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

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.

Statins and the risk of gastric cancer in diabetes patients

Background

Several studies have suggested a cancer risk reduction in statin users although the evidence remains weak for stomach cancer. The purpose of this study was to use an exact-matching case–control design to examine the risk of gastric cancer associated with the use of statins in a cohort of patients with diabetes.

Methods

Cases were defined as patients with incident gastric cancer identified by International Classification of Diseases 16.0 ~ 16.9 recorded at Samsung Medical Center database during the period of 1999 to 2008, at least 6 months after the entry date of diabetes code. Each gastric cancer case patient was matched with one control patient from the diabetes patient registry in a 1:1 fashion, blinded to patient outcomes.

Results

A total of 983 cases with gastric cancer and 983 controls without gastric cancer, matched by age and sex, were included in the analysis. The presence of prescription for any statin was inversely associated with gastric cancer risk in the unadjusted conditional logistic regression model (OR: 0.18; 95% CI: 0.14 – 0.24; P < .0001). Multivariate analysis using conditional logistic regression with Bonferroni’s correction against aspirin indicated a significant reduction in the risk of gastric cancer in diabetes patients with statin prescriptions (OR: 0.21; 95% CI: 0.16 – 0.28; P < .0001). After adjustment for aspirin use, a longer duration of statin use was associated with reduced risk of gastric cancer, with statistical significance (P<.0001).

Conclusions

A strong inverse association was found between the risk of gastric adenocarcinoma and statin use in diabetic patients.

Anticancer activity of the cholesterol exporter ABCA1 gene

The ABCA1 protein mediates the transfer of cellular cholesterol across the plasma membrane to apolipoprotein A-I. Loss-of-function mutations in the ABCA1 gene induce Tangier disease and familial hypoalphalipoproteinemia, both cardiovascular conditions characterized by abnormally low levels of serum cholesterol, increased cholesterol in macrophages, and subsequent formation of vascular plaque. Increased intracellular cholesterol levels are also frequently found in cancer cells. Here, we demonstrate anticancer activity of ABCA1 efflux function, which is compromised following inhibition of ABCA1 gene expression by oncogenic mutations or cancer-specific ABCA1 loss-of-function mutations. In concert with elevated cholesterol synthesis found in cancer cells, ABCA1 deficiency allows for increased mitochondrial cholesterol, inhibits release of mitochondrial cell death-promoting molecules, and thus facilitates cancer cell survival, suggesting that elevated mitochondrial cholesterol is essential to the cancer phenotype.

Metabolic factors and blood cancers among 578,000 adults in the metabolic syndrome and cancer project (Me-Can)

We investigated associations between metabolic factors and blood cancer subtypes. Data on body mass index (BMI), blood pressure, blood glucose, total cholesterol, and triglycerides from seven prospective cohorts were pooled (n = 578,700; mean age = 44 years). Relative risks of blood cancers were calculated from Cox regression models. During mean follow-up of 12 years, 2,751 incident and 1,070 fatal cases of blood cancers occurred. Overall, higher BMI was associated with an increased blood cancer risk. In gender-specific subgroup analyses, BMI was positively associated with blood cancer risk (p = 0.002), lymphoid neoplasms (p = 0.01), and Hodgkin's lymphoma (p = 0.02) in women. Further associations with BMI were found for high-grade B-cell lymphoma (p = 0.02) and chronic lymphatic leukemia in men (p = 0.05) and women (p = 0.01). Higher cholesterol levels were inversely associated with myeloid neoplasms in women (p = 0.01), particularly acute myeloid leukemia (p = 0.003), and glucose was positively associated with chronic myeloid leukemia in women (p = 0.03). In men, glucose was positively associated with risk of high-grade B-cell lymphoma and multiple myeloma, while cholesterol was inversely associated with low-grade B-cell lymphoma. The metabolic syndrome score was related to 48 % increased risk of Hodgkin's lymphoma among women. BMI showed up as the most consistent risk factor, particularly in women. A clear pattern was not found for other metabolic factors.

Low cholesterol is associated with depression among US household population

OBJECTIVE

Serum cholesterol was reported to be associated with depressed mood, but the studies conducted among household population are rare.

METHODS

We used the data of 4115 men and 4275 women aged 18 or older, who completed a depression screening interview and had blood collected as a part of the National Health and Nutrition Examination Survey, 2005-2008. The serum concentrations of total cholesterol, high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C) were gender-specifically categorized into lower, intermediate, and upper quartiles. Depression was measured using the Patient Health Questionnaire, a 9-item screening instrument asking about the frequency of depression symptoms over the past 2 weeks.

RESULTS

After adjustment for socio-demographics and behavioral risks, a U-shaped association was detected between severe depression and LDL-C among men. The odds ratios (ORs) of severe depression were 5.13 (95% CI=1.74-15.09), 1 (reference) and 2.28 (1.07-4.86) respectively for the men with lower (<169 mg/dL), intermediate (169-221 mg/dL), and upper quartile (≥ 222 mg/dL) LDL-C. Among women, lower HDL-C was significantly associated with an elevated odds of severe depression [OR=2.96 (1.59-5.52)] compared with upper quartile of HDL-C, the association diminished after adjustment for covariates [OR=1.24 (0.66-2.32)]. No clear pattern of association between cholesterol and moderate depression was observed from either men or women.

LIMITATION

The inherent limitation of cross-sectional design prevented the authors from investigating causality.

CONCLUSIONS

A U-shaped association was identified between LDL-C and severe depression among men. Further studies are necessary to explore the biological mechanism and identify the clinical implication among populations vulnerable to psychiatric disorders.

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.

Metabolic risk factors and primary liver cancer in a prospective study of 578,700 adults

Initial studies have indicated diabetes and obesity to be risk factors for hepatocellular carcinoma; but the association between other metabolic risk factors and primary liver cancer (PLC) has not been investigated. The metabolic syndrome and cancer project (Me-Can) includes cohorts from Norway, Austria and Sweden with data on 578,700 subjects. We used Cox proportional hazard models to calculate relative risks (RRs) of PLC by body mass index (BMI), blood pressure and plasma levels of glucose, cholesterol and triglycerides as continuous standardized variables (z-score with mean = 0 and standard deviation (SD) = 1) and their standardized sum of metabolic syndrome (MetS) z-score. RRs were corrected for random error in measurements. During an average follow-up of 12.0 years (SD = 7.8), 266 PLCs were diagnosed among cohort members. RR of liver cancer per unit increment of z-score adjusted for age, smoking status and BMI and stratified by birth year, sex and sub-cohorts, was for BMI 1.39 (95% confidence interval (CI) 1.24-1.58), mid blood pressure 2.08 (0.95-4.73), blood glucose 2.13 (1.55-2.94) cholesterol 0.62 (0.51-0.76) and serum triglycerides 0.85 (0.65-1.10). The RR per one unit increment of the MetS z-score was 1.35 (1.12-1.61). BMI, glucose and a composite MetS score were positively and cholesterol negatively associated with risk of liver cancer.

Dietary cholesterol intake and cancer

BACKGROUND

This study assesses the association between dietary cholesterol intake and the risk of various cancers.

PATIENTS AND METHODS

Mailed questionnaires were completed between 1994 and 1997 in eight Canadian provinces by 1182 incident histologically confirmed cases of the stomach, 1727 of the colon, 1447 of the rectum, 628 of the pancreas, 3341 of the lung, 2362 of the breast, 442 of the ovary, 1799 of the prostate, 686 of the testis, 1345 of the kidney, 1029 of the bladder, 1009 of the brain, 1666 non-Hodgkin's lymphomas (NHL), 1069 leukemia and 5039 population controls. Information on dietary habits and nutrition intake were obtained using a food frequency questionnaire, which provided data on eating habits 2 years before the study. Odds ratios (ORs) were derived by unconditional logistic regression to adjust for total energy intake and other potential confounding factors.

RESULTS

Dietary cholesterol was positively associated with the risk of cancers of the stomach, colon, rectum, pancreas, lung, breast (mainly postmenopausal), kidney, bladder and NHL: the ORs for the highest versus the lowest quartile ranged from 1.4 to 1.7. In contrast, cholesterol intake was inversely associated with prostate cancer.

CONCLUSIONS

Our findings add to the evidence that high cholesterol intake is linked to increased risk of various cancers. A diet low in cholesterol may play a role in the prevention of several cancers.

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.

Low-density lipoprotein cholesterol and the risk of cancer: a mendelian randomization study

BACKGROUND

Low plasma levels of low-density lipoprotein (LDL) cholesterol are associated with an increased risk of cancer, but whether this association is causal is unclear.

METHODS

We studied 10 613 participants in the Copenhagen City Heart Study (CCHS) and 59 566 participants in the Copenhagen General Population Study, 6816 of whom had developed cancer by May 2009. Individuals were genotyped for PCSK9 R46L (rs11591147), ABCG8 D19H (rs11887534), and APOE R112C (rs429358) and R158C (rs7412) polymorphisms, all of which are associated with lifelong reduced plasma LDL cholesterol levels. Plasma LDL cholesterol was calculated using the Friedewald equation in samples in which the triglyceride level was less than 354 mg/dL and measured directly by colorimetry for samples with higher triglyceride levels. Risk of cancer was estimated prospectively using Cox proportional hazards regression analyses and cross-sectionally by logistic regression analyses. Causality was studied using instrumental variable analysis. All statistical tests were two-sided.

RESULTS

In the CCHS, compared with plasma LDL cholesterol levels greater than the 66th percentile (>158 mg/dL), those lower than the 10th percentile (< 87 mg/dL) were associated with a 43% increase (95% confidence interval [CI] = 15% to 79% increase) in the risk of cancer. The polymorphisms were associated with up to a 38% reduction (95% CI = 36% to 41% reduction) in LDL cholesterol levels but not with increased risk of cancer. The causal odds ratio for cancer for a 50% reduction in plasma LDL cholesterol level due to all the genotypes in both studies combined was 0.96 (95% CI = 0.87 to 1.05), whereas the hazard ratio of cancer for a 50% reduction in plasma LDL cholesterol level in the CCHS was 1.10 (95% CI = 1.01 to 1.21) (P for causal odds ratio vs observed hazard ratio = .03).

CONCLUSION

Low plasma LDL cholesterol levels were robustly associated with an increased risk of cancer, but genetically decreased LDL cholesterol was not. This finding suggests that low LDL cholesterol levels per se do not cause cancer.

Metabolic syndrome and breast cancer in the me-can (metabolic syndrome and cancer) project

BACKGROUND

Few studies have assessed the metabolic syndrome (MetS) as an entity in relation to breast cancer risk, and results have been inconsistent. We aimed to examine the association between MetS factors (individually and combined) and risk of breast cancer incidence and mortality.

METHODS

Two hundred ninety thousand women from Austria, Norway, and Sweden were enrolled during 1974-2005, with measurements of height, weight, blood pressure, and levels of glucose, cholesterol, and triglycerides. Relative risks (RR) of breast cancer were estimated using Cox proportional hazards regression for each MetS factor in quintiles and for standardized levels (z-scores) and for a composite z-score for the MetS.

RESULTS

There were 4,862 incident cases of breast cancer and 633 deaths from breast cancer identified. In women below age 50, there was a decreased risk of incident cancer for the MetS (per 1-unit increment of z-score; RR, 0.83; 95% confidence interval, 0.76-0.90) as well as for the individual factors (except for glucose). The lowest risks were seen among the heaviest women. In women above age 60, there was an increased risk of breast cancer mortality for the MetS (RR, 1.23; 95% confidence interval, 1.04-1.45) and for blood pressure and glucose. The strongest association with mortality was seen for increased glucose concentrations.

CONCLUSIONS

The MetS was associated with a decreased risk of incident breast cancer in women below age 50 with high body mass index, and with an increased risk of breast cancer mortality in women above 60.

IMPACT

Lifestyle interventions as recommended for cardiovascular disease prevention may be of value to prevent breast cancer mortality in postmenopausal women.

Metabolic syndrome and endometrial carcinoma

The authors examined the association between the metabolic syndrome and risk of incident endometrial and fatal uterine corpus cancer within a large prospective cohort study. Approximately 290,000 women from Austria, Norway, and Sweden were enrolled during 1974-2005, with measurements of height, weight, systolic and diastolic blood pressure, and circulating levels of glucose, total cholesterol, and triglycerides. Relative risks were estimated using Cox proportional hazards regression. The metabolic syndrome was assessed as a composite z score, as the standardized sum of z scores for body mass index, blood pressure, glucose, cholesterol, and triglycerides. A total of 917 endometrial carcinomas and 129 fatal cancers were identified. Increased risks of incident endometrial carcinoma and fatal uterine corpus cancer were seen for the metabolic syndrome factors combined, as well as for individual factors (except for cholesterol). The relative risk of endometrial carcinoma for the metabolic syndrome was 1.37 (95% confidence interval: 1.28, 1.46) per 1-unit increment of z score. The positive associations between metabolic syndrome factors (both individually and combined) and endometrial carcinoma were confined to the heaviest women. The association between the metabolic syndrome and endometrial carcinoma risk seems to go beyond the risk conferred by obesity alone, particularly in women with a high body mass index.

Serum triglyceride concentrations and cancer risk in a large cohort study in Austria

Background:

Blood lipid levels as part of the metabolic syndrome are thought to be linked to cancer risk. Few epidemiological studies have addressed the association between serum triglyceride (STG) concentrations and cancer risk.

Methods:

Serum triglyceride concentrations were collected in a health investigation (1988–2003). The analyses included 156 153 subjects (71 693 men and 84 460 women), with 5079 incident cancers in men and 4738 cancers in women, and an average of 10.6 years of follow-up. All malignancies were ascertained from the population cancer registry. Multivariate Cox proportional hazard models stratified by age and sex were used to determine adjusted cancer risk estimates and 95% confidence interval (95% CI).

Results:

In men and women combined, higher STG concentrations were associated with increased risk of lung (4th vs 1st quartile: HR, 1.94; 95% CI, 1.47–2.54), rectal (HR, 1.56; 95% CI, 1.00–2.44), and thyroid cancer (HR, 1.96; 95% CI, 1.00–3.84). Serum triglyceride concentrations were inversely associated with non-Hodgkin's lymphoma. In men, STG concentrations were inversely associated with prostate cancer and positively with renal cancer. In women, STG concentrations were positively associated with gynaecological cancers. Stratification by BMI revealed a higher risk of gynaecological cancers in overweight than in normal weight women. No other associations were found.

Conclusions:

Our findings support the hypothesis that STG concentrations are involved in the pathogenesis of lung, rectal, thyroid, prostate, and gynaecological cancers.