Statin use, hyperlipidaemia, and the risk of breast cancer

The insulin sensitivity Mcauley index (MCAi) is associated with 40-year cancer mortality in a cohort of men and women free of diabetes at baseline

Background

The association between insulin resistance and cancer-mortality is not fully explored. We investigated the association between several insulin sensitivity indices (ISIs) and cancer-mortality over 3.5 decades in a cohort of adult men and women. We hypothesized that higher insulin resistance will be associated with greater cancer-mortality risk.

Methods

A cohort of 1,612 men and women free of diabetes during baseline were followed since 1979 through 2016 according to level of insulin resistance (IR) for cause specific mortality, as part of the Israel study on Glucose Intolerance, Obesity and Hypertension (GOH). IR was defined according to the Mcauley index (MCAi), calculated by fasting insulin and triglycerides, the Homeostatic Model Assessment (HOMA), the Matsuda Insulin Sensitivity Index (MISI), and the Quantitative Insulin Sensitivity Check Index (QUICKI), calculated by plasma glucose and insulin.

Results

Mean age at baseline was 51.5 ± 8.0 years, 804 (49.9%) were males and 871 (54.0%) had prediabetes. Mean follow-up was 36.7±0.2 years and 47,191 person years were accrued. Cox proportional hazard model and competing risks analysis adjusted for age, sex, country of origin, BMI, blood pressure, total cholesterol, smoking and glycemic status, revealed an increased risk for cancer-mortality, HR = 1.5 (95% CI: 1.1–2.0, p = 0.005) for the MCAi Q₁ compared with Q_2-4. No statistically significant associations were observed between the other ISIs and cancer-mortality.

Conclusion

The MCAi was independently associated with an increased risk for cancer-mortality in adult men and women free of diabetes and should be further studied as an early biomarker for cancer risk.

Association Between Dietary Patterns and Plasma Lipid Biomarker and Female Breast Cancer Risk: Comparison of Latent Class Analysis (LCA) and Factor Analysis (FA)

Background: Diet research focuses on the characteristics of "dietary patterns" regardless of the statistical methods used to derive them. However, the solutions to these methods are both conceptually and statistically different. Methods: We compared factor analysis (FA) and latent class analysis (LCA) methods to identify the dietary patterns of participants in the Chinese Wuxi Exposure and Breast Cancer Study, a population-based case-control study that included 818 patients and 935 healthy controls. We examined the association between dietary patterns and plasma lipid markers and the breast cancer risk. Results: Factor analysis grouped correlated food items into five factors, while LCA classified the subjects into four mutually exclusive classes. For FA, we found that the Prudent-factor was associated with a lower risk of breast cancer [4th vs. 1st quartile: odds ratio (OR) for 0.70, 95% CI = 0.52, 0.95], whereas the Picky-factor was associated with a higher risk (4th vs. 1st quartile: OR for 1.35, 95% CI = 1.00, 1.81). For LCA, using the Prudent-class as the reference, the Picky-class has a positive association with the risk of breast cancer (OR for 1.42, 95% CI = 1.06, 1.90). The multivariate-adjusted model containing all of the factors was better than that containing all of the classes in predicting HDL cholesterol (p = 0.04), triacylglycerols (p = 0.03), blood glucose (p = 0.04), apolipoprotein A1 (p = 0.02), and high-sensitivity C-reactive protein (p = 0.02), but was weaker than that in predicting the breast cancer risk (p = 0.03). Conclusion: Factor analysis is useful for understanding which foods are consumed in combination and for studying the associations with biomarkers, while LCA is useful for classifying individuals into mutually exclusive subgroups and compares the disease risk between the groups.

New applications of squalene synthase inhibitors: Membrane cholesterol as a therapeutic target

Squalene synthase (SQS) inhibitors, mostly known as antihyperlipidemic agents for controlling blood cholesterol levels, have been increasingly used to study alterations of the cholesterol content in cell membranes. As such, SQS inhibitors have been demonstrated to control cellular activities related to cancer cell proliferation and migration, neuron degeneration, and parasite growth. While the mechanisms behind the effects of cellular cholesterol are still being revealed in detail, the evidence for SQS as a therapeutic target for several seemingly unrelated diseases is increasing. SQS inhibitors may be the next promising candidates targeting the three remaining primary therapeutic areas, beyond cardiovascular disease, which still need to be addressed; their application as anticancer, antimicrobial, and antineurodegenerative agents appears promising for new drug discovery projects underway.

Insight into the molecular evidence supporting the remarkable chemotherapeutic potential of Hibiscus sabdariffa L

Hibiscus sabdariffa or roselle tea is popular around the globe for its antioxidant capability along with various other health benefits. Besides, it has uses in Ayurvedic and Chinese herbal medicines for the treatment of several diseases. However, the investigation for the anticancer potential of the plant began roughly in the last decade that emerged with encouraging results. Both crude extracts and pure compounds of the plant were reported to induce chemoprevention, selective cytotoxicity, cell cycle arrest, apoptosis, autophagy and anti-metastasis effects in varied types of human cancer cells. The plant contains a high quantity of polyphenolic compounds and at least two of them were proven to induce potent anticancer effects. Although, the molecular mechanism underlying the anticancer activity was roughly estimated in several studies. The present review aimed to assemble all ambiguous information to report the molecular evidence establishing the potent anticancer activity of Hibiscus sabdariffa and its implication for cancer therapy. This study suggests that Hibiscus sabdariffa is an ideal candidate to investigate its role as a herbal supplement for cancer prevention and treatment. With excellent safety and tolerability record, polyphenolic compounds from the plant need better designed clinical trials.

The contribution of cholesterol and epigenetic changes to the pathophysiology of breast cancer

Breast cancer​ is one of the most commonly diagnosed cancers in women. Accumulating evidence suggests that cholesterol plays an important role in the development of breast cancer. Even though the mechanistic link between these two factors is not well understood, one possibility is that dysregulated cholesterol metabolism may affect lipid raft and membrane fluidity and can promote tumor development. Current studies have shown oxysterol 27-hydroxycholesterol (27-HC) as a critical regulator of cholesterol and breast cancer pathogenesis. This is supported by the significantly higher expression of CYP27A1 (cytochrome P450, family 27, subfamily A, polypeptide 1) in breast cancers. This enzyme is responsible for 27-HC synthesis from cholesterol. It has been shown that 27-HC can not only increase the proliferation of estrogen receptor (ER)-positive breast cancer cells but also stimulate tumor growth and metastasis in several breast cancer models. This phenomenon is surprising since 27-HC and other oxysterols generally reduce intracellular cholesterol levels by activating the liver X receptors (LXRs). Resolving this paradox will elucidate molecular pathways by which cholesterol, ER, and LXR are connected to breast cancer. These findings will also provide the rationale for evaluating pharmaceutical approaches that manipulate cholesterol or 27-HC synthesis in order to mitigate the impact of cholesterol on breast cancer pathophysiology. In addition to cholesterol, epigenetic changes including non-coding RNAs, and microRNAs, DNA methylation, and histone modifications, have all been shown to control tumorigenesis. The purpose of this review is to discuss the link between altered cholesterol metabolism and epigenetic modification during breast cancer progression.

Status of lipid and lipoprotein in female breast cancer patients at initial diagnosis and during chemotherapy

Background

The lipid profile status among breast cancer patients at initial diagnosis and during chemotherapy remain controversial. The aim of this study is to study the status of lipid and lipoprotein in female breast cancer patients at initial diagnosis and during chemotherapy.

Methods

We conducted a retrospective cohort study of the status of the lipid and lipoprotein in 1054 primarily diagnosed breast cancer patients and 2483 normal controls with age stratification, from July 2015 to October 2016. At the same time, the status of lipid and lipoprotein were also analyzed among 394 breast cancer patients before and after adjuvant chemotherapy.

Results

The incidence of dyslipidemia was significantly lower in breast cancer group(42.98%) compared to normal group(58.28%)(P < 0.001). The levels of total cholesterol (TC), triglycerides (TG), HDL cholesterol (HDL-C), LDL cholesterol (LDL-C) among breast cancer group were significantly lower compared to normal control group (P < 0.05). With age stratification, the levels of TC and LDL-C in breast cancer group were still significantly lower than those in control group (P < 0.001). And the levels of TC, TG, LDL-C, apolipoprotein B were significantly higher among post chemotherapeutic patients compared to prechemotherapeutic patients, however HDL-C and Apo-A1 levels were contrary.

Conclusions

Breast cancer patients have lower incidence of dyslipidemia compared to normal populations. However, the situation of dyslipidemia may become worsened after chemotherapy. Therefore, lipid monitoring and dyslipidemia prevention and treatment should be conducted for breast cancer patients at initial diagnosis and during chemotherapy.

Lipid-lowering drugs, dyslipidemia, and breast cancer risk in a Medicare population

PURPOSE

We sought to disentangle the effects of statins and other lipid-lowering drugs and the underlying dyslipidemia for which they are prescribed on breast cancer risk.

METHODS

We conducted a case-control study within the linked Surveillance, Epidemiology, and End results (SEER)-Medicare data. Cases were women with invasive breast cancer aged 66 + years (N = 30,004) identified by SEER registries (years 2007-2011). Controls were women (N = 198,969) identified from a 5% random sample of Medicare recipients alive and breast cancer free in year of selection. Participants had a minimum of 13 months of Part A, Part B non-health maintenance organization Medicare and Part D Medicare coverage at least 13 months preceding cancer diagnosis/selection. Exposures were assessed until 12 months before diagnosis/control selection. Odds ratios (OR) and 99.9% confidence intervals (CI) were estimated using adjusted unconditional and multinomial logistic regression.

RESULTS

ORs of invasive breast cancer associated with dyslipidemia, statins, and non-statin lipid-lowering drugs were 0.86 (99.9% CI 0.81-0.90), 1.07 (99.9% CI 1.03-1.13) and 1.03 (99.9% CI 0.95-1.11), respectively. Risk reductions with dyslipidemia were slightly greater when untreated than treated and did not vary much by time between dyslipidemia and breast cancer diagnosis. Whether treated or untreated, dyslipidemia was associated with greater reductions in risk for later stage than earlier stage breast cancer (p-heterogeneity < 0.0001).

CONCLUSIONS

Lipid-lowering drugs did not account for the lower breast cancer risk associated with dyslipidemia. Our data do not support using statins or other lipid-lowering drugs to prevent breast cancer.

The effect of genetic variants on the relationship between statins and breast cancer in postmenopausal women in the Women's Health Initiative observational study

PURPOSE

Statins have been postulated to have chemopreventive activity against breast cancer. We evaluated whether germline genetic polymorphisms modified the relationship between statins and breast cancer risk using data from the Women's Health Initiative. We evaluated these interactions using both candidate gene and agnostic genome-wide approaches.

METHODS

To identify candidate gene-statin interactions, we tested interactions between 22 SNPS in nine candidate genes implicated in the effect of statins on lipid metabolism in 1687 cases and 1687 controls. We then evaluated statin use interaction with the remaining 30,380 SNPs available in this sample from the CGEMS GWAS study.

RESULTS

After adjusting for multiple comparisons, no SNP interactions with statin usage and risk of breast cancer were statistically significant in either the candidate genes or genome-wide approaches.

CONCLUSIONS

We found no evidence of SNP interactions with statin usage for breast cancer risk in a population of 3374 individuals. These results suggest that genome-wide common genetic variants do not moderate the association between statin usage and breast cancer in the population of women in the Women's Health Initiative.

Voluntary exercise slows breast tumor establishment and reduces tumor hypoxia in ApoE-/- mice

Exercise reduces the risk of breast cancer development and improves survival in breast cancer patients. However, the underlying mechanisms of this protective effect remain to be fully elucidated, and it is unclear whether exercise can attenuate the protumor effects of obesity and related hyperlipidemia on breast cancer growth and development. We hypothesized that exercise attenuates the negative effect of hyperlipidemia through normalization of the tumor microenvironment and improved T cell infiltrate. Hyperlipidemic ApoE^-/- mice with orthotopic EO771 breast tumors were randomly assigned to one of two voluntary running groups or sedentary controls, and muscular cytochrome c oxidase subunit IV (COX-IV) expression was used as a biomarker for the level of exercise. Tumors from mice with high muscular COX-IV expression took significantly longer to reach 100 mm³ ( P = 0.008), but showed no difference in growth rate once the tumor was established. Wheel running appeared to reduce internal metastases, but did not affect T cell infiltrate or the proportion of regulatory and cytotoxic T cells within the tumor. Serum levels of monocyte chemoattractant protein-1 (MCP-1) were significantly increased by tumor burden ( P = 0.02) and correlated with spleen weight ( P < 0.0001, R = 0.65). Furthermore, tumor hypoxia was significantly decreased in mice with high muscular COX-IV expression ( P = 0.01). Taken together, these results indicate that wheel running can slow the establishment of primary and secondary EO771 breast tumors and induce beneficial changes in the breast tumor microenvironment in ApoE^-/- mice. NEW & NOTEWORTHY In this first study to investigate the effect of exercise on tumor behavior in a hyperlipidemic model, we hypothesized that wheel running would counteract the protumorigenic environment generated by hyperlipidemia. Wheel running slowed establishment of primary and secondary tumors and reduced tumor hypoxia but did not affect exponential tumor growth in ApoE^-/- mice. Overall, voluntary wheel running induced favorable microenvironmental changes in breast tumors.

Glucose insult elicits hyperactivation of cancer stem cells through miR-424-cdc42-prdm14 signalling axis

BACKGROUND

Meta-analysis shows that women with diabetes have a 20% increased risk of breast cancer and also an increased risk for distant metastasis and mortality. The molecular mechanisms for distant metastasis and mortality in breast cancer patients with diabetes are not very well understood.

METHODS

We compared the effect of physiological (5 mM) and diabetic (10 mM) levels of glucose on malignant breast epithelial cell invasion and stemness capabilities. We performed microRNA array to determine the dysregulated microRNAs in hyperglycaemic conditions and performed functional and molecular analysis of the gene targets.

RESULTS

Hyperglycaemia leads to hyperactivation of cancer stem cell pool and enhances invasive ability of breast cancer cells. MiR-424 seems to be a key regulator of cancer cell stemness and invasion. Knockdown of miR-424 in cancer cells under euglycaemic conditions leads to enhanced invasion and stem cell activity, whereas ectopic expression of miR-424 in cancer cells under hyperglycaemic conditions results in suppressed invasion and stem cell activity. Cdc42, a target of miR-424, influences cancer stem cell activity by positively regulating prdm14 through activation of pak1 (p-21-activated kinase 1) and stat5.

CONCLUSIONS

Our findings establish miR-424→︀cdc42→︀prdm14 axis as a key molecular signalling cascade that might influence breast cancer progression in diabetic patients through hyperactivation of cancer stem cells.

Interaction between Comorbidity and Cancer

Background

Older patients have an average of three comorbidities in addition to their cancer. Oncologic studies have usually ignored this aspect when adjusting for confounders. There is mounting evidence that comorbidity interacts with risk, survival, disease progression, and treatment of elderly patients with cancer. The strength of many of these interactions increases with age.

Methods

A review of the literature was undertaken regarding two of these interactions: cancer risk and prognosis.

Results

In older patients, the risk and behavior of cancer can be strongly affected by comorbidities and their related treatment. Rather than a blanket effect, this effect might be attached to groups of syndromes with common pathophysiologic mechanisms. This is notably true for metabolic disorders and inflammatory diseases.

Conclusions

In addition to focusing on the influence of cancer treatment on comorbidity or on the effect of comorbidity in delivering cancer treatment, future endeavors will need to consider the direct impact of comorbidity on the risk and the behavior of the cancer in elderly patients.

The effect of preoperative serum triglycerides and high-density lipoprotein-cholesterol levels on the prognosis of breast cancer

OBJECTIVES

Although dyslipidemia has been documented to be associated with several types of cancer including breast cancer, it remains uncertainty the prognostic value of serum lipid in breast cancer. The purpose of this study is to evaluate the association between the preoperative plasma lipid profile and the prognostic of breast cancer patients.

METHODS

The levels of preoperative serum lipid profile (including cholesterol [CHO], Triglycerides [TG], high-density lipoprotein-cholesterol [HDL-C], low-density lipoprotein-cholesterol [LDL-C], apolipoprotein A-I [ApoAI], and apolipoprotein B [ApoB]) and the clinical data were retrospectively collected and reviewed in 1044 breast cancer patients undergoing operation. Kaplan-Meier method and the Cox proportional hazards regression model were used in analyzing the overall survival [OS] and disease-free survival [DFS].

RESULTS

Combining the receiver-operating characteristic and Kaplan-Meier analysis, we found that preoperative lower TG and HDL-C level were risk factors of breast cancer patients. In multivariate analyses, a decreased HDL-C level showed significant association with worse OS (HR: 0.528; 95% CI: 0.302-0.923; P = 0.025), whereas a decreased TG level showed significant association with worse DFS (HR: 0.569; 95% CI: 0.370-0.873; P = 0.010).

CONCLUSIONS

Preoperative serum levels of TG and HDL-C may be independent factor to predict outcome in breast cancer patient.

VLDL and LDL, but not HDL, promote breast cancer cell proliferation, metastasis and angiogenesis

Abnormal lipoprotein profiles are associated with breast cancer progression. However, the mechanisms linking abnormal lipoprotein levels to breast cancer progression, especially metastasis, remain unclear. Herein, we found that L1 and L5 subfractions of LDL and VLDL, but not HDL, enhanced breast cancer cell viability. L1, L5, and VLDL also increased the in vitro tumorigenesis of breast cancer cells in anchorage-independent soft agar assay. In addition, L1, L5, and VLDL, but not HDL, increased the levels of mesenchymal markers Slug, Vimentin, and β-Catenin, and promoted breast cancer cell migration and invasion. L1, L5, and VLDL increased Akt Ser473 phosphorylation and promoted cell migration, which were reversed by the PI3K/Akt inhibitor wortmannin. Further in vitro angiogenesis assay and cytokine array analysis demonstrated that L1, L5, and VLDL enhanced secretion of angiogenic factors in breast cancer cells and promoted angiogenic activity. However, only VLDL reduced anchorage-dependent cell death and promoted lung metastasis in nude mice. In summary, our data suggest that L1, L5, and especially VLDL promote breast cancer progression and metastasis through Akt-induced EMT and angiogenesis, and provide a novel mechanism of how dyslipoproteinemia promotes breast cancer progression.

Novel applications of COX-2 inhibitors, metformin, and statins for the primary chemoprevention of breast cancer

Recent evidence shows that commonly prescribed drugs, such as non-steroidal anti-inflammatory drugs (NSAIDs), metformin, and statins, may have beneficial roles in the primary chemoprevention of breast cancer. Therefore, these drugs could potentially be used in addition to the hormonal drugs currently used for this purpose (namely, selective estrogen receptor modulators and aromatase inhibitors) due to their alternative mechanisms of action.

A link between hypercholesterolemia and chronic lymphocytic leukemia

The incidence of hypercholesterolemia and its possible relationship with clinical course were determined by reviewing the records of 231 consecutive patients presenting to a specialized Chronic Lymphocytic Leukemia (CLL) clinic. Evidence for elevated cholesterol was found in up to 174/231 patients (75%) based on existing use of statins (107 patients) or non-fasting low-density lipoprotein cholesterol levels greater than 2.5 mM. Excluding patients with 17p deletions, time to first treatment (TFT) was prolonged if patients were taking cholesterol-lowering statins (57.5 (IQR = 32, 77) vs 36 (IQR = 11, 100) months, p < 0.02). If patients were prescribed statins after being diagnosed with CLL, TFT was longer than if they were taking statins before the diagnosis. These observations suggest there is a high incidence of hypercholesterolemia in CLL patients and cholesterol-lowering may impact the disease course.

Statin use and thyroid cancer: a population-based case-control study

OBJECTIVE

Several observational studies raised the possibility that the use of statins may decrease the overall risk of cancer and of specific cancers. This study aimed to evaluate the association of statin use with thyroid cancer based on a population-based data set.

DESIGN

The data for this case-control study were sourced from the Taiwan Longitudinal Health Insurance Database 2000. We included 500 subjects with thyroid cancer as cases and 2500 gender- and age-matched subjects without thyroid cancer as controls. We used a conditional logistic regression to calculate the odds ratio (OR) and its corresponding 95% confidence interval (CI) for having previously used statins between cases and controls.

RESULTS

The OR of prior statin use for cases was 1.39 (95% CI = 1.08-1.78) compared to controls, and thyroid cancer was significantly associated with previous regular statin use (OR = 1.40, 95% CI = 1.05-1.86). However, thyroid cancer was not significantly associated with previous irregular statin use (OR = 1.35; 95% CI = 0.88-2.07). Furthermore, the significant association between thyroid cancer and previous statin use only existed for females (OR: 1.43; 95% CI: 1.07-1.90) but not for males (OR: 1.28; 95% CI: 0.75-2.17).

CONCLUSIONS

We concluded that statin use was associated with thyroid cancer in female patients.

Hypercholesterolemia induces angiogenesis and accelerates growth of breast tumors in vivo

Obesity and metabolic syndrome are linked to an increased prevalence of breast cancer among postmenopausal women. A common feature of obesity, metabolic syndrome, and a Western diet rich in saturated fat is a high level of circulating cholesterol. Epidemiological reports investigating the relationship between high circulating cholesterol levels, cholesterol-lowering drugs, and breast cancer are conflicting. Here, we modeled this complex condition in a well-controlled, preclinical animal model using innovative isocaloric diets. Female severe combined immunodeficient mice were fed a low-fat/no-cholesterol diet and then randomized to four isocaloric diet groups: low-fat/no-cholesterol diet, with or without ezetimibe (cholesterol-lowering drug), and high-fat/high-cholesterol diet, with or without ezetimibe. Mice were implanted orthotopically with MDA-MB-231 cells. Breast tumors from animals fed the high-fat/high-cholesterol diet exhibited the fastest progression. Significant differences in serum cholesterol level between groups were achieved and maintained throughout the study; however, no differences were observed in intratumoral cholesterol levels. To determine the mechanism of cholesterol-induced tumor progression, we analyzed tumor proliferation, apoptosis, and angiogenesis and found a significantly greater percentage of proliferating cells from mice fed the high-fat/high-cholesterol diet. Tumors from hypercholesterolemic animals displayed significantly less apoptosis compared with the other groups. Tumors from high-fat/high-cholesterol mice had significantly higher microvessel density compared with tumors from the other groups. These results demonstrate that hypercholesterolemia induces angiogenesis and accelerates breast tumor growth in vivo.

A nationwide population-based cohort study on tonsillectomy and subsequent cancer incidence

OBJECTIVES/HYPOTHESIS

Tonsillectomy is related to increased risk of certain types of cancer. This study evaluates the possible association between tonsillectomy and cancer in Taiwan.

METHODS

Data from the National Health Insurance system of Taiwan was used. A cohort study consisting of 997 patients with a new diagnosis of tonsillectomy from 2000 to 2005 and a comparison cohort of 3,988 subjects without tonsillectomy were used in the Poisson regression analysis to estimate the incidence rate ratios (IRRs) and 95% confidence intervals (CIs) of cancers.

RESULTS

The incidence rate of all cancer types was higher in the tonsillectomy group than in the control group (4.28 vs. 2.97 per 1,000 person-years, respectively), with an IRR = 1.54 and 95% CI of 1.05 to 2.25, but the significant difference was limited to patients with more than 3 years follow-up. Site-specific analysis found no significant association between tonsillectomy and any individual cancer after adjusting for age, sex, hyperlipidemia, hypertension, and diabetes; however, tonsillectomy patients with more than 3 years follow-up had a marginally significantly higher risk for breast cancer development (adjusted IRR = 2.62; CI = 0.97-7.03).

CONCLUSION

Our study found that Taiwanese people with tonsillectomy have a significantly higher overall risk of developing cancer and a marginally higher risk of developing breast cancer when follow-up is longer than 3 years.

Plasma level of LDL-cholesterol at diagnosis is a predictor factor of breast tumor progression

Background

Among women, breast cancer (BC) is the leading cancer and the most common cause of cancer-related death between 30 and 69 years. Although lifestyle and diet are considered to have a role in global BC incidence pattern, the specific influence of dyslipidemia in BC onset and progression is not yet completely understood.

Methods

Fasting lipid profile (total cholesterol, LDL-C, HDL-C, and triglycerides) was prospectively assessed in 244 women with BC who were enrolled according to pre-set inclusion criteria: diagnosis of non-hereditary invasive ductal carcinoma; selection for surgery as first treatment, and no history of treatment with lipid-lowering or anti-diabetic drugs in the previous year. Pathological and clinical follow-up data were recorded for further inclusion in the statistical analysis.

Results

Univariate associations show that BC patients with higher levels of LDL-C at diagnosis have tumors that are larger, with higher differentiation grade, higher proliferative rate (assessed by Ki67 immunostaining), are more frequently Her2-neu positive and are diagnosed in more advanced stages. Cox regression model for disease-free survival (DFS), adjusted to tumor T and N stages of TNM classification, and immunohistochemical subtypes, revealed that high LDL-C at diagnosis is associated with poor DFS. At 25 months of follow up, DFS is 12% higher in BC patients within the third LDL-C tertile compared to those in the first tertile.

Conclusions

This is a prospective study where LDL-C levels, at diagnosis, emerge as a prognostic factor; and this parameter can be useful in the identification and follow-up of high-risk groups. Our results further support a possible role for systemic cholesterol in BC progression and show that cholesterol metabolism may be an important therapeutic target in BC patients.

LDL-cholesterol signaling induces breast cancer proliferation and invasion

Lipids and cholesterol in particular, have long been associated with breast cancer (BC) onset and progression. However, the causative effects of elevated lipid levels and breast cancer remain largely undisclosed and were the subject of the present study.We took advantage of well-established in vitro and in vivo models of cholesterol enrichment to exploit the mechanism involved in LDL-cholesterol favouring BC growth and invasiveness. We analyzed its effects in models that mimic different BC subtypes and stages.Our data show that LDL-cholesterol (but not HDL-cholesterol) promotes BC cells proliferation, migration and loss of adhesion, hallmarks of the epithelial to mesenchymal transition. In vivo studies modeling cholesterol levels showed that breast tumors are consistently larger and more proliferative in hypercholesterolemic mice, which also have more frequently lung metastases. Microarray analysis revealed an over expression of intermediates of Akt and ERK pathways suggesting a survival response induced by LDL, confirmed by WB analyses. Gene expression analysis also evidenced an activation of ErbB2 signaling pathway and decreased expression of adhesion molecules (cadherin-related family member3, CD226, Claudin 7 and Ocludin) in the cells exposed to LDL.Together, the present work shows novel mechanistic evidence that high LDL-cholesterol levels promote BC progression. These data provide rationale for the clinical control of cholesterol levels in BC patients.

Beyond aspirin-cancer prevention with statins, metformin and bisphosphonates

Cancer risk reduction using pharmacological means is an attractive modern preventive approach that supplements the classical behavioural prevention recommendations. Medications that are commonly used by large populations to treat a variety of common, non-cancer-related, medical situations are an attractive candidate pool. This Review discusses three pharmacological agents with the most evidence for their potential as cancer chemopreventive agents: anti-hypercholesterolaemia medications (statins), an antidiabetic agent (metformin) and antiosteoporosis drugs (bisphosphonates). Data are accumulating to support a significant negative association of certain statins with cancer occurrence or survival in several major tumour sites (mostly gastrointestinal tumours and breast cancer), with an augmented combined effect with aspirin or other non-steroidal anti-inflammatory drugs. Metformin, but not other hypoglycaemic drugs, also seems to have some antitumour growth activity, but the amount of evidence in human studies, mainly in breast cancer, is still limited. Experimental and observational data have identified bisphosphonates as a pharmacological group that could have significant impact on incidence and mortality of more than one subsite of malignancy. At the current level of evidence these potential chemopreventive drugs should be considered in high-risk situations or using the personalized approach of maximizing individual benefits and minimizing the potential for adverse effects with the aid of pharmacogenetic indicators.

The risk of a subsequent cancer diagnosis after herpes zoster infection: primary care database study

Background:

Herpes zoster and cancer are associated with immunosuppression. Zoster occurs more often in patients with an established cancer diagnosis. Current evidence suggests some risk of cancer after zoster but is inconclusive. We aimed to assess the risk of cancer following zoster and the impact of prior zoster on cancer survival.

Methods:

A primary care database retrospective cohort study was undertaken. Subjects with zoster were matched to patients without zoster. Risk of cancer following zoster was assessed by generating hazard ratios using Cox regression. Time to cancer was generated from the index date of zoster diagnosis.

Results:

In total, 2054 cancers were identified in 74 029 patients (13 428 zoster, 60 601 matches). The hazard ratio for cancer diagnosis after zoster was 2.42 (95% confidence interval 2.21, 2.66) and the median time to cancer diagnosis was 815 days. Hazard ratios varied between cancers, and were highest in younger patients. There were more cancers in patients with zoster than those without for all age groups and both genders. Prior immunosuppression was not associated with change in risk, and diagnosis of zoster before cancer did not affect survival.

Conclusion:

This study establishes an association between zoster and future diagnosis of cancer having implications for cancer case finding after zoster diagnosis.

Serum lipid profiles and cancer risk in the context of obesity: four meta-analyses

The objective here was to summarize the evidence for, and quantify the link between, serum markers of lipid metabolism and risk of obesity-related cancers. PubMed and Embase were searched using predefined inclusion criteria to conduct meta-analyses on the association between serum levels of TG, TC, HDL, ApoA-I, and risk of 11 obesity-related cancers. Pooled relative risks (RRs) and 95% confidence intervals were estimated using random-effects analyses. 28 studies were included. Associations between abnormal lipid components and risk of obesity-related cancers when using clinical cutpoints (TC ≥ 6.50; TG ≥ 1.71; HDL ≤ 1.03; ApoA-I ≤ 1.05 mmol/L) were apparent in all models. RRs were 1.18 (95% CI: 1.08–1.29) for TC, 1.20 (1.07–1.35) for TG, 1.15 (1.01–1.32) for HDL, and 1.42 (1.17–1.74) for ApoA-I. High levels of TC and TG, as well as low levels of HDL and ApoA-I, were consistently associated with increased risk of obesity-related cancers. The modest RRs suggest serum lipids to be associated with the risk of cancer, but indicate it is likely that other markers of the metabolism and/or lifestyle factors may also be involved. Future intervention studies involving lifestyle modification would provide insight into the potential biological role of lipid metabolism in tumorigenesis.

Update of carcinogenicity studies in animals and humans of 535 marketed pharmaceuticals

This survey is a compendium of information retrieved on carcinogenicity in animals and humans of 535 marketed pharmaceuticals whose expected clinical use is continuous for at least 6 months or intermittent over an extended period of time. Of the 535 drugs, 530 have the result of at least one carcinogenicity assay in animals, and 279 (52.1%) of them gave a positive response in at least one assay. Only 186 drugs (34.8%) have retrievable information on carcinogenicity in humans, and 104 of them gave to a variable extent evidence of a potential carcinogenic activity. Concerning the correlation between results obtained in animals and epidemiological findings, 58 drugs gave at least one positive result in carcinogenicity assays performed in animals and to a variable extent displayed evidence of carcinogenicity in humans, but 97 drugs tested positive in animals and were noncarcinogenic in humans or vice versa. Our findings, which are in agreement with previous studies, indicate that the evaluation of the benefit/carcinogenic risk ratio should be always made in prescribing a drug.

Statin use and risk of breast cancer: a meta-analysis of observational studies

Emerging evidence suggests that statins' may decrease the risk of cancers. However, available evidence on breast cancer is conflicting. We, therefore, examined the association between statin use and risk of breast cancer by conducting a detailed meta-analysis of all observational studies published regarding this subject. PubMed database and bibliographies of retrieved articles were searched for epidemiological studies published up to January 2012, investigating the relationship between statin use and breast cancer. Before meta-analysis, the studies were evaluated for publication bias and heterogeneity. Combined relative risk (RR) and 95 % confidence interval (CI) were calculated using a random-effects model (DerSimonian and Laird method). Subgroup analyses, sensitivity analysis, and cumulative meta-analysis were also performed. A total of 24 (13 cohort and 11 case-control) studies involving more than 2.4 million participants, including 76,759 breast cancer cases contributed to this analysis. We found no evidence of publication bias and evidence of heterogeneity among the studies. Statin use and long-term statin use did not significantly affect breast cancer risk (RR = 0.99, 95 % CI = 0.94, 1.04 and RR = 1.03, 95 % CI = 0.96, 1.11, respectively). When the analysis was stratified into subgroups, there was no evidence that study design substantially influenced the effect estimate. Sensitivity analysis confirmed the stability of our results. Cumulative meta-analysis showed a change in trend of reporting risk of breast cancer from positive to negative in statin users between 1993 and 2011. Our meta-analysis findings do not support the hypothesis that statins' have a protective effect against breast cancer. More randomized clinical trials and observational studies are needed to confirm this association with underlying biological mechanisms in the future.

Risk of cancer in patients exposed to gabapentin in two electronic medical record systems

PURPOSE

High doses of gabapentin were associated with pancreatic acinar cell tumors in male Wistar rats, but there is little published epidemiological data regarding gabapentin and carcinogenicity. We explored the association between gabapentin and cancer in a US medical care program and followed up nominally significant associations in a UK primary care database.

METHODS

In the US Kaiser Permanente Northern California (KPNC) health system, we performed nested case-control analyses of gabapentin and 55 cancer sites and all cancers combined using conditional logistic regression. Up to 10 controls were matched to each case on year of birth, sex, and year of cohort entry. No other covariates were included in models. Only dispensings for gabapentin 2 years or more before index date were considered. Nominally significant associations with an OR > 1.00 and p < 0.05 for three or more dispensings versus no dispensings were followed up by similar nested case-control analyses in the UK General Practice Research Database (GPRD), adjusting for potential indications for gabapentin and risk factors for the specific cancers.

RESULTS

The following analyses had OR > 1.00 and p < 0.05 for three or more dispensings of gabapentin versus no dispensing (2-year lag) in KPNC and were also examined in the GPRD: all cancers, breast, lung and bronchus, urinary bladder, kidney/renal pelvis, stomach, anus/anal canal/anorectum, penis, and other nervous system. These cancers were not statistically significantly associated with gabapentin in the GPRD case-control studies (2-year lag). The GPRD and KPNC studies did not identify a statistically significant increased risk of pancreatic cancer with more than two prescriptions of gabapentin in the 2-year lagged analyses.

CONCLUSIONS

The epidemiological data in a US cohort with up to 12 years of follow-up and a UK cohort with up to 15 years of follow-up do not support a carcinogenic effect of gabapentin use. However, the confidence intervals for some analyses were wide, and an important effect cannot be confidently excluded.

Total cholesterol and cancer risk in a large prospective study in Korea

PURPOSE

To further clarify the relationship between total cholesterol and cancer, which remains unclear.

METHODS

We prospectively examined the association between total cholesterol and site-specific and all-cancer incidence among 1,189,719 Korean adults enrolled in the National Health Insurance Corporation who underwent a standardized biennial medical examination in 1992 to 1995 and were observed for 14 years until cancer diagnosis or death.

RESULTS

Over follow-up, 53,944 men and 24,475 women were diagnosed with a primary cancer. Compared with levels less than 160 mg/dL, high total cholesterol (≥ 240 mg/dL) was positively associated with prostate cancer (hazard ratio [HR], 1.24; 95% CI, 1.07 to 1.44; P trend = .001) and colon cancer (HR, 1.12; 95% CI, 1.00 to 1.25; P trend = .05) in men and breast cancer in women (HR, 1.17; 95% CI, 1.03 to 1.33; P trend = .03). Higher total cholesterol was associated with a lower incidence of liver cancer (men: HR, 0.42; 95% CI, 0.38 to 0.45; P trend < .001; women: HR, 0.32; 95% CI, 0.27 to 0.39; P trend < .001), stomach cancer (men: HR, 0.87; 95% CI, 0.82 to 0.93; P trend ≤ .001; women: HR, 0.86; 95% CI, 0.77 to 0.97; P trend = .06), and, in men, lung cancer (HR, 0.89; 95% CI, 0.82 to 0.96; P trend < .001). Results for liver cancer were slightly attenuated after additional adjustment for liver enzyme levels and hepatitis B surface antigen status (men: HR, 0.60; P trend < .001; women: HR, 0.46; P trend = .003) and exclusion of the first 10 years of follow-up (men: HR, 0.59; P trend < .001; women: HR, 0.44; P trend < .001). Total cholesterol was inversely associated with all-cancer incidence in both men (HR, 0.84; 95% CI, 0.81 to 0.86; P trend < .001) and women (HR, 0.91; 95% CI, 0.87 to 0.95; P trend < .001), but these associations were attenuated after excluding incident liver cancers (men: HR, 0.95; P trend < .001; women: HR, 0.98; P trend = .32).

CONCLUSION

In this large prospective study, we found that total cholesterol was associated with the risk of several different cancers, although these relationships differed markedly by cancer site.

Increase of oxidant-related triglycerides and phosphatidylcholines in serum and small intestinal mucosa during development of intestinal polyp formation in Min mice

Recent epidemiological studies have shown a positive association of a high-fat diet with the risk of colon cancer. Indeed, increments in the serum levels of triglycerides (TG) and cholesterols are positively related with colon carcinogenesis. We previously reported that an age-dependent hyperlipidemic state is characteristic of Min mice, an animal model for human familial adenomatous polyposis (FAP). However, qualitative and quantitative changes of lipid metabolism are poorly understood in this state. Here, we provide detailed analysis of serum lipids in Min mice using reverse-phased liquid chromatography/electrospray ionization mass spectrometry (RPLC/ESI-MS). We also demonstrate local analysis of lipid droplets in the villi of the small intestine using laser capture microdissection and a sensitive chip-based nanoESI-MS system. As a result, oxidized phosphatidylcholines (PC) such as aldehyde and carboxylic acid types were increased, even at an early stage of intestinal polyp formation in serum. In addition, hydroperoxidizable TG precursors containing linoleic acid (18:2n-6) were deposited at the tip of the villi with aging, and these hydroperoxidized TG were also increased in serum. Meanwhile, increments of the oxidizable TG precursors in serum and small intestinal mucosa were suppressed by treatment with pitavastatin, a novel third generation lipophilic statin. These results suggest that quantitative and qualitative lipid changes such as hydroperoxidizable TG precursors are important in the course of intestinal polyp formation and oxidative stress might lead to the development of intestinal polyp formation in Min mice.

Statin use and cancer risk: a comprehensive review

IMPORTANCE OF THE FIELD

HMG-CoA inhibitors (statins), a class of drugs that reduce cholesterol, are used to manage and prevent coronary heart disease. They are among the most commonly prescribed drugs worldwide. Contrary to early concerns over the carcinogenicity of statins, a growing body of evidence suggests statins may in fact have a chemopreventive potential against cancer.

AREAS COVERED IN THIS REVIEW

In this paper, we review evidence on the association between statin use and cancer risk. Specifically, we report on clinical trials and observational studies that measured all cancer or site-specific cancers of the breast, colorectal, lung, prostate and reproductive organs associated with statin use.

WHAT THE READER WILL GAIN

An understanding of the evidence, including strengths and limitations, to support an association between statins and cancer. Information on the current state of the field and future directions are also discussed.

TAKE HOME MESSAGE

Few strong or consistent associations between statins and cancer incidence overall or for any of the sites reviewed were detected. Data for any effects of statins on cancer prognosis and secondary prevention are lacking; with the exception of consistent evidence that statins are associated with reduced risk of advanced/aggressive prostate cancer. Statins appear safe in relation to cancer risk but any chemopreventive effect in humans remains to be established and should not be recommended outside the context of clinical trials. It is encouraging that numerous trials are ongoing. The prospect of reducing the incidence and burden of some of the most prevalent cancers with safe, affordable and tolerable medication that already reduces the risk of the leading cause of death and cardiovascular disease warrants further exploration in clinical trials and observational studies of prognosis and survival.

Simvastatin and purine analogs have a synergic effect on apoptosis of chronic lymphocytic leukemia cells

Despite many therapeutic regimens introduced recently, chronic lymphocytic leukemia (CLL) is still an incurable disorder. Thus, there is an urgent need to discover novel, less toxic and more effective drugs for CLL patients. In this study, we attempted to assess simvastatin, widely used as a cholesterol-lowering drug, both as a single agent and in combination with purine analogs-fludarabine and cladribine-in terms of its effect on apoptosis and DNA damage of CLL cells. The experiments were done in ex vivo short-term cell cultures of blood and bone marrow cells from newly diagnosed untreated patients. We analyzed expression of active caspase-3 and the BCL-2/BAX ratio as markers of apoptosis and the expression of phosphorylated histone H2AX (named γH2AX) and activated ATM kinase (ataxia telangiectasia mutated kinase), reporters of DNA damage. Results of our study revealed that simvastatin induced apoptosis of CLL cells concurrently with lowering of BCL-2/BAX ratio, and its pro-apoptotic effect is tumor-specific, not affecting normal lymphocytes. We observed that combinations of simvastatin+fludarabine and simvastatin+cladribine had a synergic effect in inducing apoptosis. Interestingly, the rate of apoptosis caused by simvastatin alone and in combination was independent of markers of disease progression like ZAP-70 and CD38 expression or clinical stage according to Rai classification. We have also seen an increase in γH2AX expression in parallel with activation of ATM in most of the analyzed samples. The results suggest that simvastatin can be used in the treatment of CLL patients as a single agent as well as in combination with purine analogs, being equally effective both in high-risk and good-prognosis patients. One of the mechanisms of simvastatin action is inducing DNA damage that ultimately leads to apoptosis.

Overexpression of low-density lipoprotein receptor and lipid accumulation in intestinal polyps in Min mice

Apc-deficient Min mice feature low expression of lipoprotein lipase (LPL), high concentration of serum triglyceride (TG), fatty change of the liver and large numbers of intestinal polyps. We have reported that induction of LPL expression reduces serum lipid, especially TG, improves fatty change of the liver and inhibits intestinal polyp formation in the mice. In this study, fatty change/lipid accumulation in intestinal mucosa and polyps in Min mice were analyzed by Oil-red O staining and electron microscopy. A number of large lipid droplets were found in the epithelia of the upper part of polyps. On the other hand, small lipid droplets were only slightly observed at the tip of the villi in non-tumoros parts of the small intestine of Min mice and in the villi of wild-type mice. Moreover, low-density lipoprotein receptor (LDLR) was overexpressed in the area where lipid droplets were observed. The expression levels of LDLR mRNA in the intestinal polyps of Min mice were approximately 3 times higher compared to those in the non-tumoros parts. Remarkable expression of cyclooxygenase-2 was mainly distributed in stromal cells and some in epithelial cells. It is speculated that lipid accumulation in the intestinal polyps may play an important role in intestinal polyp formation in Apc-deficient mice.

Statin Use and Cancer Risk: An Epidemiologic Review

While the beneficial effects of hydroxy-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) on cardiovascular disease are well established, much uncertainty remains about their effects on cancer. The statins inhibit the rate-limiting step in the mevalonate pathway, leading to reduced levels of cholesterol and other molecules of importance for critical cellular processes. A growing body of preclinical data indicates that statins may have antineoplastic properties, but some studies raise the possibility that statins may possess a carcinogenic potential. Clinical and observational studies of the association between statin use and cancer have been inconclusive with regard to any chemopreventive or therapeutic effect, but they do provide reassuring evidence that statins do not appear to be carcinogenic. The reasons for the varying results are unclear but they may relate to methodological issues. Additional studies, including Phase II randomized trials and epidemiological studies with accurate measures of statin use and comprehensive control for confounding factors, are needed to determine the potentially beneficially effects of statins on cancer development and progression.

Serum total cholesterol and the risk of breast cancer in postmenopausal Korean women

OBJECTIVE

To evaluate an association between serum total cholesterol level and breast cancer risk, for which inconsistent findings have been reported in spite of the role of serum cholesterol as a precursor to a breast cancer-related sex steroid hormone.

METHODS

Postmenopausal Korean women (n = 170,374), categorized into four groups by quartiles of cholesterol level, were followed up for occurrence of breast cancer from 1993 to 2003. Relative risks were assessed by Cox proportional hazard analysis.

RESULTS

A positive association between cholesterol level and breast cancer risk was found with 31% greater age-adjusted risk of breast cancer in the highest cholesterol group (>or=5.95 mmol/l) than that in the lowest cholesterol group (<4.63 mmol/l). The strength of association was reduced slightly but persisted after the adjustment for reproductive and behavioral covariates. However, the association further attenuated and the positive trend was no longer significant when BMI was additionally adjusted (p-trend, 0.0684). Stratified analysis by BMI showed that the risk of breast cancer increased with increasing cholesterol level only in normal BMI (<25 kg/m(2)) group, but the interaction term was not significant.

CONCLUSION

Serum total cholesterol level is not associated with the risk of breast cancer in postmenopausal Korean women.

Statins and cancer: a meta-analysis of case-control studies

3-HMG-CoA reductase inhibitors (statins) block the growth of malignant cells in vitro. A meta-analysis of randomized controlled trials failed to show reduced risk of cancers in statin users. Case-control studies, however, have the advantage of examining remote exposures. This study determined the association between statins and breast cancer, colon cancer, lung cancer, prostate cancer, or any cancer in case-control studies. A comprehensive search for studies published through November 2006 was performed. Twenty case-control studies (100 129 incident cancer cases) were combined to obtain a pooled odds ratio using an inverse variance method. A funnel plot did not suggest a significant absence of unpublished data. The studies were significantly heterogeneous (P<0.01), thus a random effects model was used. The pooled OR and 95% confidence intervals for statin users and cancer were as follows: any cancer 0.71 (0.56-0.89), breast cancer 0.86 (0.60-1.23), colon cancer 0.89 (0.82-0.97), lung cancer 0.75 (0.50-1.11), and prostate cancer 0.74 (0.45-1.20). In this meta-analysis of case-control studies, we found a significant association between statin usage and any cancer, but when stratified by cancer type, only the association with colon cancer remained. On the basis of these results, randomized control trials with longer follow-up times than previously used are warranted.

Statins and cancer risk

OBJECTIVE

Despite numerous randomized clinical trials and observational epidemiologic studies, evidence on the potential effectiveness of statins for prevention of cancer remains controversial. The objective of this study was to investigate the relation between lipophilic statin use and cancer occurrence.

METHODS

We conducted a retrospective observational study based on a medical administrative database in the province of Quebec, Canada (1998-2004). Patients aged 45 years or more and discharged from the hospital alive after admission for acute myocardial infarction were included. High- and low-dose statin use were defined as a filled prescription, within 3 days after index discharge, at or above (below) the statin-specific target dose, for any of the 4 lipophilic statin medications: atorvastatin, simvastatin, lovastatin, or fluvastatin. Statin non-use was defined as non-use of any statins while simultaneously using major non-statin cardiac medications. A total of 30,076 patients, including high-dose statin users (n=6015), low-dose statin users (n=5323), and non-users (n=18,738), were followed for up to 7 years. Multivariable Cox regression analyses were performed to estimate associations between statin dose category and the incidence of admission to hospital with a diagnosis of any type of cancer.

RESULTS

The crude incidence rates of hospital admission with the diagnosis of any type of cancer were 13.9, 17.2, and 26.0 per 1000 person-years in statin high-dose users, low-dose users, and non-users, respectively. The estimated adjusted hazard ratios were 0.75 (95% confidence interval [CI], 0.60-0.95) for statin use at high dose and 0.89 (95% CI, 0.75-1.07) for statin use at low dose. No significant time-dependence of the effect of statins at either dose was detected.

CONCLUSION

The use of lipophilic statins at sufficiently high dose might be associated with a clinically important reduction in the incidence of cancer.

Reduced thyroid volume and nodularity in dyslipidaemic patients on statin treatment

BACKGROUND

Little information is available concerning the possible antiproliferative effects of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) on the thyroid gland. We have hypothesized that the antiproliferative effects of statins observed in thyroid cell lines in vitro may have a clinical counterpart that could be detected by investigating the prevalence and size of thyroid nodules in patients on long-term treatment with statins.

METHODS

We retrospectively evaluated 135 dyslipidaemic patients receiving statin therapy continuously for at least 5 years, and 137 controls. All the subjects were submitted to ultrasound investigation of the thyroid gland, to establish prevalence, number and volume of thyroid nodules.

RESULTS

Subjects treated with statins showed markedly lower prevalence of thyroid nodules (36.3%vs. 67.9%, P < 0.001), as well as reduced number and smaller total volume of lesions, as compared to the control group. A logistic regression analysis, taking into account age, sex, risk factors for the development of thyroid nodules and concomitant drug treatment, revealed that treatment with statins remained the only important predictor of the presence of thyroid nodules [odds ratio (OR) 0.312, 95% confidence interval (CI) 0.156-0.625, P < 0.001] besides risk factors.

CONCLUSIONS

Our data provide the first circumstantial evidence of an association between HMG-CoA reductase inhibitor treatment and reduced prevalence, number and volume of thyroid nodules. This finding may be explained by an antiproliferative and/or pro-apoptotic effect of long-term statin treatment on thyroid cells, in vivo.

Breast cancer growth prevention by statins

Statins are cholesterol-lowering drugs with pleiotropic activities including inhibition of isoprenylation reactions and reduction of signals driving cell proliferation and survival responses. The objectives of this study were to examine the effects of statins on breast cancer cells, both in vitro and in vivo, and to begin to determine their mechanism of action. We evaluated the effects of statins on breast cancer cell growth, phosphoprotein signaling intermediates, survival/apoptosis regulators, cell cycle regulators, and activated transcription factors. We also examined the in vivo effect of statin administration in a mouse ErbB2(+) breast cancer model. Only lipophilic statins had direct anticancer activity in vitro. Breast cancer cells with activated Ras or ErbB2 pathways seemed to be more sensitive than those overexpressing estrogen receptor, and this correlated with endogenous levels of activated nuclear factor kappaB (NF-kappaB). Key intermediates regulating cell survival by NF-kappaB activation, as well as cell proliferation by the mitogen activated protein kinase cascade, were among the earliest phosphoproteins influenced by statin treatment. These early effects were followed by declines in activator protein-1 and NF-kappaB activation and concordant changes in other mediators of proliferation and apoptosis. In vivo results showed that oral dosing of statins significantly inhibited the growth of a mouse mammary carcinoma. Lipophilic statins can exert direct anticancer activity in vitro by reducing proliferation and survival signals in susceptible breast cancer phenotypes. Tumor growth inhibition in vivo using a clinically relevant statin dose also seems to be associated with reduced tumor cell proliferation and survival. These findings provide supporting rationale for future statin trials in breast cancer patients.

Diabetes, metabolic syndrome, and breast cancer: a review of the current evidence

Incidences of breast cancer, type 2 diabetes, and metabolic syndrome have increased over the past decades with the obesity epidemic, especially in industrialized countries. Insulin resistance, hyperinsulinemia, and changes in the signaling of growth hormones and steroid hormones associated with diabetes may affect the risk of breast cancer. We reviewed epidemiologic studies of the association between type 2 diabetes and risk of breast cancer and the available evidence on the role of hormonal mediators of an association between diabetes and breast cancer. The combined evidence supports a modest association between type 2 diabetes and the risk of breast cancer, which appears to be more consistent among postmenopausal than among premenopausal women. Despite many proposed potential pathways, the mechanisms underlying an association between diabetes and breast cancer risk remain unclear, particularly because the 2 diseases share several risk factors, including obesity, a sedentary lifestyle, and possibly intake of saturated fat and refined carbohydrates, that may confound this association. Although the metabolic syndrome is closely related to diabetes and embraces additional components that might influence breast cancer risk, the role of the metabolic syndrome in breast carcinogenesis has not been studied and thus remains unknown.

Statins reduce the risk of lung cancer in humans: a large case-control study of US veterans

BACKGROUND

Statins are commonly used cholesterol-lowering agents that are noted to suppress tumor cell growth in several in vitro and animal models.

METHODS

We studied the association of lung cancer and the use of statins in patients enrolled in the Veterans Affairs (VA) Health Care System. A retrospective case-control study nested in a cohort study was conducted using prospectively collected data from the Veterans Integrated Service Networks 16 VA database from 1998 to 2004. We analyzed data on 483,733 patients from eight states located in south central United States. The primary variables of interest were lung cancer and the use of statins prior to the diagnosis of lung cancer. Multiple logistic regression analysis was done to adjust for covariates including age, sex, body mass index, smoking, diabetes, and race. Statistical software was used for statistical computing.

RESULTS

Of the 483,733 patients in the study, 163,662 patients (33.8%) were receiving statins and 7,280 patients (1.5%) had a primary diagnosis of lung cancer. Statin use > 6 months was associated with a risk reduction of lung cancer of 55% (adjusted odds ratio, 0.45; 95% confidence interval, 0.42 to 0.48; p < 0.01). Furthermore, the protective effect of statin was seen across different age and racial groups and was irrespective of the presence of diabetes, smoking, or alcohol use.

CONCLUSIONS

Statins appear to be protective against the development of lung cancer, and further studies need to be done to define the clinical utility of statins as chemo protective agents.

Statins and risk of cancer: a systematic review and metaanalysis

We conducted a systematic review of the association between HMG-CoA reductase inhibitor (statin) use and cancer risk. We searched MEDLINE, EMBASE, Web of Science, ISI Proceedings and BIOSIS Previews bibliographic databases, electronic trials registers and reference lists for potentially eligible randomized trials and observational studies. Thirty-eight individual studies (26 randomized trials involving 103,573 participants and 12 observational studies with 826,854 participants) were included. Median follow-up was 3.6 and 6.2 years for trials and observational studies, respectively. In metaanalyses of randomized trials, there was no evidence that statin therapy was associated with incidence of all-cancers (26 trials; pooled risk ratio = 1.00; 95% CI 0.95-1.05; I(2) = 0%) or the following site-specific cancers: breast (7 trials; risk ratio = 1.01; 0.79-1.30; I(2) = 43%), prostate (4 trials; risk ratio = 1.00; 0.85-1.17; I(2) = 0%), colorectum (9 trials; risk ratio = 1.02; 0.89-1.16; I(2) = 0%), lung (9 trials; risk ratio = 0.96; 0.84-1.09; I(2) = 0%), genito-urinary (5 trials; risk ratio = 0.95; 0.83-1.09; I(2) = 0%), melanoma (4 trials; risk ratio = 0.86; 0.62-1.20; I(2) = 17%) or gastric (1 trial; risk ratio = 1.00; 0.35-2.85). There was no evidence of differential effects by length of follow-up, statin type (lipophilic vs. lipophobic) or potency. Trial results were generally consistent with observational studies. We conclude that statin use is not associated with short-term cancer risk, but longer-latency effects remain possible.

Statin use and breast cancer risk in a large population-based setting

BACKGROUND

Mechanistic studies suggest that 3-hydroxy-3-methylglutaryl CoA inhibitors (statins) reduce the risk of breast cancer. Observational studies offer mixed results.

METHODS

To evaluate the relation between statin use and breast cancer risk, we conducted a cohort study among women ages 45 to 89 years within an integrated health care delivery system. Information on statin use and covariates were obtained from automated databases. We identified breast cancer cases through the Surveillance, Epidemiology, and End Results registry. We used Cox proportional hazards models to estimate the hazard ratios (HR) and 95% confidence intervals (95% CI) for invasive breast cancer among statin users compared with nonusers.

RESULTS

Among 92,788 women studied from 1990 to 2004, median follow-up time was 6.4 years, and 2,707 breast cancer cases were identified. During the study period, 7.4% of women used statins for at least 1 year, and the median duration of use was 3.1 years. We found no difference in breast cancer risk among statin users (HR, 1.07; 95% CI, 0.88-1.29) compared with nonusers. Risk of breast cancer did not differ by duration of use (1-2.9, 3-4.9, or >or=5 years) or hydrophobic statin use. We found a suggestive increased risk of breast cancer among statin users of >or=5 years (HR, 1.27; 95% CI, 0.89-1.81 for any statins and HR, 1.47; 95% CI, 0.89-2.44 for hydrophobic statins) and of estrogen receptor-negative tumors with increasing duration of statin use (1-2.9 years: HR, 1.33; 95% CI, 0.64-2.77; 3-4.9 years: HR, 1.68; 95% CI, 0.72-3.92; >or=5 years: HR, 1.81; 95% CI, 0.75-4.36).

CONCLUSION

This study does not support an association between statin use and breast cancer risk.

Statins reduce the risk of pancreatic cancer in humans: a case-control study of half a million veterans

OBJECTIVE

Statins are commonly used cholesterol-lowering agents that are noted to suppress tumor cell growth in several in vitro and animal models.

METHODS

We studied the association between pancreatic cancer and statins in veterans. A retrospective, nested case-control study was conducted using prospectively collected data from the Veterans Integrated Service Networks 16 Veteran Affairs database from 1998 to 2004. We analyzed data on 483,733 patients from 8 states located in south central United States. The primary variables of interest were pancreatic cancer and the use of statins before the diagnosis of pancreatic cancer. Multiple logistic regression analysis was done to adjust for covariates including age, sex, body mass index, smoking, diabetes, and race. The SAS software was used for statistical computing.

RESULTS

Of the 483,733 patients in the study, 163,467 (33.79%) were on statins, and 475 (0.098%) patients had a primary diagnosis of pancreatic cancer. Statin use of more than 6 months was associated with a risk reduction of pancreatic cancer of 67% (adjusted odds ratio, 0.33; 95% confidence interval, 0.26-0.41; P < 0.01).A dose-response relationship was noted between statin use and pancreatic cancer with an 80% risk reduction (adjusted odds ratio, 0.2; 95% confidence interval, 0.13-0.29; P < 0.01) with use of statin for more than 4 years. Furthermore, the protective effect of statin was seen across different age and racial groups, and was irrespective of the presence of diabetes, smoking, or alcohol use.

CONCLUSIONS

Statins seem to be protective against the development of pancreatic cancer, and the magnitude of the effect correlates with the duration of statin use.

Statin drugs and risk of advanced prostate cancer

BACKGROUND

Statins are commonly used cholesterol-lowering drugs that have proapoptotic and antimetastatic activities that could affect cancer risk or progression. Results from previous epidemiologic studies of the association between statin use and cancer have been inconsistent. We investigated the association of statin use with total and advanced prostate cancer, the latter being the most important endpoint to prevent.

METHODS

We analyzed data from an ongoing prospective cohort study of 34,989 US male health professionals who were cancer free in 1990 and were followed to 2002. Participants reported their use of cholesterol-lowering drugs on biennial questionnaires. Prostate cancer diagnosis was confirmed by medical record review. Multivariable-adjusted relative risks (RRs) were estimated from Cox proportional hazards regression models. Statistical tests were two-sided.

RESULTS

During 376,939 person-years of follow-up, we ascertained 2579 prostate cancer cases, 316 of which were advanced (regionally invasive, metastatic, or fatal). The age-standardized incidence rates of advanced prostate cancer were 38 and 89 per 100,000 person-years in current statin users and in past or never users, respectively. The multivariable-adjusted relative risk of advanced disease was 0.51 (95% confidence interval [CI] = 0.30 to 0.86) and of metastatic or fatal disease was 0.39 (95% CI = 0.19 to 0.77) for current statin use compared with no current use. The associations remained after adjusting for prostate-specific antigen screening history (advanced disease: RR = 0.57, 95% CI = 0.30 to 1.11; metastatic or fatal disease: RR = 0.35, 95% CI = 0.14 to 0.92). Risk of advanced disease was lower with longer statin use (P(trend) = .003); compared with never use, the relative risk for less than 5 years of use was 0.60 (95% CI = 0.35 to 1.03) and for 5 or more years of use was 0.26 (95% CI = 0.08 to 0.83). We found no association between statin use and risk of total prostate cancer (RR = 0.96, 95% CI = 0.85 to 1.09).

CONCLUSIONS

In this cohort of male health professionals, use of statin drugs was not associated with risk of prostate cancer overall but was associated with a reduced risk of advanced (especially metastatic or fatal) prostate cancer.