Specific fatty acid intake and the risk of pancreatic cancer in Canada

Associations of dietary factors with gastric cancer risk: insights from NHANES 2003-2016 and mendelian randomization analyses

Background: Gastric cancer (GC) continues to be one of the leading causes of cancer-related deaths globally. Diet significantly influences the incidence and progression of GC. However, the relationship between dietary intake and GC is inconsistent. Methods: A study was conducted with adults who participated in the National Health and Nutrition Examination Survey (NHANES) from 2003 to 2016 to investigate possible associations between 32 dietary factors and GC. To further detect potential causal relationships between these dietary factors and the risk of GC, a two-sample Mendelian randomization (MR) analysis was conducted. The primary method employed was the inverse variance weighted (IVW) analysis, and its results were further validated by four other methods. Results: Of the 35,098 participants surveyed, 20 had a history of GC. Based on the results of weighted logistic multivariate analysis, it was observed that there was a positive correlation between total fat intake [odds ratio (OR) = 1.09, 95% confidence interval (CI): (1.01-1.17), p = 0.03] and GC as well as negative association of dietary monounsaturated fatty acids (MUFAs) intake [OR = 0.83, 95% CI: (0.76-0.92), p < 0.001]. Further evaluations of the odds of GC across the quartiles of dietary MUFAs showed that the top quartile of total MUFA intake was associated with a lower likelihood of GC in three different models [model1: OR = 0.03, 95% CI: (0.00-0.25), p < 0.01; model2: OR = 0.04, 95% CI: (0.00-0.38), p = 0.01; model3: OR = 0.04, 95% CI: (0.00-0.40), p = 0.01]. For the MR analyses, genetic instruments were selected from the IEU Open GWAS project; IVW analysis showed that GC risk was not associated with MUFAs [OR = 0.82, 95% CI: (0.59-1.14), p = 0.23] or the ratio of MUFAs to total fatty acids [OR = 1.00, 95% CI: (0.75-1.35), p = 0.98]. Similar results were observed when using the other MR methods. Conclusion: The NHANES study revealed that consuming MUFAs was linked to a lower risk of GC, although the results of MR analyses do not provide evidence of a causal relationship. Additional research is therefore necessary to clarify these findings.

Association of saturated fatty acids with cancer risk: a systematic review and meta-analysis

OBJECTIVE

Extensive research has explored the link between saturated fatty acids (SFAs) and cardiovascular diseases, alongside other biological dysfunctions. Yet, their association with cancer risk remains a topic of debate among scholars. The present study aimed to elucidate this association through a robust meta-analysis.

METHODS

PubMed, Embase, Cochrane Library, and Web of Science databases were searched systematically to identify relevant studies published until December 2023. The Newcastle-Ottawa Scale was used as the primary metric for evaluating the quality of the included studies. Further, fixed- or random-effects models were adopted to determine the ORs and the associated confidence intervals using the Stata15.1 software. The subsequent subgroup analysis revealed the source of detection and the cancer types, accompanied by sensitivity analyses and publication bias evaluations.

RESULTS

The meta-analysis incorporated 55 studies, comprising 38 case-control studies and 17 cohort studies. It revealed a significant positive correlation between elevated levels of total SFAs and the cancer risk (OR of 1.294; 95% CI: 1.182-1.416; P-value less than 0.001). Moreover, elevated levels of C14:0, C16:0, and C18:0 were implicated in the augmentation of the risk of cancer. However, no statistically significant correlation of the risk of cancer was observed with the elevated levels of C4:0, C6:0, C8:0, C10:0, C12:0, C15:0, C17:0, C20:0, C22:0, and C24:0. Subgroup analysis showed a significant relationship between excessive dietary SFA intake, elevated blood SFA levels, and heightened cancer risk. Increased total SFA levels correlated with higher risks of breast, prostate, and colorectal cancers, but not with lung, pancreatic, ovarian, or stomach cancers.

CONCLUSION

High total SFA levels were correlated with an increased cancer risk, particularly affecting breast, prostate, and colorectal cancers. Higher levels of specific SFA subtypes (C14:0, C16:0, and C18:0) are also linked to an increased cancer risk. The findings of the present study would assist in providing dietary recommendations for cancer prevention, thereby contributing to the development of potential strategies for clinical trials in which diet-related interventions would be used in combination with immunotherapy to alter the levels of SFAs in patients and thereby improve the outcomes in cancer patients. Nonetheless, further high-quality studies are warranted to confirm these associations.

Unveiling the MUFA-Cancer Connection: Insights from Endogenous and Exogenous Perspectives

Monounsaturated fatty acids (MUFAs) have been the subject of extensive research in the field of cancer due to their potential role in its prevention and treatment. MUFAs can be consumed through the diet or endogenously biosynthesized. Stearoyl-CoA desaturases (SCDs) are key enzymes involved in the endogenous synthesis of MUFAs, and their expression and activity have been found to be increased in various types of cancer. In addition, diets rich in MUFAs have been associated with cancer risk in epidemiological studies for certain types of carcinomas. This review provides an overview of the state-of-the-art literature on the associations between MUFA metabolism and cancer development and progression from human, animal, and cellular studies. We discuss the impact of MUFAs on cancer development, including their effects on cancer cell growth, migration, survival, and cell signaling pathways, to provide new insights on the role of MUFAs in cancer biology.

What Dietary Patterns and Nutrients are Associated with Pancreatic Cancer? Literature Review

This narrative review summarizes the main findings of observational studies (case-control and cohort) as well as systematic reviews and meta-analyses on the role of nutrients and dietary patterns on pancreatic cancer (PC) risk and elucidates possible mechanisms for the association between nutrients or specific food components and the risk of PC. A literature search of MEDLINE (PubMed), Google Scholar, ScienceDirect, and Scopus was performed. An extensive search of related articles published in the English language from 1985 to 2022 was carried out. Our search included macro- and micronutrient intake as well as dietary patterns associated with PC. In conclusion, the consumption of a diet high in nutrients such as sugar, fats, and red and processed meats can increase the risk of PC. Conversely, a high dietary intake of fresh fruit and vegetables and their associated nutrients like fiber, antioxidants, and polyphenols may prevent PC. Dietary patterns loaded with red and processed meats were also linked to an increased risk of PC, whereas dietary patterns rich in plant-based foods like vegetables, fruits, whole grains, and legumes were associated with a reduced risk of PC. Dietary fiber, fat-soluble vitamins, water-soluble vitamins, and minerals might also play a protective role against PC.

A ketogenic diet in combination with gemcitabine increases survival in pancreatic cancer KPC mice

Pancreatic ductal adenocarcinoma (PDAC) continues to be a major health problem. A ketogenic diet (KD), characterized by a very low carbohydrate and high fat composition, has gained attention for its anti-tumor potential. We evaluated the effect and mechanisms of feeding a strict KD alone or in combination with gemcitabine in the autochthonous LSL-Kras^G12D/+; LSL-Trp53 ^R172H/+; Pdx1-Cre (KPC) mouse model. For this purpose, both male and female pancreatic tumor-bearing KPC mice were allocated to a control diet (CD; %kcal: 70% carb, 14% protein, 16% fat), a KD (%kcal: 14% protein, 1% carb, 85% fat), a CD + gemcitabine (CG), or a KD + gemcitabine (KG) group. Mice fed a KD alone or in combination with gemcitabine showed significantly increased blood β-hydroxybutyrate levels compared to mice fed a CD or CG. KPC mice fed a KG had a significant increase in overall median survival compared to KPC mice fed a CD (increased overall median survival by 42%). Interestingly, when the data was disaggregated by sex, the effect of a KG was significant in female KPC mice (60% increase in median overall survival), but not in male KPC mice (28% increase in median overall survival). Mechanistically, the enhanced survival response to a KD combined with gemcitabine was multifactorial, including inhibition of ERK and AKT pathways, regulation of fatty acid metabolism and the modulation of the gut microbiota. In summary, a KD in combination with gemcitabine appears beneficial as a treatment strategy in PDAC in KPC mice, deserving further clinical evaluation.

Butyrate, a postbiotic of intestinal bacteria, affects pancreatic cancer and gemcitabine response in in vitro and in vivo models

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive cancer. The characteristic excessive stromatogenesis accompanying the growth of this tumor is believed to contribute to chemoresistance which, together with drug toxicity, results in poor clinical outcome. An increasing number of studies are showing that gut microbiota and their metabolites are implicated in cancer pathogenesis, progression and response to therapies. In this study we tested butyrate, a product of dietary fibers' bacterial fermentation, whose anticancer and anti-inflammatory functions are known. We provided in vitro evidence that, beside slowing proliferation, butyrate enhanced gemcitabine effectiveness against two human pancreatic cancer cell lines, mainly inducing apoptosis. In addition, we observed that, when administered to a PDAC mouse model, alone or combined with gemcitabine treatment, butyrate markedly reduced the cancer-associated stromatogenesis, preserved intestinal mucosa integrity and affected fecal microbiota composition by increasing short chain fatty acids producing bacteria and decreasing some pro-inflammatory microorganisms. Furthermore, a biochemical serum analysis showed butyrate to ameliorate some markers of kidney and liver damage, whereas a metabolomics approach revealed a deep modification of lipid metabolism, which may affect tumor progression or response to therapy. Such results support that butyrate supplementation, in addition to conventional therapies, can interfere with pancreatic cancer biology and response to treatment and can alleviate some damages associated to cancer itself or to chemotherapy.

Restriction of extracellular lipids renders pancreatic cancer dependent on autophagy

BACKGROUND

KRAS is the predominant oncogene mutated in pancreatic ductal adenocarcinoma (PDAC), the fourth cause of cancer-related deaths worldwide. Mutant KRAS-driven tumors are metabolically programmed to support their growth and survival, which can be used to identify metabolic vulnerabilities. In the present study, we aimed to understand the role of extracellularly derived fatty acids in KRAS-driven pancreatic cancer.

METHODS

To assess the dependence of PDAC cells on extracellular fatty acids we employed delipidated serum or RNAi-mediated suppression of ACSL3 (to inhibit the activation and cellular retention of extracellular fatty acids) followed by cell proliferation assays, qPCR, apoptosis assays, immunoblots and fluorescence microscopy experiments. To assess autophagy in vivo, we employed the KrasG12D/+;p53flox/flox;Pdx1-CreERT2 (KPC) mice crossed with Acsl3 knockout mice, and to assess the efficacy of the combination therapy of ACSL3 and autophagy inhibition we used xenografted human cancer cell-derived tumors in immunocompromised mice.

RESULTS

Here we show that depletion of extracellularly derived lipids either by serum lipid restriction or suppression of ACSL3, triggers autophagy, a process that protects PDAC cells from the reduction of bioenergetic intermediates. Combined extracellular lipid deprivation and autophagy inhibition exhibits anti-proliferative and pro-apoptotic effects against PDAC cell lines in vitro and promotes suppression of xenografted human pancreatic cancer cell-derived tumors in mice. Therefore, we propose lipid deprivation and autophagy blockade as a potential co-targeting strategy for PDAC treatment.

CONCLUSIONS

Our work unravels a central role of extracellular lipid supply in ensuring fatty acid provision in cancer cells, unmasking a previously unappreciated metabolic vulnerability of PDAC cells.

Dietary Intake of Fatty Acids and Risk of Pancreatic Cancer: A Case-Control Study

BACKGROUND

Epidemiological findings on dietary fat intake and risk of pancreatic cancer (PanC) are inconsistent.

OBJECTIVES

This study aimed to determine the association between types of dietary fat intake and PanC.

METHODS

We conducted a hospital-based case-control study in 957 pathologically confirmed PanC cases and 938 cancer-free controls. Cases and controls were frequency matched by age, sex, and race. Dietary information was collected using a self-administered validated FFQ. Unconditional logistic regression models were used to estimate the ORs and 95% CIs of PanC risk by quintiles of fat intake with the lowest quintile as referent and with adjustment for other risk factors and dietary factors.

RESULTS

We observed no difference in (median) intake of total fat standardized for energy among cases versus controls. The multivariable-adjusted OR (95% CI) of the highest versus the lowest quintile of intake (ORQ5 compared with Q1) was 2.51 (1.68-3.72) for fat from animal sources and 0.41 (0.29-0.58) for fat from plant sources. Intakes of total MUFA, total PUFA, and linoleic (n-6) and long chain n-3 fatty acids were inversely associated with PanC (ORQ5 compared with Q1 and 95% CI: 0.55 [0.36-0.82], 0.59 [0.42-0.82], 0.64 [0.43-0.84], and 0.60 [0.42-0.84], respectively). Arachidonic acid (n-6) and several SFAs were positively associated with PanC.

CONCLUSION

Although some observed associations with pancreatic cancer risk could be explained by reverse causation, the potential protective associations with intakes of largely plant-derived PUFAs and MUFAs and fish-derived long chain n-3 PUFAs warrant further prospective investigation.

Dietary intake of fatty acids and risk of pancreatic cancer: Golestan cohort study

Background

As pancreatic cancer (PC) is a malignancy with poor prognosis, finding strategies for its prevention became a notable priority. Among all the factors influencing the risk of PC, dietary items especially fats are considered as the most modifiable risk factors.This study is designed to assess the associations of dietary intake of fatty acids with the risk of PC incidence.

Methods

A total of 50,045 adults between 40 and 75 years old participated in this cohort study in 2004–2008 and were followed up to the present. Intakes of fatty acids was evaluated by validated food-frequency questionnaire (FFQ). Cox proportional hazards regression model was used to estimate hazard ratio (HR) with 95 % confidence interval of differing levels of dietary intakes of fatty acids for incidence of PC.

Results

At the end of follow-up period, 76 cases of PC were identified and 46,904 participants without history of cancer, acute kidney disorders, fibrosis and cirrhosis were included in the study. Dietary total saturated fatty acids (SFAS) was associated with PC risk (HR = 1.05 (1.01–1.09), P_trend=0.01), whereas dietary total monounsaturated fatty acids (MUFAS) was inversely associated with the risk of PC (HR = 0.92 (0.86–0.99), P_trend=0.04). Dietary total polyunsaturated fatty acids (PUFAS) did show a protective but not significant association with the risk of PC (HR = 0.91(0.84-1.00), P_trend=0.05).

Conclusions

The amount of total fat intake is not a risk factor for PC in our study and focusing on the intake of specific fatty acids becomes more striking. Unsaturated fatty acids including PUFAS and especially MUFAS are considered as protective dietary factors in PC prevention. In contrast, total SFAS is positively associated with the increased risk of PC. However, very long chain and odd-chain saturated fatty acids intake may be protective against PC.

Impact of dietary fat composition and quantity in pancreatic carcinogenesis: Recent advances and controversies

A significant number of pancreatic cancer cases are due to modifiable risk factors, with many being attributed to increased body fatness. This has sparked investigators to examine the role played by high dietary fat intake in pancreatic cancer development and the mechanisms driving this connection. However, there is currently no consensus on how dietary fat quantity and composition specifically affect pancreatic carcinogenesis. The objective of this narrative review is to discuss the link between high total fat consumption and fatty acid composition (saturated, mono-, or poly-unsaturated fats) with pancreatic cancer incidence and progression. Following our detailed analysis of the strengths and weaknesses of recent preclinical and human studies, we discuss existing research gaps and opportunities, and provide recommendations for future studies. Numerous studies suggest that diets high in omega-3 polyunsaturated fatty acids are associated with reduced pancreatic cancer risk. However, the current evidence appears insufficient for a general conclusion regarding the impact of other types of fat in pancreatic carcinogenesis, with many studies providing inconclusive findings due to study limitations. Thus, we recommend future studies to include detailed methodology of the animal experiments, not limited to the diet composition, type of ingredients, formulations, and administration of the diets. Moreover, human studies should include a diverse population and well-characterized biomarkers for accurate determination of dietary fat intake. Ultimately, this will aid the study rigor, and improve our understanding of the impact of fat quantity and composition in pancreatic carcinogenesis.

Circulating plasma fatty acids and risk of pancreatic cancer: Results from the Golestan Cohort Study

BACKGROUND & AIMS

Pancreatic cancer (PC) with a dismal prognosis is considered as a fatal malignancy, attracting the scientists' attention to study its causes and pathogenesis pathways. Given the lack of enough evidence and conflicting findings about the association of PC risk with plasma fatty acids, we aimed to explore the associations of circulating plasma fatty acids with the risk of PC in a cohort study.

METHODS

From about 50,000 subjects participated in this cohort study in 2004-2008, fifty incident cases of PC were recruited and 150 controls matched by age, sex and residence place (urban/rural) were randomly selected. The plasma fatty acids composition was measured by gas chromatography with Flame Ionization Detector (GC-FID) in plasma samples collected at the baseline of cohort study. Multivariable conditional logistic regression was used to estimate OR (with 95% CI) of PC risk associated with plasma levels of fatty acids considering known potential risk factors for PC.

RESULTS

Our findings showed that total saturated fatty acids and total industrial trans fats were not associated with the risk of PC; whereas, statistically significant inverse associations were found between high plasma levels of total mono-unsaturated fatty acids (MUFAs), omega-3 and ruminant trans fatty acids with the risk of PC [OR_Q1-Q4 = 0.31 (0.11-0.89), OR _Q2-Q1 = 0.30 (0.10-0.91) and OR_Q2-Q1 = 0.15 (0.04-0.49), respectively]. Omega-6 fatty acids especially high plasma levels of Arachidonic acid was positively associated with the risk of PC [OR_Q1-Q3 = 11.07 (3.50-35.02)].

CONCLUSION

Except for the plasma circulating whole fats, the levels of different classes of fats may significantly change pancreatic cancer susceptibility. Unsaturated fatty acids including omega-3-PUFA and MUFA are considered as protective biomarkers in PC prevention. On the contrary, omega-6-fatty acids are positively associated with the risk of PC.

Dietary Fat and Cancer-Which Is Good, Which Is Bad, and the Body of Evidence

A high-fat diet (HFD) induces changes in gut microbiota leading to activation of pro-inflammatory pathways, and obesity, as a consequence of overnutrition, exacerbates inflammation, a known risk factor not only for cancer. However, experimental data showed that the composition of dietary fat has a greater impact on the pathogenesis of cancer than the total fat content in isocaloric diets. Similarly, human studies did not prove that a decrease in total fat intake is an effective strategy to combat cancer. Saturated fat has long been considered as harmful, but the current consensus is that moderate intake of saturated fatty acids (SFAs), including palmitic acid (PA), does not pose a health risk within a balanced diet. In regard to monounsaturated fat, plant sources are recommended. The consumption of plant monounsaturated fatty acids (MUFAs), particularly from olive oil, has been associated with lower cancer risk. Similarly, the replacement of animal MUFAs with plant MUFAs decreased cancer mortality. The impact of polyunsaturated fatty acids (PUFAs) on cancer risk depends on the ratio between ω-6 and ω-3 PUFAs. In vivo data showed stimulatory effects of ω-6 PUFAs on tumour growth while ω-3 PUFAs were protective, but the results of human studies were not as promising as indicated in preclinical reports. As for trans FAs (TFAs), experimental data mostly showed opposite effects of industrially produced and natural TFAs, with the latter being protective against cancer progression, but human data are mixed, and no clear conclusion can be made. Further studies are warranted to establish the role of FAs in the control of cell growth in order to find an effective strategy for cancer prevention/treatment.

Monosodium L-glutamate and fats change free fatty acid concentrations in intestinal contents and affect free fatty acid receptors express profile in growing pigs

Background

Obesity and its related metabolic syndrome continue to be major public health problems. Monosodium L-glutamate (MSG) may cause metabolic diseases such as obesity. Meanwhile, the Chinese population has undergone rapid transition to a high-fat diet. There is little information available on the effect of MSG and fat alone, or in combination, on free fatty acids (FFAs), lipid metabolism and FFA receptors.

Objective

The aim of this study was to evaluate the effects of MSG and fat alone, or in combination, on intestinal luminal FFAs and expression of gastrointestinal FFA receptors. The aim was also to test whether dietary fat and/or MSG could affect expression of genes related to fatty acid metabolism.

Design

A total of 32 growing pigs were used and fed with four iso-nitrogenous and iso-caloric diets. Pigs in the four treatments received diets with one of two fat concentrations levels (4.4 and 9.4%) and one of two MSG dose levels (0 and 3%), in which most of the fat were brought by soybean oil. The concentration of short chain fatty acids (SCFAs) in cecum and colon, long chain fatty acids (LCFAs) in ileum, cecum and colon, and FFAs receptors expression in hypothalamus and gastrointestinal tract were determined.

Results

MSG and/or fat changed intestinal luminal SCFAs, levels of LCFAs, and showed an antagonistic effect on most of LCFAs. Simultaneously, MSG and/or fat decreased the expression of FFA receptors in hypothalamus and gastrointestinal tract. MSG and/or fat promoted fat deposition through different ways in back fat.

Conclusion

Our results support that MSG and/or fat can alter intestinal luminal FFAs composition and concentration, especially LCFAs, in addition, the expression of FFA receptors in ileum and hypothalamus could be decreased. Moreover, MSG and/or fat can promote protein deposition in back fat, and affect the distribution and metabolism of fatty acids in the body tissues and the body’s ability to perceive fatty acids; these results provide a reference for the occurrence of fat deposition and obesity caused by high-fat and monosodium glutamate diet.

Marine omega-3 fatty acid intake and survival of stage III colon cancer according to tumor molecular markers in NCCTG Phase III trial N0147 (Alliance)

Marine omega-3 polyunsaturated fatty acids (MO3PUFAs) have anticancer properties and may improve colon cancer survival. However, it remains unknown whether the benefit differs by tumor molecular subtype. We examined data from a phase III randomized trial of FOLFOX or FOLFOX + cetuximab among 1,735 stage III colon cancer patients who completed a dietary questionnaire at enrollment. Multivariable hazard ratios and 95% confidence intervals (CIs) were calculated for the association between MO3PUFA and disease-free survival (DFS) and overall survival according to KRAS and BRAF^V600E mutations and DNA mismatch repair (MMR) status. Higher MO3PUFA intake was associated with improved 3-year DFS for KRAS wild-type tumors (77% vs. 73%; HR: 0.84; 95% CI: 0.67-1.05) but not KRAS-mutant tumors (64% vs. 70%; HR: 1.30; 95% CI: 0.97-1.73; P_interaction = 0.02). Similar heterogeneity was found by MMR (P_interaction = 0.14): higher MO3PUFA was associated with better 3-year DFS for tumors with deficient MMR (72% vs. 67%) but not proficient MMR (72% vs. 72%). No heterogeneity was found by BRAF^V600E mutation. Similar findings were obtained for overall survival. In conclusion, we found a suggestive beneficial association between higher MO3PUFA intake and improved survival among stage III colon cancer patients with wild-type KRAS and deficient MMR. Given the relatively small number of cases with tumor molecular assessments, further studies, preferably through pooled analyses of multiples cohorts, are needed to validate our findings.

Dietary oleic acid is inversely associated with pancreatic cancer - Data from food diaries in a cohort study

BACKGROUND

Dietary oleic acid may prevent pancreatic ductal adenocarcinoma (PDA) by reducing hyperinsulinaemia which can otherwise promote DNA damage and tumour growth. Results from previous epidemiological studies investigating oleic acid are inconsistent. This study aims to clarify the relationship between dietary oleic acid intake and the risk of developing PDA using nutritional information from food diaries plus published serum biomarker data from HbA1c.

METHODS

23,658 participants, aged 40-74 years, were recruited into EPIC-Norfolk and completed 7-day food diaries which recorded; foods, brands and portion sizes to calculate nutrient intakes. Serum HbA1c was measured at recruitment in 11,147 participants (48.7% of cohort). Hazard ratios (HRs) for quintiles of dietary oleic acid intake and serum HbA1c were estimated using Cox regression. Additional analyses were made according to whether body mass index (BMI) was greater or less than 25 kg/m² as this influences hyperinsulinaemia.

RESULTS

88 participants (55% women) developed PDA after a mean follow-up of 8.4 years (SD = 3.9) (mean age at diagnosis = 72.6 years, SD = 8.8). A decreased risk of PDA was associated with increased dietary oleic acid intake (highest vs lowest quintile, HR = 0.29, 95% CI = 0.10-0.81, P trend across quintiles = 0.011), with statistical significance maintained when BMI>25 kg/m² but not if BMI<25 kg/m². An elevated serum HbA1c was associated with increased risk of disease (highest vs lowest quintiles, HR = 6.32, 95% CI = 1.38-28.89, P for trend = 0.004).

CONCLUSIONS

The data supports a protective role of oleic acid against development of PDA in those with higher BMIs possibly through influencing hyperinsulinaemia. Oleic acid intake should be accurately measured in future aetiological studies.

Metabolomic profile in pancreatic cancer patients: a consensus-based approach to identify highly discriminating metabolites

Purpose

pancreatic adenocarcinoma is the fourth leading cause of cancer related deaths due to its aggressive behavior and poor clinical outcome. There is a considerable variability in the frequency of serum tumor markers in cancer' patients. We performed a metabolomics screening in patients diagnosed with pancreatic cancer.

Experimental Design

Two targeted metabolomic assays were conducted on 40 serum samples of patients diagnosed with pancreatic cancer and 40 healthy controls. Multivariate methods and classification trees were performed.

Materials and Methods

Sparse partial least squares discriminant analysis (SPLS-DA) was used to reduce the high dimensionality of a pancreatic cancer metabolomic dataset, differentiating between pancreatic cancer (PC) patients and healthy subjects. Using Random Forest analysis palmitic acid, 1,2-dioleoyl-sn-glycero-3-phospho-rac-glycerol, lanosterol, lignoceric acid, 1-monooleoyl-rac-glycerol, cholesterol 5α,6α epoxide, erucic acid and taurolithocholic acid (T-LCA), oleoyl-L-carnitine, oleanolic acid were identified among 206 metabolites as highly discriminating between disease states. Comparison between Receiver Operating Characteristic (ROC) curves for palmitic acid and CA 19-9 showed that the area under the ROC curve (AUC) of palmitic acid (AUC=1.000; 95% confidence interval) is significantly higher than CA 19-9 (AUC=0.963; 95% confidence interval: 0.896-1.000).

Conclusion

Mass spectrometry-based metabolomic profiling of sera from pancreatic cancer patients and normal subjects showed significant alterations in the profiles of the metabolome of PC patients as compared to controls. These findings offer an information-rich matrix for discovering novel candidate biomarkers with diagnostic or prognostic potentials.

Saturated, Monounsaturated and Polyunsaturated Fatty Acids Intake and Risk of Pancreatic Cancer: Evidence from Observational Studies

Background

Although the relationship between dietary monounsaturated fatty acids (MUFAs), polyunsaturated fatty acids (PUFAs), and saturated fatty acids (SFAs) intake and pancreatic cancer risk has been reported by several studies, the evidence is controversial. We firstly conducted this comprehensive meta-analysis to summarize the aforementioned evidence from observational studies.

Methods

The MEDLINE (PubMed), Embase, and ISI Web of Science databases were used to search for epidemiological studies of dietary SFA, MUFA, and PUFA and pancreatic cancer risk that were published until the end of June 2014. Random- or fixed-effects models were used to estimate the relative risks (RRs) and 95% confidence intervals (CIs). We also carried out subgroup, sensitivity, and publication bias analyses.

Results

We identified 13 case-control studies and 7 prospective studies which including 6270 pancreatic cancer cases in the meta-analysis of SFA, MUFA, and PUFA and risk of pancreatic cancer. The summary RR was 1.13 (95%CI = 0.94-1.35, I² = 70.7%) for SFA, 1.00 (95%CI = 0.87-1.14, I² = 43.4%) for MUFA, and 0.87 (95%CI = 0.75-1.00, I² = 55.3%) for PUFA for high versus low intake categories. We found no evidence of publication bias.

Conclusion

In summary, findings of this study supports an inverse association between diets high in PUFA and pancreatic cancer risk. Further large prospective studies are warranted to report the results stratified by the subtypes of MUFA and PUFA and adjust for other potential risk factors to eliminate residual confounding.

Establishing a clinic-based pancreatic cancer and periampullary tumour research registry in Quebec

BACKGROUND

Enrolling patients in studies of pancreatic ductal adenocarcinoma (pdac) is challenging because of the high fatality of the disease. We hypothesized that a prospective clinic-based study with rapid ascertainment would result in high participation rates. Using that strategy, we established the Quebec Pancreas Cancer Study (qpcs) to investigate the genetics and causes of pdac and other periampullary tumours (pats) that are also rare and underrepresented in research studies.

METHODS

Patients diagnosed with pdac or pat were introduced to the study at their initial clinical encounter, with a strategy to enrol participants within 2 weeks of diagnosis. Patient self-referrals and referrals of unaffected individuals with an increased risk of pdac were also accepted. Family histories, epidemiologic and clinical data, and biospecimens were collected. Additional relatives were enrolled in families at increased genetic risk.

RESULTS

The first 346 completed referrals led to 306 probands being enrolled, including 190 probands affected with pdac, who represent the population focus of the qpcs. Participation rates were 88.4% for all referrals and 89.2% for pdac referrals. Family history, epidemiologic and clinical data, and biospecimens were ascertained from 91.9%, 54.6%, and 97.5% respectively of patients with pdac. Although demographics and trends in risk factors in our patients were consistent with published statistics for patients with pdac, the qpcs is enriched for families with French-Canadian ancestry (37.4%), a population with recurrent germ-line mutations in hereditary diseases.

CONCLUSIONS

Using rapid ascertainment, a pdac and pat research registry with high participation rates can be established. The qpcs is a valuable research resource and its enrichment with patients of French-Canadian ancestry provides a unique opportunity for studies of heredity in these diseases.

Fatty acids found in dairy, protein and unsaturated fatty acids are associated with risk of pancreatic cancer in a case-control study

Although many studies have investigated meat and total fat in relation to pancreatic cancer risk, few have investigated dairy, fish and specific fatty acids (FAs). We evaluated the association between intake of meat, fish, dairy, specific FAs and related nutrients and pancreatic cancer. In our American-based Mayo Clinic case-control study 384 cases and 983 controls frequency matched on recruitment age, race, sex and residence area (Minnesota, Wisconsin or Iowa, USA) between 2004 and 2009. All subjects provided demographic information and completed 144-item food frequency questionnaire. Logistic regression-calculated odds ratios (ORs) and 95% confidence intervals (95% CIs) were adjusted for age, sex, cigarette smoking, body mass index and diabetes mellitus. Significant inverse association (trend p-value < 0.05) between pancreatic cancer and the groupings (highest vs. lowest consumption quintile OR [95% CI]) was as follows: meat replacement (0.67 [0.43-1.02]), total protein (0.58 [0.39-0.86]), vitamin B12 (0.67 [0.44, 1.01]), zinc (0.48 [0.32, 0.71]), phosphorus (0.62 [0.41, 0.93]), vitamin E (0.51 [0.33, 0.78]), polyunsaturated FAs (0.64 [0.42, 0.98]) and linoleic acid (FA 18:2) (0.62 [0.40-0.95]). Increased risk associations were observed for saturated FAs (1.48 [0.97-2.23]), butyric acid (FA 4:0) (1.77 [1.19-2.64]), caproic acid (FA 6:0) (2.15 [1.42-3.27]), caprylic acid (FA 8:0) (1.87 [1.27-2.76]) and capric acid (FA 10:0) (1.83 [1.23-2.74]). Our study suggests that eating a diet high in total protein and certain unsaturated FAs is associated with decreased risk of developing pancreatic cancer in a dose-dependent manner, whereas fats found in dairy increase risk.

Dietary fat intake and risk of pancreatic cancer in the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial

PURPOSE

Epidemiologic and experimental studies suggest that dietary fat intake may affect risk of pancreatic cancer, but published results are inconsistent.

METHODS

We examined risk associations for specific types of dietary fat intakes and related food sources among 111,416 participants in the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial. We used Cox proportional hazards regression to examine associations between fat intake and pancreatic cancer risk.

RESULTS

Over a mean 8.4 years of follow-up, 411 pancreatic cancer cases were identified. We observed an inverse association between saturated fat intake and pancreatic cancer risk (hazard ratio [HR], 0.64 comparing extreme quintiles; 95% confidence interval [CI], 0.46-0.88), but the association became weaker and nonsignificant when individuals with fewer than 4 years of follow-up were excluded to avoid possible reverse causation (HR, 0.88; 95% CI, 0.58-1.33). Total fat intake showed a similar pattern of association, whereas intakes of monounsaturated and polyunsaturated fats and fats from animal or plant sources showed no associations with risk.

CONCLUSIONS

These results do not support the hypothesis of increased pancreatic cancer risk with higher fat consumption overall or by specific fat type or source. Dietary changes owing to undetected disease may explain the observed inverse association with saturated fat.

Plasma fatty acid composition in patients with pancreatic cancer: correlations to clinical parameters

Pancreatic cancer (PC) ranks as the fourth cause of cancer-related deaths in the Czech Republic. Evidence exists that deregulation of fatty acid (FA) metabolism is connected with some malignancies; therefore, we decided to analyze FA profile in plasma lipid classes in patients with PC with relation to tumor staging, nutritional status, and survival. The study included 84 patients (47 males, 37 females) with PC and 68 controls (36 males, 32 females). FA patterns were analyzed in plasma lipid classes by gas-chromatography. We observed increased proportion of total monounsaturated FA (MUFA) in PC group in all plasma lipid classes. These changes were connected with increased Δ9-desaturase (SCD1) and Δ5-desaturase indices. Correlations of dihomo-γ-linolenic acid (DHGLA) with these variables were opposite. Longer survival of patients was connected with higher content of EPA, DHA, and with lower SCD1 index, respectively. Plasma phospholipid proportions of α-linolenic acid, DHGLA, EPA, and n-3 polyunsaturated fatty acids displayed negative trend with tumor staging. Plasma lipid FA pattern in PC patients resulted from decreased dietary fat intake and increased de novo synthesis of FA with transformation into MUFA. Changes in FA profile implicated some pathophysiological mechanisms responsible for disturbed FA metabolism in PC and importance of appropriate nutritional support.

Diets rich in n-6 PUFA induce intestinal microbial dysbiosis in aged mice

Controversies have emerged regarding the beneficial v. detrimental effects of dietary n-6 PUFA. The alteration of the intestinal microbiota, a phenomenon termed dysbiosis, occurs during several chronic inflammatory diseases, but has not been well studied in an aged population. With present ‘Western’ diets predominantly composed of n-6 PUFA, we hypothesised that PUFA-rich diets cause intestinal dysbiosis in an aged population. C57BL/6 mice (aged 2 years) were fed a high-fat (40% energy), isoenergetic and isonitrogenous diet composed of rapeseed oil, maize oil or maize oil supplemented with fish oil. We examined ileal microbiota using fluorescence in situ hybridisation and stained tissues by immunofluorescence for the presence of immune cells and oxidative stress. We observed that feeding high-fat diets rich in n-6 PUFA promoted bacterial overgrowth but depleted microbes from the Bacteroidetes and Firmicutes phyla. This corresponded with increased body mass and infiltration of macrophages and neutrophils. Fish oil supplementation (rich in long-chain n-3 PUFA like DHA and EPA) restored the microbiota and inflammatory cell infiltration and promoted regulatory T-cell recruitment. However, fish oil supplementation was associated with increased oxidative stress, evident by the increased presence of 4-hydroxynonenal, a product of lipid peroxidation. These results suggest that an n-6 PUFA-rich diet can cause dysbiosis and intestinal inflammation in aged mice. However, while fish oil supplementation on an n-6 PUFA diet reverses dysbiosis, the combination of n-6 and n-3 PUFA, like DHA/EPA, leads to increased oxidative stress, which could exacerbate gastrointestinal disorders in the elderly.

Association of dietary magnesium intake with radiographic knee osteoarthritis: results from a population-based study

OBJECTIVE

To examine the cross-sectional association between dietary magnesium intake and radiographic knee osteoarthritis (OA) among African American and white men and women.

METHODS

The presence of radiographic knee OA was examined among participants from the Johnston County Osteoarthritis Project and was defined as a Kellgren/Lawrence grade of at least 2 in at least 1 knee. The Block Food Frequency Questionnaire was used to assess magnesium intake. Effect modifiers were explored by testing interactions of magnesium intake and selected factors based on previous studies. The multivariable logistic regression model with standard energy adjustment method was used to estimate the relationship between magnesium intake and radiographic knee OA.

RESULTS

The prevalence of knee OA was 36.27% among the 2,112 participants. The relationship between magnesium intake and radiographic knee OA was found to be modified by race (P for interaction = 0.03). An inverse threshold association was observed among whites. Compared to participants in the lowest quintile, the relative odds of radiographic knee OA were cut by one-half for participants in the second quintile of magnesium intake (odds ratio 0.52, 95% confidence interval 0.34-0.79); further magnesium intake did not provide further benefits (P for trend = 0.51). A statistically significant association was not observed among African Americans.

CONCLUSION

A modest inverse threshold association was found between dietary magnesium intake and knee OA in whites, but not in African Americans. Further studies are needed to confirm these results and to elucidate the possible mechanisms of action for the racial modification.

Fish or long-chain (n-3) PUFA intake is not associated with pancreatic cancer risk in a meta-analysis and systematic review

Long-chain (n-3) PUFA (LC-PUFA) have been hypothesized to be beneficial in preventing pancreatic carcinogenesis, but the associations of fish or LC-PUFA intake with pancreatic cancer found in epidemiologic studies have been controversial and inconclusive. To estimate the overall association of LC-PUFA or fish intake with pancreatic cancer, we performed a systematic literature search of English-language articles using PubMed and EMBASE through February 2012 and reviewed the reference lists from retrieved articles. Prospective cohort or case-control studies that reported ratio estimates and corresponding 95% CI for the associations of fish or LC-PUFA intake and pancreatic cancer were selected. Independent data extraction was performed by 2 of the authors. The pooled associations were obtained by using a random-effects model. A database was derived from 9 independent cohorts that included 1,209,265 participants (3082 events) with a mean follow-up of 9 y and 10 independent case-control studies that included 2514 cases and 18,779 controls. Compared with those having the lowest fish consumption, the pooled RR of pancreatic cancer was 0.98 (95% CI: 0.86, 1.12) for those who had the highest fish intake from 8 cohort studies and was 0.96 (95% CI: 0.76, 1.21) from 9 case-control studies. We found similar results for LC-PUFA intake by combining data from 4 cohorts or 2 case-control studies. Our results do not support an overall inverse association of fish or LC-PUFA intake with risk of pancreatic cancer. Further studies that consider different species and preparation methods of fish, and additional adjustment for contaminants in fish, are warranted.

Is dietary fat, vitamin D, or folate associated with pancreatic cancer?

Although potentially modifiable risk factors for pancreatic cancer include smoking, obesity, and diabetes, less is known about the extent to which diet affects cancer risk. Recent studies have demonstrated some consistency for dietary fat being associated with elevated pancreatic cancer risk, particularly from animal sources. However, less is known about which fatty acids pose the greatest risk. Vitamin D, due to its endogenous production following UV-B exposure, is a unique risk factor in that researchers have created several methods to assess its exposure in humans. Studies that measured vitamin D exposure differently have shown inconsistent results. Dietary studies suggest protective associations, whereas studies of circulating 25-hydroxyvitamin D status show null or positive associations with low or very high concentrations, respectively. Several, but not all epidemiologic studies provide evidence of an inverse relationship between total and/or dietary folate and risk of pancreatic cancer. Protective associations for circulating folate are more often observed among populations with inadequate status. This article reviews the current epidemiological and experimental evidence investigating the relationship of dietary fat, vitamin D, and folate with pancreatic cancer. Additionally the mechanisms by which these risk factors may contribute to cancer, the methodological challenges involved with assessing risk, and other obstacles encountered when ascertaining the magnitude and direction of these three exposures are discussed.

Olive oil intake is inversely related to cancer prevalence: a systematic review and a meta-analysis of 13,800 patients and 23,340 controls in 19 observational studies

Dietary fat, both in terms of quantity and quality, has been implicated to cancer development, either positively or negatively. The aim of this work was to evaluate whether olive oil or monounsaturated fat intake was associated with the development of cancer. A systematic search of relevant studies, published in English, between 1990 and March 1, 2011, was performed through a computer-assisted literature tool (i.e., Pubmed). In total 38 studies were initially allocated; of them 19 case-control studies were finally studied (13800 cancer patients and 23340 controls were included). Random effects meta-analysis was applied in order to evaluate the research hypothesis. It was found that compared with the lowest, the highest category of olive oil consumption was associated with lower odds of having any type of cancer (log odds ratio = -0.41, 95%CI -0.53, -0.29, Cohran's Q = 47.52, p = 0.0002, I-sq = 62%); the latter was irrespective of the country of origin (Mediterranean or non-Mediterranean). Moreover, olive oil consumption was associated with lower odds of developing breast cancer (logOR = -0,45 95%CI -0.78 to -0.12), and a cancer of the digestive system (logOR = -0,36 95%CI -0.50 to -0.21), compared with the lowest intake. The strength and consistency of the findings states a hypothesis about the protective role of olive oil intake on cancer risk. However, it is still unclear whether olive oil's monounsaturated fatty acid content or its antioxidant components are responsible for its beneficial effects.

Management of pancreatic adenocarcinoma in Ontario, Canada: a population-based study using novel case ascertainment

BACKGROUND

Pancreatic adenocarcinoma (PA) is largely incurable, although recent progress has been made in the safety of surgery for PA and in adjuvant and palliative chemotherapy. The purpose of this study was to describe the management of PA in Ontario, Canada.

METHODS

The Pathology Information Management System (PIMS), which uses electronic pathology reporting (E-path), was used to rapidly identify and recruit patients based on a pathologic diagnosis of PA between 2003 and 2006. Patients were mailed questionnaires for additional data.

RESULTS

The patient participation rate was 26% (351 of 1325). Nonresponders were more likely to be older than 70 years (43% v. 28%, p < 0.001) and to have received treatment in nonacademic centres (53% v. 34%, p < 0.001). Fifty-four percent of responders underwent a potentially curative operation, and most (77%) were 70 years or younger (p = 0.03). Completed resections were documented in 83% of patients who underwent exploratory surgery with curative intent; 17% of patients had unresectable and/or metastatic disease at laparotomy. Of the completed resections, 24% were performed in nonacademic centres with a 32% positive margin rate; 76% were performed in academic centres with a 29% positive margin rate (p = 0.84). Resections with curative intent were less frequently aborted in academic centres (10% v. 33%, p < 0.001). Of the patients who responded to our questionnaire, 43% received chemotherapy and 7% participated in clinical trials.

CONCLUSION

Despite using PIMS and E-path, the response rate for this study was low (< 30%). Nonresponders were older and more commonly treated in nonacademic centres. Patients undergoing surgery in academic centres had higher resection rates. The rate of adjuvant and palliative chemotherapy was stage-dependent and low.

Intake of fatty acids and antioxidants and pancreatic cancer in a large population-based case-control study in the San Francisco Bay Area

There are no well-established modifiable risk factors for pancreatic cancer except smoking. Some dietary factors have been associated with pancreatic cancer risk and require further study. We examined the associations among intake of specific fatty acids and antioxidants and risk of pancreatic cancer in a large population-based case-control study in the San Francisco Bay Area. Unconditional logistic regression models were used to compute odds ratios (ORs) and 95% confidence intervals (CI) as estimates of relative risk. Positive associations were observed for high levels of the 8 individual saturated fatty acids (4th vs. 1st quartile: ORs ranged from 1.6 to 2.6; all p(trend) < 0.01), monounsaturated palmitoleic and oleic fatty acids [OR = 1.6 (95% CI: 1.2-2.1) and 1.4 (95% CI: 1.1-1.9); both p(trend) < 0.01], and polyunsaturated linolenic acid [OR = 1.5 (95% CI: 1.1-2.0); p(trend) = 0.02]. Inverse associations were observed for high levels of gadolic acid [4th vs. 1st quartile: OR = 0.68 (95% CI: 0.50-0.92); p(trend) = 0.007] and omega-3 fatty acids [>or=0.85 g/day vs. 1st quartile: OR = 0.47 (95% CI: 0.25-0.90)]. An inverse association was also observed for high total intake of vitamin C [4th vs. 1st quartile: OR = 0.69 (95% CI: 0.51-0.94); p(trend) = 0.004] and of vitamin E [OR = 0.67 (95% CI: 0.49-0.92); p(trend) = 0.01]. Although similar decreased risks were also observed for high supplemental intake of these 2 vitamins (both p(trend) < 0.01), no association was observed for intake from food alone. These results support the hypotheses that a high intake of saturated and certain monounsaturated fatty acids may increase the risk of pancreatic cancer, whereas greater intake of omega-3 fatty acids, vitamins C and E may reduce the risk.

Consumption of food groups and the risk of pancreatic cancer: a case-control study

PURPOSE

The purpose of this study is to investigate whether the consumption of specific food groups predicts the risk of pancreatic cancer, a case-control study of nutrition and pancreatic cancer among French-Canadians was carried out in Montreal, Quebec, Canada.

METHODS

A total of 179 pancreatic cancer cases (97 males and 82 females) and 239 population-based control subjects were interviewed. Dietary intake was evaluated via a validated food frequency questionnaire that gathers information on over 200 different food items and beverages. Odd ratios (ORs) and 95% confidence intervals (CIs) were computed by unconditional logistic regression.

RESULTS

After adjustment for age, smoking, diabetes status, proxy interview, gender and total energy intake, a reduced risk of pancreatic cancer was related to vegetables and vegetable products [OR = 0.47; 95%CI: (0.21-1.06) p-trend = 0.024], while an increased risk was associated with the consumption of lamb, veal and game [OR = 2.24; 95%CI: (1.11-4.52) p-trend = 0.026], when the upper and lower quartiles of intake were compared. Changes in dietary intake over the last decade revealed an elevated risk with augmented consumption of soups, sauces and gravies [OR = 2.32; 95%CI: (1.20-4.49) p-trend=0.03], beef products [OR = 2.07; 95%CI: (0.95-4.51) p-trend=0.05] as well as fish and shellfish [OR = 1.48; 95%CI: (0.78-2.80) p-trend=0.05].

CONCLUSIONS

These findings suggest that a diet rich in vegetables and vegetable products may decrease the risk of pancreatic cancer.

Available carbohydrates, glycemic load, and pancreatic cancer: is there a link?

High-carbohydrate diets have been linked to pancreatic cancer risk in case-control studies, but prospective studies have shown mostly null results. The authors investigated the associations of glycemic load, glycemic index, and carbohydrate intake with pancreatic cancer risk in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial. Dietary intake was assessed by using a self-administered questionnaire. Between 1998 and 2006 (median follow-up = 6.5 years), 266 incident, confirmed pancreatic cancers were identified among 109,175 participants. Hazards ratios and 95% confidence intervals were adjusted for sex, smoking, body mass index, and total energy. Overall, elevated risks for pancreatic cancer were observed in the 90th versus 10th percentile of glycemic load (hazards ratio (HR) = 1.45, 95% confidence interval (CI): 1.05, 2.00), available carbohydrate (HR = 1.47, 95% CI: 1.05, 2.06), and sucrose (HR = 1.37, 95% CI: 0.99, 1.89) intake. The positive association for available carbohydrate intake was observed during the first 4 years of follow-up (HR(<2 years) = 2.60, 95% CI: 1.34, 5.06; HR(2-<4 years) = 1.94, 95% CI: 1.06, 3.55) but not subsequently (HR = 0.86, 95% CI: 0.52, 1.44); the opposite pattern was observed for total fat and saturated fat intake. Rather than being causal, the short-term increase in pancreatic cancer risk associated with high available carbohydrate and low fat intake may be capturing dietary changes associated with subclinical disease.

Can physical activity modulate pancreatic cancer risk? a systematic review and meta-analysis

Numerous epidemiological studies have examined the association between physical activity and pancreatic cancer; however, findings from individual cohorts have largely not corroborated a protective effect. Among other plausible mechanisms, physical activity may reduce abdominal fat depots inducing metabolic improvements in glucose tolerance and insulin sensitivity, thereby potentially attenuating pancreatic cancer risk. We performed a systematic review to examine associations between physical activity and pancreatic cancer. Six electronic databases were searched from their inception through July 2009, including MEDLINE and EMBASE, seeking observational studies examining any physical activity measure with pancreatic cancer incidence/mortality as an outcome. A random effects model was used to pool individual effect estimates evaluating highest vs. lowest categories of activity. Twenty-eight studies were included. Pooled estimates indicated a reduction in pancreatic cancer risk with higher levels of total (five prospective studies, RR: 0.72, 95% CI: 0.52-0.99) and occupational activity (four prospective studies, RR: 0.75, 95% CI: 0.59-0.96). Nonsignificant inverse associations were seen between risks and recreational and transport physical activity. When examining exercise intensity, moderate activity appeared more protective (RR: 0.79, 95% CI: 0.52-1.20) than vigorous activity (RR: 0.97, 95% CI: 0.85-1.11), but results were not statistically significant and the former activity variable incorporated marked heterogeneity. Despite indications of an inverse relationship with higher levels of work and total activity, there was little evidence of such associations with recreational and other activity exposures.

High levels of dietary stearate promote adiposity and deteriorate hepatic insulin sensitivity

BACKGROUND

Relatively little is known about the role of specific saturated fatty acids in the development of high fat diet induced obesity and insulin resistance. Here, we have studied the effect of stearate in high fat diets (45% energy as fat) on whole body energy metabolism and tissue specific insulin sensitivity.

METHODS

C57Bl/6 mice were fed a low stearate diet based on palm oil or one of two stearate rich diets, one diet based on lard and one diet based on palm oil supplemented with tristearin (to the stearate level of the lard based diet), for a period of 5 weeks. Ad libitum fed Oxidative metabolism was assessed by indirect calorimetry at week 5. Changes in body mass and composition was assessed by DEXA scan analysis. Tissue specific insulin sensitivity was assessed by hyperinsulinemic-euglycemic clamp analysis and Western blot at the end of week 5.

RESULTS

Indirect calorimetry analysis revealed that high levels of dietary stearate resulted in lower caloric energy expenditure characterized by lower oxidation of fatty acids. In agreement with this metabolic phenotype, mice on the stearate rich diets gained more adipose tissue mass. Whole body and tissue specific insulin sensitivity was assessed by hyperinsulinemic-euglycemic clamp and analysis of insulin induced PKBser473 phosphorylation. Whole body insulin sensitivity was decreased by all high fat diets. However, while insulin-stimulated glucose uptake by peripheral tissues was impaired by all high fat diets, hepatic insulin sensitivity was affected only by the stearate rich diets. This tissue-specific pattern of reduced insulin sensitivity was confirmed by similar impairment in insulin-induced phosphorylation of PKBser473 in both liver and skeletal muscle.

CONCLUSION

In C57Bl/6 mice, 5 weeks of a high fat diet rich in stearate induces a metabolic state favoring low oxidative metabolism, increased adiposity and whole body insulin resistance characterized by severe hepatic insulin resistance. These results indicate that dietary fatty acid composition per sé rather than dietary fat content determines insulin sensitivity in liver of high fat fed C57Bl/6 mice.

Dietary fatty acids and pancreatic cancer in the NIH-AARP diet and health study

BACKGROUND

Previous research relating dietary fat, a modifiable risk factor, to pancreatic cancer has been inconclusive.

METHODS

We prospectively analyzed the association between intakes of fat, fat subtypes, and fat food sources and exocrine pancreatic cancer in the National Institutes of Health-AARP Diet and Health Study, a US cohort of 308 736 men and 216 737 women who completed a 124-item food frequency questionnaire in 1995-1996. Hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated using Cox proportional hazards regression models, with adjustment for energy intake, smoking history, body mass index, and diabetes. Statistical tests were two-sided.

RESULTS

Over an average follow-up of 6.3 years, 865 men and 472 women were diagnosed with exocrine pancreatic cancer (45.0 and 34.5 cases per 100 000 person-years, respectively). After multivariable adjustment and combination of data for men and women, pancreatic cancer risk was directly related to the intakes of total fat (highest vs lowest quintile, 46.8 vs 33.2 cases per 100 000 person-years, HR = 1.23, 95% CI = 1.03 to 1.46; P(trend) = .03), saturated fat (51.5 vs 33.1 cases per 100 000 person-years, HR = 1.36, 95% CI = 1.14 to 1.62; P(trend) < .001), and monounsaturated fat (46.2 vs 32.9 cases per 100 000 person-years, HR = 1.22, 95% CI = 1.02 to 1.46; P(trend) = .05) but not polyunsaturated fat. The associations were strongest for saturated fat from animal food sources (52.0 vs 32.2 cases per 100 000 person-years, HR = 1.43, 95% CI = 1.20 to 1.70; P(trend) < .001); specifically, intakes from red meat and dairy products were both statistically significantly associated with increased pancreatic cancer risk (HR = 1.27 and 1.19, respectively).

CONCLUSION

In this large prospective cohort with a wide range of intakes, dietary fat of animal origin was associated with increased pancreatic cancer risk.

Allergies: their role in cancer prevention

The nature of the biological relationships between cancers and allergies has intrigued researchers and health care providers for five decades. Three hypotheses have been proposed: antigenic stimulation predicts positive associations between cancers and allergies (i.e., allergy sufferers are more likely to get cancer), whereas immunosurveillance and prophylaxis predict inverse associations (i.e., allergy sufferers are less likely to get cancer). Immunosurveillance predicts inverse associations for cancers of all tissues and organ systems, and prophylaxis predicts inverse associations specifically for cancers of tissues and organ systems that interface with the external environment. To comparatively evaluate these hypotheses, we comprehensively reviewed the literature on cancer and allergies. We located 148 papers published from 1955 through 2006 that reported results of 463 studies of relationships between patients' histories of 11 specific allergies and cancers of 19 tissues and organ systems, and 183 studies of patients' histories of multiple allergies in relation to various types/sites of cancers. Analyses of these studies revealed that (1) frequencies of positive, inverse, and null allergy-cancer associations differed considerably among cancers of different tissues and organ systems; (2) more than twice as many studies reported inverse allergy-cancer associations as reported positive associations; (3) inverse associations were particularly common for cancers of the mouth and throat, brain glia, colon and rectum, pancreas, skin, and cervix but (4) particularly rare for cancers of the breast, prostate, and brain meninges, and for myeloma, non-Hodgkin's lymphoma, and myelocytic leukemia; (5) lung cancer was positively associated with asthma but inversely associated with other allergies; (6) inverse associations with allergies were more than twice as common for cancers of nine tissues and organ systems that interface with the external environment compared to cancers of nine tissues and organ systems that do not interface with the external environment; and (7) eczema, hives, and allergies to animal dander and food were most frequently inversely associated with cancers of tissues that interface with the external environment. Taken together, these results are more consistent with the prophylaxis hypothesis than the two alternatives. IgE is a widespread and ancient immunoglobulin isotype in mammals, occurring among all known marsupials, monotremes, and eutherians. The IgE system and its associated allergy symptoms may serve a common protective function: the rapid expulsion of pathogens, dangerous natural toxins, and other carcinogenic antigens before they can trigger malignant neoplasia in exposed tissues.

Lifestyle, dietary, and medical history factors associated with pancreatic cancer risk in Ontario, Canada

OBJECTIVES

Pancreatic adenocarcinoma has one of the worst survival rates of all the cancers. Established risk factors for this malignancy are smoking, body mass index (BMI) and family history of pancreatic cancer. Findings are inconsistent regarding pancreatitis, diabetes, allergies, intake of fruit, vegetables, red meat, alcohol, caffeine, vitamin C, calcium, and folate supplements. Possible pancreatic cancer risk factors were evaluated within the population-based Ontario Pancreas Cancer Study.

METHODS

Pathologically confirmed pancreatic cancer cases (n = 422) were identified from the Ontario Cancer Registry between 2003 and 2007. Controls (n = 312) were recruited through random digit dialing. Data were collected using self-administered questionnaires. Multivariate logistic regression was used to obtain odds ratios.

RESULTS

Smoking, BMI, family history of pancreatic cancer, and caffeine were significantly associated with increased pancreatic cancer risk, while fruit intake and allergies significantly decreased risk. No other significant associations were observed in the multivariate model. Effect modification by smoking status was suggested for caffeine, family history of pancreatic cancer, BMI, and fruit.

CONCLUSIONS

This study further clarifies the association between several lifestyle, dietary and medical history factors, and pancreatic cancer risk, many of which are potentially modifiable. Possible effect modification by smoking status should be further explored in future etiologic studies.

Predictors of fasting serum insulin and glucose and the risk of pancreatic cancer in smokers

OBJECTIVES

A history of type 2 diabetes is one of few consistent risk factors for pancreatic cancer. Potentially modifiable factors related to fasting insulin and glucose concentrations may influence pancreatic cancer risk.

METHODS

Multiple linear regression models were used to identify anthropometric, clinical, behavioral, and dietary factors associated with fasting insulin and glucose in a subcohort of non-diabetics in the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study (n = 366). Hazards ratios (HRs) and 95% confidence intervals (CIs) were calculated among the larger cohort (n = 27,035).

RESULTS

During follow-up (median 16.1 years), 305 participants developed pancreatic cancer. Fasting insulin and/or glucose were positively associated with body mass index (BMI), height, and dietary total and saturated fat and inversely associated with serum high-density lipoprotein cholesterol (HDL) and dietary available carbohydrates, sucrose, and alcohol. Comparing highest to lowest quintiles, total fat (HR = 1.54, 95% CI 1.05-2.25, p-trend = 0.01) and saturated fat (HR = 1.38, 95% CI 0.97-1.98, p-trend = 0.06) were positively associated and available carbohydrates (HR = 0.63, 95% CI 0.44-0.90, p-trend = 0.01), particularly sucrose (HR = 0.62, 95% CI 0.43-0.89, p-trend = 0.09), were inversely associated with risk of pancreatic cancer. BMI, HDL, height, and alcohol were not associated with pancreatic cancer risk.

CONCLUSION

Dietary fat is associated with higher fasting insulin concentrations and may increase pancreatic cancer risk in smokers.