Risks of cancer of the colon and rectum in relation to serum cholesterol and beta-lipoprotein

Trans-ancestry analysis in over 799,000 individuals yields new insights into the genetic etiology of colorectal cancer

BACKGROUND

Recent studies have demonstrated the relevance of circulating factors in the occurrence and development of colorectal cancer (CRC); however, the causal relationship remains unclear.

METHODS

Summary-level data for CRC were obtained from the UK Biobank (5,657 cases and 372,016 controls), FinnGen cohort (3,022 cases and 215,770 controls), and BioBank Japan Project (BBJ, 7,062 cases and 195,745 controls). Thirty-two peripheral markers with consistent definitions were collected from the three biobanks. Mendelian randomization (MR) was used to evaluate the causal effect of circulating factors on CRC. The effects from the three consortiums were combined using trans-ancestry meta-analysis methods.

RESULTS

Our analysis provided compelling evidence for the causal association of higher genetically predicted eosinophil cell count (EOS, odds ratio [OR], 0.8639; 95% confidence interval [CI] 0.7922-0.9421) and red cell distribution width (RDW, OR, 0.9981; 95% CI, 0.9972-0.9989) levels with a decreased risk of CRC. Additionally, we found suggestive evidence indicating that higher levels of total cholesterol (TC, OR, 1.0022; 95% CI, 1.0002-1.0042) may increase the risk of CRC. Conversely, higher levels of platelet count (PLT, OR, 0.9984; 95% CI, 0.9972-0.9996), total protein (TP, OR, 0.9445; 95% CI, 0.9037-0.9872), and C-reactive protein (CRP, OR, 0.9991; 95% CI, 0.9983-0.9999) may confer a protective effect against CRC. Moreover, we identified six ancestry-specific causal factors, indicating the necessity of considering patients' ancestry backgrounds before formulating prevention strategies.

CONCLUSIONS

MR findings support the independent causal roles of circulating factors in CRC, which might provide a deeper insight into early detection of CRC and supply potential preventative strategies.

FOXA3 regulates cholesterol metabolism to compensate for low uptake during the progression of lung adenocarcinoma

Cholesterol metabolism is vital for multiple cancer progression, while how cholesterol affects lung, a low-cholesterol tissue, for cancer metastasis and the underlying mechanism remain unclear. In this study, we found that metastatic lung adenocarcinoma cells acquire cellular dehydrocholesterol and cholesterol by endogenous cholesterol biosynthesis, instead of uptake upon cholesterol treatment. Besides, we demonstrated that exogenous cholesterol functions as signaling molecule to induce FOXA3, a key transcription factor for lipid metabolism via GLI2. Subsequently, ChIP-seq analysis and molecular studies revealed that FOXA3 transcriptionally activated Hmgcs1, an essential enzyme of cholesterol biosynthesis, to induce endogenous dehydrocholesterol and cholesterol level for membrane composition change and cell migration. Conversely, FOXA3 knockdown or knockout blocked cholesterol biosynthesis and lung adenocarcinoma metastasis in mice. In addition, the potent FOXA3 inhibitor magnolol suppressed metastatic gene programs in lung adenocarcinoma patient-derived organoids (PDOs). Altogether, our findings shed light onto unique cholesterol metabolism and FOXA3 contribution to lung adenocarcinoma metastasis.

A new modality for cholesterol impact tracking in colon cancer development - Raman imaging, fluorescence and AFM studies combined with chemometric analysis

Colorectal cancer (CRC) is the third most common cancer worldwide. Obesity, alcohol consumption, smoking, high consumption of red or processed meat and a diet with low fibre, fruit, and vegetable intake increase CRC risk. Despite advances in surgery (the basic treatment for recovery), chemotherapy, and radiotherapy, CRC remains the second leading cause of cancer-related deaths in the world. Therefore the social importance of this problem stimulates research aimed at developing new tools for rapid CRC diagnosis and analysis of CRC risk factors. Considering the association between the cholesterol level and CRC, we hypothesize that cholesterol spectroscopic and AFM (atomic force microscopy) studies combined with chemometric analysis can be new, powerful tools used to visualize the cholesterol distribution, estimate cholesterol content and determine its influence on the biochemical and nanomechanical properties of colon cells. Our paper presents the analysis of human colon tissues: normal and cancer and human colon single cells normal CCD18-Co and cancer CaCo-2 in the physiological state and CaCo-2 upon mevastatin supplementation. Based on vibrational features we have shown that Raman spectroscopy and imaging allow cholesterol content in human colon tissues and human colon single cells of both types to be tracked and allow the effectiveness of mevastatin in the mevalonate pathway modulation and disruption of the cholesterol level to be proven. All observations have been confirmed by chemometric analysis including principal component analysis (PCA) and partial least squares discriminant analysis (PLSDA). The positive impact of statins on cholesterol content has also been studied by using fluorescence microscopy and atomic force microscopy (AFM). A significant increase in Young modulus as a mechanomarker for CaCo-2 human cancer colon cells upon mevastatin supplementation compared to CCD18-Co human normal colon cells was observed. This paper is one of the first reports about the use of Raman spectroscopic techniques in cholesterol investigations and the first one about cholesterol investigation using Raman spectroscopy (RS) on human cells ex vivo in the context of colon cancer development.

Benign gallbladder disease is a risk factor for colorectal cancer, but cholecystectomy is not: A propensity score matching analysis

Background

Previous studies reported controversial results on the relationship between cholecystectomy (CHE) and colorectal cancer (CRC). We hypothesized that gallbladder disease (GBD), instead of cholecystectomy, increased the risk of CRC. We aimed to investigate the incidence of benign gallbladder disease (BGBD) and CHE in CRC patients and local adults undergoing annual health examination by analyzing large data from a tertiary hospital in southwest China.

Methods

A propensity score matching (PSM) analyzed, retrospective study from January 1, 2013, to August 31, 2020, including 7,471 pathologically confirmed CRC patients and 860,160 local annual health examination adults in the First Affiliated Hospital of Chongqing Medical University, was conducted. The prevalence of BGBD and the CHE rate were analyzed before and after a 1:1 PSM.

Results

Of the 7,471 CRC patients, 7,160 were eligible for the case group. In addition, 860,160 local health examination adults were included for comparison. The incidence of BGBD was higher in the CRC patients than in the local adults (19.2% vs. 11.3%, P < 0.001), but no significant difference in CHE rate existed between the case group and the control group (5.0% vs. 4.8%, P = 0.340). In the subgroup analysis, patients with BGBD had a higher risk of colon cancer than rectal cancer (20.4% vs. 18.2%, P = 0.024) and more significantly in the right colon (P = 0.037). A weakly positive correlation between CHE and right colon cancer was observed before PSM but no longer existed after PSM (P = 0.168).

Conclusions

Benign gallbladder disease was positively correlated with colorectal cancer, especially right colon cancer. Cholecystectomy did not increase the risk of colorectal cancer.

Effects of APOE gene ε4 allele on serum lipid profiles and risk of cardiovascular disease and tumorigenesis in southern Chinese population

Background

Human apolipoprotein E (APOE) polymorphisms are attributable to the presence of three common alleles, namely, ε2, ε3, and ε4, which generate six genotypes, viz, E2/E2, E2/E3, E3/E3, E3/E4, E4/E4, and E2/E4. APOE polymorphisms are associated with all types of tumors and cardiovascular diseases (CVD). However, the relationship between the type of APOE polymorphisms and tumorigenesis remains debatable. Therefore, we aimed to investigate the role of APOE polymorphisms on the tumor with or without CVD in southern China.

Methods

A total of 1438 participants were categorized into 4 groups: 409 patients with tumor, 369 patients with CVD, 338 patients with both tumor and CVD, and 322 controls. APOE polymorphisms were determined by genotyping assay. The factors influencing tumor patients with or without CVD were also analyzed by logistic regression analysis.

Results

The present study involved different types of solid tumors. Lung cancer was the most common cancer (20.2%, 151/747), followed by colorectal (17%, 127/747), esophageal (9.8%, 73/747), and liver (8.7%, 65/747) cancers. E3/E3 was the most frequent genotype, and ɛ3 was the greatest allele frequency in our study population. The frequencies of the E3/E3, E3/E4, E2/E3, E2/E4, E4/E4, and E2/E2 genotypes in tumor patients were 76.97% (575/747), 14.19% (106/747), 6.83% (51/747), 1.2% (9/747), 0.4% (3/747), and 0.4% (3/747), respectively. Tumor patients carrying ε3 with or without CVD showed higher levels of TG, TC, and LDL-C and lower levels of HDL-C compared to the controls carrying ε3. On the other hand, the tumor patients carrying ε4 with or without CVD showed higher levels of TG and LDL-C and lower levels of HDL-C (all P < 0.05). The frequency of APOE ε4 allele and the E3/E4 genotype was relatively greater in tumor or CVD patients (P < 0.001). In addition, ε4 allele acted as an independent risk factor for tumor patients group (P = 0.037, adjusted OR = 1.92, 95% CI 1.04–3.55) and tumor + CVD patients group (P = 0.012, adjusted OR = 2.53, 95% CI 1.22–5.23).

Conclusions

Individuals carrying ε4 are at a higher risk of tumor with or without CVD, and APOE polymorphisms affect the serum lipid profiles.

Metformin, Statin Use, and Female Colorectal Cancer: A Population-Based Cohort Study in Taiwan

In the last few years, the incidence of colorectal cancer (CRC) in women has gradually increased. However, epidemiological studies on the relationship between type II diabetes mellitus (T2DM) and female CRC and the effect of metformin or statins on female CRC are insufficient. To determine their association, we conducted a population-based cohort study on women in Taiwan. We collected data on a total of 396,521 women aged 40 to 64 years old from 1 January 2007 to 31 December 2009 from the National Health Insurance Research Database. We followed up on all participants in the cohort until the occurrence of CRC, the date for all death, or 31 December 2015. Full development of CRC was identified using the International Classification of Disease (ICD), 9th Revision, code 153. We estimated hazard ratios (HRs) and corresponding 95% confidence intervals (CIs) using the Cox proportional hazards model. Both metformin (adjusted hazard ratio, aHR = 1.12; 95% CI: 0.934–1.335, p = 0.227) and statin (aHR = 1.03; 95% CI: 0.906–1.172, p = 0.645) use showed no association with female CRC in a multivariate analysis. The findings indicate that metformin and statin use showed no protective effect against female colorectal cancer (CRC). An additional randomized trial is necessary to investigate the effect of metformin and statin use in CRC prevention.

The Association between Hypertriglyceridemia and Colorectal Cancer: A Long-Term Community Cohort Study in Taiwan

(1) Background: Colorectal cancer (CRC) is the third most common malignancy and the second leading cause of cancer deaths worldwide. It often diagnosed at advanced stages, and with increasing incidence at younger generation. CRC poses a heavy financial burden and a huge public health challenge nowadays. Lipoproteins and serum lipids may have an influence on carcinogenesis by making oxidative stress, inflammation, and insulin resistance. Dyslipidemia plays a potential role in the risk of CRC. The purpose of this study is to use nationally representative samples to determine epidemiologic characteristics of CRC in the Taiwanese population, and to evaluate the associations between baseline levels of lipid profile and their effect on risk of colorectal cancer (CRC) comprehensively and quantitatively. The control of dyslipidemia in primary and secondary prevention may reduce the disease burden of CRC. (2) Methods: This is a nationwide long-term community-based prospective cohort study. Data were retrieved from the nationwide population-based Taiwanese Survey on Hypertension, Hyperglycemia and Hyperlipidemia (TwSHHH). Variables were estimated by the Cox proportional hazards model which was then further adjusted for age. We also calculated the relative ratios (RRs) of CRC for joint categories of serum cholesterol, triglyceride (TG), low-density lipoproteins cholesterol (LDL-C), and high-density lipoprotein cholesterol (HDL-C) level, and to examine their combined effect and statistical interactions. (3) Results: Male, age, waist circumference, diabetes mellitus (DM), high TG, high cholesterol level, smoking history, and metabolic syndrome were proved to increase the risk of CRC. In addition, DM patients with a TG level ≥150 mg/dL and cholesterol ≥180 mg/dL had a 4.118-fold higher risk of CRC as compared with a TG level <150 mg/dL and cholesterol level <180 mg/dL, which was a significant difference (95% CI, 1.061−15.975; p = 0.0407). (4) Conclusions: Patients with DM should control TG and cholesterol level through diet, exercise, or taking medications more aggressively, not only for preventing cardiovascular disease, but also for first prevention of CRC. The study can be valuable for the clinicians and policy makers to implement more precisely goals about dyslipidemia management.

Relationship between serum lipid level and colorectal cancer: a systemic review and meta-analysis

OBJECTIVE

Investigative studies report contradictory results of the relationship between serum lipid levels and the risk of colorectal cancer (CRC). We conducted a meta-analysis of prospective published studies to clarify the relationship between serum lipid and CRC risk.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

PubMed and Embase from inception until December 2020.

ELIGIBILITY CRITERIA

We considered prospective cohort and case-control studies that evaluated differences in serum lipid levels with the risk of developing CRC.

DATA EXTRACTION AND SYNTHESIS

Two independent reviewers screened and included the studies using standardised electronic data extraction forms. The relative risks of the studies were combined with random-effect and fixed-effect models and were analysed for heterogeneity, publication bias and sensitivity.

RESULTS

Twenty-four prospective studies, including 4 224 317 individuals with 29 499 CRC cases, were included in the meta-analysis. The total pooled risk ratio (RR) for high vs low concentrations of triglyceride (TG) concentrations was reported at 1.21 (95% CI 1.09 to 1.34; I²=46.8%), total cholesterol (TC) was at 1.15 (95% CI 1.08 to 1.22; I²=36.8%), high-density lipoprotein cholesterol (HDL-C) was 0.86 (95% CI 0.77 to 0.97; I²=28.8%) and low-density lipoprotein cholesterol (LDL-C) was observed at 1.03 (95% CI 0.75 to 1.41; I²=69.4%).

CONCLUSIONS

This meta-analysis shows that high levels of serum TG and TC are positively correlated with the incidence rate of CRC, while high levels of serum HDL-C are negatively correlated with CRC incidence rate. Furthermore, no association was found between LDL-C and the risk of developing CRC. Nevertheless, the heterogeneity brought about by comparative methods, demographic differences and pathological differences between the research subjects limits the effectiveness of the overall pooled results.

Influence of cholesterol on cancer progression and therapy

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Abnormality in blood cholesterol level is significantly correlated with risk of different cancers.

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Majority of tumor tissue from cancer patient exhibits overexpression of LDLR and ACAT for supporting rapid cancer cell proliferation.

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Alteration of the cholesterol metabolism in cancer cells hampers therapeutic response.

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Targeting cholesterol metabolism for treatment of cancer with other conventional chemotherapeutic drugs appears to be beneficial.

Cholesterol is a fundamental molecule necessary for the maintenance of cell structure and is vital to various normal biological functions. It is a key factor in lifestyle-related diseases including obesity, diabetes, cardiovascular disease, and cancer. Owing to its altered serum chemistry status under pathological states, it is now being investigated to unravel the mechanism by which it triggers various health complications. Numerous clinical studies in cancer patients indicate an alteration in blood cholesterol level (either decreased or increased) in comparison to normal healthy individuals. This article elaborates on our understanding as to how cholesterol is being hijacked in the malignancy for the development, survival, stemness, progression, and metastasis of cancerous cells. Also, it provides a glimpse of how cholesterol derived entities, alters the signaling pathway towards their advantage. Moreover, deregulation of the cholesterol metabolism pathway has been often reported to hamper various treatment strategies in different cancer. In this context, attempts have been made to bring forth its relevance in being targeted, in pre-clinical and clinical studies for various treatment modalities. Thus, understanding the role of cholesterol and deciphering associated molecular mechanisms in cancer progression and therapy are of relevance towards improvement in the management of various cancers.

A Mendelian randomization analysis of circulating lipid traits and breast cancer risk

BACKGROUND

Conventional epidemiologic studies have evaluated associations between circulating lipid levels and breast cancer risk, but results have been inconsistent. As Mendelian randomization analyses may provide evidence for causal inference, we sought to evaluate potentially unbiased associations between breast cancer risk and four genetically predicted lipid traits.

METHODS

Previous genome-wide association studies (GWAS) have identified 164 discrete variants associated with high density lipoprotein-cholesterol (HDL-C), low density lipoprotein-cholesterol (LDL-C), triglycerides and total cholesterol. We used 162 of these unique variants to construct weighted genetic scores (wGSs) for a total of 101 424 breast cancer cases and 80 253 controls of European ancestry from the Breast Cancer Association Consortium (BCAC). Unconditional logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals (CI) for associations between per standard deviation increase in genetically predicted lipid traits and breast cancer risk. Additional Mendelian randomization analysis approaches and sensitivity analyses were conducted to assess pleiotropy and instrument validity.

RESULTS

Corresponding to approximately 15 mg/dL, one standard deviation increase in genetically predicted HDL-C was associated with a 12% increased breast cancer risk (OR: 1.12, 95% CI: 1.08-1.16). Findings were consistent after adjustment for breast cancer risk factors and were robust in several sensitivity analyses. Associations with genetically predicted triglycerides and total cholesterol were inconsistent, and no association for genetically predicted LDL-C was observed.

CONCLUSIONS

This study provides strong evidence that circulating HDL-C may be associated with an increased risk of breast cancer, whereas LDL-C may not be related to breast cancer risk.

The association between serum lipids and colorectal neoplasm: a systemic review and meta-analysis

OBJECTIVE

There have been inconsistent results published regarding the relationship between dyslipidaemia and an increased risk of colorectal neoplasia (CRN), including colorectal adenoma (CRA) and colorectal cancer (CRC). We conducted a meta-analysis to explore the relationship between dyslipidaemia and CRN.

DESIGN

We identified studies by performing a literature search using PubMed, EMBASE and the Science Citation Index through October 2013.

SETTING

We analysed thirty-three independent studies reporting the association between CRN and at least one of the selected lipid components, including total cholesterol (TC), TAG, HDL-cholesterol (HDL-C) and LDL-cholesterol (LDL-C).

SUBJECTS

CRN cases (n 21 809) were identified.

RESULTS

Overall, people with high levels of serum TAG (risk ratio (RR)=1.08; 95% CI 1.05, 1.12, P<0.00001) and LDL-C (RR=1.07; 95% CI 1.00, 1.14, P=0.04) presented an increased prevalence of CRN. Subgroup analyses revealed that high levels of serum TC (RR=1.04; 95% CI 1.01, 1.09, P=0.02), TAG (RR=1.06; 95% CI 1.03, 1.10, P=0.0009) and LDL-C (RR=1.11; 95% CI 1.04, 1.19, P=0.003) increased the risk of CRA but not of CRC. No association between serum HDL-C and risk for CRN (including CRA and CRC) was observed.

CONCLUSIONS

Both TAG and LDL-C were significantly associated with an increasing prevalence of CRN. High levels of serum TC, TAG and LDL-C were positively associated with CRA but not with CRC. No significant association was observed between levels of serum HDL-C and CRN.

NPC1L1 knockout protects against colitis-associated tumorigenesis in mice

Background

Colorectal cancer is strongly associated with lipid metabolism. NPC1L1, a sterol transporter, plays a key role in modulating lipid homeostasis in vivo. Its inhibitor, ezetimibe, began to be used clinically to lower cholesterol and this caused the great debate on its role in causing carcinogenesis. Here we explored the role of NPC1L1 in colorectal tumorigenesis.

Methods

Wild-type mice and NPC1L1^−/− (NPC1L1 knockout) mice were treated with azoxymethane (AOM)-dextran sodium sulfate (DSS) to induce colitis-associated colorectal tumorigenesis. Mice were sacrificed 10, 15, 18 or 20 weeks after AOM treatment, respectively. Colorectal tumors were counted and analyzed. Plasma lipid concentrations were measured using enzymatic reagent kit. Protein expression level was assayed by western blot.

Results

NPC1L1^−/− mice significantly had fewer tumors than wild-type. The ratio of malignant/tumor in NPC1L1^−/− mice was significantly lower than in wild-type 20 weeks after AOM-DSS treatment. NPC1L1 was highly expressed in the small intestine of wild-type mice but its expression was undetectable in colorectal mucous membranes or tumors in either group. NPC1L1 knockout decreased plasma total cholesterol and phospholipid. NPC1L1^−/− mice had significant lower intestinal inflammation scores and expressed inflammatory markers p-c-Jun, p-ERK and Caspase-1 p20 lower than wild-type. NPC1L1 knockout also reduced lymphadenectasis what may be caused by inflammation. NPC1L1 knockout in mice decreased β-catenin in tumors and regulated TGF-β and p-gp in adjacent colons or tumors. There was not detectable change of p53 by NPC1L1 knockout.

Conclusions

Our results provide the first evidence that NPC1L1 knockout protects against colitis-associated tumorigenesis. NPC1L1 knockout decreasing plasma lipid, especially cholesterol, to reduce inflammation and decreasing β-catenin, p-c-Jun and p-ERK may be involved in the mechanism.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-1230-0) contains supplementary material, which is available to authorized users.

Dyslipidemia and colorectal cancer risk: a meta-analysis of prospective studies

PURPOSE

The findings from epidemiologic studies of dyslipidemia and colorectal cancer risk have been conflicting. We performed a dose-response meta-analysis of published prospective studies to assess the aforementioned association.

METHODS

Relevant studies that reported the association between the components of dyslipidemia (serum triglyceride, total cholesterol, and high-/low-density lipoprotein cholesterol) and colorectal cancer risk were identified by searching PubMed until the end of May 2014. We pooled the relative risks (RRs) from individual studies using a random- and fixed-effects models and performed dose-response, heterogeneity, and publication bias analyses.

RESULTS

Seventeen prospective studies, including 1,987,753 individuals with 10,876 colorectal cancer events, were included in the meta-analysis. The overall pooled RR for high versus low concentrations for triglyceride (n = 9 studies) was 1.18 (95 % CI 1.04-1.34; I (2) = 47.8 %), for total cholesterol (n = 10 studies) was 1.11 (95 % CI 1.01-1.21; I (2) = 46.7 %), for high-density lipoprotein cholesterol (n = 6 studies) was 0.84 (95 % CI 0.69-1.02; I (2) = 42.5 %), and for low-density lipoprotein cholesterol (n = 3 studies) was 1.04 (95 % CI 0.60-1.81; I (2) = 82.7 %). In the dose-response analysis, the overall pooled RR was 1.01 (95 % CI 1.00-1.03; I (2) = 0 %) per 50 mg/dL of triglyceride and 1.01 (95 % CI 0.97-1.05; I (2) = 64.3 %) per 100 mg/dL of total cholesterol.

CONCLUSIONS

This meta-analysis of prospective studies suggests that dyslipidemia, especially high levels of serum triglyceride and total cholesterol, is associated with an increased risk of colorectal cancer, whereas high-density lipoprotein cholesterol might associate with a decreased risk of colorectal cancer. Further studies are warranted to determine whether altering the concentrations of these metabolic variables may reduce colorectal cancer risk.

Colorectal cancer risk and dyslipidemia: a case-cohort study nested in an Italian multicentre cohort

BACKGROUND

Dyslipidemia is an established risk factor for many diseases, but its effect on colorectal cancer risk is less clear. We investigated the association of colorectal cancer risk with plasma triglycerides, total, HDL, and LDL cholesterol in four Italian EPIC centers.

METHODS

We conducted a case-cohort study on participants recruited to four Italian EPIC centers (Turin, Varese, Naples, and Ragusa; 34,148 subjects). A random subcohort of 850 subjects was obtained and 286 colorectal cancer cases were diagnosed. Triglycerides, total and HDL cholesterol were determined in plasma samples obtained at baseline and stored at -196°C; LDL cholesterol was calculated. Hazard ratios (HR) with 95% confidence intervals (CI), adjusted for potential confounders, were estimated by Cox regression models using the Prentice method.

RESULTS

The highest tertiles of total (HR 1.66, 95%CI 1.12-2.45) and LDL cholesterol (HR 1.87, 95%CI 1.27-2.76) were associated with increased colorectal cancer risk compared to lowest tertiles. Risks were greater for men than women, and for postmenopausal than premenopausal women. Highest tertiles of total and LDL cholesterol were also significantly associated with increased risks of colon cancer, distal colon cancer, and rectal cancer, but not proximal colon cancer.

CONCLUSIONS

Our findings suggest that high levels of total and LDL cholesterol increase colorectal cancer risk, particularly in men and postmenopausal women. However additional studies are needed to clarify the role of plasma lipids in these cancers, particularly in view of the conflicting findings of previous studies.

Total serum cholesterol and cancer incidence in the Metabolic syndrome and Cancer Project (Me-Can)

OBJECTIVE

To investigate the association between total serum cholesterol (TSC) and cancer incidence in the Metabolic syndrome and Cancer project (Me-Can).

METHODS

Me-Can consists of seven cohorts from Norway, Austria, and Sweden including 289,273 male and 288,057 female participants prospectively followed up for cancer incidence (n = 38,978) with a mean follow-up of 11.7 years. Cox regression models with age as the underlying time metric were used to estimate hazard ratios (HR) and their 95% confidence intervals (CI) for quintiles of cholesterol levels and per 1 mmol/l, adjusting for age at first measurement, body mass index (BMI), and smoking status. Estimates were corrected for regression dilution bias. Furthermore, we performed lag time analyses, excluding different times of follow-up, in order to check for reverse causation.

RESULTS

In men, compared with the 1st quintile, TSC concentrations in the 5th quintile were borderline significantly associated with decreasing risk of total cancer (HR = 0.94; 95%CI: 0.88, 1.00). Significant inverse associations were observed for cancers of the liver/intrahepatic bile duct (HR = 0.14; 95%CI: 0.07, 0.29), pancreas cancer (HR = 0.52, 95% CI: 0.33, 0.81), non-melanoma of skin (HR = 0.67; 95%CI: 0.46, 0.95), and cancers of the lymph-/hematopoietic tissue (HR = 0.68, 95%CI: 0.54, 0.87). In women, hazard ratios for the 5th quintile were associated with decreasing risk of total cancer (HR = 0.86, 95%CI: 0.79, 0.93) and for cancers of the gallbladder (HR = 0.23, 95%CI: 0.08, 0.62), breast (HR = 0.70, 95%CI: 0.61, 0.81), melanoma of skin (HR = 0.61, 95%CI: 0.42, 0.88), and cancers of the lymph-/hematopoietic tissue (HR = 0.61, 95%CI: 0.44, 0.83).

CONCLUSION

TSC was negatively associated with risk of cancer overall in females and risk of cancer at several sites in both males and females. In lag time analyses some associations persisted, suggesting that for these cancer sites reverse causation did not apply.

A longitudinal study of the metabolic syndrome and risk of colorectal cancer in postmenopausal women

The metabolic syndrome is associated with increased risk of diabetes and coronary heart disease. Although higher BMI and other related factors have been frequently associated with colorectal cancer, whether the metabolic syndrome is associated with the risk of colorectal cancer is unclear. We therefore assessed the association of the metabolic syndrome with the risk of colorectal cancer in a subsample of participants of the Women's Health Initiative who had repeated measurements of the components of the syndrome at baseline and during follow-up. Women with diabetes at baseline enrollment were excluded. Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% confidence intervals (95% CI) at baseline and in time-dependent analyses. Among 4862 eligible women, 81 incident cases of colorectal cancer were identified over a median follow-up of 12 years. Presence of the metabolic syndrome at baseline was associated with increased risk of colorectal cancer (HR 2.15, 95% CI 1.30-3.53) and colon cancer (HR 2.28, 95% CI 1.31-3.98). These associations were largely explained by positive associations of serum glucose and systolic blood pressure with both outcomes. Time-dependent covariate analyses supported the baseline findings. Our results suggest that the positive association of the metabolic syndrome with risk of colorectal cancer is largely accounted for by serum glucose levels and systolic blood pressure. The biological mechanism underlying these associations remains to be clarified.

Metabolic risk factors and ovarian cancer in the Metabolic Syndrome and Cancer project

BACKGROUND

No studies have so far evaluated the impact of the metabolic syndrome (MetS) as an entity on ovarian cancer risk. The authors aimed to examine the association between factors in the MetS, individually and combined, and risk of ovarian cancer incidence and mortality.

METHODS

Altogether, 290,000 women from Austria, Norway and Sweden were enrolled during 1974-2005, with measurements taken of height, weight, blood pressure and levels of glucose, cholesterol and triglycerides. Relative risks (RRs) of ovarian cancer were estimated using Cox regression for each MetS factor in quintiles and for standardized levels (z-scores), and for a composite z-score for the MetS. RRs were corrected for random error in measurements.

RESULTS

During follow-up, 644 epithelial ovarian cancers and 388 deaths from ovarian cancer were identified. There was no overall association between MetS and ovarian cancer risk. Increasing levels of cholesterol [RR 1.52, 95% confidence interval (95% CI) 1.01-2.29, per 1-U increment of z-score] and blood pressure (RR 1.79, 95% CI 1.12-2.86) conferred, however, increased risks of mucinous and endometrioid tumours, respectively. In women below the age of 50 years, there was increased risk of ovarian cancer mortality for MetS (RR 1.52, 95% CI 1.00-2.30). Increasing levels of BMI (RR 1.17, 95% CI 1.01-1.37) conferred increased risk of ovarian cancer mortality in women above the age of 50 years.

CONCLUSION

There was no overall association between MetS and ovarian cancer risk. However, increasing levels of cholesterol and blood pressure increased the risks of mucinous and endometrioid tumours, respectively. Increasing levels of BMI conferred an increased risk of ovarian cancer mortality in women above the age of 50 years.

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.

Time-dependent association of total serum cholesterol and cancer incidence in a cohort of 172,210 men and women: a prospective 19-year follow-up study

BACKGROUND

The relationship between serum cholesterol and cancer incidence remains controversial.

PATIENTS AND METHODS

We investigated the association of total serum cholesterol (TSC) with subsequent cancer incidence in a population-based cohort of 172 210 Austrian adults prospectively followed up for a median of 13.0 years. Cox regression, allowing for time-dependent effects, was used to estimate adjusted hazard ratios (HRs) with 95% confidence intervals (95% CIs) for the association of TSC with cancer.

RESULTS

We observed pronounced short-term associations of TSC and overall cancer incidence in both men and women. For malignancies diagnosed shortly (<5 months) after baseline TSC measurement, the highest TSC tertile (>235.0 mg/dl in men and >229.0 in women) compared with the lowest tertile (<194.0 mg/dl in men and <190.0 in women) was associated with a significantly lower overall cancer risk [HR = 0.58 (95% CI 0.43-0.78, P(trend) = 0.0001) in men, HR = 0.69 (95% CI 0.49-0.99, P(trend) = 0.03) in women]. However, after roughly 5 months from baseline measurement, overall cancer risk was not significantly associated with TSC. The short-term inverse association of TSC with cancer was mainly driven by malignancies of the digestive organs and lymphoid and hematopoietic tissue.

CONCLUSION

The short-term decrease of cancer risk seen for high levels of TSC may largely capture preclinical effects of cancer on TSC.

Multivariate explanatory model for sporadic carcinoma of the colon in Dukes' stages I and IIa

OBJECTIVE

We obtained before an explanatory model with six dependant variables: age of the patient, total cholesterol (TC), HDL cholesterol (HDL-C), VLDL cholesterol (VLDL-C), alkaline phosphatase (AP) and the CA 19.9 tumour marker. Our objective in this study was to validate the model by means of the acquisition of new records for an additional analysis.

DESIGN

Non-paired case control study.

SETTING

Urban and rural hospitals and primary health facilities in Western Andalusia and Extremadura (Spain).

PATIENTS

At both the primary care facilities and hospital level, controls were gathered in a prospective manner (n= 275). Cases were prospective and retrospective manner collected on (n=126).

MAIN OUTCOME MEASURES

Descriptive statistics, logistic regression and bootstrap analysis.

RESULTS

The AGE (odds ratio 1.02; 95% CI 1.003-1.037) (p= 0.01), the TC (odds ratio 0.986; 95% C.I. 0.980-0.992) (p< 0.001) and the CA 19.9 (odds ratio 1.023; 95% C.I. 1.012- 1.034) (p<0.001) were the variables that showed significant values at logistic regression analysis and bootstrap. Berkson's bias was statistically assessed.

CONCLUSIONS

The model, validated by means of logistic regression and bootstrap analysis, contains the variables AGE, TC, and CA 19.9 (three of the original six) and has a level 4 over 5 according to the criteria of Justice et al. (multiple independent validations) [Ann. Intern. Med.1999; 130: 515].

Increased risk of colorectal cancer due to interactions between meat consumption and the CD36 gene A52C polymorphism among Japanese

A previous study showed expression of CD36, recently reported to play important roles in metabolism of oxidized low-density lipoprotein and long-chain fatty acids and to be positively correlated with colon cancer prognosis. To examine relationships between colorectal cancer and the CD36 gene A52C polymorphism according to meat consumption as a surrogate for saturated fatty acid intake, we conducted the present hospital-based, case-control study of 128 cases and 238 non-cancer controls. Consumption of meat and vegetables/fruit was divided into three (low, moderate, and high) and two (low and high) groups, respectively. Regarding the risk of colorectal cancer on cross-classifying subjects for the CD36 genotype and meat consumption, the odds ratio (OR) for the C/C genotype with moderate meat consumption relative to the A/A genotype with low meat consumption was 8.30 (95% confidence interval, CI=2.15-32.00). None of individuals with the C/C genotype was in the high meat consumption group. In the low vegetables/fruit consumption group, the OR for the C/C genotype relative to the A/A genotype was 3.03 (95% CI=1.12-7.90). Our findings suggest that interactions between moderate-high meat consumption and the CD36 gene A52C polymorphism may increase the risk of colorectal cancer.

Serum cholesterol and testicular cancer incidence in 45,000 men followed for 25 years

In a 25-year follow-up study of 44 864 men with measured serum cholesterol levels, the testicular cancer hazard ratios for the serum cholesterol categories 5.7–6.9 and ⩾7.0 mmol l⁻¹vs the reference category (<5.7 mmol l⁻¹) were 1.3 and 4.5, respectively; P-value for trend=0.005. This highly significant association suggests that high-serum cholesterol is a risk factor for testicular cancer.

Total Cholesterol and Mortality in China, Poland, Russia, and the US

PURPOSE

To examine the relationships of total and cause-specific mortality to serum cholesterol in four diverse populations.

METHODS

Chinese, Polish, Russian, and US population-based samples were studied. The relationship between cholesterol levels and mortality was assessed by Cox proportional hazard regression with restricted piecewise cubic splines.

RESULTS

The cholesterol and total mortality relationship was statistically significantly J-shaped for all men combined. In country-specific relationships, cholesterol was significantly, linearly, and positively related to total mortality in Russian and US men. For women, the relationship was non-linear, but not statistically significant, and became statistically significant upon adjustment for other risk factors. For Polish women, a statistically significant inverse relationship existed. CHD mortality and cardiovascular disease (CVD) mortality increased linearly with cholesterol in Polish, Russian, and US men and the aggregate of men, but there was no relationship for women. Cancer mortality was not related to cholesterol except for the Polish cohort and Russian women, where there was an inverse relationship.

CONCLUSIONS

Serum cholesterol was a strong, consistent predictor of CHD and CVD mortality in Polish, Russian, and US men despite their social diversity. In contrast to CHD mortality, the relation of cholesterol to total mortality and non-CVD mortality varied by country and gender.

Serum antioxidant and cholesterol levels in patients with different types of cancer

Serum antioxidant (urate, alpha-tocopherol) activity and cholesterol concentration in 142 patients of Indian and Arab (Kuwaitis and other Arabs) origin with different types of cancer (breast, colon, stomach, thyroid, oral, rectal, pancreatic, and renal) were compared to 100 age- and sex-matched control subjects. Values were expressed as medians (interquartile range). Urate concentration was significantly decreased in male patients compared to male controls (P < 0.0001) and in female patients and female breast cancer cases compared to female controls; P < 0.0001 and P = 0.001, respectively. Alpha-tocopherol concentration decreased significantly in total cancer, stomach, colon, rectal, and breast cancer cases than the controls; P < 0.0001, P < 0.0001, P < 0.0001, P = 0.012, and P = 0.022, respectively. Cholesterol concentration decreased significantly in stomach, oral, colon, and total cancer cases compared to the controls; P < 0.0001, P < 0.0001, P = 0.002, and P = 0.012, respectively. Among controls, females had significantly (P < 0.0001) lower concentrations of alpha-tocopherol than males. Among patients, cholesterol, urate, and alpha-tocopherol concentrations decreased significantly in smokers than in nonsmokers; P < 0.0001, P = 0.004, and P = 0.047, respectively. Generally, changes in alpha-tocopherol/cholesterol ratios mimicked changes in alpha-tocopherol concentration. Concentrations of all parameters decreased significantly in male patients compared to male controls. Age was positively associated with all three analytes with respect to the controls. Alpha-tocopherol correlated with cholesterol in cancer patients (r = 0.367; P < 0.0001) and with urate in the controls (r = 0.342; P < 0.0001). The data suggest cancer-related diminished synthesis of cholesterol and, generally, a greater antioxidant burden for alpha-tocopherol than urate in cancer-generated oxidative stress. The increased incidence of pancreatic cancer in Kuwaitis warrants further study.

Association of low plasma cholesterol with mortality for cancer at various sites in men: 17-y follow-up of the prospective Basel study

BACKGROUND

Low serum cholesterol has been associated with an increased risk of cancer mortality in various studies, which has led to uncertainty regarding the benefit of lower blood cholesterol.

OBJECTIVE

The aim of our study was to evaluate the association between low blood cholesterol (<5.16 mmol/L) and cancer at sites that have rarely been evaluated. We placed special emphasis on the potential confounding effect of antioxidant vitamins.

DESIGN

Plasma concentrations of cholesterol and antioxidant vitamins were measured in 1971-1973 in 2974 men working in Basel, Switzerland. In 1990, the vital status of all participants was assessed.

RESULTS

Two hundred ninety of the participants had died from cancer, 87 from lung, 30 from prostate, 28 from stomach, and 22 from colon cancer. Group means for plasma cholesterol concentrations did not differ significantly between survivors and those who died from cancer at any of the studied sites. With plasma cholesterol, vitamins C and E, retinol, carotene, smoking, and age accounted for in a Cox model, an increase in total cancer mortality in lung, prostate, and colon but not in stomach cancer mortality was observed in men >60 y of age with low plasma cholesterol. When data from the first 2 y of follow-up were excluded from the analysis, the relative risk estimates remained practically unchanged with regard to lung cancer but decreased for colon, prostate, and overall cancer.

CONCLUSIONS

Increased cancer mortality risks associated with low plasma cholesterol were not explained by the confounding effect of antioxidant vitamins, but were attributed in part to the effect of preexisting cancer.

Serum cholesterol and mortality rates in a Native American population with low cholesterol concentrations: a U-shaped association

BACKGROUND

Low serum cholesterol concentrations are associated with high death rates from cancer, trauma, and infectious diseases, but the meaning of these associations remains controversial. The present report evaluates whether low cholesterol is likely to be a causal factor for mortality from all causes or from specific causes.

METHODS AND RESULTS

Among 4553 Pima Indians > or =20 years old, a population with low serum cholesterol (median, 4.50 mmol/L), 1077 deaths occurred during a mean follow-up of 12.8 years. Trauma was the most common cause. The relationship between serum cholesterol measured at 2-year intervals and age- and sex-standardized mortality rates was U-shaped. Cholesterol was related positively to mortality from cardiovascular diseases and diabetes (including nephropathy) and negatively to mortality from cancer and alcohol-related diseases. The relationship was U-shaped for mortality from infectious diseases, and cholesterol was not related to mortality from trauma. Change in cholesterol from one examination to the next was positively related to mortality from diabetes. In proportional-hazards models adjusted for potential confounders, the relationship between baseline cholesterol and mortality was U-shaped for all causes and diabetes and positive for cardiovascular diseases. Other relationships were nonsignificant. Among 3358 subjects followed > or =5 years, the relationship was significant and positive only for mortality from cardiovascular diseases.

CONCLUSIONS

Despite a high exposure risk for Pima Indians, if low cholesterol level is a causal factor, the relationships between low serum cholesterol and high mortality rates probably result from diseases lowering cholesterol rather than from a low cholesterol causing the diseases.

Blood lipid and lipoprotein levels and the risk of cancer of the colon and rectum. A prospective study of 62,173 Norwegian men and women

BACKGROUND

Concern has been raised that a low total serum cholesterol level, although beneficial for cardiovascular diseases, may increase the risk of cancer. This prospective cohort study analyses the hypotheses that a low total serum cholesterol level or its subfractions (serum low-density-lipoprotein cholesterol, high-density-lipoprotein cholesterol, and triglycerides) increase the risk of cancer of the colon and rectum.

METHODS

Between 1977 and 1983, 62,173 men and women attended a health screening carried out by the Norwegian National Health Screening Service. The screening consisted of a questionnaire, anthropometric measurements, and samples of non-fasting blood drawn for analyses of serum total cholesterol, low-density-lipoprotein cholesterol, high-density-lipoprotein cholesterol, and triglycerides.

RESULTS

During the 7- to 13-year follow-up, 186 patients were found to have colon cancer and 106 rectal cancer by linkage to the Norwegian Cancer Registry. Among men there were no associations between blood lipid and lipoprotein levels and risk of cancer of the proximal colon, distal colon, or the rectum. Among women there was a formal statistically significant inverse relationship between level of total cholesterol and low-density-lipoprotein cholesterol and risk of distal colon cancer, and a positive trend between total cholesterol level and rectal cancer.

CONCLUSIONS

The statistically significant results among women were interpreted as incidental, and we conclude that blood lipid and lipoprotein levels were not associated with the risk of colon or rectum cancer in men or women in this cohort.

Recent and past physical activity and prevalence of colorectal adenomas

Epidemiological evidence has generally supported a protective association of physical activity with large-bowel adenomas, but whether the protective effects are restricted to recent or past activity is uncertain. We determined whether recent and past recreational or total daily activity was associated with prevalence of colorectal adenomas among male and female members of a prepaid health plan in Los Angeles who underwent sigmoidoscopy (n = 488 matched pairs). Participants, aged 50-74 years, completed a 126-item semiquantitative food frequency questionnaire and were also interviewed regarding non-dietary risk factors in 1991-93. In the univariate analysis, all measures of recent recreational physical activity were associated with reduced prevalence of polyps. After adjustment for body mass index, smoking status, daily servings of fruit and vegetables, use of non-steroidal anti-inflammatory agents and intakes of calories, saturated fat and alcohol, the associations were weakened. For subjects engaging in high-intensity activities compared with subjects not engaging in vigorous activities, the multivariate odds ratio (OR) for recent recreational activity was 0.7 [95% confidence interval (CI) 0.4-1.1, trend P = 0.08]. Past recreational activity and past or recent total daily activity were not associated with prevalence of adenomas. These results support a modest association of recent recreational physical activity with prevalence of colorectal adenomas.

A prospective study of colon and rectal cancer among Hawaii Japanese men

The goals of this study were to assess the association of diet, alcohol, smoking, and other life-style factors with the risk of colon and rectal cancer and to examine the differences in the risk factors associated with each cancer site. Information on diet, alcohol, smoking, and other life-style factors was obtained from 7945 Japanese-American men who were living in Hawaii and examined from 1965 through 1968. After 174,514 person-years of observation, 330 incident cases of colon cancer and 123 incident cases of rectal cancer were diagnosed by histology. The risk of both colon and rectal cancer increased with age, alcohol intake, and pack-years of cigarette smoking. For colon cancer, there was also a direct association with body mass index and heart rate, while an inverse association was observed with serum cholesterol, intake of monounsaturated fatty acid, and percentage of calories from fat. For rectal cancer, the risk decreased with an increase in the intake of carbohydrates as percentage of calories. These findings suggest that some of the risk factors for colon cancer are different from those for rectal cancer.

Dietary fat and colon cancer

Dietary fat in general, and perhaps animal and polyunsaturated fats in particular, appear to increase colon carcinogenesis in animal models and epidemiologic studies. This observation holds the potential to shed light on the underlying mechanisms of colorectal carcinogenesis and reduce morbidity and mortality from the disease by dietary and chemoprevention. While research continues into the relationship between prostglandins and other putative mediators of the effects of fats on the colon, we can suggest that a diet which protects against colorectal cancer would be low in fat with most of that fat coming from vegetable sources. Prospective dietary trials are ongoing which may strengthen or modify these preliminary recommendations.

Increased LDL receptor mRNA expression in colon cancer is correlated with a rise in plasma cholesterol levels after curative surgery

It is currently under debate whether the low serum cholesterol levels that are frequently observed in cancer patients represent a risk factor for/or, rather, are a consequence of the tumour. We postulate that malignant tumours are directly involved in an increased catabolism of cholesterol-rich low-density lipoprotein (LDL) particles. In a prospective study of 25 patients with colorectal carcinoma, we measured intraindividual shifts in serum cholesterol levels after surgery, and the expression of LDL-receptor mRNA in surgically removed specimens. A significant rise in plasma cholesterol levels was observed in patients 3 and 12 months after curative surgery, but not after non-curative surgery. In human colon carcinoma tissues LDL receptor mRNA expression, as determined by competitive reverse-transcriptase-polymerase-chain reaction, was found to be significantly increased when compared to tissues from the tumour-free margin (median values, 1.2 x 10(6) vs. 2.0 x 10(5) molecules/micrograms total cellular RNA, respectively, n = 17). The extent of LDL-receptor mRNA expression positively correlated to the percentage rise of plasma cholesterol levels 3 months (n = 7, r = 0.8763) and 12 months (n = 6, r = 0.9181) after curative surgery. This finding provides in vivo evidence that the tumour tissue itself contributes to decreased plasma cholesterol levels in patients suffering from colorectal carcinomas. It supports the hypothesis that low cholesterol levels in cancer patients are a consequence, and not the cause, of the malignancy.

The prognostic value of hypocholesterolemia in hospitalized patients

Clinical observations show that severe illness often leads to hypocholesterolemia. To verify this finding and to define the relationship between serum cholesterol and a patient's prognosis, a study was conducted in two large hospital populations. Of 24,000 and 61,463 adult patients (populations I and II) an average of 3.8% and 3.6% died in hospital, respectively. The mean serum cholesterol levels of patients who died was significantly lower than that of those who survived (163.6 mg/dl versus 217.8 mg/dl; P < 0.0001). The average cholesterol of surviving patients was similar to that of 6,543 healthy controls. During hospitalization serum cholesterol levels of < or = 100 mg/dl were encountered in 1.2% and 3.6% of patients of populations I and II, respectively. The mortality of these hypocholesterolemic patients was about tenfold higher than average and showed a strong, inverse, linear relationship with serum cholesterol concentrations. Patients whose serum cholesterol level dropped to less than 45 mg/dl did not survive. These data show that in severely ill patients serum cholesterol may decline to very low concentrations, and the prognosis is reflected by the degree of hypocholesterolemia, which thus may serve as a clinically useful prognostic parameter.

Serum total cholesterol and mortality in a Japanese population

Although the relation between serum total cholesterol and coronary heart disease is well established, the relation with mortality from non-coronary disease is controversial. Inverse relations of serum cholesterol with hemorrhagic stroke and cancer have stimulated the examination of cholesterol-non-coronary mortality associations. The population surveyed is 12,187 men and women aged 40-69 years living in Yao City, a suburb of Osaka, who undertook baseline examinations between 1975 and 1984 and had no history of stroke and coronary heart disease at baseline. The subjects were followed on average 8.9 years until the end of 1988 using systematic mortality surveillance. During the follow-up, there were 343 deaths, comprising 170 cancer deaths (International Classification of Death 9th edition: ICD-9, 140-239), 21 coronary heart disease deaths (ICD-9, 410-414), 67 other cardiovascular deaths (ICD-9, 390-458 excluding 410-414), and 85 non-cardiovascular, non-cancer deaths. There was a significant inverse association of serum cholesterol with total and cancer mortality for men, and no significant association for women. The cholesterol-disease association, although not significant, was positive for coronary heart disease and other cardiovascular disease deaths, and inverse for non-cardiovascular, non-cancer deaths in both sexes. The inverse association of serum cholesterol with total and cancer mortality for men remained significant after controlling for age, job classification, hypertension category, usual alcohol intake, cigarette smoking, and relative weight index.(ABSTRACT TRUNCATED AT 250 WORDS)

Low cholesterol and risk of non-coronary mortality

Based on a systematic review of over 20 cohort studies, a clear association exists, for both men and women, between particularly low cholesterol levels and the rate of non-coronary mortality. The excess in women appears mainly confined to non-cancer causes, particularly respiratory and digestive diseases, while there is also an excess of deaths from cancer seen in men with low cholesterol levels. Higher mortality rates from trauma, haemorrhagic stroke and cirrhosis have also been observed. Much of this association is known to be as a consequence of the disease with a fall in cholesterol levels seen after developing a variety of inflammatory diseases. However, the excess risk of non-coronary heart disease deaths is still apparent by excluding deaths within five years suggesting that effect-cause is not the only explanation. Confounding still remains the most likely explanation for the association with an underlying chronic disease or risk factor causing both the low cholesterol and the fatal event. However, there is still the possibility that some of the increased risk is due to the low cholesterol. This makes it important that appropriately controlled trials of both drug and dietary interventions demonstrate net clinical benefit among those with low levels of coronary risk before cholesterol-lowering strategies are adopted more widely in these groups.

Dietary risk factors for cancer and adenomas of the large intestine. A case-control study within a screening trial in Denmark

The aims of the study were to estimate the importance of dietary habits for colorectal cancers and adenomas. By comparing risk factors among cancer and adenoma patients the adenoma cancer theory was indirectly evaluated. The study was performed as a case-control study within a large screening trial in Denmark. All cancer and adenoma patients diagnosed at the screening were recruited as cases; controls were selected among test negatives after matching for age, sex and time of screening. All those selected except 85, participated in a 7-day dietary recall. Altogether 49 colorectal cancer patients and 172 with adenomas were examined; 362 individuals who were test negatives in the Hemoccult-II screen served as controls. The intake of crude dietary fibres was shown to be associated with reduced risk of cancer as well as adenomas. Neither cancer nor adenoma occurrences were related to total energy intake or body mass. Vitamins E and A were negatively associated with adenoma occurrence.

Red blood cell folate is associated with the development of dysplasia and cancer in ulcerative colitis

Patients with extensive ulcerative colitis have a high risk of developing colon cancer. The etiology of mucosal dysplasia, a premalignant lesion that is used as a screening test in surveillance programs, is unknown. Previously, a case-control study [Lashner et al. (1989) Gastroenterology 97:255-259] suggested that folate supplementation was associated with a 62% reduction in the risk of developing dysplasia or cancer. The current case-control study was performed to obtain a better definition of this risk. All 67 patients with chronic ulcerative pancolitis having surveillance colonoscopy during a 1-year period were entered. There were 6 cases (4 with dysplasia and 2 with cancer) and 61 controls (no cancer or dysplasia). Red blood cell folate, reflecting intermediate-term stores, was a mean of 66.2 ng/ml lower in cases compared to controls. Serum folate, reflecting short-term stores, was not different between groups. Adjusting for confounding effects of age, sex, race, disease duration, and folate supplementation, the risk of dysplasia or cancer was significantly decreased by 18% for each 10 ng/ml increase in red blood cell folate (odds ratio 0.82, 95% confidence interval 0.68-0.99). Vitamins A, D, and E and carotene were lower in cases than in controls, but no water-soluble vitamin other than red blood cell folate was associated with an increased cancer risk. Depressed red blood cell folate is associated with an increased risk of dysplasia and cancer in patients with ulcerative colitis and may be a risk factor for neoplastic transformation.

Epidemiology of low cholesterol levels in older adults. The Cardiovascular Health Study

BACKGROUND

Low cholesterol levels have been associated with increased mortality from stroke, cancer, and other noncardiovascular diseases, but the reasons for this association remain unclear. One explanation is that persons with low cholesterol levels have early or occult disease that eventually leads to their deaths.

METHODS AND RESULTS

This possibility was explored in 2,091 men and 2,714 women 65-100 years old in the Cardiovascular Health Study, a multicenter observational study of risk factors for heart disease and stroke in older adults. Cholesterol levels < or = 160 mg/dL were present in 11.6% of men and 3.7% of women and increased in prevalence with age. After adjustment for age, total cholesterol levels in this range were associated with a twofold increased prevalence of treated diabetes in men and women and with a twofold increased prevalence of cancer diagnosed in the preceding 5 years in women only. Low cholesterol was also associated with lower levels of hemoglobin, albumin, and factor VII, suggesting a link with hepatic synthetic function. On multivariate analysis, factors most strongly associated with low cholesterol levels in men and women were decreased factor VII levels, decreased albumin, and diabetes.

CONCLUSIONS

Cross-sectional associations with low cholesterol levels differ by sex and suggest poorer health by some measures. The observed relations with treated diabetes and impaired hepatic synthetic function should be examined for risk of mortality in longitudinal data from this and other observational studies.

Increased serum deoxycholic acid levels in men with colorectal adenomas

BACKGROUND

Epidemiological and animal studies have suggested that the secondary bile acid deoxycholic acid is cocarcinogenic in colorectal cancer, but this hypothesis was not confirmed by case-control studies investigating fecal bile acids.

METHODS

Individual serum bile acid concentrations were investigated in 25 men and 25 women with colorectal adenomas and in an equal number of age- and sex-matched controls by gas-liquid chromatography.

RESULTS

Deoxycholic acid levels were significantly higher in the sera of men with colorectal adenomas (1.70 +/- 0.59 vs. 1.16 +/- 0.39 mumol/L, P < 0.0005) and in a combined analysis of both sexes (1.47 +/- 0.78 vs. 1.08 +/- 0.39 mumol/L, P < 0.0025). Six- and 12-month follow-up measurements of deoxycholic acid concentrations in a subgroup of 22 men and 17 women showed higher serum levels in men with adenomas, indicating that measurement of deoxycholic acid concentration may be a reliable parameter to investigate its pathogenetic role in colonic neoplasia.

CONCLUSIONS

The data of this study support the hypothesis that deoxycholic acid may play a role in the pathogenesis of colorectal cancer.

Increased risk of 'high-risk' colorectal adenomas in overweight men

BACKGROUND

Epidemiologic studies have suggested that the incidence of colorectal carcinoma may be related to overnutrition, but retrospective analysis of its relation to the body mass index (BMI: kg/m2) has produced conflicting data.

METHODS

To avoid as many sources of statistical bias as possible, the relation between BMI and the presence of colorectal adenomas was investigated in a cross-sectional study.

RESULTS

Two thousand twelve consecutive colonoscoped patients were investigated (532 patients with malignancies or other conditions associated with weight loss were excluded). The relation between BMI and observed colorectal adenomas was evaluated by a logistic model controlling for other prognostic factors such as age, sex, and serum cholesterol level. The subgroup of "high-risk" adenomas with an increased risk of malignant transformation was positively associated with the BMI in men of the age group 50.5-68.1 years (quintiles III and IV: odds ratio for the top quintile vs. the lowest quintile, 3.21; 95% confidence interval, 1.15-8.98).

CONCLUSIONS

It was concluded that the risk of developing high-risk adenomas tends to be increased in men who are overweight and that this association is independent of the positive association with the serum cholesterol level recently described.

Report of the Conference on Low Blood Cholesterol: Mortality Associations

BACKGROUND

A National Heart, Lung, and Blood Institute (NHLBI) Conference was held October 9-10, 1990, to review and discuss existing data on U-shaped relations found between mortality rates and blood total cholesterol levels (TC) in some but not other studies. Presentations were given from 19 cohort studies from the United States, Europe, Israel, and Japan. A representative of each study presented its findings and also submitted tables of proportional hazards regression coefficients for entry TC levels in regard to death, and these were incorporated into a formal statistical overview adjusted for age, diastolic blood pressure, cigarette smoking, body mass index, and alcohol intake, as available.

METHODS AND RESULTS

The U-shape for total mortality in men and the flat relation in women resulted largely from a positive relation of TC with coronary heart disease death and an inverse relation with deaths caused by some cancers (e.g., lung but not colon), respiratory disease, digestive disease, trauma, and residual deaths. Risk for combined noncardiovascular, noncancer causes of death decreased steadily across the range of TC. The conference considered possible explanations for the statistical associations found between low TC levels or active TC lowering and certain causes of death. One is that TC is lowered by some disease conditions themselves, such as wasting in chronic pulmonary disease or reduced production and secretion of cholesterol-bearing lipoproteins with liver disease. In this sort of situation, the TC:mortality association found in observational studies may be due to preexisting disease. This was addressed by excluding early deaths from the analysis, which did not change the results. The conference considered as well the biological function of cholesterol, which, if seriously deranged, might hypothetically cause a wide variety of diseases and dysfunction. The conference also considered the biological functions that might provide plausible mechanisms for the associations found.

CONCLUSIONS

Definitive interpretation of the associations observed was not possible, although most participants considered it likely that many of the statistical associations of low or lowered TC level are explainable by confounding in one form or another. The conference focused on the apparent existence and nature of these associations and on the need to understand their source rather than on any pertinence of the findings for public health policy. Further research is recommended to explain the observed associations of low TC levels (and TC lowering) with certain noncardiovascular diseases. This includes studies of the time course of TC change in disease, the relation of TC to morbidity, further studies of possible epidemiological confounding, monitoring of population trends in TC and mortality, further studies of the relations in women, auditing of noncardiovascular events in trials, studies of cell membrane, genetic and molecular links to cholesterol metabolism, TC level and disease, studies of disease manifestations in specific lipid disorders, and further study of the proposed causal mechanisms linking low TC and hemorrhagic stroke.

High protein, saturated fat and cholesterol diet, and low levels of serum lipids in colorectal cancer

In a case-control study probing the role of diet on the occurrence of colorectal cancer and undertaken in Athens, Greece, sera were collected from 100 cases and 100 controls, and serum total cholesterol, high-density-lipoprotein (HDL) cholesterol and triglycerides were determined. The biochemical results were analyzed in conjunction with nutrient intakes and a dietary score that summarizes in a linear way the dietary contrast between high-risk (high protein, saturated fat and dietary cholesterol; low vegetable) and low-risk (low protein, saturated fat and cholesterol; high vegetable) patterns. Cases with colorectal cancer had significantly (p less than 0.001) and substantially lower values of serum total cholesterol and particularly HDL cholesterol, but these associations did not reflect dietary practices, since protein intake and, to a lesser (and nonsignificant) extent, saturated fat and dietary cholesterol intake were higher among cases than among controls. In absolute terms, the dietary effect (as summarized in the linear dietary score) is more evident among persons with low serum total cholesterol and HDL cholesterol than among those with high levels of these serum lipids. These results indicate that a diet beneficial with respect to the risk of coronary heart disease is also likely to reduce the risk of colorectal cancer, even though low levels of serum total cholesterol and particularly HDL cholesterol represent important independent correlates of clinically overt colorectal cancer.

Serum levels of cholesterol and ischemic heart disease mortality. The Värmland Study

The objective of the Värmland Study was to examine how serum cholesterol can be used to predict short- and long-term ischemic heart disease (IHD) mortality, especially in women aged 65 or older. This prospective cohort study involved about 20 years of follow-up after a single determination of serum cholesterol and included participants in a health screening undertaken from 1962 to 1965 (48,076 men, 48,732 women). The main outcome measures were mortality from IHD, acute myocardial infarction (MI), and chronic ischemic heart disease (CIHD). An IHD mortality trend was associated with increasing cholesterol levels for people younger than 65 years, and was more pronounced for men than women. For people 65 years or older, there was a weak trend for men, but not even a tendency for women. Regarding acute MI, significant trends were observed for males as well as females, for young as well as old people. A mild CIHD mortality trend was observed for young men. Otherwise no significant trend was seen.

Serum cholesterol concentration and coronary heart disease in population with low cholesterol concentrations

OBJECTIVE

To examine the relation between serum cholesterol concentration and mortality (from coronary heart disease and from other causes) below the range of cholesterol values generally seen in Western populations.

DESIGN

Prospective observational study based on 8-13 years of follow up of subjects in a population with low cholesterol concentrations.

SETTING

Urban Shanghai, China.

SUBJECTS

9021 Chinese men and women aged 35-64 at baseline.

MAIN OUTCOME MEASURE

Death from coronary heart disease and other causes.

RESULTS

The average serum cholesterol concentration was 4.2 mmol/l at baseline examination, and only 43 (7%) of the deaths that occurred during 8-13 years of follow up were attributed to coronary heart disease. There was a strongly positive, and apparently independent, relation between serum cholesterol concentration and death from coronary heart disease (z = 3.47, p less than 0.001), and within the range of usual serum cholesterol concentration studied (3.8-4.7 mmol/l) there was no evidence of any threshold. After appropriate adjustment for the regression dilution bias, a 4 (SD 1)% difference in usual cholesterol concentration was associated with a 21 (SD 6)% (95% confidence interval 9% to 35%) difference in mortality from coronary heart disease. There was no significant relation between serum cholesterol concentration and death from stroke or all types of cancer. The 79 deaths due to liver cancer or other chronic liver disease were inversely related to cholesterol concentration at baseline.

CONCLUSION

Blood cholesterol concentration was directly related to mortality from coronary heart disease even in those with what was, by Western standards, a "low" cholesterol concentration. There was no good evidence of an adverse effect of cholesterol on other causes of death.

Low serum cholesterol and the risk of cancer: an analysis of the published prospective studies

Data were analyzed from 33 prospective studies to assess the evidence for a long-term association of low serum cholesterol with cancer. In subjects with cancer diagnosed within two years of the cholesterol measurement or causing death within five years (n = 4,661), the level of serum cholesterol was on average lower than in controls by 0.18 (SE = 0.02) mmol/l in men and 0.11 (SE = 0.04) mmol/l in women; this effect can be attributed to preclinical cancer. For cancers presenting after these intervals (n = 22,030), the average differences were smaller but statistically significant (0.04 [SE = 0.01] mmol/1 [P less than 0.001) in men, and 0.03 [SE = 0.01] mmol/1 [P = 0.005] in women), equivalent to about a 15 percent increase in cancer incidence in the lowest cholesterol quintile. This cannot be attributed entirely to preclinical cancer. In men, there was significant (P = 0.01) heterogeneity between studies as to the extent of a long-term association. The heterogeneity could be substantially explained by socioeconomic status, the association being pronounced in studies of manual workers but absent in studies of professional men. The overall long-term association was attributable mainly to lung cancer in men, and partly to hemopoietic cancers (representing prolongation of survival by treatment). Colon cancer and other cancers unrelated to smoking showed no long-term association with low cholesterol. The data collectively do not justify concern that lowering serum cholesterol to reduce ischemic heart-disease risk might cause cancer. The long-term association with lung cancer is probably caused by smoking and we propose a mechanism.