Christel Häggström

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. Cancer Epidemiol Biomarkers Prev; 19(7); 1737–45. ©2010 AACR.

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.

Prospective study on metabolic factors and risk of prostate cancer

There are inconsistent data regarding the association between metabolic factors, separately and combined, and the risk of prostate cancer and death from prostate cancer.

Metabolic factors and the risk of pancreatic cancer: a prospective analysis of almost 580,000 men and women in the Metabolic Syndrome and Cancer Project.

Background: The aim of this study was to investigate the association between factors in metabolic syndrome (MetS; single and combined) and the risk of pancreatic cancer. Methods: The Metabolic Syndrome and Cancer Project is a pooled cohort containing data on body mass index, blood pressure, and blood levels of glucose, cholesterol, and triglycerides. During follow-up, 862 individuals were diagnosed with pancreatic cancer. Cox proportional hazards analysis was used to calculate relative risks (RR) with 95% confidence intervals using the abovementioned factors categorized into quintiles and transformed into z-scores. All z-scores were summarized and a second z-transformation creating a composite z-score for MetS was done. All risk estimates were calibrated to correct for a regression dilution bias. Results: The trend over quintiles was positively associated with the risk of pancreatic cancer for mid-blood pressure (mid-BP) and glucose in men and for body mass index, mid-BP, and glucose in women. The z-score for the adjusted mid-BP (RR, 1.10; 1.01-1.20) and the calibrated z-score for glucose (RR, 1.37; 1.14-1.34) were positively associated with pancreatic cancer in men. In women, a positive association was found for calibrated z-scores for mid-BP (RR, 1.34; 1.08-1.66), for the calibrated z-score for glucose (RR, 1.98; 1.41-2.76), and for the composite z-score for MetS (RR, 1.58; 1.34-1.87). Conclusion: Our study adds further evidence to a possible link between abnormal glucose metabolism and risk of pancreatic cancer. Impact: To our knowledge, this is the first study on MetS and pancreatic cancer using prediagnostic measurements of the examined factors. Cancer Epidemiol Biomarkers Prev; 19(9); 2307–17. ©2010 AACR.

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.

Metabolic risk score and cancer risk: Pooled analysis of seven cohorts

Background: There are few data on the joint influence of metabolic factors on risk of separate cancers. Methods: We analysed data on body mass index, blood pressure and plasma levels of glucose, total cholesterol and triglycerides from seven European cohorts comprising 564 596 men and women with a mean age of 44 years. We weighted those factors equally into a standardized metabolic risk score [MRS, mean = 0, standard deviation (SD) = 1], with an individual’s level indicated as SDs from the sex- and cohort-specific means. Cancer hazard ratios were calculated by Cox regression with age as timescale and with relevant adjustments including smoking status. All statistical tests were two-sided. Results: During a mean follow-up of 12 years, 21 593 men and 14 348 women were diagnosed with cancer. MRS was linearly and positively associated with incident cancer in total and at sites (P < 0.05). In men, risk per SD MRS was increased by 43% (95% confidence interval: 27–61) for renal cell cancer, 43% (16–76) for liver cancer, 29% (20–38) for colon cancer, 27% (5–54) for oesophageal cancer, 20% (9–31) for rectal cancer, 19% (4–37) for leukaemias, 15% (1–30) for oral cancer and 10% (2–19) for bladder cancer. In women, risk increases per SD MRS were 56% (42–70) for endometrial cancer, 53% (29–81) for pancreatic cancer, 40% (16–67) for renal cell cancer, 27% (9–47) for cervical cancer and 17% (3–32) for rectal cancer. Conclusion: This largest study to date on the joint influence of metabolic factors on risk of separate cancers showed increased risks for several cancers, in particular renal cell and liver cancer in men and endometrial and pancreatic cancer in women.

Metabolic syndrome and risk of bladder cancer: prospective cohort study in the metabolic syndrome and cancer project (Me-Can)

There are little data on the putative association between factors in the metabolic syndrome (MetS) and risk of bladder cancer. In the Metabolic Syndrome and Cancer project (Me‐Can), measurements of height, weight, blood pressure and circulating levels of glucose, cholesterol, and triglycerides had been collected from 578,700 subjects in cohorts in Norway, Austria, and Sweden. We used Cox proportional hazard models to calculate relative risks (RRs) of bladder cancer by exposures divided into quintiles, in categories according to the World Health Organisation (WHO) and as a continuous standardized variable (z‐score with mean = 0 and standard deviation = 1) for each separate component and its standardized sum, a composite MetS score. RRs were corrected for random error in measurements. During a mean follow‐up of 11.7 years (SD = 7.6), 1,587 men and 327 women were diagnosed with bladder cancer. Significant associations with risk were found among men per one unit increment of z‐score for blood pressure, RR = 1.13 (95% CI 1.03–1.25), and the composite MetS score, RR = 1.10 (95% CI 1.01–1.18). Among women, glucose was nonsignificantly associated with risk, RR = 1.41 (95% CI 0.97–2.06). No statistically significant interactions were found between the components in the MetS in relation to bladder cancer risk. Hypertension and a composite MetS score were significantly but modestly associated with an increased risk of bladder cancer among men and elevated glucose was associated with a nonsignificant increase in risk among women.

Metabolic risk factors for esophageal squamous cell carcinoma and adenocarcinoma : a prospective study of 580 000 subjects within the Me-Can project

BackgroundObesity is associated with an increased risk of esophageal adenocarcinoma (EAC) and a decreased risk of esophageal squamous cell carcinoma (ESCC). However, little is known about the risk of EAC and ESCC related to other metabolic risk factors. We aimed to examine the risk of EAC and ESCC in relation to metabolic risk factors, separately and combined in a prospective cohort study.MethodsThe Metabolic Syndrome and Cancer cohort includes prospective cohorts in Austria, Norway and Sweden, with blood pressure, lipids, glucose and BMI available from 578 700 individuals. Relative risk (RR) for EAC and ESCC was calculated using Cox’s proportional hazards analysis for metabolic risk factors categorized into quintiles and transformed into z-scores. The standardized sum of all z-scores was used as a composite score for the metabolic syndrome (MetS).ResultsIn total, 324 histologically verified cases of esophageal cancer were identified (114 EAC, 184 ESCC and 26 with other histology). BMI was associated with an increased risk of EAC (RR 7.34 (95% confidence interval, 2.88-18.7) top versus bottom quintile) and negatively associated with the risk of ESCC (RR 0.38 (0.23-0.62)). The mean value of systolic and diastolic blood pressure (mid blood pressure) was associated with the risk of ESCC (RR 1.77 (1.37-2.29)). The composite MetS score was associated with the risk of EAC (RR 1.56 (1.19-2.05) per one unit increase of z-score) but not ESCC.ConclusionsIn accordance with previous studies, high BMI was associated with an increased risk of EAC and a decreased risk of ESCC. An association between high blood pressure and risk of ESCC was observed but alcohol consumption is a potential confounding factor that we were not able to adjust for in the analysis. The MetS was associated with EAC but not ESCC. However this association was largely driven by the strong association between BMI and EAC. We hypothesize that this association is more likely to be explained by factors directly related to obesity than the metabolic state of the MetS, considering that no other metabolic factor than BMI was associated with EAC.

Metabolic Factors Associated with Risk of Renal Cell Carcinoma

Previous studies have shown that obesity and hypertension are associated with increased risk of renal cell carcinoma (RCC), but less is known about the association to other metabolic factors. In the Metabolic Syndrome and Cancer project (Me-Can) data on body mass index (BMI, kg/m2), blood pressure, and circulating levels of glucose, cholesterol, and triglycerides were collected from 560,388 men and women in cohorts from Norway, Austria, and Sweden. By use of Cox proportional hazard models, hazard ratios (HR) were calculated for separate and composite metabolic exposures. During a median follow-up of 10 years, 592 men and 263 women were diagnosed with RCC. Among men, we found an increased risk of RCC for BMI, highest vs. lowest quintile, (HR = 1.51, 95% CI 1.13–2.03), systolic blood pressure, (HR = 3.40, 95% CI 1.91–6.06), diastolic blood pressure, (HR = 3.33, 95% CI 1.85–5.99), glucose, (HR = 3.75, 95% CI 1.46–9.68), triglycerides, (HR = 1.79, 95% CI 1.00–3.21) and a composite score of these metabolic factors, (HR = 2.68, 95% CI 1.75–4.11). Among women we found an increased risk of RCC for BMI, highest vs. lowest quintile, (HR = 2.21, 95% CI 1.32–3.70) and the composite score, (HR = 2.29, 95% CI 1.12–4.68). High levels of the composite score were also associated with risk of death from RCC among both men and women. No multiplicative statistical or biological interactions between metabolic factors on risk of RCC were found. High levels of BMI, blood pressure, glucose and triglycerides among men and high BMI among women were associated with increased risk of RCC.

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.