Vitamin E Cancer Prevention Trial) status

Various formulations of selenium and vitamin E, both essential human dietary components, have been shown to possess a therapeutic and preventive effect against prostate cancer. Fortuitous results of clinical trials also implied a risk-reduction effect of selenium and vitamin E supplements. The Selenium and Vitamin E Cancer Prevention Trial (SELECT), using oral selenium and vitamin E supplementation in disease-free volunteers, was designed to test a prostate cancer chemoprevention hypothesis. SELECT was terminated early because of both safety concerns and negative data for the formulations and doses given. Here, we review and discuss the studies done before and since the inception of SELECT, as well as the parameters of the trial itself. We believe that there is a lack of appropriate in vivo preclinical studies on selenium and vitamin E despite many promising in vitro studies on these agents. It seems that the most effective doses and formulations of these agents for prostate cancer chemoprevention have yet to be tested. Also, improved understanding of selenium and vitamin E biology may facilitate the discovery of these doses and formulations.     

Selenium,but Not Lycopene or Vitamin E,Decreases Growth of Transplantable Dunning R3327-H Rat Prostate Tumors

Background

Lycopene, selenium, and vitamin E are three micronutrients commonly consumed and supplemented by men diagnosed with prostate cancer. However, it is not clear whether consumption of these compounds, alone or in combination, results in improved outcomes.

Methodology/Principal Findings

We evaluated the effects of dietary lycopene (250 mg/kg diet), selenium (methylselenocysteine, 1 mg/kg diet), and vitamin E (γ-tocopherol, 200 mg/kg diet) alone and in combination on the growth of androgen-dependent Dunning R3327-H rat prostate adenocarcinomas in male, Copenhagen rats. AIN-93G diets containing these micronutrients were prefed for 4 to 6 weeks prior to tumor implantation by subcutaneous injection. Tumors were allowed to grow for ∼18 weeks. Across diet groups, methylselenocysteine consumption decreased final tumor area (P = 0.003), tumor weight (P = 0.003), and the tumor weight/body weight ratio (P = 0.003), but lycopene and γ-tocopherol consumption intake did not alter any of these measures. There were no significant interactions among nutrient combinations on tumor growth. Methylselenocysteine consumption also led to small, but significant decreases in body weight (P = 0.007), food intake (P = 0.012), and body weight gain/food intake ratio (P = 0.022). However, neither body weight nor gain/food intake ratio was correlated with tumor weight. Methylselenocysteine, lycopene, and γ-tocopherol consumed alone and in combination did not alter serum testosterone or dihydrotestosterone concentrations; tumor proliferation or apoptosis rates. In addition, the diets also did not alter tumor or prostate androgen receptor, probasin, selenoprotein 15, selenoprotein P, or selenium binding protein 2 mRNA expression. However, using castration and finasteride-treated tissues from a previous study, we found that androgen ablation altered expression of these selenium-associated proteins.

Conclusions

Of the three micronutrients tested, only methylselenocysteine consumption reduced growth of transplantable Dunning R3327-H prostate tumors, albeit through an unresolved mechanism.     

Vitamin D Supplementation and Breast Cancer Prevention: A Systematic Review and Meta-Analysis of Randomized Clinical Trials

In recent years, the scientific evidence linking vitamin D status or supplementation to breast cancer has grown notably. To investigate the role of vitamin D supplementation on breast cancer incidence, we conducted a systematic review and meta-analysis of randomized controlled trials comparing vitamin D with placebo or no treatment. We used OVID to search MEDLINE (R), EMBASE and CENTRAL until April 2012. We screened the reference lists of included studies and used the “Related Article” feature in PubMed to identify additional articles. No language restrictions were applied. Two reviewers independently extracted data on methodological quality, participants, intervention, comparison and outcomes. Risk Ratios and 95% Confident Intervals for breast cancer were pooled using a random-effects model. Heterogeneity was assessed using the I² test. In sensitivity analysis, we assessed the impact of vitamin D dosage and mode of administration on treatment effects. Only two randomized controlled trials fulfilled the pre-set inclusion criteria. The pooled analysis included 5372 postmenopausal women. Overall, Risk Ratios and 95% Confident Intervals were 1.11 and 0.74–1.68. We found no evidence of heterogeneity. Neither vitamin D dosage nor mode of administration significantly affected breast cancer risk. However, treatment efficacy was somewhat greater when vitamin D was administered at the highest dosage and in combination with calcium (Risk Ratio 0.58, 95% Confident Interval 0.23–1.47 and Risk Ratio 0.93, 95% Confident Interval 0.54–1.60, respectively). In conclusions, vitamin D use seems not to be associated with a reduced risk of breast cancer development in postmenopausal women. However, the available evidence is still limited and inadequate to draw firm conclusions. Study protocol code: FARM8L2B5L.     

Tocopherol Transfer Protein Sensitizes Prostate Cancer Cells to Vitamin E

Prostate cancer is a major cause of mortality in men in developed countries. It has been reported that the naturally occurring antioxidant α-tocopherol (vitamin E) attenuates prostate cancer cell proliferation in cultured cells and mouse models. We hypothesized that overexpression of the tocopherol transfer protein (TTP), a vitamin E-binding protein that regulates tocopherol status, will sensitize prostate cancer cells to the anti-proliferative actions of the vitamin. To test this notion, we manipulated the expression levels of TTP in cultured prostate cells (LNCaP, PC3, DU145, and RWPE-1) using overexpression and knockdown approaches. Treatment of cells with tocopherol caused a time- and dose-dependent inhibition of cell proliferation. Overexpression of TTP dramatically sensitized the cells to the apoptotic effects of α-tocopherol, whereas reduction (“knockdown”) of TTP expression resulted in resistance to the vitamin. TTP levels also augmented the inhibitory effects of vitamin E on proliferation in semi-solid medium. The sensitizing effects of TTP were paralleled by changes in the intracellular accumulation of a fluorescent analog of vitamin E and by a reduction in intracellular levels of reactive oxygen species and were not observed when a naturally occurring, ligand binding-defective mutant of TTP was used. We conclude that TTP sensitizes prostate cancer cells to the anti-proliferative effects of vitamin E and that this activity stems from the ability of protein to increase the intracellular accumulation of the antioxidant. These observations support the notion that individual changes in the expression level or activity of TTP may determine the responsiveness of prostate cancer patients to intervention strategies that utilize vitamin E.     

Vitamin D for Treatment and Prevention of Infectious Diseases; A Systematic Review of Randomized Controlled Trials

ObjectiveTo review the existing human controlled intervention studies of vitamin D as adjunctive therapy in settings of infection and provide recommendations for design and implementation of future studies in this field on the basis of the evidence reviewed.MethodsWe conducted a systematic review of randomized controlled clinical trials that studied vitamin D for treatment or prevention of infectious diseases in humans. Studies from 1948 through 2009 were identified through search terms in PubMed and Ovid MEDLINE.ResultsThirteen published controlled trials were identified by our search criteria. Ten trials were placebo controlled, and 9 of the 10 were conducted in a rigorous double-blind design. The selected clinical trials demonstrated substantial heterogeneity in baseline patient demographics, sample size, and vitamin D intervention strategies. Serious adverse events attributable to vitamin D supplementation were rare across all studies. On the basis of studies reviewed to date, the strongest evidence supports further research into adjunctive vitamin D therapy for tuberculosis, influenza, and viral upper respiratory tract illnesses. In the selected studies, certain aspects of study design are highlighted to help guide future clinical research in the field.ConclusionMore rigorously designed clinical trials are needed for further evaluation of the relationship between vitamin D status and the immune response to infection as well as for delineation of necessary changes in clinical practice and medical care of patients with vitamin D deficiency in infectious disease settings. (Endocr Pract. 2009;15:438-449)     

Selenium and Vitamin E Deficiency in Pigs

The effect of selenium (Se) and vitamin E (Vit. E) on reproductive performance, growth and health was studied in pigs. Two levels of Se were used, 0.03 and 0.06 nag per kg feed. The major component of the experimental diets was barley originating from soil which had formerly produced crops with a very low content of Se. Prior to seeding, the area was divided into 2 plots, 1 of which was treated with Se in the form of sodium selenite, 100 g Se per ha. The use of Se enriched fertilizer was an effective way of increasing the Se concentration of the grain. Thus the concentration of Se in the barley produced on the treated area was 5 times higher than in barley from the untreated one. Vit. E was added at a level of 30 i.u. per kg feed, and the concentrations were approx. 15 and 45 i.u. in the basal and experimental diets, respectively. The higher level of Se or Vit. E was not significantly associated with milk yield of the sow, litter size, birth weight or haemoglobin levels. However, there was a tendency to an increase in milk yield of the sows following additions of Se plus Vit. E, and litter size was slightly higher from sows which had received an addition of Vit. E. The concentration of Se and Vit. E was much higher in colostrum than in sow milk, and additions of dietary Se and Vit. E were associated with marked increases in the concentrations of these compounds in both colostrum and sow milk. There was a moderately improving effect of a high Se concentration in feed on growth rate and feed utilization. Low dietary levels of Se and Vit. E were followed by increased mortality rate in piglets; iron toxicity in connection with iron treatment was observed in piglets on low dietary Vit. E. Symptoms characteristic of PSE were not observed in the Se and Vit. E deficient pigs.     

Intravenous N-Acetylcysteine for Prevention of Contrast-Induced Nephropathy: A Meta-Analysis of Randomized,Controlled Trials

Background

Contrast-induced nephropathy (CIN) is one of the common causes of acute renal insufficiency after contrast procedures. Whether intravenous N-acetylcysteine (NAC) is beneficial for the prevention of contrast-induced nephropathy is uncertain. In this meta-analysis of randomized controlled trials, we aimed to assess the efficacy of intravenous NAC for preventing CIN after administration of intravenous contrast media.

Study Design

Relevant studies published up to September 2012 that investigated the efficacy of intravenous N-acetylcysteine for preventing CIN were collected from MEDLINE, OVID, EMBASE, Web of Science, Cochrane Central Register of Controlled Trials, and the conference proceedings from major cardiology and nephrology meetings. The primary outcome was CIN. Secondary outcomes included renal failure requiring dialysis, mortality, and length of hospitalization. Data were combined using random-effects models with the performance of standard tests to assess for heterogeneity and publication bias. Meta-regression analyses were also performed.

Results

Ten trials involving 1916 patients met our inclusion criteria. Trials varied in patient demographic characteristics, inclusion criteria, dosing regimens, and trial quality. The summary risk ratio for contrast-induced nephropathy was 0.68 (95% CI, 0.46 to 1.02), a nonsignificant trend towards benefit in patients treated with intravenous NAC. There was evidence of significant heterogeneity in NAC effect across studies (Q = 17.42, P = 0.04; I² = 48%). Meta-regression revealed no significant relation between the relative risk of CIN and identified differences in participant or study characteristics.

Conclusion

This meta-analysis showed that research on intravenous N-acetylcysteine and the incidence of CIN is too inconsistent at present to warrant a conclusion on efficacy. A large, well designed trial that incorporates the evaluation of clinically relevant outcomes in participants with different underlying risks of CIN is required to more adequately assess the role for intravenous NAC in CIN prevention.     

Prostate Cancer Prevention Through Pomegranate Fruit

Prostate cancer (CaP) is the second leading cause of cancer-related deaths among U.S. males with a similar trend in many Western countries. CaP is an ideal candidate disease for chemoprevention because it is typically diagnosed in men over 50 years of age, and thus even a modest delay in disease progression achieved through pharmacological or nutritional intervention could significantly impact the quality of life of these patients. In this regard we and others have proposed the use of dietary antioxidants as candidate CaP chemopreventive agents. The fruit pomegranate derived from the tree Punica granatum has been shown to possess strong antioxidant and anti-inflammatory properties. In a recent study, we showed that pomegranate fruit extract (PFE), through modulations in the cyclin kinase inhibitor-cyclin-cyclin-dependent kinase machinery, resulted in inhibition of cell growth followed by apoptosis of highly aggressive human prostate carcinoma PC3 cells. These events were associated with alterations in the levels of Bax and Bcl-2 shifting the Bax:Bcl-2 ratio in favor of apoptosis. Further, we showed that oral administration of a human acceptable dose of PFE to athymic nude mice implanted with CWR22R1 cells resulted in significant inhibition of tumor growth with concomitant reduction in secretion of prostate-specific antigen (PSA) in the serum. The outcome of this study could have a direct practical implication and translational relevance to CaP patients, because it suggests that pomegranate consumption may retard CaP progression, which may prolong the survival and quality of life of the patients.     

Focal Laser Ablation for Localized Prostate Cancer: Principles,Clinical Trials,and Our Initial Experience

Focal therapy of prostate cancer is an evolving treatment strategy that destroys a predefined region of the prostate gland that harbors clinically significant disease. Although long-term oncologic control has yet to be demonstrated, focal therapy is associated with a marked decrease in treatment-related morbidity. Focal laser ablation is an emerging modality that has several advantages, most notably real-time magnetic resonance imaging (MRI) compatibility. This review presents the principles of laser ablation, the role of multiparametric MRI for delineating the site of significant prostate cancer, a summary of published clinical studies, and our initial experience with 23 patients, criteria for selecting candidates for focal prostate ablation, and speculation regarding future directions.Key words: Laser ablation, Prostate cancer, Focal therapy, Targeted therapyProstate cancer is the most common solid organ malignancy and the second most common cause of cancer death among men living in the Western world.¹ Widespread prostate-specific antigen (PSA) testing and decreased thresholds for prostate biopsy have led to both a reduction in the proportion of men diagnosed with advanced disease and disease-specific mortality. The consequence of widespread PSA screening has been a dramatic increase in both the detection of low-risk disease and the proportion of men diagnosed with prostate cancer undergoing radical prostatectomy (RP) or radiation therapy (RT).² In many cases, the complications associated with treating low-risk disease by RP or RT outweigh the benefits.^3,4 Although active surveillance (AS) is an appealing alternative for managing low-risk disease, it potentially decreases long-term survival rates.⁵ Due to the unreliability of disease risk stratification at the time of diagnosis, 14% to 41% of men assigned to AS will cross over to RP or RT due to upgrading or upstaging.⁶There is increasing evidence that multiparametric magnetic resonance imaging (mpMRI) localizes the site(s) of clinically significant prostate cancer prior to prostate biopsy.⁷ These suspicious MRI focal abnormalities can be biopsied directly in the MRI unit or under transrectal ultrasound (TRUS) guidance using software that co-registers and fuses the MRI and ultrasound (US) images.⁸ In many cases, MRI image-guided biopsy identifies a single clinically significant cancer. Although prostate cancer is typically a multifocal disease, the index, or dominant, lesion is typically predictive of extraprostatic extension and disease progression.^9–11 The majority of the secondary tumor sites are composed of small Gleason 6 disease, which represent no immediate threat.¹² It is theoretically possible to focally ablate only the index lesion, thereby achieving oncologic control while minimizing treatment-related morbidity by minimizing collateral damage to adjacent structures.Focal ablation of prostate cancer is an evolving treatment strategy that destroys a predefined region (or target) of the prostate that harbors the clinically significant cancer. A number of energy sources have been investigated for focal ablation of the prostate, including cryotherapy,¹³ high-intensity focused ultrasound (HIFU),¹⁴ photodynamic therapy,¹⁵ and laser ablation.¹⁶ Although long-term oncologic control has yet to be demonstrated, all of these targeted ablative options are associated with marked decrease in treatment-related complications. One of the advantages of laser technology is that the ablation can be performed with real-time MRI imaging. Because the target lesion are almost always defined by the MRI, laser ablation is currently the most accurate way to deliver ablative energy to the intended target. Other advantages of laser ablation include its homogeneous tissue necrosis, relatively low cost, and wide availability.¹⁷ MRI-guided focal ablation allows treatment monitoring using MR thermometry and real-time visualization of the targeted treatment zone.^18,19This review presents the principles of laser ablation, the role of mpMRI for delineating the site of significant prostate cancer, a summary of published clinical studies and the New York University Langone Medical Center (NYULMC)/Sperling Prostate Cancer Center experience on focal laser ablation of prostate cancer, criteria for selecting candidates for focal prostate ablation, and speculation regarding future directions of focal laser ablation for the treatment of localized prostate cancer.     

Finasteride Concentrations and Prostate Cancer Risk: Results from the Prostate Cancer Prevention Trial

ObjectiveIn the Prostate Cancer Prevention Trial (PCPT), finasteride reduced the risk of prostate cancer by 25%, even though high-grade prostate cancer was more common in the finasteride group. However, it remains to be determined whether finasteride concentrations may affect prostate cancer risk. In this study, we examined the association between serum finasteride concentrations and the risk of prostate cancer in the treatment arm of the PCPT and determined factors involved in modifying drug concentrations.MethodsData for this nested case-control study are from the PCPT. Cases were drawn from men with biopsy-proven prostate cancer and matched controls. Finasteride concentrations were measured using a liquid chromatography-mass spectrometry validated assay. The association of serum finasteride concentrations with prostate cancer risk was determined by logistic regression. We also examine whether polymorphisms in the enzyme target and metabolism genes of finasteride are related to drug concentrations using linear regression.

Results and Conclusions

Among men with detectable finasteride concentrations, there was no association between finasteride concentrations and prostate cancer risk, low-grade or high-grade, when finasteride concentration was analyzed as a continuous variable or categorized by cutoff points. Since there was no concentration-dependent effect on prostate cancer, any exposure to finasteride intake may reduce prostate cancer risk. Of the twenty-seven SNPs assessed in the enzyme target and metabolism pathway, five SNPs in two genes, CYP3A4 (rs2242480; rs4646437; rs4986910), and CYP3A5 (rs15524; rs776746) were significantly associated with modifying finasteride concentrations. These results suggest that finasteride exposure may reduce prostate cancer risk and finasteride concentrations are affected by genetic variations in genes responsible for altering its metabolism pathway.

Trial Registration

ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT00288106","term_id":"NCT00288106"}}NCT00288106     

Screening for Prostate Cancer: A Review of the ERSPC and PLCO Trials

The advent of prostate-specific antigen (PSA) testing in the early 1980s revolutionized the diagnosis of prostate cancer. As a result of PSA testing, there has been a surge in the number of prostate cancer diagnoses. This review examines the results of 2 recent landmark trials that studied the effect of screening on prostate cancer mortality: the European Randomized Study of Screening for Prostate Cancer (ERSPC) and the US-based Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial.Key words: PSA screening, European Randomized Study of Screening for Prostate Cancer (ERSPC), Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening TrialProstate cancer poses a significant problem for men’s health; it has become the most common malignancy and the second most common cause of cancer death in American men. It is estimated that 1 in 6 men will be diagnosed with prostate cancer at some time in their lives, and more than 30,000 men died of the disease in 2002.¹ The advent of prostate-specific antigen (PSA) testing in the early 1980s revolutionized the diagnosis of prostate cancer, and, as a result, there has been a surge in the number of prostate cancer diagnoses.Similar to other common malignancies, such as breast and cervical cancer, population screening with this effective tumor marker appears enticing, and the American health care model has advocated PSA screening since the early 1990s. This review examines the results of 2 recent landmark trials: the European Randomized Study of Screening for Prostate Cancer (ERSPC)¹ and the US-based Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial.² The results of these trials have contributed significantly to our understanding of the effects and efficacy of prostate cancer screening, and its difficulties. Both trials examined mortality as the endpoint, and both found little effect on mortality from screening.     

Vitamin E Improves the Aminotransferase Status of Patients Suffering from Viral Hepatitis C: A Randomized,Double-Blind,Placebo-Controlled Study

Vitamin E has been shown to protect against liver damage induced by oxidative stress in animal experiments. Based on our previous findings of diminished vitamin E levels in patients suffering from viral hepatitis, we treated 23 hepatitis C patients refractory to a-interferon therapy with high doses of vitamin E (2 × 400 IU RRR-α-tocopherol/day) for 12 weeks. Study design: pro-spective randomized double-blind crossover design. Clinical parameters including alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were determined for monitoring the disease state, in parallel vitamin E plasma levels and plasma lipids were determined. The plasma levels of the a-tocopherol were increased about 2-fold in all 23 patients. In 11 of 23 patients the clinical parameters indicative of liver damage were improved during the phase of vitamin E treatment (48% responders). ALT levels in responders were lowered by 46% and AST levels were lowered by 35% after 12 weeks of vitamin E treatment. Cessation of vitamin E treatment was followed by a rapid relapse of ALT and AST elevation, whereas retreatment led to a reproducible ALT decrease by 45% and AST decrease of 37% after a 6 months followup. Since vitamin E is non-toxic even at elevated doses ingested over extended periods, we suggest the treatment of patients refractory to α-interferon therapy suffering from hepatitis C with vitamin E as a supportive therapy.     

Randomization to Screening for Prostate,Lung, Colorectal and Ovarian Cancers and Thyroid Cancer Incidence in Two Large Cancer Screening Trials

Background

Thyroid cancer incidence has increased significantly over the past three decades due, in part, to incidental detection. We examined the association between randomization to screening for lung, prostate, colorectal and/or ovarian cancers and thyroid cancer incidence in two large prospective randomized screening trials.

Methods

We assessed the association between randomization to low-dose helical CT scan versus chest x-ray for lung cancer screening and risk of thyroid cancer in the National Lung Screening Trial (NLST). In the Prostate Lung Colorectal and Ovarian Cancer Screening Trial (PLCO), we assessed the association between randomization to regular screening for said cancers versus usual medical care and thyroid cancer risk. Over a median 6 and 11 years of follow-up in NLST and PLCO, respectively, we identified 60 incident and 234 incident thyroid cancer cases. Cox proportional hazards regression was used to calculate the cause specific hazard ratios (HR) and 95% confidence intervals (CI) for thyroid cancer.

Results

In NLST, randomization to lung CT scan was associated with a non-significant increase in thyroid cancer risk (HR  = 1.61; 95% CI: 0.96–2.71). This association was stronger during the first 3 years of follow-up, during which participants were actively screened (HR  = 2.19; 95% CI: 1.07–4.47), but not subsequently (HR  = 1.08; 95% CI: 0.49–2.37). In PLCO, randomization to cancer screening compared with usual care was associated with a significant decrease in thyroid cancer risk for men (HR  = 0.61; 95% CI: 0.49–0.95) but not women (HR  = 0.91; 95% CI: 0.66–1.26). Similar results were observed when restricting to papillary thyroid cancer in both NLST and PLCO.

Conclusion

Our study suggests that certain medical encounters, such as those using low-dose helical CT scan for lung cancer screening, may increase the detection of incidental thyroid cancer.     

内镜黏膜切除术治疗低位直肠侧向发育型肿瘤随机对照研究

目的:探讨内镜黏膜切除术治疗低位直肠侧向发育型肿瘤的临床效果。方法:收集我院收治的低位直肠侧向发育型肿瘤患者40例,随机分为对照组和实验组,每组各20例,对照组患者给予常规内镜下粘膜切除术,实验组患者给予内镜反转黏膜切除术,治疗结束后,对所有患者的病变残留例数、手术时间以及住院时间、并发症发生情况、手术切除效果进行检测并比较。结果:与对照组患者相比,实验组患者复发率较低(P0.05),手术时间以及住院时间、并发症发生率较低(P0.05);两组患者切除效果相比较,实验组分次切除、肿瘤残留例数患者较少,完全切除患者例数较多(P0.05),两组患者的整块切除例数无差异(P0.05)。结论:内镜反转黏膜切除术对于低位直肠侧向发育型肿瘤患者的临床疗效优于常规内镜下粘膜切除术,对临床有指导意义。