Metabolic Phenotype and Risk of Colorectal Cancer in Normal-Weight Postmenopausal Women

Pre-diagnosis lipid levels and mortality after obesity-related cancer diagnosis in the Women's Health Initiative cardiovascular disease biomarker cohort

BACKGROUND

Published studies have demonstrated inconclusive relationships between serum lipid levels and mortality after cancer.

METHODS

The primary objective was to evaluate the relationship between fasting lipid levels and mortality after cancer. Data were obtained on baseline lipids and outcomes after cancer from 1263 postmenopausal women diagnosed with 13 obesity-related cancers who were part of the Women's Health Initiative (WHI) lipid biomarkers cohort. Obesity-related cancers included incident invasive cancers of the breast, colorectum, endometrium, esophagus (adenocarcinoma), kidney, liver, gallbladder, pancreas, ovaries, small intestine, thyroid, stomach, as well as multiple myeloma. Baseline lipid measurements included high-density lipoprotein (HDL)-cholesterol, low-density lipoprotein (LDL)-cholesterol, and non-HDL-cholesterol. Outcomes were all cause, cancer-specific, and CVD mortality. Multivariable Cox proportional hazards models were used to measure associations between lipid levels and mortality (all cause, cancer, and CVD) after a cancer diagnosis, with lipids analyzed as continuous variables.

RESULTS

Among women with obesity-related cancer, there were 707 deaths, of which 379 (54%) were due to cancer and 113 (16%) were due to CVD. Mean time from blood draw to cancer diagnosis was 5.1 years (range: 0.05-10 years). LDL-C values above the 95th percentile were associated with higher risk of all-cause mortality (p < 0.001), and cancer-specific mortality (p < 0.001), but not mortality due to CVD. Non-HDL-C values above the 65th percentile were associated with higher risk of all-cause mortality (p = 0.01) and mortality due to CVD (p = 0.003), but not cancer-specific mortality (p = 0.37). HDL-C values above the 95th percentile were associated with lower all-cause mortality (p = 0.002), and above the 65th percentile with lower cancer-specific mortality (p = 0.003), but no significant relationship with mortality due to CVD was observed.

CONCLUSIONS

The relationship between pre-diagnosis fasting lipid levels and mortality after cancer diagnosis is complex. These results suggest that improved lipid control through lifestyle and anti-lipid medications could have a meaningful impact on outcomes after cancer.

Metabolic phenotypes and risk of end-stage kidney disease in patients with type 2 diabetes

Background

Obesity often initiates or coexists with metabolic abnormalities. This study aimed to investigate the pathological characteristics and the independent or mutual relations of obesity and metabolic abnormalities with end-stage kidney disease (ESKD) in patients with type 2 diabetes (T2D) and associated diabetic kidney disease (DKD).

Methods

A total of 495 Chinese patients with T2D and biopsy-confirmed DKD between 2003 and 2020 were enrolled in this retrospective study. The metabolic phenotypes were based on the body weight index (BMI)-based categories (obesity, BMI ≥ 25.0 kg/m²) and metabolic status (metabolically unhealthy status, ≥ 1 criterion National Cholesterol Education Program Adult Treatment Panel III (NCEP/ATP III) excluding waist circumference and hyperglycemia) and were categorized into four types: metabolically healthy non-obesity (MHNO), metabolically healthy obesity (MHO), metabolically unhealthy non-obesity (MUNO), and metabolically unhealthy obesity (MUO). The pathological findings were defined by the Renal Pathology Society classification. Cox proportional hazards models were used to estimate hazard ratios (HRs) for ESKD.

Results

There are 56 (11.3%) MHNO patients, 28 (5.7%) MHO patients, 176 (35.6%) MUNO patients, and 235 (47.5%) MUO patients. The high prevalence of the Kimmelstiel-Wilson nodule and severe mesangial expansion were associated with obesity, whereas severe IFTA was related to metabolically unhealthy status. In the multivariate analysis, the adjusted HR (aHR) was 2.09 [95% confidence interval (CI) 0.99-4.88] in the MHO group, 2.16 (95% CI 1.20-3.88) in the MUNO group, and 2.31 (95% CI 1.27-4.20) in the MUO group compared with the MHNO group. Furthermore, the presence of obesity was insignificantly associated with ESKD compared with non-obese patients (aHR 1.22, 95% CI 0.88-1.68), while the metabolically unhealthy status was significantly associated with ESKD compared to the metabolically healthy status in the multivariate analysis (aHR 1.69, 95% CI 1.10-2.60).

Conclusion

Obesity itself was insignificantly associated with ESKD; however, adding a metabolically unhealthy status to obesity increased the risk for progression to ESKD in T2D and biopsy-proven DKD.

Insight into the causality between basal metabolic rate and endometrial and ovarian cancers: Analysis utilizing systematic Mendelian randomization and genetic association data from over 331,000 UK biobank participants

BACKGROUND

Observational studies have demonstrated that basal metabolic rate (BMR) is associated with the risk of endometrial cancer (EC) and ovarian cancer (OC). However, it is unclear whether these associations reflect a causal relationship.

OBJECTIVE

To reveal the causality between BMR and EC and OC, we performed the first comprehensive two-sample Mendelian randomization (MR) analyses.

METHODS

Genetic variants were used as proxies of BMR. GWAS summary statistics of BMR, EC and OC were obtained from the UK Biobank Consortium, Endometrial Cancer Association Consortium and Ovarian Cancer Association Consortium respectively. The inverse variance weighted method was employed as the main approach for MR analysis. A series of sensitivity analyses were implemented to validate the robustness and reliability of the results.

RESULTS

BMR was significantly related to an increased risk of EC (OR_SD  = 1.49; 95% CI: 1.29-1.72; p-Value < .001) and OC (OR_SD  = 1.21; 95% CI: 1.08-1.35; p-Value < .001). Furthermore, the stratified analysis indicated that BMR was positively associated with endometrioid endometrial cancer (EEC) (OR_SD  = 1.45; 95% CI, 1.23-1.70; p-Value < .001), clear cell ovarian cancer(CCOC) (OR_SD  = 1.89; 95% CI:1.35-2.64; p-Value < .001) and endometrioid ovarian cancer risk (EOC) (OR_SD  = 1.45; 95% CI: 1.12-1.88; p-Value = .005). However, there were no significant associations of BMR with invasive mucinous ovarian cancer (IMOC), high-grade serous ovarian cancer (HGSOC) and low-grade serous ovarian cancer (LGSOC). The robustness of the above results was further verified in sensitivity analyses.

CONCLUSION

The MR study provided etiological evidence for the positive association of BMR with the risk of EC, EEC, OC, CCOC and EOC. But this study did not provide enough evidence suggesting the causal associations of BMR with IMOC, HGSOC and LGSOC.

Metabolism of Selenium, Selenocysteine, and Selenoproteins in Ferroptosis in Solid Tumor Cancers

A potential target of precision nutrition in cancer therapeutics is the micronutrient selenium (Se). Se is metabolized and incorporated as the amino acid selenocysteine (Sec) into 25 human selenoproteins, including glutathione peroxidases (GPXs) and thioredoxin reductases (TXNRDs), among others. Both the processes of Se and Sec metabolism for the production of selenoproteins and the action of selenoproteins are utilized by cancer cells from solid tumors as a protective mechanism against oxidative damage and to resist ferroptosis, an iron-dependent cell death mechanism. Protection against ferroptosis in cancer cells requires sustained production of the selenoprotein GPX4, which involves increasing the uptake of Se, potentially activating Se metabolic pathways such as the trans-selenation pathway and the TXNRD1-dependent decomposition of inorganic selenocompounds to sustain GPX4 synthesis. Additionally, endoplasmic reticulum-resident selenoproteins also affect apoptotic responses in the presence of selenocompounds. Selenoproteins may also help cancer cells adapting against increased oxidative damage and the challenges of a modified nutrient metabolism that result from the Warburg switch. Finally, cancer cells may also rewire the selenoprotein hierarchy and use Se-related machinery to prioritize selenoproteins that are essential to the adaptations against ferroptosis and oxidative damage. In this review, we discuss both the evidence and the gaps in knowledge on how cancer cells from solid tumors use Se, Sec, selenoproteins, and the Se-related machinery to promote their survival particularly via resistance to ferroptosis.

A bidirectional Mendelian randomization study supports the causal effects of a high basal metabolic rate on colorectal cancer risk

Purpose

We conducted a bidirectional two-sample Mendelian randomization (MR) study to determine whether genetically predicted basal metabolic rate (BMR) was a causal risk factor for colorectal cancer (CRC) or whether a genetically predicted CRC risk can influence the BMR level (i.e., reverse causation).

Methods

We employed 1,040 genetic variants as proxies for BMR to obtain effect estimates on CRC risk. Another 58 CRC-associated variants were used to estimate effects on BMR levels. Stratified analysis by tumor site was used to examine the causal associations between BMR and colon/rectal cancer risk.

Results

The inverse variance weighted (IVW) method indicated a significant causal effect of genetically determined BMR on CRC risk (OR_SD = 1.27, 95% CI = 1.07–1.51). No significant reverse causal association was identified between genetically increased CRC risk and BMR levels [IVW (β = 0, 95% CI = -0.01 to 0)]. The results of MR-Egger and the weighted median method were consistent with the IVW method. Stratified analysis by CRC sites identified significant causal associations between BMR and colon cancer [IVW (OR_SD = 1.45, 95% CI = 1.16-1-80)], and null evidence of a causal association between BMR and rectal cancer risk was found (p > 0.05).

Conclusion

Our findings add to the current literature by validating a positive relationship between high BMR levels and CRC risk instead of reverse causality. The genetically predicted BMR level was causally associated with colon cancer risk but not rectal cancer risk.

Metabolic phenotypes and risk of colorectal cancer: a systematic review and meta-analysis of cohort studies

BACKGROUND

The association of obesity with colorectal cancer (CRC) may vary depending on metabolic status.

OBJECTIVE

This meta-analysis aimed to investigate the combined impacts of obesity and metabolic status on CRC risk.

METHODS

The Scopus, PubMed, and web of sciences databases were systematically searched up to Jun 2021 to find all eligible publications examining CRC risk in individuals with metabolically unhealthy normal-weight (MUHNW), metabolically healthy obesity (MHO), and metabolically unhealthy obesity (MUHO) phenotypes.

RESULTS

A total of 7 cohort studies with a total of 759,066 participants were included in this meta-analysis. Compared with healthy normal-weight people, MUHNW, MHO, and MUHO individuals indicated an increased risk for CRC with a pooled odds ratio of 1.19 (95% CI = 1.09-1.31) in MUHNW, 1.14 (95% CI = 1.06-1.22) in MHO, and 1.24 (95% CI = 1.19-1.29) in MUHO subjects. When analyses were stratified based on gender, associations remained significant for males. However, the elevated risk of CRC associated with MHO and MUHO was not significant in female participants.

CONCLUSIONS

The individuals with metabolic abnormality, although at a normal weight, have an increased risk for CRC. Moreover, obesity is associated with CRC irrespective of metabolic status.

Metabolic syndrome and the risk of colorectal cancer: a systematic review and meta-analysis

PURPOSE

Observational studies have reported an association between metabolic syndrome (MetS) and colorectal cancer risk with inconsistent risk estimates. We conducted this meta-analysis to evaluate the risk of colorectal cancer in individuals with MetS.

METHODS

PubMed, Embase, and Web of Science were searched for related studies from database inception to 21 January 2021. Risk estimates for colorectal cancer were extracted from individual articles and pooled using a fixed-effect or random-effect model according to the heterogeneity.

RESULTS

MetS was significantly associated with a higher risk of colorectal cancer in both sexes (relative risk [RR] 1.36, 95% confidence interval [CI] 1.26-1.47, P < 0.001), men (RR 1.33, 95% CI 1.21-1.47, P < 0.001), and women (RR 1.34, 95% CI 1.19-1.52, P < 0.001). The risk of colorectal cancer seemed to increase as the number of MetS components rose. Moreover, the high body mass index (BMI)/waist circumference (WC) and hyperglycemia were all significantly associated with a higher risk of colorectal cancer (RR 1.28 [1.20-1.37] and 1.31 [1.14-1.50] in both sexes, RR 1.31 [1.19-1.45] and 1.23 [1.03-1.46] in men, and RR 1.22 [1.02-1.46] and 1.63 [1.16-2.28] in women, respectively).

CONCLUSIONS

MetS was significantly associated with a higher risk of colorectal cancer. The high BMI/WC or hyperglycemia might largely account for this association. Further analysis suggested that, as the number of MetS components increased, the risk of colorectal cancer rose.

Metabolic signatures of greater body size and their associations with risk of colorectal and endometrial cancers in the European Prospective Investigation into Cancer and Nutrition

BACKGROUND

The mechanisms underlying the obesity-cancer relationship are incompletely understood. This study aimed to characterise metabolic signatures of greater body size and to investigate their association with two obesity-related malignancies, endometrial and colorectal cancers, and with weight loss within the context of an intervention study.

METHODS

Targeted mass spectrometry metabolomics data from 4326 participants enrolled in the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort and 17 individuals from a single-arm pilot weight loss intervention (Intercept) were used in this analysis. Metabolic signatures of body size were first determined in discovery (N = 3029) and replication (N = 1297) sets among EPIC participants by testing the associations between 129 metabolites and body mass index (BMI), waist circumference (WC), and waist-to-hip ratio (WHR) using linear regression models followed by partial least squares analyses. Conditional logistic regression models assessed the associations between the metabolic signatures with endometrial (N = 635 cases and 648 controls) and colorectal (N = 423 cases and 423 controls) cancer risk using nested case-control studies in EPIC. Pearson correlation between changes in the metabolic signatures and weight loss was tested among Intercept participants.

RESULTS

After adjustment for multiple comparisons, greater BMI, WC, and WHR were associated with higher levels of valine, isoleucine, glutamate, PC aa C38:3, and PC aa C38:4 and with lower levels of asparagine, glutamine, glycine, serine, lysoPC C17:0, lysoPC C18:1, lysoPC C18:2, PC aa C42:0, PC ae C34:3, PC ae C40:5, and PC ae C42:5. The metabolic signature of BMI (OR1-sd 1.50, 95% CI 1.30-1.74), WC (OR1-sd 1.46, 95% CI 1.27-1.69), and WHR (OR1-sd 1.54, 95% CI 1.33-1.79) were each associated with endometrial cancer risk. Risk of colorectal cancer was positively associated with the metabolic signature of WHR (OR1-sd: 1.26, 95% CI 1.07-1.49). In the Intercept study, a positive correlation was observed between weight loss and changes in the metabolic signatures of BMI (r = 0.5, 95% CI 0.06-0.94, p = 0.03), WC (r = 0.5, 95% CI 0.05-0.94, p = 0.03), and WHR (r = 0.6, 95% CI 0.32-0.87, p = 0.01).

CONCLUSIONS

Obesity is associated with a distinct metabolic signature comprising changes in levels of specific amino acids and lipids which is positively associated with both colorectal and endometrial cancer and is potentially reversible following weight loss.

Obesity, Type 2 Diabetes, and Cancer Risk

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

The association between hypertension and colorectal cancer: a meta-analysis of observational studies

The relationship between hypertension and risk of colorectal cancer (CRC) is unclear. This meta-analysis aims to explore the association between them. Six databases were searched for studies published before August 2019. The pooled relative risk (RR) and 95% confidence intervals (CIs) were calculated to estimate the association between the hypertension and CRC risk. A total of 2841 potentially relevant articles were obtained, and 25 studies with a pooled 1.95 million participants were finally included in the meta-analysis. These results suggested a positive association between hypertension and risk of CRC with a pooled RR of 1.15 (95% CI: 1.08, 1.23). Male patients with hypertension had a 13% (95% CI: 1.06, 1.20) increased risk of CRC. The risk of colon cancer and rectal cancer in male patients was 1.17 (95% CI: 1.01, 1.36) and 1.35 (95% CI: 1.04, 1.74), respectively, while no association between hypertension and the risk of CRC in females was elucidated. This meta-analysis demonstrated that a positive association between hypertension and CRC exists, with male patients having a higher risk of developing CRC than female patients.

The association of Metabolic Syndrome and its Components with the Incidence and Survival of Colorectal Cancer: A Systematic Review and Meta-analysis

Background: This meta-analysis was aimed to quantitatively assess the associations of metabolic syndrome (MetS) and its components with colorectal cancer (CRC). Methods: PubMed, EMBASE and Web of Science databases were systematically searched for eligible studies. A total of 18 studies for CRC incidence and 12 studies for CRC mortality were identified. Results: MetS was associated with an increased risk of CRC incidence and mortality in male (RR: 1.28, 95 % CI 1.16-1.39, and 1.24, 1.18-1.31, respectively) and correlated with an increased risk of CRC incidence in female (RR: 1.21, 1.13-1.30), but not with CRC mortality in female. MetS increased the risk of cancer-specific mortality (RR: 1.72, 1.03-2.42), but not overall mortality. The risk estimates of CRC incidence changed little depending on age, sex, cancer site, the type of studies, ethnicity, publication year, or definition of MetS. As for CRC mortality, further stratified analyses indicated statistical significance in studies with assessing cancer-specific survival outcome, in male, a cohort design, ethnicity of non-Chinese or with definition of MetS as ≥ 3 metabolic abnormalities. Obesity and hyperglycemia are risk factors of CRC incidence in both male and female. Only dysglycemia is the risk factor for CRC mortality. Conclusions: MetS is associated with an increased risk of CRC incidence and cancer-specific mortality, but not overall mortality. In addition, MetS may increase the CRC mortality in male rather than in female. However, since most of the studies on CRC mortality were conducted in Chinese, further studies are needed to clarify this connection.

Visceral Obesity and Its Shared Role in Cancer and Cardiovascular Disease: A Scoping Review of the Pathophysiology and Pharmacological Treatments

The association between obesity, cancer and cardiovascular disease (CVD) has been demonstrated in animal and epidemiological studies. However, the specific role of visceral obesity on cancer and CVD remains unclear. Visceral adipose tissue (VAT) is a complex and metabolically active tissue, that can produce different adipokines and hormones, responsible for endocrine-metabolic comorbidities. This review explores the potential mechanisms related to VAT that may also be involved in cancer and CVD. In addition, we discuss the shared pharmacological treatments which may reduce the risk of both diseases. This review highlights that chronic inflammation, molecular aspects, metabolic syndrome, secretion of hormones and adiponectin associated to VAT may have synergistic effects and should be further studied in relation to cancer and CVD. Reductions in abdominal and visceral adiposity improve insulin sensitivity, lipid profile and cytokines, which consequently reduce the risk of CVD and some cancers. Several medications have shown to reduce visceral and/or subcutaneous fat. Further research is needed to investigate the pathophysiological mechanisms by which visceral obesity may cause both cancer and CVD. The role of visceral fat in cancer and CVD is an important area to advance. Public health policies to increase public awareness about VAT's role and ways to manage or prevent it are needed.

Young-onset colorectal cancer is associated with a personal history of type 2 diabetes

BACKGROUND

Colorectal cancer (CRC) is rising in incidence in young adults, and this observation is currently unexplained. We investigated whether having a personal history of type 2 diabetes mellitus (T2D) was a potential risk factor for young-onset colorectal cancer (YOCRC).

METHODS

The South Australian Young Onset (SAYO) CRC study is a series of young adults with CRC below age 55. Ninety unrelated YOCRC cases were recruited to the study. Personal history and detailed family history of T2D were obtained at face-to-face interview and confirmed from medical records. Whole exome sequencing was conducted on germline DNA from each CRC case. Controls for personal history studies of T2D were 240 patients with proven clear colonoscopies and no known CRC predispositions.

RESULTS

The median age of YOCRC cases was 44 years (18-54) and of controls was 45 years (18-54), and 53% of both cases and controls were females (P = 0.99). Left-sided (distal) CRC was seen in 67/89 (75%) of cases. A personal history of T2D was confirmed in 17/90 (19%) YOCRC patients compared with controls (12/240, 5%; P < 0.001; odds ratio = 4.4; 95% confidence interval, 2.0-9.7). YOCRC patients frequently reported at least one first-degree relative with T2D (32/85, 38%). Ten of 87 (12%) of YOCRC cases had CRC-related pathogenic germline variants, however, no pathogenic variants in familial diabetes-associated genes were seen.

CONCLUSIONS

Though the mechanism remains unclear, our observations suggest that there is enrichment for personal history of T2D in YOCRC patients.

IMPACT

A diagnosis of T2D could therefore potentially identify a subset of young adults at increased risk for CRC and in whom early screening might be appropriate.

Predicted basal metabolic rate and cancer risk in the European Prospective Investigation into Cancer and Nutrition

Emerging evidence suggests that a metabolic profile associated with obesity may be a more relevant risk factor for some cancers than adiposity per se. Basal metabolic rate (BMR) is an indicator of overall body metabolism and may be a proxy for the impact of a specific metabolic profile on cancer risk. Therefore, we investigated the association of predicted BMR with incidence of 13 obesity-related cancers in the European Prospective Investigation into Cancer and Nutrition (EPIC). BMR at baseline was calculated using the WHO/FAO/UNU equations and the relationships between BMR and cancer risk were investigated using multivariable Cox proportional hazards regression models. A total of 141,295 men and 317,613 women, with a mean follow-up of 14 years were included in the analysis. Overall, higher BMR was associated with a greater risk for most cancers that have been linked with obesity. However, among normal weight participants, higher BMR was associated with elevated risks of esophageal adenocarcinoma (hazard ratio per 1-standard deviation change in BMR [HR1-SD ]: 2.46; 95% CI 1.20; 5.03) and distal colon cancer (HR1-SD : 1.33; 95% CI 1.001; 1.77) among men and with proximal colon (HR1-SD : 1.16; 95% CI 1.01; 1.35), pancreatic (HR1-SD : 1.37; 95% CI 1.13; 1.66), thyroid (HR1-SD : 1.65; 95% CI 1.33; 2.05), postmenopausal breast (HR1-SD : 1.17; 95% CI 1.11; 1.22) and endometrial (HR1-SD : 1.20; 95% CI 1.03; 1.40) cancers in women. These results indicate that higher BMR may be an indicator of a metabolic phenotype associated with risk of certain cancer types, and may be a useful predictor of cancer risk independent of body fatness.

Dietary polyunsaturated fatty acids modulate adipose secretome and is associated with changes in mammary epithelial stem cell self-renewal

Chronic low-grade adipose inflammation, characterized by aberrant adipokine production and pro-inflammatory macrophage activation/polarization is associated with increased risk of breast cancer. Adipocyte fatty acid composition is influenced by dietary availability and may regulate adipokine secretion and adipose inflammation. After feeding F344 rats for 20 weeks with a Western diet or a fish oil-supplemented diet, we cultured primary rat adipose tissue in a three-dimensional explant culture and collected the conditioned medium. The rat adipose tissue secretome was assayed using the Proteome Profiler Cytokine XL Array, and adipose tissue macrophage polarization (M1/M2 ratio) was assessed using the iNOS/ARG1 ratio. We then assessed the adipokine's effects upon stem cell self-renewal using primary human mammospheres from normal breast mammoplasty tissue. Adipose from rats fed the fish oil diet had an ω-3:ω-6 fatty acid ratio of 0.28 compared to 0.04 in Western diet rats. The adipokine profile from the fish oil-fed rats was shifted toward adipokines associated with reduced inflammation compared to the rats fed the Western diet. The M1/M2 macrophage ratio decreased by 50% in adipose of fish oil-fed rats compared to that from rats fed the Western diet. Conditioned media from rats fed the high ω-6 Western diet increased stem cell self-renewal by 62%±9% (X¯%±SD) above baseline compared to only an 11%±11% increase with the fish oil rat adipose. Modulating the adipokine secretome with dietary interventions therefore may alter stromal-epithelial signaling that plays a role in controlling mammary stem cell self-renewal.

Worldwide burden of cancer attributable to diabetes and high body-mass index: a comparative risk assessment

BACKGROUND

Diabetes and high body-mass index (BMI) are associated with increased risk of several cancers, and are increasing in prevalence in most countries. We estimated the cancer incidence attributable to diabetes and high BMI as individual risk factors and in combination, by country and sex.

METHODS

We estimated population attributable fractions for 12 cancers by age and sex for 175 countries in 2012. We defined high BMI as a BMI greater than or equal to 25 kg/m2. We used comprehensive prevalence estimates of diabetes and BMI categories in 2002, assuming a 10-year lag between exposure to diabetes or high BMI and incidence of cancer, combined with relative risks from published estimates, to quantify contribution of diabetes and high BMI to site-specific cancers, individually and combined as independent risk factors and in a conservative scenario in which we assumed full overlap of risk of diabetes and high BMI. We then used GLOBOCAN cancer incidence data to estimate the number of cancer cases attributable to the two risk factors. We also estimated the number of cancer cases in 2012 that were attributable to increases in the prevalence of diabetes and high BMI from 1980 to 2002. All analyses were done at individual country level and grouped by region for reporting.

FINDINGS

We estimated that 5·7% of all incident cancers in 2012 were attributable to the combined effects of diabetes and high BMI as independent risk factors, corresponding to 804 100 new cases. 187 600 (24·5%) of 766 000 cases of liver cancer and 121 700 (38·4%) of 317 000 cases of endometrial cancer were attributable to these risk factors. In the conservative scenario, about 4·5% (629 000 new cases) of all incident cancers assessed were attributable to diabetes and high BMI combined. Individually, high BMI (544 300 cases) was responsible for almost twice as many cancer cases as diabetes (293 300 cases). 25·8% of diabetes-related cancers (equating to 75 600 new cases) and 31·9% of high BMI-related cancers (174 040 new cases) were attributable to increases in the prevalence of these risk factors from 1980 to 2002.

INTERPRETATION

A substantial number of cancer cases are attributable to diabetes and high BMI. As the prevalence of these cancer risk factors increases, clinical and public health efforts should focus on identifying optimal preventive and screening measures for whole populations and individual patients.

FUNDING

NIHR and Wellcome Trust.

Lifestyle Modifications and Policy Implications for Primary and Secondary Cancer Prevention: Diet, Exercise, Sun Safety, and Alcohol Reduction

Improved cancer treatments and cancer detection methods are not likely to completely eradicate the burden of cancer. Primary prevention of cancer is a logical strategy to use to control cancer while also seeking novel treatments and earlier detection. Lifestyle modification strategies to improve primary prevention and risk reduction for the development of cancer include choosing a healthy diet with an emphasis on plant sources, maintaining a healthy weight throughout life, being physically active, regularly using sunscreen and wearing protective clothing, limiting sun exposure during the hours of 10 AM to 2 PM, avoiding indoor tanning, and reducing or eliminating alcohol use. In addition to continued use of ongoing education of the public, health care providers, and cancer support communities, other policy and public health efforts should be pursued as well. Examples of supported and successful policy approaches are included in this article, including efforts to limit indoor tanning and improve community-wide interventions to reduce ultraviolet radiation exposure as well as to formally support various alcohol policy strategies including increasing alcohol taxes, reducing alcohol outlet density, improving clinical screening for alcohol use disorders, and limiting youth exposure to alcohol marketing and advertising. These prevention strategies are expected to have the largest impact on the development of melanoma as well as breast, colorectal, head and neck, liver, and esophageal cancers. The impact of these strategies as secondary prevention is less well understood. Areas of additional needed research and implementation are also highlighted. Future areas of needed research are the effects of these modifications after the diagnosis of cancer (as secondary prevention).

Metabolic obesity phenotypes and risk of colorectal cancer in postmenopausal women

Obesity has been postulated to increase the risk of colorectal cancer by mechanisms involving insulin resistance and the metabolic syndrome. We examined the associations of body mass index (BMI), waist circumference, the metabolic syndrome, metabolic obesity phenotypes and homeostasis model-insulin resistance (HOMA-IR-a marker of insulin resistance) with risk of colorectal cancer in over 21,000 women in the Women's Health Initiative CVD Biomarkers subcohort. Women were cross-classified by BMI (18.5-<25.0, 25.0-<30.0 and ≥30.0 kg/m² ) and presence of the metabolic syndrome into 6 phenotypes: metabolically healthy normal weight (MHNW), metabolically unhealthy normal weight (MUNW), metabolically healthy overweight (MHOW), metabolically unhealthy overweight (MUOW), metabolically healthy obese (MHO) and metabolically unhealthy obese (MUO). Neither BMI nor presence of the metabolic syndrome was associated with risk of colorectal cancer, whereas waist circumference showed a robust positive association. Relative to the MHNW phenotype, the MUNW phenotype was associated with increased risk, whereas no other phenotype showed an association. Furthermore, HOMA-IR was not associated with increased risk. Overall, our results do not support a direct role of metabolic dysregulation in the development of colorectal cancer; however, they do suggest that higher waist circumference is a risk factor, possibly reflecting the effects of increased levels of cytokines and hormones in visceral abdominal fat on colorectal carcinogenesis.

Worldwide burden of cancer attributable to diabetes and high body-mass index: a comparative risk assessment

BACKGROUND

Diabetes and high body-mass index (BMI) are associated with increased risk of several cancers, and are increasing in prevalence in most countries. We estimated the cancer incidence attributable to diabetes and high BMI as individual risk factors and in combination, by country and sex.

METHODS

We estimated population attributable fractions for 12 cancers by age and sex for 175 countries in 2012. We defined high BMI as a BMI greater than or equal to 25 kg/m2. We used comprehensive prevalence estimates of diabetes and BMI categories in 2002, assuming a 10-year lag between exposure to diabetes or high BMI and incidence of cancer, combined with relative risks from published estimates, to quantify contribution of diabetes and high BMI to site-specific cancers, individually and combined as independent risk factors and in a conservative scenario in which we assumed full overlap of risk of diabetes and high BMI. We then used GLOBOCAN cancer incidence data to estimate the number of cancer cases attributable to the two risk factors. We also estimated the number of cancer cases in 2012 that were attributable to increases in the prevalence of diabetes and high BMI from 1980 to 2002. All analyses were done at individual country level and grouped by region for reporting.

FINDINGS

We estimated that 5·6% of all incident cancers in 2012 were attributable to the combined effects of diabetes and high BMI as independent risk factors, corresponding to 792 600 new cases. 187 600 (24·5%) of 766 000 cases of liver cancer and 121 700 (38·4%) of 317 000 cases of endometrial cancer were attributable to these risk factors. In the conservative scenario, about 4·5% (626 900 new cases) of all incident cancers assessed were attributable to diabetes and high BMI combined. Individually, high BMI (544 300 cases) was responsible for twice as many cancer cases as diabetes (280 100 cases). 26·1% of diabetes-related cancers (equating to 77 000 new cases) and 31·9% of high BMI-related cancers (174 040 new cases) were attributable to increases in the prevalence of these risk factors from 1980 to 2002.

INTERPRETATION

A substantial number of cancer cases are attributable to diabetes and high BMI. As the prevalence of these cancer risk factors increases, clinical and public health efforts should focus on identifying optimal preventive and screening measures for whole populations and individual patients.

FUNDING

NIHR and Wellcome Trust.

The Anti-inflammatory Effect of Personalized Omega-3 Fatty Acid Dosing for Reducing Prostaglandin E2 in the Colonic Mucosa Is Attenuated in Obesity

This clinical trial developed a personalized dosing model for reducing prostaglandin E₂ (PGE₂) in colonic mucosa using ω-3 fatty acid supplementation. The model utilized serum eicosapentaenoic acid (EPA, ω-3):arachidonic acid (AA, ω-6) ratios as biomarkers of colonic mucosal PGE₂ concentration. Normal human volunteers were given low and high ω-3 fatty acid test doses for 2 weeks. This established a slope and intercept of the line for dose versus serum EPA:AA ratio in each individual. The slope and intercept was utilized to calculate a personalized target dose that was given for 12 weeks. This target dose was calculated on the basis of a model, initially derived from lean rodents, showing a log-linear relationship between serum EPA:AA ratios and colonic mucosal PGE₂ reduction. Bayesian methods allowed addition of human data to the rodent model as the trial progressed. The dosing model aimed to achieve a serum EPA:AA ratio that is associated with a 50% reduction in colonic PGE₂ Mean colonic mucosal PGE₂ concentrations were 6.55 ng/mg protein (SD, 5.78) before any supplementation and 3.59 ng/mg protein (SD, 3.29) after 12 weeks of target dosing. In secondary analyses, the decreases in PGE₂ were significantly attenuated in overweight and obese participants. This occurred despite a higher target dose for the obese versus normal weight participants, as generated by the pharmacodynamic predictive model. Large decreases also were observed in 12-hydroxyicosatetraenoic acids, and PGE₃ increased substantially. Future biomarker-driven dosing models for cancer prevention therefore should consider energy balance as well as overall eicosanoid homeostasis in normal tissue. Cancer Prev Res; 10(12); 729-37. ©2017 AACR.

Association between Dietary Energy Density and Obesity-Associated Cancer: Results from the Women's Health Initiative

BACKGROUND

Dietary energy density (DED) is the ratio of energy (kilocalories or kilojoules) intake to food weight (grams) and is a measure of diet quality. Consumption of foods high in DED has been associated with weight gain in adults.

OBJECTIVE

To investigate the association between baseline DED and incident obesity-associated cancers in the Women's Health Initiative.

DESIGN

Prospective cohort study of clinical trial and observational study participants.

PARTICIPANTS/SETTING

Postmenopausal women aged 50 to 79 years (N=92,295) enrolled in the observational study or the calcium and vitamin D trial and hormone replacement therapy trials of the Women's Health Initiative.

MAIN OUTCOME MEASURES

Incident, medical record-adjudicated, obesity-related cancers during follow-up. Exposure variable was DED (kilocalories per gram for the total diet) from self-reported dietary intake at baseline using a food frequency questionnaire.

STATISTICAL ANALYSES

The associations between DED and each incident cancer, or any obesity-related cancer, were examined using competing-risks regression models, with death as a competing risk. Body mass index-stratified models were generated to investigate body mass index as a potential modifying factor.

RESULTS

DED was associated with higher body mass index (28.9±6.0 vs 26.3±4.9) and waist circumference (89.3±14.2 vs 82.4±12.4 cm) for DED quintiles 5 vs 1, respectively. DED was associated with a 10% increased risk of any obesity-related cancer (subhazard ratio_{Q5 vs Q1}: 1.1, 95% CI 1.03 to 1.2; P=0.004). This increased risk appeared limited to women who were normal weight at enrollment.

CONCLUSIONS

Higher DED may be a contributing factor for obesity-related cancers, especially among normal-weight postmenopausal women and, as such, could serve as a modifiable behavior for dietary interventions to reduce obesity-associated cancer risk.