Lycopene for advanced hormone refractory prostate cancer: a prospective, open phase II pilot study

A phase I study of docetaxel plus synthetic lycopene in metastatic prostate cancer patients

PURPOSE

Our preclinical studies showed that lycopene enhanced the anti-prostate cancer efficacy of docetaxel in animal models. A phase I trial (NCT0149519) was conducted to identify an optimum dose of synthetic lycopene in combination with docetaxel (and androgen blockade [androgen deprivation therapy, ADT]), and to evaluate its effect on the safety and pharmacokinetics of docetaxel in men with metastatic prostate cancer.

METHODS

Subjects were treated with 21-day cycles of 75 mg/m2 docetaxel (and ADT), plus lycopene at 30, 90 or 150 mg/day. A Bayesian model averaging continual reassessment method was used to guide dose escalation. Pharmacokinetics of docetaxel and multiple correlative studies were carried out.

RESULTS

Twenty-four participants were enrolled, 18 in a dose escalation cohort to define the maximum tolerated dose (MTD), and six in a pharmacokinetic cohort. Docetaxel/ADT plus 150 mg/day synthetic lycopene resulted in dose-limiting toxicity (pulmonary embolus) in one out of 12 participants with an estimated probability of .106 and thus was chosen as the MTD. Lycopene increased the AUCinf and Cmax of plasma docetaxel by 9.5% and 15.1%, respectively. Correlative studies showed dose-related changes in circulating endothelial cells and vascular endothelial growth factor A, and reduction in insulin-like growth factor 1R phosphorylation, associated with lycopene therapy.

CONCLUSIONS

The combination of docetaxel/ADT and synthetic lycopene has low toxicity and favourable pharmacokinetics. The effects of lycopene on biomarkers provide additional support for the toxicity-dependent MTD definition.

HIGHLIGHTS

The maximum tolerated dose was identified as 150 mg/day of lycopene in combination with docetaxel/ADT for the treatment of metastatic prostate cancer patients. Small increases in plasma exposure to docetaxel were observed with lycopene co-administration. Mechanistically significant effects were seen on angiogenesis and insulin-like growth factor 1 signalling by lycopene co-administration with docetaxel/ADT.

The influence of lifestyle changes (diet, exercise and stress reduction) on prostate cancer tumour biology and patient outcomes: A systematic review

Background

The mostly indolent natural history of prostate cancer (PCa) provides an opportunity for men to explore the benefits of lifestyle interventions. Current evidence suggests appropriate changes in lifestyle including diet, physical activity (PA) and stress reduction with or without dietary supplements may improve both disease outcomes and patient's mental health.

Objective

This article aims to review the current evidence on the benefits of all lifestyle programmes for PCa patients including those aimed at reducing obesity and stress, explore their affect on tumour biology and highlight any biomarkers that have clinical utility.

Evidence acquisition

Evidence was obtained from PubMed and Web of Science using keywords for each section on the affects of lifestyle interventions on (a) mental health, (b) disease outcomes and (c) biomarkers in PCa patients. PRISMA guidelines were used to gather the evidence for these three sections (15, 44 and 16 publications, respectively).

Evidence synthesis

For lifestyle studies focused on mental health, 10/15 demonstrated a positive influence, although for those programmes focused on PA it was 7/8. Similarly for oncological outcomes, 26/44 studies demonstrated a positive influence, although when PA was included or the primary focus, it was 11/13. Complete blood count (CBC)-derived inflammatory biomarkers show promise, as do inflammatory cytokines; however, a deeper understanding of their molecular biology in relation to PCa oncogenesis is required (16 studies reviewed).

Conclusions

Making PCa-specific recommendations on lifestyle interventions is difficult on the current evidence. Nevertheless, notwithstanding the heterogeneity of patient populations and interventions, the evidence that dietary changes and PA may improve both mental health and oncological outcomes is compelling, especially for moderate to vigorous PA. The results for dietary supplements are inconsistent, and although some biomarkers show promise, significantly more research is required before they have clinical utility.

The Anti-Cancer Activity of Lycopene: A Systematic Review of Human and Animal Studies

Lycopene is a nutraceutical with health-promoting and anti-cancer activities, but due to a lack of evidence, there are no recommendations regarding its use and dosage. This review aimed to evaluate the benefits of lycopene supplementation in cancer prevention and treatment based on the results of in vivo studies. We identified 72 human and animal studies that were then analysed for endpoints such as cancer incidence, improvement in treatment outcomes, and the mechanisms of lycopene action. We concluded that the results of most of the reviewed in vivo studies confirmed the anti-cancer activities of lycopene. Most of the studies concerned prostate cancer, reflecting the number of in vitro studies. The reported mechanisms of lycopene action in vivo included regulation of oxidative and inflammatory processes, induction of apoptosis, and inhibition of cell division, angiogenesis, and metastasis formation. The predominance of particular mechanisms seemed to depend on tumour organ localisation and the local storage capacity of lycopene. Finally, there is a need to look for predictive factors to identify a population that may benefit from lycopene supplementation. The potential candidates appear to be race, single nucleotide polymorphisms in carotene-cleaving enzymes, some genetic abbreviations, and insulin-like growth factor-dependent and inflammatory diseases.

Anti-prostate cancer protection and therapy in the framework of predictive, preventive and personalised medicine — comprehensive effects of phytochemicals in primary, secondary and tertiary care

According to the GLOBOCAN 2020, prostate cancer (PCa) is the most often diagnosed male cancer in 112 countries and the leading cancer-related death in 48 countries. Moreover, PCa incidence permanently increases in adolescents and young adults. Also, the rates of metastasising PCa continuously grow up in young populations. Corresponding socio-economic burden is enormous: PCa treatment costs increase more rapidly than for any other cancer. In order to reverse current trends in exploding PCa cases and treatment costs, pragmatic decisions should be made, in favour of advanced populational screening programmes and effective anti-PCa protection at the level of the health-to-disease transition (sub-optimal health conditions) demonstrating the highest cost-efficacy of treatments. For doing this, the paradigm change from reactive treatments of the clinically manifested PCa to the predictive approach and personalised prevention is essential.

Phytochemicals are associated with potent anti-cancer activity targeting each stage of carcinogenesis including cell apoptosis and proliferation, cancer invasiveness and metastatic disease. For example, their positive effects are demonstrated for stabilising and restoring mitochondrial health quality, which if compromised is strongly associated with sub-optimal health conditions and strong predisposition to aggressive PCa sub-types. Further, phytochemicals significantly enhance response of cancer cells to anti-cancer therapies including radio- and chemotherapy. Evident plant-based mitigation of negative side-effects frequently observed for conventional anti-cancer therapies has been reported. Finally, dual anti-cancer and anti-viral effects of phytochemicals such as these of silibinin have been demonstrated as being highly relevant for improved PCa management at the level of secondary and tertiary care, for example, under pandemic conditions, since PCa-affected individuals per evidence are highly vulnerable towards COVID-19 infection.

Here, we present a comprehensive data analysis towards clinically relevant anti-cancer effects of phytochemicals to be considered for personalised anti-PCa protection in primary care as well as for an advanced disease management at the level of secondary and tertiary care in the framework of predictive, preventive and personalised medicine.

A phase II study of docetaxel plus lycopene in metastatic castrate resistant prostate cancer

We carried out a phase II study to investigate the activity of docetaxel plus lycopene in advanced castrate resistant adenocarcinoma of the prostate. Patients were chemotherapy and biological therapy naive. Docetaxel 75 mg/m² was given every 21 days with daily oral lycopene 30 mg. The primary endpoint was a ≥50% reduction in PSA. Secondary endpoints were median time to PSA progression, duration of response and overall survival. Thirteen patients were initiated on protocol therapy. Median age was 77 (range 55-90). Twelve patients (92%) had bone metastases. Four patients (30%) had both bone and visceral metastases. PSA response was seen in 10 patients (76.9% [95% confidence interval (CI), 46.2-94.9%]). Two patients had stable disease (SD), yielding a disease control rate of 92%. Median time to PSA progression was 8 months [95% CI, 3.5-8.7]. Median duration of response (DOR) was 7.3 months [95% CI, 4.8-13.2]. Median overall survival at 5 years was 35.1 months [95% CI 25.7-57.7]. No new safety signals were noted. No patients experienced grade 3 or above anemia. One patient (7%) experienced febrile neutropenia. A PSA response rate of 76.9% and median survival of 35.1 months compares favorably to the 45% PSA response rate and 17.4 months median survival reported for the TAX 237 trialists. While our study was limited due to small sample size, our results suggest that the combination of docetaxel and lycopene merits further study.

Recent Progress in Discovering the Role of Carotenoids and Metabolites in Prostatic Physiology and Pathology-A Review-Part II: Carotenoids in the Human Studies

Among the vast variety of plant-derived phytochemicals, the group of carotenoids has continuously been investigated in order to optimize their potential application in the area of dietary intervention related to chronic diseases. One organ that has been especially targeted in many of these studies and clinical trials is the human prostate. Without doubt, carotenoids (and their endogenous derivatives-retinoids and apo-carotenoids) are involved in a plethora of intra- and intercellular signaling, cell growth, and differentiation of prostate tissue. Due to the accumulation of new data on the role of different carotenoids, such as lycopene (LYC) and β-carotene (BC), in prostatic physiology and pathology, the present review aimed to cover the past ten years of research in this regard. Data from experimental studies are presented in the first part of the review, while epidemiological studies are disclosed in this second part. The objective of this compilation was to emphasize the present state of knowledge about the most potent molecular targets of carotenoids, as well as to propose promising carotenoid agents for the prevention and possible treatment of prostatic diseases.

Lycopene Does Not Affect Prostate-Specific Antigen in Men with Non-Metastatic Prostate Cancer: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Several randomized controlled trials (RCTs) have investigated the effect of lycopene supplementation on serum levels of prostate-specific antigen (PSA) in patients with prostate cancer. However, results have been inconclusive. We systematically searched PubMed, Embase, and Scopus up to January 2020 to find RCTs investigating the effect of lycopene supplementation on serum levels of PSA in patients with non-metastatic prostate cancer. Using a random-effects model, the reported risk estimates were pooled. A total of six trials were included in the final analysis. we found no significant effect of lycopene on circulating PSA (WMD: -0.60, 95% CI: -2.01, 0.81 µg/L). However, we observed a significant reducing effect when the analysis was confined to studies that included patients with higher baseline levels of PSA (≥6.5 µg/L) (WMD: -3.74 µg/L, 95% CI: -5.15, -2.32, P < 0.001). Subgroup analysis based on the duration of intervention did not result in any significant effect. Non-linear dose-response analysis did not show any significant effects of lycopene dosage (P_{non-linearity} = 0.50) and duration of the intervention (P_{non-linearity} = 0.63) on serum levels of PSA. Although lycopene supplementation did not produce any reduction in PSA levels overall, a significant reducing effect was observed in patients with higher levels of baseline PSA. Due to the heterogeneity of our results, further high-quality clinical trials with long-term duration are required to determine the efficacy of lycopene in patients with non-metastatic prostate cancer.

Dietary Tomato or Lycopene Do Not Reduce Castration-Resistant Prostate Cancer Progression in a Murine Model

BACKGROUND

Dietary tomato products or lycopene protect against prostate carcinogenesis, but their impact on the emergence of castration-resistant prostate cancer (CRPC) is unknown.

OBJECTIVE

We hypothesized that tomato or lycopene products would reduce the emergence of CRPC.

METHODS

Transgenic adenocarcinoma of the mouse prostate (TRAMP) mice were castrated at 12-13 wk and the emergence of CRPC was monitored by ultrasound in each study. In Study 1, TRAMP mice (n = 80) were weaned onto an AIN-93G-based control diet (Con-L, n = 28), a 10% tomato powder diet (TP-L, 10% lyophilized w/w, n = 26), or a control diet followed by a tomato powder diet after castration (TP-Int1, n = 26). In Study 2, TRAMP mice (n = 85) were randomized onto a control diet with placebo beadlets (Con-Int, n = 29), a tomato diet with placebo beadlets (TP-Int2, n = 29), or a control diet with lycopene beadlets (Lyc-Int, n = 27) following castration (aged 12 wk). Tumor incidence and growth were monitored by ultrasound beginning at an age of 10 wk. Mice were euthanized 4 wk after tumor detection or aged 30 wk if no tumor was detected. Tissue weights were compared by ANOVA followed by Dunnett's test. Tumor volumes were compared using generalized linear mixed model regression.

RESULTS

Ultrasound estimates for the in vivo tumor volume were strongly correlated with tumor weight at necropsy (R2 = 0.75 and 0.94, P <0.001 for both Studies 1 and 2, respectively). Dietary treatments after castration did not significantly impact cancer incidence, time to tumor detection, or final tumor weight.

CONCLUSIONS

In contrast to studies of de novo carcinogenesis in multiple preclinical models, tomato components had no significant impact on the emergence of CRPC in the TRAMP model. It is possible that specific mutant subclones of prostate cancer may continue to show some antiproliferative response to tomato components, but further studies are needed to confirm this.

Potential inhibitory effect of lycopene on prostate cancer

Studying prostate cancer is important due to its high annual incidences and mortality rates in the world. Although prostate cancer mortality rates are reduced using new therapy, complicated routes and side effects of these current drugs require a daily available treatment for prevention. Lycopene is a natural, prominent, and effective product which has a high value in diet. The anti-cancer effect, non-toxicity, safety and preventive or therapeutic roles of lycopene have been investigated in several studies. In the current review, we have collected information about the anti-cancer, anti-progressive and apoptotic effects of lycopene on prostate cancer. This article is a summary of the most important original and review articles on lycopene and its anticancer effects that are systematically categorized and presents information about the molecular structure, different sources, biological functions, and its in-vivo and in-vitro effects of lycopene on variety of cancerous and normal cells. The clinical studies provide a clear image for continuous use of this adjunctive dietary for different type of cancers, especially prostate cancer in men. In addition, this article discusses the various molecular pathways activated by lycopene that eventually prevent or suppress cancer. Lycopene has been found to effectively suppress the progression and proliferation, arrest in-cell cycle, and induce apoptosis of prostate cancer cells in both in-vivo and in-vitro conditions. Additionally, lycopene showed that it could modulate the signaling pathways and their protein for the treatment or prevention of prostate cancer.

Epidemiology of Prostate Cancer

Prostate cancer is the second most frequent cancer diagnosis made in men and the fifth leading cause of death worldwide. Prostate cancer may be asymptomatic at the early stage and often has an indolent course that may require only active surveillance. Based on GLOBOCAN 2018 estimates, 1,276,106 new cases of prostate cancer were reported worldwide in 2018, with higher prevalence in the developed countries. Differences in the incidence rates worldwide reflect differences in the use of diagnostic testing. Prostate cancer incidence and mortality rates are strongly related to the age with the highest incidence being seen in elderly men (> 65 years of age). African-American men have the highest incidence rates and more aggressive type of prostate cancer compared to White men. There is no evidence yet on how to prevent prostate cancer; however, it is possible to lower the risk by limiting high-fat foods, increasing the intake of vegetables and fruits and performing more exercise. Screening is highly recommended at age 45 for men with familial history and African-American men. Up-to-date statistics on prostate cancer occurrence and outcomes along with a better understanding of the etiology and causative risk factors are essential for the primary prevention of this disease.

Increased dietary and circulating lycopene are associated with reduced prostate cancer risk: a systematic review and meta-analysis

BACKGROUND

Prostate cancer (PCa) is the fifth leading cause of cancer-related deaths worldwide. Many epidemiological studies have investigated the association between prostate cancer and lycopene, however, results have been inconsistent. This study aims to determine the impact of dietary and circulating concentrations of lycopene on PCa risk and to investigate potential dose-response associations.

METHODS

We conducted a systematic review and dose-response meta-analysis for the for the association between dietary and circulating lycopene and PCa risk. Eligible studies were published before 1 December 2016 and were identified from PubMed, Web of Science and the Cochrane Library. We estimated pooled relative risk ratios (RR) and 95% confidence intervals (CI) using random and fixed effects models. Linear and nonlinear dose-response relationships were also evaluated for PCa risk.

RESULTS

Forty-two studies were included in the analysis, which included 43 851 cases of PCa reported from 692 012 participants. Both dietary intake (RR=0.88, 95% CI: 0.78-0.98, P=0.017) and circulating concentrations (RR=0.88, 95% CI: 0.79-0.98, P=0.019) of lycopene were significantly associated with reduced PCa risk. Sensitivity analyses within the dose-response analysis further revealed a significant linear dose-response for dietary lycopene and PCa risk such that PCa decreased by 1% for every additional 2 mg of lycopene consumed (P=0.026). Additionally, PCa risk decreased by 3.5 to 3.6% for each additional 10 μgdl^-1 of circulating lycopene in the linear and nonlinear models respectively (p_linear=0.004, p_nonlinear=0.006). While there were no associations between lycopene and advanced PCa, there was a trend for protection against PCa aggressiveness (RR=0.74, 95% CI: 0.55-1.00, P=0.052).

CONCLUSIONS

Our data demonstrate that higher dietary and circulating lycopene concentrations are inversely associated with PCa risk. This was accompanied by dose-response relationships for dietary and circulating lycopene. However, lycopene was not associated with a reduced risk of advanced PCa. Further studies are required to determine the mechanisms underlying these associations.

Food-based natural products for cancer management: Is the whole greater than the sum of the parts?

The rise in cancer incidence and mortality in developing countries together with the human and financial cost of current cancer therapy mandates a closer look at alternative ways to overcome this burgeoning global healthcare problem. Epidemiological evidence for the association between cancer and diet and the long latency of most cancer progression have led to active exploration of whole and isolated natural chemicals from different naturally occurring substances in various preclinical and clinical settings. In general the lack of systemic toxicities of most 'whole' and 'isolated' natural compounds, their potential to reduce toxic doses and potential to delay the development of drug-resistance makes them promising candidates for cancer management. This review article examines the suggested molecular mechanisms affected by these substances focusing to a large extent on prostate cancer and deliberates on the disparate results obtained from cell culture, preclinical and clinical studies in an effort to highlight the use of whole extracts and isolated constituents for intervention. As such these studies underscore the importance of factors such as treatment duration, bioavailability, route of administration, selection criteria, standardized formulation and clinical end points in clinical trial design with both entities. Overall lack of parallel comparison studies between the whole natural products and their isolated compounds limits decisive conclusions regarding the superior utility of one over the other. We suggest the critical need for rigorous comparative research to identify which one of the two or both entities from nature would be best qualified to take on the mantle of cancer management.

Mitochondrial β-Carotene 9',10' Oxygenase Modulates Prostate Cancer Growth via NF-κB Inhibition: A Lycopene-Independent Function

Despite numerous inquiries into protective roles of lycopene in prostate cancer prevention or therapy, little is known about mechanisms by which lycopene or its metabolites inhibit prostate cancer. The enzyme β-carotene 9',10'-oxygenase (BCO2), which catalyzes asymmetric cleavage of several carotenoids, is the principal regulator of lycopene metabolism, but the range of BCO2 biological functions is incompletely understood. This study investigated expression and functional roles of BCO2 in human prostate cancer. Expression of the bco2 gene is dramatically decreased in prostate cancer tissue and in a range of prostate cancer cell lines as compared with nonneoplastic prostate tissue and normal prostatic epithelial cells, respectively. Inhibition of DNA methyltransferase activity restored bco2 expression in prostate cancer cell lines tested. Treatment with lycopene or its metabolite, apo-10-lycopenal, also increased bco2 expression and reduced cell proliferation in androgen-sensitive cell lines, but lycopene neither altered bco2 expression nor cell growth in androgen-resistant cells. Notably, restoring bco2 expression in prostate cancer cells inhibited cell proliferation and colony formation, irrespective of lycopene exposure. Exogenous expression of either wild-type BCO2 or a mutant (enzymatically inactive) BCO2 in prostate cancer cells reduced NF-κB activity and decreased NF-κB nuclear translocation and DNA binding. Together, these results indicate epigenetic loss of BCO2 expression is associated with prostate cancer progression. Moreover, these findings describe previously unanticipated functions of BCO2 that are independent of its enzymatic role in lycopene metabolism.

IMPLICATIONS

This study identifies BCO2 as a tumor suppressor in prostate cancer. BCO2-mediated inhibition of NF-κB signaling implies BCO2 status is important in prostate cancer progression. Mol Cancer Res; 14(10); 966-75. ©2016 AACR.

Assessment of anticancer-treatment outcome in patients with metastatic castration-resistant prostate cancer-going beyond PSA and imaging, a systematic literature review

BACKGROUND

In the past years, there has been significant progress in anticancer drug development for patients with metastatic castration-resistant prostate cancer (CRPC). However, the current instruments to assess clinical treatment response have limitations and may not sufficiently reflect patient benefit. Our objective was to systematically identify tools to evaluate both patient benefit and clinical anticancer-treatment response as basis for an international consensus process and development of a specific pragmatic instrument for men with CRPC.

METHODS

PubMed, Embase and CINAHL were searched to identify currently available tools to assess anticancer-treatment benefit, other than standard imaging procedures and prostate-specific antigen measurements, namely quality of life (QoL), detailed pain assessment, physical function and objective measures of other complex cancer-related syndromes in patients with CRPC. Additionally, all CRPC phase III trials published in the last 5 years were reviewed as well as studies using physical function tools in a general cancer population. The PRIMSA statement was followed for the systematic review process.

RESULTS

The search generated 1096 hits, 185 full-text papers were screened and finally 73 publications were included. Additional 89 publications were included by hand-search. We identified a total of 98 tools used in CRPC trials and grouped these into three categories: 22 tools assessing QoL domains and subgroups, 47 tools for pain assessment and 29 tools for objective measures, mainly physical function and assessment of skeletal disease burden.

CONCLUSION

A wide variety of assessment tools and also efforts to standardize and harmonize patient-reported outcomes and pain assessment were identified. However, the specific needs of the increasing CRPC population living longer with their incurable cancer are insufficiently captured and objective physical outcome measures are under-represented. In the age of new anticancer drug targets and principles, new methods to monitor patient relevant outcomes of antineoplastic therapy are of utmost importance.

Tomato and tomato byproducts. Human health benefits of lycopene and its application to meat products: a review

During recent decades, the food industry, consumers, and regulatory authorities have developed a significant interest in functional foods because of their potential benefits for human health over and above their basic nutritional value. Tomato is the second most important vegetable crop in the world. The amount of the related wastes is estimated at up to 50,000 tons per year, representing a serious disposal problem with a consequent negative impact on the environment. Tomato byproducts contain a great variety of biologically active substances, principally lycopene, which have been demonstrated by in vitro and in vivo studies to possess antioxidant, hypolipidemic, and anticarcinogenic activities. The aim of this review is to present an overview of the functional and physiological properties of the principal bioactive compound present in tomato and tomato byproducts, lycopene, its addition to meat, and meat products.

Nutraceuticals for older people: facts, fictions and gaps in knowledge

In the last decades nutraceuticals have entered the health market as an easy and attractive means of preventing diseases. These products are of interest for an increasingly health-concerned society and may be especially relevant for preventing or delaying a number of age-related diseases, i.e. arthritis, cancer, metabolic and cardiovascular diseases, osteoporosis, cataracts, brain disorders, etc. Nutraceuticals are marketed in a variety of forms, composition and potential applications which have made their definition ambiguous and their use uncontrolled and poorly funded. Although epidemiological, animal and in vitro studies have given evidence of the potential benefits of some of these nutraceuticals or of their components, definitive proof of their effects in appropriate human clinical trials is still lacking in most cases, more critically among people above 65 years of age. We cover the well-established nutraceuticals (polyvitamins, omega-3 fatty acids, etc.) and will focus on many other 'novel' commercial nutraceuticals where the scientific evidence is more limited (food extracts, polyphenols, carotenoids, etc.). Solid scientific evidence has been reported only for a few nutraceuticals, which have some health claims approved by the European Food Safety Authority (EFSA). Further well-designed trials are needed to improve the current knowledge on the health benefits of nutraceuticals in the elderly. Overall, there are some facts, a lot of fiction and many gaps in the knowledge of nutraceutical benefits.

Prostate cancer and diet: food for thought?

• There is now increasing evidence that diet plays a major role in prostate cancer biology and tumorigenesis. • In a health conscious society, it is becoming increasingly common for Urologists to be asked about the impact of diet on prostate cancer. • In the present review, we explore the current evidence for the role of different dietary components and its' effect on prostate cancer prevention and progression. • A literature search was conducted using PubMed® to identify key studies. • There was some evidence to suggest that green tea, isoflavones, lycopenes, cruciferous vegetables and omega 3 polyunsaturated fatty acid intake to be beneficial in the prevention and/or progression of prostate cancer. • There was also evidence to suggest that a high total fat, meat (especially well cooked) and multivitamin intake may be associated with an increased risk of developing prostate cancer. • To date publications have been highly heterogeneous and variable in quality and design. More robust, high quality research trials are needed to help us understand the complex relationship between diet and prostate cancer.

Lycopene enhances docetaxel's effect in castration-resistant prostate cancer associated with insulin-like growth factor I receptor levels

Docetaxel is currently the most effective drug for the treatment of castration-resistant prostate cancer (CRPC), but it only extends life by an average of 2 months. Lycopene, an antioxidant phytochemical, has antitumor activity against prostate cancer (PCa) in several models and is generally safe. We present data on the interaction between docetaxel and lycopene in CRPC models. The growth-inhibitory effect of lycopene on PCa cell lines was positively associated with insulin-like growth factor I receptor (IGF-IR) levels. In addition, lycopene treatment enhanced the growth-inhibitory effect of docetaxel more effectively on DU145 cells with IGF-IR high expression than on those PCa cell lines with IGF-IR low expression. In a DU145 xenograft tumor model, docetaxel plus lycopene caused tumor regression, with a 38% increase in antitumor efficacy (P = .047) when compared with docetaxel alone. Lycopene inhibited IGF-IR activation through inhibiting IGF-I stimulation and by increasing the expression and secretion of IGF-BP3. Downstream effects include inhibition of AKT kinase activity and survivin expression, followed by apoptosis. Together, the enhancement of docetaxel's antitumor efficacy by lycopene supplementation justifies further clinical investigation of lycopene and docetaxel combination for CRPC patients. CRPC patients with IGF-IR-overexpressing tumors may be most likely to benefit from this combination.

Diet and prostate cancer: mechanisms of action and implications for chemoprevention

As one of the most prevalent cancers, prostate cancer has enormous public health significance and prevention strategies would attenuate its economic, emotional, physical and social impact. Until recently, however, we have had only modest information about risk factors for this disease, apart from the well-established characteristics of age, family history and place of birth. The large worldwide variation in the incidence of prostate cancer and the increased risk in migrants who move from low-risk to high-risk countries provide strong support for modifiable environmental factors, particularly diet, in its etiology. Thus, dietary agents have gained considerable attention as chemopreventive agents against prostate cancer. Dietary fat, red and processed meat, vitamin E, selenium, tomatoes, cruciforms and green tea have all been linked with the development and aggressiveness of prostate cancer, through a range of molecular mechanisms. The direction of future clinical trials lies in clarifying the effects of these agents and exploring the biological mechanisms responsible for the prevention of prostate cancer. However, owing to the short time period between diagnosis and treatment, conventional dietary intervention techniques are not always realistic. Until large randomized trials confirm the benefit of chemopreventive and dietary modifications, patients can be advised to pursue a diet and lifestyle that enhances overall health.

Nutraceuticals and prostate cancer prevention: a current review

Nutraceuticals are 'natural' substances isolated or purified from food substances and used in a medicinal fashion. Several naturally derived food substances have been studied in prostate cancer in an attempt to identify natural preventative therapies for this disease. Vitamin E, selenium, vitamin D, green tea, soy, and lycopene have all been examined in human studies. Other potential nutraceuticals that lack human data, most notably pomegranate, might also have a preventative role in this disease. Unfortunately, most of the literature involving nutraceuticals in prostate cancer is epidemiological and retrospective. The paucity of randomized control trial evidence for the majority of these substances creates difficulty in making clinical recommendations particularly when most of the compounds have no evidence of toxicity and occur naturally. Despite these shortcomings, this area of prostate cancer prevention is still under intense investigation. We believe many of these 'natural' compounds have therapeutic potential and anticipate future studies will consist of well-designed clinical trials assessing combinations of compounds concurrently.