Statin use and risk of lung cancer: a meta-analysis of observational studies and randomized controlled trials

Long-term use of anti-cholesterol drugs and cancer risks in a Japanese population

Several studies have investigated the association between the use of anti-cholesterol drugs and cancer risks, of which results have been inconsistent. This study included 67,768 participants from the Japan Public Health Center-based Prospective Study. The data on anti-cholesterol drug use was collected using three questionnaires of the survey conducted every five years. We divided the participants into three groups according to the duration of the anti-cholesterol drug use. Multivariable-adjusted Cox proportional hazard regression models were used to calculate hazard ratios (HR) and 95% confidence intervals (CI). During the 893,009 person-years of follow-up from the 10-year follow-up survey, 8,775 participants (5,387 men and 3,388 women) were newly diagnosed with cancers. The duration of anti-cholesterol drug use was significantly associated with a decreased risk of liver cancer (HR:0.26, 95% CI 0.11-0.64 in > 5 y group) and with an increased risk of pancreatic cancer (HR:1.59, 95% CI 1.03-2.47 in > 5 y group). Moreover, a different trend was observed between men and women in the association with the risk of lung cancer. This study suggested that long-term use of anti-cholesterol drugs may have associations with a decreased incidence of liver cancer and with an increased incidence of pancreatic cancers.

Lipid-lowering drugs and cancer: an updated perspective

Statins and non-statin medications used for the management of dyslipidemia have been shown to possess antitumor properties. Since the use of these drugs has steadily increased over the past decades, more knowledge is required about their relationship with cancer. Lipid-lowering agents are heterogeneous compounds; therefore, it remains to be revealed whether anticancer potential is a class effect or related to them all. Here, we reviewed the literature on the influence of lipid-lowering medications on various types of cancer during development or metastasis. We also elaborated on the underlying mechanisms associated with the anticancer effects of antihyperlipidemic agents by linking the reported in vivo and in vitro studies.

Mechanisms Contributing to the Comorbidity of COPD and Lung Cancer

Lung cancer and chronic obstructive pulmonary disease (COPD) often co-occur, and individuals with COPD are at a higher risk of developing lung cancer. While the underlying mechanism for this risk is not well understood, its major contributing factors have been proposed to include genomic, immune, and microenvironment dysregulation. Here, we review the evidence and significant studies that explore the mechanisms underlying the heightened lung cancer risk in people with COPD. Genetic and epigenetic changes, as well as the aberrant expression of non-coding RNAs, predispose the lung epithelium to carcinogenesis by altering the expression of cancer- and immune-related genes. Oxidative stress generated by tobacco smoking plays a role in reducing genomic integrity, promoting epithelial-mesenchymal-transition, and generating a chronic inflammatory environment. This leads to abnormal immune responses that promote cancer development, though not all smokers develop lung cancer. Sex differences in the metabolism of tobacco smoke predispose females to developing COPD and accumulating damage from oxidative stress that poses a risk for the development of lung cancer. Dysregulation of the lung microenvironment and microbiome contributes to chronic inflammation, which is observed in COPD and known to facilitate cancer initiation in various tumor types. Further, there is a need to better characterize and identify the proportion of individuals with COPD who are at a high risk for developing lung cancer. We evaluate possible novel and individualized screening strategies, including biomarkers identified in genetic studies and exhaled breath condensate analysis. We also discuss the use of corticosteroids and statins as chemopreventive agents to prevent lung cancer. It is crucial that we optimize the current methods for the early detection and management of lung cancer and COPD in order to improve the health outcomes for a large affected population.

Effect of Statins on Lung Cancer Molecular Pathways: A Possible Therapeutic Role

Lung cancer is a common neoplasm, usually treated through chemotherapy, radiotherapy and/or surgery. Both clinical and experimental studies on cancer cells suggest that some drugs (e.g., statins) have the potential to improve the prognosis of cancer. In fact, statins blocking the enzyme "hydroxy-3-methylglutaryl-coenzyme A reductase" exert pleiotropic effects on different genes involved in the pathogenesis of lung cancer. In this narrative review, we presented the experimental and clinical studies that evaluated the effects of statins on lung cancer and described data on the effectiveness and safety of these compounds. We also evaluated gender differences in the treatment of lung cancer to understand the possibility of personalized therapy based on the modulation of the mevalonate pathway. In conclusion, according to the literature data, statins exert multiple effects on lung cancer cells, even if the evidence for their use in clinical practice is lacking.

A chemokine regulatory loop induces cholesterol synthesis in lung-colonizing triple-negative breast cancer cells to fuel metastatic growth

Triple-negative breast cancer (TNBC) has a high propensity for organ-specific metastasis. However, the underlying mechanisms are not well understood. Here we show that the primary TNBC tumor-derived C-X-C motif chemokines 1/2/8 (CXCL1/2/8) stimulate lung-resident fibroblasts to produce the C-C motif chemokines 2/7 (CCL2/7), which, in turn, activate cholesterol synthesis in lung-colonizing TNBC cells and induce angiogenesis at lung metastatic sites. Inhibiting cholesterol synthesis in lung-colonizing breast tumor cells by pulmonary administration of simvastatin-carrying HER3-targeting nanoparticles reduces angiogenesis and growth of lung metastases in a syngeneic TNBC mouse model. Our findings reveal a novel, chemokine-regulated mechanism for the cholesterol synthesis pathway and a critical role of metastatic site-specific cholesterol synthesis in the pulmonary tropism of TNBC metastasis. The study has implications for the unresolved epidemiological observation that use of cholesterol-lowering drugs has no effect on breast cancer incidence but can unexpectedly reduce breast cancer mortality, suggesting interventions of cholesterol synthesis in lung metastases as an effective treatment to improve survival in individuals with TNBC.

ABL allosteric inhibitors synergize with statins to enhance apoptosis of metastatic lung cancer cells

Targeting mitochondrial metabolism has emerged as a treatment option for cancer patients. The ABL tyrosine kinases promote metastasis, and enhanced ABL signaling is associated with a poor prognosis in lung adenocarcinoma patients. Here we show that ABL kinase allosteric inhibitors impair mitochondrial integrity and decrease oxidative phosphorylation. To identify metabolic vulnerabilities that enhance this phenotype, we utilized a CRISPR/Cas9 loss-of-function screen and identified HMG-CoA reductase, the rate-limiting enzyme of the mevalonate pathway and target of statin therapies, as a top-scoring sensitizer to ABL inhibition. Combination treatment with ABL allosteric inhibitors and statins decreases metastatic lung cancer cell survival in vitro in a synergistic manner. Notably, combination therapy in mouse models of lung cancer brain metastasis and therapy resistance impairs metastatic colonization with a concomitant increase in animal survival. Thus, metabolic combination therapy might be effective to decrease metastatic outgrowth, leading to increased survival for lung cancer patients with advanced disease.

Metabolic reprogramming in tumors is an adaptation that generates vulnerabilities that can be exploited for developing new therapies. Here Luttman et al. identify synergism between ABL allosteric inhibitors and lipophilic statins to impair metastatic lung cancer cell outgrowth and colonization, leading to increased survival in mouse models of advanced disease.

Associations of Variability in Metabolic Parameters with Lung Cancer: A Nationwide Population-Based Study

Simple Summary

Lung cancer is currently the most common cancer worldwide. This study investigates whether visit-to-visit variability in metabolic parameters is associated with lung cancer risk. We found that a high variability in fasting blood glucose, systolic blood pressure, total cholesterol, and body weight were each associated with increased risk of lung cancer. A higher number of high-variability parameters were also associated with increased lung cancer risk. Further research is needed to examine whether reducing variability can lead to decreased lung cancer risk.

Abstract

We investigated whether visit-to-visit variability in metabolic parameters is associated with lung cancer risk. We used nationally representative data from the Korean National Health Insurance System, and 8,011,209 lung-cancer-free subjects who underwent over three health examinations from 2005 to 2010 were followed until 2017. Variability of fasting blood glucose, total cholesterol, systolic blood pressure, and body weight were measured by the variability independent of the mean, assessed by quartiles. There were 44,982 lung cancer events. The hazard ratio (HR) and 95% confidence interval (CI) for lung cancer risk was 1.07 (1.04, 1.10) for fasting blood glucose in the highest quartile, 1.08 (1.05, 1.10) for systolic blood pressure, 1.04 (1.01, 1.07) for weight, and 1.11 (1.08, 1.14) for total cholesterol. When comparing ≥3 vs. 0 high-variability metabolic parameters, the HR for lung cancer was 1.18 (95% CI, 1.14, 1.22). However, while ≥3 high-variability parameters showed an increased lung cancer risk in men (HR 1.26, 95% CI 1.21, 1.31), women did not show increased risk (HR 0.99, 95% CI 0.92, 1.06). High variability in each metabolic parameter, and a higher number of high-variability parameters, were associated with increased lung cancer risk.

Obesity, Type 2 Diabetes, and Cancer Risk

Obesity and type 2 diabetes have both been associated with increased cancer risk and are becoming increasingly prevalent. Metabolic abnormalities such as insulin resistance and dyslipidemia are associated with both obesity and type 2 diabetes and have been implicated in the obesity-cancer relationship. Multiple mechanisms have been proposed to link obesity and diabetes with cancer progression, including an increase in insulin/IGF-1 signaling, lipid and glucose uptake and metabolism, alterations in the profile of cytokines, chemokines, and adipokines, as well as changes in the adipose tissue directly adjacent to the cancer sites. This review aims to summarize and provide an update on the epidemiological and mechanistic evidence linking obesity and type 2 diabetes with cancer, focusing on the roles of insulin, lipids, and adipose tissue.

Statins decrease the expression of c-Myc protein in cancer cell lines

Statins are potent inhibitors of the mevalonate/cholesterol biosynthetic pathway and are widely prescribed for the prevention of cardiovascular diseases. Here, we carried out a comprehensive analysis of the effects of three statins, simvastatin, atorvastatin, and lovastatin, on six different cancer cell lines that include a P-glycoprotein-expressing, multidrug resistant variant of an ovarian cancer cell line. Incubation of all cancer cell lines with statins resulted in suppression of cell proliferation without inducing apoptotic cell death. The cell proliferation arrest could be reversed upon transfer of cells to statin-free growth media as well as by the supplementation of the growth media with mevalonate. Further analysis suggested that statins induced cell cycle arrest at G0/G1 phase in four cancer cell lines and the loss of c-Myc protein in three cancer cell lines. The c-Myc expression and the progression of cell division cycle were restored upon the addition of mevalonate to the culture media containing statins. Finally, cells incubated with statins contained an increased level of phosphorylated histone H2AX, an observation previously correlated to cellular senescence. Together, these data demonstrate that statins inhibit the mevalonate pathway which is tightly coupled to oxidative branch of the pentose phosphate pathway, c-Myc expression, cell division cycle progression, and cellular senescence. Implications of these observations in the application of statins as cancer therapeutics are discussed.

Lipid-lowering medication use and cancer-specific survival among endometrial or lung cancer patients: an Australian nationwide cohort study

PURPOSE

Inconsistent results of lipid-lowering medications (LLMs) on improved cancer survival need more investigations. We tested the hypothesis that adherence to the drug would be associated with a lower cancer-specific mortality in a homogeneous population who has ever used the drug.

METHODS

Utilising data from the Australian Cancer database, linked to the Pharmaceutical Benefits Scheme data and the National Death Index, we identified two separate cohorts of 4519 and 3083 women patients with newly diagnosed endometrial and lung cancer respectively between 2003 and 2013. Adherence to this drug was calculated by proportion of days covered. Cox regression models with time-varying covariates were used to estimate the multivariable-adjusted cause-specific hazard ratios (HRs) and 95% confidence intervals (CIs) for the association of adherence to LLMs, statins, lipophilic and hydrophilic statins, and cancer-specific mortality.

RESULTS

Each 10% increase in 1-year adherence to LLMs reduced cancer-specific mortality among women with endometrial cancer (adjusted HR=0.93, 95% CI 0.90-0.96) or lung cancer (adjusted HR=0.95, 95% CI 0.93-0.97). The inverse associations remained unchanged in different subgroup analyses. The reductions in lung cancer mortality were not apparent for women who adhered to lipophilic statins albeit better endometrial cancer survival appeared in the lipophilic statin group and borderline statistical improvement in the hydrophilic statin group.

CONCLUSIONS

Among LLM users, adherence to this drug is inversely associated with reduced cancer-specific mortality. Together with previous evidence, randomised controlled trials are called for to confirm whether LLMs could be considered as an adjuvant treatment to improve prognosis.

Effect of Statin on Cancer Incidence: An Umbrella Systematic Review and Meta-Analysis

Statins are reported to reduce the risk of cancer, but the results of various published studies have been contradictory. We carried out an umbrella review to provide an overview and understand the strength of evidence, extent of potential biases, and validity of claimed associations between the use of statins and cancer incidence. We comprehensively re-analyzed the data of meta-analyses of randomized controlled trials (RCTs) and observational studies on associations between statin use and cancer incidence. We also assessed the strength of evidence of the re-analyzed outcomes, which were determined from the criteria including statistical significance of the p-value of random-effects, as well as fixed-effects meta-analyses, small study effects, between-study heterogeneity, and a 95% prediction interval. Using a conventional method to assess the significance of meta-analysis (p-value < 0.05), statins had a statistically significant effect on reducing cancer incidence in 10 of 18 types of cancer. When we graded the level of evidence, no cancer type showed convincing evidence, and four cancers (esophageal cancer, hematological cancer, leukemia, and liver cancer) showed suggestive evidence of a preventive effect. There was weak evidence of an association with six cancers, and no significance for the remaining eight cancers. None of the meta-analyses of RCTs on the association of statin and cancer incidence showed a statistical significance. Although there was a preventive effect of statin on cancer incidence in 10 of the 18 cancer types, the evidence supporting the use of statins to reduce cancer incidence was low. Therefore, the associations between statin use and cancer incidence should be carefully considered by clinicians.

Bladder cancer risk in users of selected drugs for cardiovascular disease prevention

The aim of this study was to investigate the relation between bladder cancer risk and the use of selected drugs for cardiovascular disease (CVD) prevention, such as aspirin, statins, and calcium channel blockers (CCBs). We analyzed data from a multicentric case-control study carried out in Italy between 2003 and 2014, including 690 bladder cancer cases and 665 hospital controls. Odds ratios (ORs) of bladder cancer and corresponding 95% confidence intervals (CIs) were estimated using unconditional multiple logistic regression models. The ORs for bladder cancer were 1.21 (95% CI: 0.87-1.68) for regular use of aspirin, 0.72 (95% CI: 0.54-0.97) for use of any CCBs, and 1.32 (95% CI: 0.87-1.99) for use of any statins. A slight inverse association was found with duration of use of CCBs, whereas no consistent association was found with duration of use, age at first use, and frequency for aspirin and statin use, or with indication of use for aspirin (as an analgesic or, for CVD prevention). No significant association was found for various combinations of drugs or for all drugs combined (OR=1.23, 95% CI: 0.31-4.85). Our data indicate the lack of a relevant association between the use of selected drugs for CVD prevention and bladder cancer risk, although suggest a potential favorable role for CCBs.

Statin use and prognosis of lung cancer: a systematic review and meta-analysis of observational studies and randomized controlled trials

Background

Previous clinical studies reported inconsistent results on the associations of statins with the mortality and survival of lung cancer patients. This review and meta-analysis summarized the impact of statins on mortality and survival of lung cancer patients.

Materials and methods

Eligible papers of this meta-analysis were searched by using PubMed, EMBASE, and Cochrane until July 2017. Primary end points were the mortality (all-cause mortality and cancer-specific mortality) and survival (progression-free survival and overall survival) of patients with statin use. Secondary end points were overall response rate and safety. The random-effects model was used to calculate pooled HRs and 95% CIs.

Results

Seventeen studies involving 98,445 patients were included in the meta-analysis. In observational studies, the pooled HR indicated that statins potentially decreased the cancer-specific mortality and promoted the overall survival of lung cancer patients. Statins showed an association with decreased all-cause mortality in cohort studies (HR =0.77, 95% CI: 0.59–0.99), but not in case-control studies (HR =0.75, 95% CI: 0.50–1.10). However, statin use showed no impact on mortality and overall survival in randomized controlled trials. Meanwhile, this meta-analysis indicated that statin use did not affect the progression-free survival of lung cancer patients in observational studies and randomized controlled trials. In addition, statins potentially enhanced the effects of tyrosine kinase inhibitors (HR=0.86, 95% CI: 0.76–0.98) and chemotherapy (HR=0.86, 95% CI: 0.81–0.91) on the overall survival of patients with non-small-cell lung cancer, but did not increase overall response rate and toxicity.

Conclusion

Statins were potentially associated with the decreasing risk of mortality and the improvement of overall survival in observational studies but not in randomized controlled trials.

High Receipt of Statins Reduces the Risk of Lung Cancer in Current Smokers With Hypercholesterolemia: The National Health Insurance Service-Health Screening Cohort

BACKGROUND

The incidence and mortality of lung cancer have risen steadily with the increasing popularity of tobacco smoking. Observational studies suggest that statins, which are widely used to lower cholesterol, may prevent lung cancer; however, other studies have produced conflicting results. We investigated the effect of statin receipt on lung cancer risk in Korean men according to smoking status.

PATIENTS AND METHODS

We collected data from the 2002-2015 National Health Insurance Service-National Health Screening Cohort (NHIS-HEALS). We included a total of 16,588 men in the final analysis. We classified the participants as having high or low statin receipt or as not receiving statins. We used Cox proportional hazards regression models to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) for lung cancer risk by statin receipt after adjusting for potential confounders.

RESULTS

We identified 363 patients with a new diagnosis of lung cancer from 2005 to 2015. Compared to participants who did not receive statins, high statin receipt resulted in a reduced lung cancer risk (HR = 0.64; 95% CI, 0.47, 0.85) after adjustment for confounders. Among current smokers, the fully adjusted HR for high statin receipt compared to those who did not receive statin therapy was 0.50 (95% CI, 0.32, 0.79).

CONCLUSION

High statin receipt was associated with lower risk of lung cancer in Korean men with hypercholesterolemia, especially current smokers.

Statin drugs to reduce breast cancer recurrence and mortality

Epidemiologic studies have, variably, shown the concomitant use of statin drugs to be beneficial to cancer outcomes. Statin drugs have been FDA approved for three decades for the treatment of high cholesterol and atherosclerotic coronary artery disease and are widely used. This has engendered studies as to their influence on concomitant diseases, including cancers. In this context, statin use has been correlated, variably, with a decrease in deaths from breast cancer. However, there is no extant model for this effect, and the extent of efficacy is open to question.The overarching goal of this article is to communicate to the reader of the potential of statins to reduce breast cancer progression and mortality. This is the use as a secondary prevention measure, and not as a therapy to directly counter active cancer. First, salient aspects of statin pharmacology, as relates to cardiovascular disease, will be discussed. Second, the basic and clinical research studies that investigate statin usage in breast cancer will be presented. Additionally, statin effects in other cancer types will be included for context. Finally, proposals for future basic and clinical research studies to determine the role of statins in breast cancer management will be presented.

Impact of Statin Use on Recurrence or Survival After Surgical Curative Resection of Non-Small Cell Lung Cancer

Statins are known for their anticancer effects, and many studies have shown the effectiveness of statins for cancer prevention and improvement of cancer-related long-term oncologic outcome. However, their effectiveness on recurrence or survival of non-small cell lung cancer (NSCLC) after curative resection remains unknown. This was a retrospective cohort study that assessed the medical records of patients who were diagnosed with NSCLC and treated with curative resection at a tertiary care hospital between August 2003 and July 2012. The primary outcome was the comparison of postoperative overall survival (OS) and recurrence-free survival (RFS) between the statin group of patients, who were administered statins at least 1 month before the surgery and continued it after the surgery, and the nonstatin group of patients, who were not administered statins. Propensity score (PS) matching was used to balance the 2 groups, and the analysis was performed using a Cox proportional hazards model. In total, 994 patients with NSCLC were included in the final analysis: 135 patients in the statin group and 859 patients in the nonstatin group. After PS matching, there was no significant difference in postoperative recurrence (P = .862) or death (P = .074) between the statin group and the nonstatin group. Similarly, there was no significant difference in postoperative RFS (P = .862) and OS (P = .072) between the 2 groups after PS matching. This study demonstrated that statin administration had no significant association with recurrence or survival after NSCLC treatment.

Long-term statin use in patients with lung cancer and dyslipidemia reduces the risk of death

Background

Clinical studies have obtained inconsistent results of statin use on cancer outcomes. This study investigated the association between statin use and lung cancer mortality.

Results

The use of statin decreased mortality (hazard ratio = 0.91; 95% confidence interval: 0.86–0.96; P < .01). The patients with a high cumulative defined daily dose of statin use before lung cancer diagnosis exhibited a low risk of mortality.

Materials and Methods

We conducted a population-based case-control study of patients with dyslipidemia. Among them, 6270 had used statins for at least 3 months before lung cancer diagnosis, and 6270 had never used statins.

Conclusions

We found that statin use can reduce lung cancer mortality. A further prospective study is necessary to confirm these findings.

Lung cancer and chronic obstructive pulmonary disease: From a clinical perspective

Chronic obstructive pulmonary disease (COPD) and lung cancer are devastating pulmonary diseases that commonly coexist and present a number of clinical challenges. COPD confers a higher risk for lung cancer development, but available chemopreventive measures remain rudimentary. Current studies have shown a marked benefit of cancer screening in the COPD population, although challenges remain, including the common underdiagnosis of COPD. COPD-associated lung cancer presents distinct clinical features. Treatment for lung cancer coexisting with COPD is challenging as COPD may increase postoperative morbidities and decrease survival. In this review, we outline current progress in the understanding of the clinical association between COPD and lung cancer, and suggest possible cancer prevention strategies in this patient population.

Protective Effects of Statins in Cancer: Should They Be Prescribed for High-Risk Patients?

PURPOSE OF REVIEW

Statins are one of the most widely prescribed drug classes in the USA. This review aims to summarize recent research on the relationship between statin use and cancer outcomes, in the context of clinical guidelines for statin use in patients with cancer or who are at high risk for cancer.

RECENT FINDINGS

A growing body of research has investigated the relationship between statins and cancer with mixed results. Cancer incidence has been more extensively studied than cancer survival, though results are inconsistent as some large meta-analyses have not found an association, while other studies have reported improved cancer outcomes with the use of statins. Additionally, two large studies reported increased all-cancer survival with statin use. Studies on specific cancer types in relation to cancer use have also been mixed, though the most promising results appear to be found in gastrointestinal cancers. Few studies have reported an increased risk of cancer incidence or decreased survival with statin use, though this type of association has been more commonly reported for cutaneous cancers. The overall literature on statins in relation to cancer incidence and survival is mixed, and additional research is warranted before any changes in clinical guidelines can be recommended. Future research areas include randomized controlled trials, studies on specific cancer types in relation to statin use, studies on populations without clinical indication for statins, elucidation of underlying biological mechanisms, and investigation of different statin types. However, studies seem to suggest that statins may be protective and are not likely to be harmful in the setting of cancer, suggesting that cancer patients who already take statins should not have this medication discontinued.

The protective study about alleviation of simvastatin on the damages of PEG-BNs in mice

Boron nitride nanoparticles have been proved to cause various toxicities, damages or inflammations after entering into in vivo in previous reports. However, up to now, there are rare investigations about the alleviation of damages caused by nanoparticles in vivo through natural small molecule drugs. Therefore, in this work, PEG-BNs with high solubility was successfully synthesized, and then their biodistribution in mice were studied using radiolabeling technique. And the heart, lung, liver, spleen, kidney tissues and blood samples were done for histology and biochemical analysis. The results showed that PEG-BNs were mainly distributed in lung, liver, kidney and spleen with an obviouse decreasing distribution as the experimental time was increasing. Besides, significantly serum biochemical and tissue pathological changes induced by PEG-BNs were confirmed. Moreover, after simvastatin (SST) exposure to the PEG-BNs model mice, the damages and biochemical indexes were recovered significantly as compared to the single exposure group mice in serum, which indicates a good treatment effect on the toxicity of PEG-BNs in vivo in mice. This study provides some basic data and useful information for the treatment of damages caused by the nanoparticles in mice in the future.

Blood lipids profile and lung cancer risk in a meta-analysis of prospective cohort studies

BACKGROUND

Emerging evidence has connected lipid metabolism disturbance with lung diseases, but the relationship between blood lipid profile and lung cancer risk is controversial and inconclusive.

OBJECTIVE

We conducted a meta-analysis of prospective cohort studies to evaluate the relationship between blood lipids profile and lung cancer incidence.

METHODS

Relevant studies were identified by searching PubMed, Cochrane Library, Web of Science, EBSCO, Ovid, CNKI, VIP, and WANGFANG MED through August 2016. Nine prospective cohort studies were included in the meta-analysis, and fixed or random effects model was used to calculate pooled relative risk (RRs). The RR was calculated using either highest vs lowest categories, or upper quantile vs lowest quantile. The thresholds were determined by the authors of each original publication, based on either predefined cut-offs or the distributions within their study population.

RESULTS

Analysis of 18,111 lung cancer cases among 1,832,880 participants showed that serum total cholesterol levels were inverse associated with lung cancer risk (RR = 0.93, 95% confidence interval [CI]: 0.85-1.03). Further analysis considered the lag time and excluded the effects of preclinical cancer, with totally 1,239,948 participants and 14,052 lung cancer cases, found a significantly inverse association between total cholesterol and lung cancer risk (RR = 0.89, 95% CI: 0.83-0.94). Analysis of 3067 lung cancer cases among 59,242 participants found that the high-density lipoprotein cholesterol levels (RR = 0.76, 95% CI: 0.59-0.97) was negatively associated with lung cancer risk and 4673 lung cancer cases among 685,852 participants showed that the total triglyceride (RR = 1.68, 95% CI: 1.44-1.96) was positively associated with lung cancer risk.

CONCLUSION

Cholesterol and fatty acid metabolism might present different and specific mechanism on lung cancer etiology and needs further elucidation.

Statin use and risk of cancer: An overview of meta-analyses

AIM

To conduct an overview of meta-analyses to critically appraise the evidence and present a comprehensive evaluation of the association between statin use and risk of site specific cancers.

METHODS

MEDLINE, EMBASE, the Cochrane Database of Systematic Reviews and Web of Science databases were searched from inception until 31^st May 2016. The electronic database search was supplemented by a hand search in PROSPERO and relevant journals which are not indexed in above databases. Meta-analyses that examined the association between statin use and risk of site specific cancers were included. Two reviewers independently screened the literature, abstracted data, and assessed study quality using the Assessment of Multiple Systematic Reviews (AMSTAR) tool.

RESULTS

Overall, 38 meta-analyses covered 13 site specific cancers were included. More than half (68%) of the meta-analyses were moderate in quality with an AMSTAR score 4-7 out of a possible 11. Based on current evidence from meta-analyses, use of statin decreases the risk of certain cancers, such as colorectal (8%-12%), gastric (27%-44%), hematological (19%), liver (37%-42%), oesophageal (14%-28%), ovarian (21%) and prostate cancer (7%). On the other side, evidence from meta-analyses also suggests that there is no association between statin use and risk of bladder, breast, endometrial, kidney, lung, pancreatic and skin cancers.

CONCLUSION

This overview of meta-analyses with variable quality has been shown that the statins may have a potential role in cancer chemoprevention and reduce the risk of some site specific cancers, but not all.

Risk factors of postoperative pancreatic fistula in patients after distal pancreatectomy: a systematic review and meta-analysis

Postoperative pancreatic fistula (POPF) is a common complication following distal pancreatectomy (DP). However, the risk factors of this complication in patients after DP still remain controversial. The aim of our study is to estimate the association between potential risk factors and POPF. Relevant articles published up to June 21, 2016 were identified via PubMed, EMBASE, Web of Science, and The Cochrane Library. Studies that examined the risk factors of POPF following DP were enrolled. 20 articles (2070 patients) were finally included in this study. The pooled data suggested that patients with soft pancreas, higher Body Mass Index (BMI), blood transfusion, elevated intraoperative blood loss, and longer operative time had a decreased risk for POPF. However, age, gender, malignant pathology, types of stump closure, octreotide therapy, history of diabetes and chronic pancreatitis, splenectomy, multiorgan resection, main duct ligation, preoperative serum albumin levels, PGA felt wrapping, and extended lymphadenectomy could not be regarded as risk factors for POPF. Our analytic data demonstrated that pancreas texture, BMI, blood transfusion, intraoperative blood loss, and operative time were clinical predictor for POPF. This study may assist surgeons to screen patients with high risk of POPF and select appropriate treatment measures.

Novel Uses for Lipid-Lowering Agents

Statin use leads to a reduction in the downstream products of the mevalonate pathway. Knowledge of this pathway has led scientists to investigate the role of statins in cancer prevention and treatment. Statins appear to possess a variety of pleiotropic effects, including inhibition of cell proliferation; enhanced apoptosis; and modulation of inflammation, endothelial function, and angiogenesis. In cancer specifically, experimental studies have found that statins may induce cancer cell apoptosis and inhibit tumor growth, angiogenesis, and metastasis. These mechanisms have steered researchers into evaluating the possible benefit of statins in the prevention and treatment of malignancies. This review will discuss the literature supporting the use of statins to prevent and treat cancer.

Association of Dietary Vitamin A and β-Carotene Intake with the Risk of Lung Cancer: A Meta-Analysis of 19 Publications

Whether dietary β-carotene and vitamin A intake protect against lung cancer risk is not clear. Therefore, we performed this meta-analysis to investigate the association between them. The related articles were searched using the databases PubMed and the Web of Knowledge up to May 2015. We used the random-effect model to estimate the relative risk (RR) and their 95% CI. Small-study effect was assessed using Egger’s test. In total, 19 studies comprising 10,261 lung cancer cases met the inclusion criteria. The pooled RR and their 95% CI was 0.855 (0.739–0.989) for higher category of dietary vitamin A intake and lung cancer risk, especially among Asian populations and in the cohort studies. Evidence from 18 studies suggested that higher category of dietary β-carotene intake could reduce lung cancer risk (0.768 (0.675–0.874)).The associations were also significant in American and Asian populations. In conclusions, higher category of dietary β-carotene and vitamin A intakes could reduce the risk of lung cancer. However, the dose-response analysis was not performed due to the limited data in each individual study. Due to this limitation, further studies with detailed dose, cases and person-years for β-carotene and vitamin A of each category are wanted to assess this dose-response association.

Statins: do they have a potential role in cancer prevention and modifying cancer-related outcomes?

3-Hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors (statins) are currently among the most commonly prescribed pharmaceutical agents worldwide. Apart from their well-established therapeutic value in cardiovascular disease, there is a long-standing debate on their potential association with cancer. To obtain and discuss the existing clinical evidence, an overview of meta-analysis articles addressing this issue was carried out. As of today, the accumulated evidence does not support the hypothesis that statins affect the risk of developing cancer, when they are taken at low doses for managing hypercholesterolaemia. However, current data cannot exclude an increased cancer risk in elderly patients associated with hydrophilic statin use, or decreases in the risks of certain cancers, such as gastric, oesophageal, liver, colorectal and advanced/aggressive prostate cancer. On the other hand, some recent observational studies have provided evidence that statins might be useful in modifying the prognosis of patients diagnosed with malignancy. Until a definitive benefit is demonstrated in randomized controlled trials, statins cannot be recommended either for cancer prevention or for modifying cancer-related outcomes. Further research is warranted to clarify the potential role(s) of statins in the prevention and treatment of cancer.

Relationship between the use of statins and patient survival in colorectal cancer: a systematic review and meta-analysis

Background

Studies have indicated that statins influence the risks and mortality rates of several types of solid tumors. However, the association between statin use and survival in patients with colorectal cancer (CRC) remains unclear.

Methods

We searched the PubMed and Embase databases for relevant studies published up to September 2014 that assessed statin use and CRC prognosis. The primary outcomes were overall survival (OS) and cancer-specific survival (CSS). The secondary outcomes were disease-free survival (DFS) and recurrence-free survival (RFS). Hazard ratios (HRs) and 95% confidence intervals (CIs) were extracted and pooled with Mantel–Haenszel random-effect modeling. All statistical tests were two-sided.

Results

Four studies on post-diagnosis statin therapy and five studies on pre-diagnosis statin use were included in our meta-analysis of 70,608 patients. Compared with the non-users, the patients with post-diagnosis statin use gained survival benefits for OS (HR 0.76; 95% CI: 0.68 to 0.85, P<0.001) and CSS (HR 0.70; 95% CI: 0.60 to 0.81, P<0.001). In addition, we observed that pre-diagnosis statin use prolonged the survival of patients with CRC for OS (HR 0.70; 95% CI: 0.54 to 0.91, P=0.007) and CSS (HR 0.80; 95% CI: 0.74 to 0.86, P<0.001). However, we did not observe a survival benefit for DFS (HR 1.13; 95% CI: 0.78 to 1.62, P=0.514) or RFS (HR 0.98; 95% CI: 0.36 to 2.70, P=0.975) in the CRC patients with post-diagnosis statin use.

Conclusions

Statin use before or after cancer diagnosis is related to reductions in overall and cancer-specific mortality in colorectal cancer survivors.

Correlation between use of simvastatin and lovastatin and female lung cancer risk: a nationwide case-control study

BACKGROUND

The objective of this study was to determine the association between statin use and female lung cancer in Taiwan.

METHODS

In this case-control study, we used information from the Taiwan National Health Institute Research Database on 17,329 patients (cases) aged 20 years or older recently diagnosed with lung cancer between 2005 and 2010 and 17,329 patients without lung cancer to assess the association between female lung cancer and statin use, even adjustment for its comorbidities.

RESULTS

After adjusting for age and associated risk factors, we determined that women who engaged in long-term use of simvastatin at a defined daily dose (DDD) of over 150 have a reduced risk of lung cancer compared with those who did not use statins (odds ratio: 0.77, 95% confidence interval: 0.62-0.97) in women. However, lovastatin was not significantly associated with lung cancer in women. Among female patients with pre-existing comorbidities of respiratory diseases such as chronic obstructive pulmonary disease, hypertension, stroke and pulmonary tuberculosis, statins reduced the risk of lung cancer.

CONCLUSIONS

Simvastatin use at a DDD of more than 150 is correlated with an approximately 20% reduction in the risk of lung cancer in women.

The effect of fruit and vegetable intake on the development of lung cancer: a meta-analysis of 32 publications and 20,414 cases

BACKGROUND/OBJECTIVES

Quantification of the association between the intake of vegetables and fruits and the risk of lung cancer is controversial. Thus, we conducted a meta-analysis to assess the relationship between vegetables and fruits and lung cancer risk.

SUBJECTS/METHODS

Pertinent studies were identified by a search in PubMed and Web of Knowledge. Random-effects models were used to calculate summary relative risks (RR) and the corresponding 95% confidence intervals (CI). Publication bias was estimated using Begg's test.

RESULTS

Finally, 30 articles with 37 studies comprising of 20,075 lung cancer cases for vegetables intake with lung cancer risk and 31 articles with 38 studies comprising of 20,213 lung cancer cases for fruits intake with lung cancer risk were included in this meta-analysis. The combined results showed that there were significant associations between vegetables and fruits intake and lung cancer risk. The pooled RR were 0.74 (95% CI: 0.67, 0.82) for vegetables and 0.80 (95% CI: 0.74, 0.88) for fruits. Significant association was found in females on vegetables intake and lung cancer but not in males. The association was also stronger in females than males on fruits intake and lung cancer risk. No publication bias was detected.

CONCLUSIONS

Our analysis indicated that intake of vegetables and fruits may have a protective effect on lung cancer, and the associations were stronger in females. As the potential biases and confounders could not be ruled out completely in this meta-analysis, further studies are needed.

Dietary vitamin E intake could reduce the risk of lung cancer: evidence from a meta-analysis

BACKGROUND

Quantification of the association between the intake of vitamin E and risk of lung cancer is still conflicting. Thus, we conducted a meta-analysis to summarize the evidence from epidemiological studies of vitamin E intake with the risk of lung cancer.

METHODS

Pertinent studies were identified by a search in PubMed and Web of Knowledge up to October 2014. Random-effect model was used to combine study-specific results. Publication bias was estimated using Egger's regression asymmetry test.

RESULTS

Ten articles reporting 11 studies (10 prospective studies and 1 case-control studies) involving 4434 lung cancer cases were used in this meta-analysis. The combined relative risk (RR) of lung cancer associated with vitamin E intake was 0.858 (95% CI=0.742-0.991) overall, significant protective associations were also found in America population (RR=0.862, 95% CI=0.715-0.996) and prospective studies (RR=0.913, 95% CI=0.827-0.996). No publication bias was found.

CONCLUSIONS

Our analysis indicated that vitamin E intake might decrease the risk of lung cancer, especially in America.

Prognostic value of rsf-1/hbxap in human solid tumors: a meta-analysis of cohort studies

PURPOSE

Recent studies have investigated remodeling and spacing factor 1 (Rsf-1) as a molecular marker in various solid tumors. However, whether or not Rsf-1 exerts a negative or positive effect on the survival of patients with solid cancers remains controversial. Therefore, this study aims to determine whether or not Rsf-1 may be a predicative marker of poor prognosis and aggressive tumor progression.

METHODS

We conducted a meta-analysis of 11 cohort studies (n = 1620 patients) to evaluate the relationship between Rsf-1 and clinical outcome. We included studies with data on overall survival (OS), disease-specific survival (DSS), recurrent-free survival (RFS), metastasis-free survival (MFS), and hazard ratios (HRs) with 95% confidence intervals (CIs).

RESULTS

High Rsf-1 expression was significantly associated with poor survival in solid tumors. Overall, the combined HR for OS was 1.49 (95% CI = 1.21-1.84, P < 0.001), DSS 3.07 (95% CI = 1.67-5.62, P < 0.001), RFS 2.51 (95% CI = 1.12-5.63, P = 0.025), and MFS 2.14 (95% CI = 1.49-3.06, P < 0.001). In addition, Rsf-1 overexpression was significantly associated with tumor stage (OR = 4.13, 95% CI = 2.84-6.00, P < 0.001), primary tumor (OR = 2.09, 95% CI = 1.58-2.75, P < 0.001), nodal status (OR = 1.95, 95% CI = 1.40-2.72, P < 0.001), and histological grade (OR = 3.09, 95% CI = 2.10-4.54, P < 0.001).

CONCLUSIONS

Rsf-1 may be a predicative marker of poor prognosis and aggressive tumor progression.

Effects of simvastatin on cell viability and proinflammatory pathways in lung adenocarcinoma cells exposed to hydrogen peroxide

Lung cancer is characterized by a high mortality rate probably attributable to early metastasis. Oxidative stress is involved in development and progression of lung cancer, through cellular and molecular mechanisms which at least in part overlap with proinflammatory pathways. Simvastatin is a statin with pleiotropic effects that can also act as an anti-oxidant agent, and these pharmacologic properties may contribute to its potential anti-cancer activity. Therefore, the aim of this study was to evaluate, in the human lung adenocarcinoma cell line GLC-82, the effects of a 24-hour treatment with simvastatin on hydrogen peroxide (H2O2)-induced changes in cell viability, ERK phosphorylation, matrix metalloproteinase (MMP) expression, innate immunity signaling, NF-κB activation and IL-8 secretion. Cell counting was performed after trypan blue staining, cell proliferation was assessed using MTT assay, and apoptosis was evaluated through caspase-3 activation and Tunel assay. Western blotting was used to analyze protein extracts, and IL-8 release into cell culture supernatants was assessed by ELISA. Our results show that simvastatin (30 μM) significantly (P <0.01) inhibited the proliferative effect of H2O2 (0.5 mM) and its stimulatory actions on ERK1/2 phosphorylation, NF-κB activation and IL-8 production. Furthermore, simvastatin decreased H2O2-mediated induction of the cellular expression of MMP-2 and MMP-9, as well as of several components of the signaling complex activated by innate immune responses, including MyD88, TRAF2, TRAF6 and TRADD. In conclusion, these findings suggest that simvastatin could play a role in prevention and treatment of lung cancer via modulation of important proinflammatory and tumorigenic events promoted by oxidative stress.

Association between vitamin C intake and lung cancer: a dose-response meta-analysis

Epidemiological studies evaluating the association between the intake of vitamin C and lung cancer risk have produced inconsistent results. We conducted a meta-analysis to assess the association between them. Pertinent studies were identified by a search of PubMed, Web of Knowledge and Wan Fang Med Online through December of 2013. Random-effect model was used to combine the data for analysis. Publication bias was estimated using Begg's funnel plot and Egger's regression asymmetry test. Eighteen articles reporting 21 studies involving 8938 lung cancer cases were included in this meta-analysis. Pooled results suggested that highest vitamin C intake level versus lowest level was significantly associated with the risk of lung cancer [summary relative risk (RR) = 0.829, 95%CI = 0.734–0.937, I² = 57.8%], especially in the United States and in prospective studies. A linear dose-response relationship was found, with the risk of lung cancer decreasing by 7% for every 100 mg/day increase in the intake of vitamin C [summary RR = 0.93, 95%CI = 0.88–0.98]. No publication bias was found. Our analysis suggested that the higher intake of vitamin C might have a protective effect against lung cancer, especially in the United States, although this conclusion needs to be confirmed.

Novel prospects of statins as therapeutic agents in cancer

Statins are well known competitive inhibitors of hydroxymethylglutaryl-CoA reductase enzyme (HMG-CoA reductase), thus traditionally used as cholesterol-lowering agents. In recent years, more and more effects of statins have been revealed. Nowadays alterations of lipid metabolism have been increasingly recognized as a hallmark of cancer cells. Consequently, much attention has been directed toward the potential of statins as therapeutic agents in the oncological field. Accumulated in vitro and in vivo clinical evidence point out the role of statins in a variety of human malignancies, in regulating tumor cell growth and anti-tumor immune response. Herein, we summarize and discuss, in light of the most recent observations, the anti-tumor effects of statins, underpinning the detailed mode of action and looking for their true significance in cancer prevention and treatment, to determine if and in which case statin repositioning could be really justified for neoplastic diseases.

Metastasis-associated protein 1 as a new prognostic marker for solid tumors: a meta-analysis of cohort studies

Metastasis-associated protein 1 (MTA1) is a molecular marker in various solid tumors that has recently been investigated. The prognostic significance of MAT1 expression remains controversial. In this work, we aimed to determine the relationship between immunohistochemistry-detected MAT1 expression and survival of patients with solid tumors by conducting a meta-analysis of cohort studies. Relevant studies were identified via an electronic database search updated on October 28, 2013. We included cohort studies that reported hazard ratios (HRs) or odds ratios (ORs) with 95 % confidence intervals (CIs) to determine the association of high MTA1 expression with overall survival (OS) and clinicopathological characteristics. Heterogeneity was quantified using I (2) statistics, and publication bias was evaluated using funnel plots. Sensitivity analysis was conducted to evaluate the robustness of meta-analysis findings. We identified 16 cohort studies that focused on MTA1 overexpression and prognosis involving 2,253 cancer patients. Overall, the combined HR for OS was 1.85 (95 % CI: 1.55-2.28, P<0.001). Omission of any single study had no significant effect on the pooled HR estimate. When the studies were stratified by tumor type, similar results of poor prognosis were observed in non-small cell lung cancer (HR=2.05, 95 % CI: 1.14-3.68, P=0.016) and esophageal squamous cell carcinoma (HR=1.86, 95 % CI: 1.44-2.39, P<0.001). Moreover, multivariate survival analysis showed that MTA1 overexpression was an independent predictor of poor prognosis (HR=1.90, 95 % CI: 1.53-2.37, P<0.001). In addtional, MTA1 overexpression was significantly associated with tumor size (OR=2.72, 95 % CI=1.44-5.14, P=0.002), tumor stage (OR=2.44, 95 % CI=1.67-3.57, P<0.001), depth of invasion (OR=2.63, 95 % CI=1.74-3.97, P<0.001), and lymph node metastasis (OR=2.57, 95 % CI=1.57-4.19, P<0.001). However, when age, sex, and tumor differentiation were considered, no obvious association was observed. This study provides a comprehensive examination of the literature available on the association of MTA1 overexpression with OS and some clinicopathological features in solid tumors. Meta-analysis results provide evidence that MTA1 may be a new indicator of poor cancer prognosis. Considering the limitations of the eligible studies, other large-scale prospective trials must be conducted to clarify the prognostic value of MTA1 in predicting cancer survival.

Association between 3801T>C polymorphism of CYP1A1 and idiopathic male infertility risk: a systematic review and meta-analysis

BACKGROUND

Epidemiological studies have evaluated the association between 3801T>C polymorphism of CYP1A1 gene and the risk for idiopathic male infertility, but the results are inconclusive. We aimed to derive a more precise estimation of the relationship by conducting a meta-analysis of case-control studies.

METHODS

This study conformed to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. PubMed, Embase and CNKI databases were searched through November 2013 to identify relevant studies. Pooled odds ratios with 95% confidence intervals were used to assess the strength of the association between CYP1A1 3801T>C polymorphism and idiopathic male infertility risk. Q-test was performed to evaluate between-study heterogeneity and publication bias was appraised using funnel plots. Sensitivity analyses were conducted to evaluate the robustness of meta-analysis findings.

RESULTS

Six studies involving 1,060 cases and 1,225 controls were included in this meta-analysis. Overall, significant associations between 3801T>C polymorphism and idiopathic male infertility risk were observed in allelic comparison (OR = 1.36, 95% CI: 1.01-1.83), homozygous model (OR = 2.18, 95% CI: 1.15-4.12), and recessive model (OR = 1.86, 95% CI: 1.09-3.20), with robust findings according to sensitivity analyses. However, subgroup analyses did not further identify the susceptibility to idiopathic male infertility in all comparisons. Funnel plot inspections did not reveal evidence of publication bias.

CONCLUSIONS

The current meta-analysis provides evidence of a significant association between CYP1A1 3801T>C polymorphism and idiopathic male infertility risk. Considering the limitation inherited from the eligible studies, further confirmation in large-scale and well-designed studies is needed.