Opposing roles by KRAS and BRAF mutation on immune cell infiltration in colorectal cancer - possible implications for immunotherapy.

BACKGROUND: The immune response has important clinical value in colorectal cancer (CRC) in both prognosis and response to immunotherapy. This study aims to explore tumour immune cell infiltration in relation to clinically well-established molecular markers of CRC. METHODS: Multiplex immunohistochemistry and multispectral imaging was used to evaluate tumour infiltration of cytotoxic T cells (CD8+), Th1 cells (T-bet+), T regulatory cells (FoxP3+), B cells (CD20+), and macrophages (CD68+) in a cohort of 257 CRC patients. RESULTS: We found the expected association between higher immune-cell infiltration and microsatellite instability. Also, whereas BRAF-mutated tumours displayed increased immune-cell infiltration compared to BRAF wild-type tumours, the opposite was seen for KRAS-mutated tumours, differences that were most prominent for cytotoxic T cells and Th1 cells. The opposing relationships of BRAF and KRAS mutations with tumour infiltration of cytotoxic T cells was validated in an independent cohort of 608 CRC patients. A positive prognostic importance of cytotoxic T cells was found in wild-type as well as KRAS and BRAF-mutated CRCs in both cohorts. CONCLUSION: A combined evaluation of MSI status, KRAS and BRAF mutational status, and immune infiltration (cytotoxic T cells) may provide important insights to prognosis and response to immunotherapy in CRC.

Association of pre-diagnostic physical exercise and peri-diagnostic body composition with mortality in non-metastatic colorectal cancer.

PURPOSE: Sarcopenia and myosteatosis, quantified via computed tomography (CT), are associated with poor colorectal cancer outcomes. These body composition estimates can be influenced by physical exercise. We explored the correlation between pre-diagnostic physical exercise, body composition close to diagnosis, and the combined prognosis impact of these factors. METHODS: We studied 519 stage I-III colorectal cancer (CRC) cases diagnosed 2000-2016 with pre-diagnostic self-reported recreational physical exercise data collected in the prospective, population-based Northern Sweden Health and Disease Study, and CT-estimated skeletal muscle index (SMI) or skeletal muscle density (SMD). Risk estimates were calculated by multivariable logistic regression and Cox proportional hazards models. RESULTS: No association was seen between low pre-diagnostic physical exercise and sarcopenia/myosteatosis in the multivariable model adjusted for age, sex, educational level, tumor stage, and tumor location. In multivariable Cox regression models, the combination of low pre-diagnostic physical exercise and either sarcopenia or myosteatosis at the time of diagnosis was associated with cancer-specific mortality compared to the reference group of high physical exercise combined with no sarcopenia/myosteatosis (adjusted HR 1.94 95% CI 1.00-3.76 for sarcopenia and adjusted HR 2.39 95% CI 1.16-4.94 for myosteatosis). CONCLUSIONS: The combined presence of low pre-diagnostic physical exercise and sarcopenia or myosteatosis was associated with increased CRC-specific mortality. Despite the positive effect on prognosis, physical exercise did not alter body composition estimates at diagnosis, which could indicate attenuation from other factors.

Diabetes mellitus in relation to colorectal tumor molecular subtypes: A pooled analysis of more than 9000 cases.

Diabetes is an established risk factor for colorectal cancer. However, colorectal cancer is a heterogeneous disease and it is not well understood whether diabetes is more strongly associated with some tumor molecular subtypes than others. A better understanding of the association between diabetes and colorectal cancer according to molecular subtypes could provide important insights into the biology of this association. We used data on lifestyle and clinical characteristics from the Colorectal Cancer Family Registry (CCFR) and the Genetics and Epidemiology of Colorectal Cancer Consortium (GECCO), including 9756 colorectal cancer cases (with tumor marker data) and 9985 controls, to evaluate associations between reported diabetes and risk of colorectal cancer according to molecular subtypes. Tumor markers included BRAF and KRAS mutations, microsatellite instability and CpG island methylator phenotype. In the multinomial logistic regression model, comparing colorectal cancer cases to cancer-free controls, diabetes was positively associated with colorectal cancer regardless of subtype. The highest OR estimate was found for BRAF-mutated colorectal cancer, n = 1086 (ORfully adj : 1.67, 95% confidence intervals [CI]: 1.36-2.05), with an attenuated association observed between diabetes and colorectal cancer without BRAF-mutations, n = 7959 (ORfully adj : 1.33, 95% CI: 1.19-1.48). In the case only analysis, BRAF-mutation was differentially associated with diabetes (Pdifference  = .03). For the other markers, associations with diabetes were similar across tumor subtypes. In conclusion, our study confirms the established association between diabetes and colorectal cancer risk, and suggests that it particularly increases the risk of BRAF-mutated tumors.

Dietary B group vitamin intake and the bladder cancer risk: a pooled analysis of prospective cohort studies.

PURPOSE: Diet may play an essential role in the aetiology of bladder cancer (BC). The B group complex vitamins involve diverse biological functions that could be influential in cancer prevention. The aim of the present study was to investigate the association between various components of the B group vitamin complex and BC risk. METHODS: Dietary data were pooled from four cohort studies. Food item intake was converted to daily intakes of B group vitamins and pooled multivariate hazard ratios (HRs), with corresponding 95% confidence intervals (CIs), were obtained using Cox-regression models. Dose-response relationships were examined using a nonparametric test for trend. RESULTS: In total, 2915 BC cases and 530,012 non-cases were included in the analyses. The present study showed an increased BC risk for moderate intake of vitamin B1 (HRB1: 1.13, 95% CI: 1.00-1.20). In men, moderate intake of the vitamins B1, B2, energy-related vitamins and high intake of vitamin B1 were associated with an increased BC risk (HR (95% CI): 1.13 (1.02-1.26), 1.14 (1.02-1.26), 1.13 (1.02-1.26; 1.13 (1.02-1.26), respectively). In women, high intake of all vitamins and vitamin combinations, except for the entire complex, showed an inverse association (HR (95% CI): 0.80 (0.67-0.97), 0.83 (0.70-1.00); 0.77 (0.63-0.93), 0.73 (0.61-0.88), 0.82 (0.68-0.99), 0.79 (0.66-0.95), 0.80 (0.66-0.96), 0.74 (0.62-0.89), 0.76 (0.63-0.92), respectively). Dose-response analyses showed an increased BC risk for higher intake of vitamin B1 and B12. CONCLUSION: Our findings highlight the importance of future research on the food sources of B group vitamins in the context of the overall and sex-stratified diet.

Association of prediagnostic vitamin D status with mortality among colorectal cancer patients differs by common, inherited vitamin D-binding protein isoforms.

Lower prediagnostic circulating 25-hydroxyvitamin D (25[OH]D)-considered the best marker of total vitamin D exposure-is associated with higher mortality risk among colorectal cancer (CRC) patients. However, it is unknown whether this association differs by the vitamin D-binding protein (GC) isoform Gc2 (encoded by GC rs4588*C>A, Thr436Lys), which may substantially affect vitamin D metabolism and modify associations of 25(OH)D with colorectal neoplasm risk. Prediagnostic 25(OH)D-mortality associations according to Gc2 isoform were estimated using multivariable Cox proportional hazards regression among 1281 CRC cases (635 deaths, 483 from CRC) from two large prospective cohorts conducted in the United States (Cancer Prevention Study-II) and Europe (European Prospective Investigation into Cancer and Nutrition). 25(OH)D measurements were calibrated to a single assay, season standardized, and categorized using Institute of Medicine recommendations (deficient [<30], insufficient [30 - <50], sufficient [≥50 nmol/L]). In the pooled analysis, multivariable-adjusted hazard ratios (HRs) for CRC-specific mortality associated with deficient relative to sufficient 25(OH)D concentrations were 2.24 (95% CI 1.44-3.49) among cases with the Gc2 isoform, and 0.94 (95% CI 0.68-1.22) among cases without Gc2 (Pinteraction = .0002). The corresponding HRs for all-cause mortality were 1.80 (95% CI 1.24-2.60) among those with Gc2, and 1.12 (95% CI 0.84-1.51) among those without Gc2 (Pinteraction = .004). Our findings suggest that the association of prediagnostic vitamin D status with mortality among CRC patients may differ by functional GC isoforms, and patients who inherit the Gc2 isoform (GC rs4588*A) may particularly benefit from higher circulating 25(OH)D for improved CRC prognosis.

Body composition measured by computed tomography is associated with colorectal cancer survival, also in early-stage disease.

Background: Cachexia and sarcopenia are associated with poor survival after colorectal cancer (CRC) diagnosis. Computed tomography (CT) can be used to measure aspects of cachexia including sarcopenia, myosteatosis and the amount of subcutaneous and visceral adipose tissue. The aim of this study was to relate CT-based body composition variables with survival outcomes in CRC.Material and methods: In this population-based, retrospective cohort study, CT scans of 974 patients with pathological stages I-IV CRCs, collected at or very near diagnosis (years 2000-2016), were used to measure cross-sectional fat and muscle tissue areas. Body composition variables based on these measurements were assessed in relation to tumor stage and site and cancer-specific survival in stages I-III CRC (n = 728) using Cox proportional hazards models and Kaplan-Meier estimators.Results: Sarcopenia was associated with decreased cancer-specific survival, especially in patients with stages I-II tumors. The hazard ratio (HR) for the lowest versus highest tertile of skeletal muscle index (SMI) was 1.67; 95% confidence interval (CI), 1.08-2.58 for all stages, and HR 2.22; 95% CI 1.06-4.68, for stages I-II. Myosteatosis was also associated with decreased cancer-specific survival [(HR 2.03; 95% CI 1.20-3.34 for the lowest versus the highest tertile of skeletal muscle radiodensity (SMR)]. SMI and SMR were lower in patients with right-sided CRC, independent of age and sex. No adipose tissue measurement was significantly associated with cancer-specific survival.Conclusion: In concordance with previous studies, sarcopenia and myosteatosis were associated with decreased cancer-specific survival. The strong association between sarcopenia and poor cancer-specific survival in early-stage disease could have clinical implications for personalizing therapy decisions, including nutritional support.

Metabolic factors and the risk of colorectal cancer by KRAS and BRAF mutation status.

Factors related to energy metabolism and the metabolic syndrome, such as higher body mass index (BMI), blood glucose, or blood lipids, and blood pressure, are associated with an increased risk of colorectal cancer (CRC). However, CRC is a heterogeneous disease, developing through distinct pathways with differences in molecular characteristics and prognosis, and possibly also in risk factors. For subtypes defined by KRAS and BRAF mutation status, BMI is the only metabolic factor previously studied, with inconsistent findings. We investigated whether associations between BMI, blood glucose, blood lipids, and blood pressure and CRC risk differed by tumor KRAS and BRAF mutation status in 117,687 participants from two population-based cohorts within the Northern Sweden Health and Disease Study (NSHDS). Hazard ratios (HRs) for overall CRC and CRC subtypes by metabolic factors were estimated with Cox proportional hazards regression, using multiple imputation to handle missing exposure and tumor data. During a median follow-up of 15.6 years, we acquired 1,250 prospective CRC cases, of which 766 cases had complete baseline and molecular tumor data. Consistent with previous evidence, higher BMI, total cholesterol, triglyceride levels, and blood pressure were associated with an increased risk of overall CRC (HRs per 1 standard deviation increase: 1.07 to 1.12). These associations were similar regardless of CRC subtype by KRAS and BRAF mutation status (all pheterogeneity > 0.05). The same was true for subtypes based on microsatellite instability status. Poor metabolic health may therefore be a universal mechanism for colorectal cancer, acting across multiple developmental pathways.

One-carbon metabolite ratios as functional B-vitamin markers and in relation to colorectal cancer risk.

One-carbon metabolism biomarkers are easily measured in plasma, but analyzing them one at a time in relation to disease does not take into account the interdependence of the many factors involved. The relative dynamics of major one-carbon metabolism branches can be assessed by relating the functional B-vitamin marker total homocysteine (tHcy) to transsulfuration (total cysteine) and methylation (creatinine) outputs. We validated the ratios of tHcy to total cysteine (Hcy:Cys), tHcy to creatinine (Hcy:Cre) and tHcy to cysteine to creatinine (Hcy:Cys:Cre) as functional markers of B-vitamin status. We also calculated the associations of these ratios to colorectal cancer (CRC) risk. Furthermore, the relative contribution of potential confounders to the variance of the ratio-based B-vitamin markers was calculated by linear regression in a nested case-control study of 613 CRC cases and 1,190 matched controls. Total B-vitamin status was represented by a summary score comprising Z-standardized plasma concentrations of folate, cobalamin, betaine, pyridoxal 5'-phosphate and riboflavin. Associations with CRC risk were estimated using conditional logistic regression. We found that the ratio-based B-vitamin markers all outperformed tHcy as markers of total B-vitamin status, in both CRC cases and controls. In addition, associations with CRC risk were similar for the ratio-based B-vitamin markers and total B-vitamin status (approximately 25% lower risk for high vs. low B-vitamin status). In conclusion, ratio-based B-vitamin markers were good predictors of total B-vitamin status and displayed similar associations as total B-vitamin status with CRC risk. Since tHcy and creatinine are routinely clinically analyzed, Hcy:Cre could be easily implemented in clinical practice.

Dietary folate intake and pancreatic cancer risk: Results from the European prospective investigation into cancer and nutrition.

Pancreatic cancer (PC) has an exceptionally low survival rate and primary prevention strategies are limited. Folate plays an important role in one-carbon metabolism and has been associated with the risk of several cancers, but not consistently with PC risk. We aimed to investigate the association between dietary folate intake and PC risk, using the standardised folate database across 10 European countries. A total of 477,206 participants were followed up for 11 years, during which 865 incident primary PC cases were recorded. Folate intake was energy-adjusted using the residual method. Hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using Cox proportional hazards models. In multivariable analyses stratified by age, sex, study centre and adjusted for energy intake, smoking status, BMI, educational level, diabetes status, supplement use and dietary fibre intake, we found no significant association between folate intake and PC risk: the HR of PC risk for those in the highest quartile of folate intake (≥353 µg/day) compared to the lowest (<241 µg/day) was 0.81 (95% CI: 0.51, 1.31; ptrend = 0.38). In current smokers, a positive trend was observed in PC risk across folate quartiles [HR = 4.42 (95% CI: 1.05, 18.62) for ≥353 µg/day vs. <241 µg/day, ptrend = 0.01]. Nonetheless, there was no significant interaction between smoking and dietary folate intake (pinteraction = 0.99). We found no association between dietary folate intake and PC risk in this large European study.

Heterogeneity of Colorectal Cancer Risk Factors by Anatomical Subsite in 10 European Countries: A Multinational Cohort Study.

BACKGROUND & AIMS: Colorectal cancer located at different anatomical subsites may have distinct etiologies and risk factors. Previous studies that have examined this hypothesis have yielded inconsistent results, possibly because most studies have been of insufficient size to identify heterogeneous associations with precision. METHODS: In the European Prospective Investigation into Cancer and Nutrition study, we used multivariable joint Cox proportional hazards models, which accounted for tumors at different anatomical sites (proximal colon, distal colon, and rectum) as competing risks, to examine the relationships between 14 established/suspected lifestyle, anthropometric, and reproductive/menstrual risk factors with colorectal cancer risk. Heterogeneity across sites was tested using Wald tests. RESULTS: After a median of 14.9 years of follow-up of 521,330 men and women, 6291 colorectal cancer cases occurred. Physical activity was related inversely to proximal colon and distal colon cancer, but not to rectal cancer (P heterogeneity = .03). Height was associated positively with proximal and distal colon cancer only, but not rectal cancer (P heterogeneity = .0001). For men, but not women, heterogeneous relationships were observed for body mass index (P heterogeneity = .008) and waist circumference (P heterogeneity = .03), with weaker positive associations found for rectal cancer, compared with proximal and distal colon cancer. Current smoking was associated with a greater risk of rectal and proximal colon cancer, but not distal colon cancer (P heterogeneity = .05). No heterogeneity by anatomical site was found for alcohol consumption, diabetes, nonsteroidal anti-inflammatory drug use, and reproductive/menstrual factors. CONCLUSIONS: The relationships between physical activity, anthropometry, and smoking with colorectal cancer risk differed by subsite, supporting the hypothesis that tumors in different anatomical regions may have distinct etiologies.

Smokeless tobacco (snus) use and colorectal cancer incidence and survival: Results from nine pooled cohorts.

AIMS: Although smoking is considered to be an established risk factor for colorectal cancer, the current evidence on the association between smokeless tobacco and colorectal cancer is scant and inconclusive. We used pooled individual data from the Swedish Collaboration on Health Effects of Snus Use to assess this association. METHODS: A total of 417,872 male participants from nine cohort studies across Sweden were followed up for incidence of colorectal cancer and death. Outcomes were ascertained through linkage to health registers. We used shared frailty models with random effects at the study level to estimate hazard ratios (HRs) and 95% confidence intervals (CIs). RESULTS: During 7,135,504 person-years of observation, 4170 men developed colorectal cancer. There was no clear association between snus use and colorectal cancer overall. Exclusive current snus users, however, had an increased risk of rectal cancer (HR 1.40: 95% CI 1.09, 1.79). There were no statistically significant associations between snus use and either all-cause or colorectal cancer-specific mortality after colorectal cancer diagnosis. CONCLUSIONS: Our findings, from a large sample, do not support any strong relationships between snus use and colorectal cancer risk and survival among men. However, the observed increased risk of rectal cancer is noteworthy, and in merit of further attention.

Components of One-carbon Metabolism Other than Folate and Colorectal Cancer Risk.

BACKGROUND: Despite extensive study, the role of folate in colorectal cancer remains unclear. Research has therefore begun to address the role of other elements of the folate-methionine metabolic cycles. This study investigated factors other than folate involved in one-carbon metabolism, i.e., choline, betaine, dimethylglycine, sarcosine, and methionine and relevant polymorphisms, in relation to the risk of colorectal cancer in a population with low intakes and circulating levels of folate. METHODS: This was a prospective case-control study of 613 case subjects and 1,190 matched control subjects nested within the population-based Northern Sweden Health and Disease Study. We estimated odds ratios (OR) by conditional logistic regression, and marginal risk differences with weighted maximum likelihood estimation using incidence data from the study cohort. RESULTS: Higher plasma concentrations of methionine and betaine were associated with modest colorectal cancer risk reductions (OR [95% confidence interval {CI}] for highest versus lowest tertile: 0.76 [0.57, 0.99] and 0.72 [0.55, 0.94], respectively). Estimated marginal risk differences corresponded to approximately 200 fewer colorectal cancer cases per 100,000 individuals on average. We observed no clear associations between choline, dimethylglycine, or sarcosine and colorectal cancer risk. The inverse association of methionine was modified by plasma folate concentrations (OR [95% CI] for highest/lowest versus lowest/lowest tertile of plasma methionine/folate concentrations 0.39 [0.24, 0.64], Pinteraction = 0.06). CONCLUSIONS: In this population-based, nested case-control study with a long follow-up time from baseline to diagnosis (median: 8.2 years), higher plasma concentrations of methionine and betaine were associated with lower colorectal cancer risk.See Video Abstract at http://links.lww.com/EDE/B83.

Pre-diagnostic meat and fibre intakes in relation to colorectal cancer survival in the European Prospective Investigation into Cancer and Nutrition.

Improvements in colorectal cancer (CRC) detection and treatment have led to greater numbers of CRC survivors, for whom there is limited evidence on which to provide dietary guidelines to improve survival outcomes. Higher intake of red and processed meat and lower intake of fibre are associated with greater risk of developing CRC, but there is limited evidence regarding associations with survival after CRC diagnosis. Among 3789 CRC cases in the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort, pre-diagnostic consumption of red meat, processed meat, poultry and dietary fibre was examined in relation to CRC-specific mortality (n 1008) and all-cause mortality (n 1262) using multivariable Cox regression models, adjusted for CRC risk factors. Pre-diagnostic red meat, processed meat or fibre intakes (defined as quartiles and continuous grams per day) were not associated with CRC-specific or all-cause mortality among CRC survivors; however, a marginal trend across quartiles of processed meat in relation to CRC mortality was detected (P 0·053). Pre-diagnostic poultry intake was inversely associated with all-cause mortality among women (hazard ratio (HR)/20 g/d 0·92; 95 % CI 0·84, 1·00), but not among men (HR 1·00; 95 % CI 0·91, 1·09) (P for heterogeneity=0·10). Pre-diagnostic intake of red meat or fibre is not associated with CRC survival in the EPIC cohort. There is suggestive evidence of an association between poultry intake and all-cause mortality among female CRC survivors and between processed meat intake and CRC-specific mortality; however, further research using post-diagnostic dietary data is required to confirm this relationship.

Plasma Concentrations of Gut Hormones Acyl Ghrelin and Peptide YY and Subsequent Risk of Colorectal Cancer and Molecular Tumor Subtypes.

Obesity and metabolic dysfunction are implicated in colorectal cancer development. Appetite-regulating gut hormones might have a role in colorectal cancer risk. We investigated whether circulating levels of the gut hormones ghrelin (analyzed as acyl ghrelin) and Peptide YY (PYY) were associated with subsequent colorectal cancer risk, including clinical and molecular tumor subtypes. We also provide descriptive data on these hormones in relation to background participant characteristics and metabolic biomarkers. This population-based study included 1,010 matched case-control pairs with a median of 12.3 years of follow-up. Acyl ghrelin and PYY were measured by multiplex immunoassay. Data on KRAS and BRAF mutations and microsatellite instability (MSI) status were available for 704 and 708 cases, respectively. Conditional logistic regression models estimated association to colorectal cancer risk. Partial correlation and linear regression were used to investigate relationships between background and metabolic variables and variation in plasma gut hormone concentrations. Acyl ghrelin was not clearly associated with colorectal cancer risk (multivariable OR per 1 SD increase: 1.11; 95% CI, 1.00-1.23). Positive associations were observed for specific subtypes, in particular BRAF-mutated colorectal cancer and right-sided colon cancer, although with nonsignificant heterogeneity. PYY was not related to colorectal cancer risk (multivariable OR per 1 SD: 1.04; 95% CI, 0.95-1.14) or any tumor subtype. In the control participants, ghrelin was inversely correlated with BMI, and PYY was positively correlated with C-peptide and insulin levels. These findings provide limited support for a possible role for ghrelin in colorectal cancer development, primarily in specific anatomical and molecular tumor subtypes. PREVENTION RELEVANCE: The findings of this study do not support a major role for the metabolic gut hormones ghrelin and PYY in colorectal cancer development but suggest the possibility of an involvement for ghrelin in specific tumor subtypes. Elucidating subtype-specific risk factors and mechanisms of carcinogenesis may have implications for precision prevention.

Prediagnostic serum calcium concentrations and risk of colorectal cancer development in 2 large European prospective cohorts.

BACKGROUND: Higher dietary calcium consumption is associated with lower colorectal cancer (CRC) risk. However, little data are available on the association between circulating calcium concentrations and CRC risk. OBJECTIVES: To explore the association between circulating calcium concentrations and CRC risk using data from 2 large European prospective cohort studies. METHODS: Conditional logistic regression models were used to calculate multivariable-adjusted ORs and 95% CIs in case-control studies nested within the European Prospective Investigation into Cancer and Nutrition (EPIC; n-cases = 947, n-controls = 947) and the UK Biobank (UK-BB; n-cases = 2759, n-controls = 12,021) cohorts. RESULTS: In EPIC, nonalbumin-adjusted total serum calcium (a proxy of free calcium) was not associated with CRC (OR: 0.94; 95% CI: 0.85, 1.03; modeled as continuous variable, per 1 mg/dL increase), colon cancer (OR: 0.93; 95% CI: 0.82, 1.05) or rectal cancer (OR: 1.01; 95% CI: 0.84, 1.20) risk in the multivariable adjusted model. In the UK-BB, serum ionized calcium (free calcium, most active form) was inversely associated with the risk of CRC (OR: 0.85; 95% CI: 0.76, 0.95; per 1 mg/dL) and colon cancer (OR: 0.78; 95% CI: 0.68, 0.90), but not rectal cancer (OR: 1.02; 95% CI: 0.83, 1.24) in multivariable adjusted models. Meta-analysis of EPIC and UK-BB CRC risk estimates showed an inverse risk association for CRC in the multivariable adjusted model (OR: 0.90; 95%CI: 0.84, 0.97). In analyses by quintiles, in both cohorts, higher levels of serum calcium were associated with reduced CRC risk (EPIC: ORQ5vs.Q1: 0.69; 95% CI: 0.47, 1.00; P-trend = 0.03; UK-BB: ORQ5vs.Q1: 0.82; 95% CI: 0.72, 0.94; P-trend < 0.01). Analyses by anatomical subsite showed an inverse cancer risk association in the colon (EPIC: ORQ5vs.Q1: 0.63, 95% CI: 0.39, 1.02; P-trend = 0.05; UK-BB: ORQ5vs.Q1: 0.75; 95% CI: 0.64, 0.88; P-trend < 0.01) but not the rectum. CONCLUSIONS: In UK-BB, higher serum ionized calcium levels were inversely associated with CRC, but the risk was restricted to the colon. Total serum calcium showed a null association in EPIC. Additional prospective studies in other populations are needed to better investigate these associations.

Density of CD3+ and CD8+ Cells in the Microenvironment of Colorectal Cancer according to Prediagnostic Physical Activity.

BACKGROUND: Physical activity is associated not only with a decreased risk of developing colorectal cancer but also with improved survival. One putative mechanism is the infiltration of immune cells in the tumor microenvironment. Experimental findings suggest that physical activity may mobilize immune cells to the tumor. We hypothesized that higher levels of physical activity prior to colorectal cancer diagnosis are associated with higher densities of tumor-infiltrating T-lymphocytes in colorectal cancer patients. METHODS: The study setting was a northern Swedish population-based cohort, including 109,792 participants with prospectively collected health- and lifestyle-related data. For 592 participants who later developed colorectal cancer, archival tumor tissue samples were used to assess the density of CD3+ and CD8+ cytotoxic T cells by IHC. Odds ratios for associations between self-reported, prediagnostic recreational physical activity and immune cell infiltration were estimated by ordinal logistic regression. RESULTS: Recreational physical activity >3 times per week was associated with a higher density of CD8+ T cells in the tumor front and center compared with participants reporting no recreational physical activity. Odds ratios were 2.77 (95% CI, 1.21-6.35) and 2.85 (95% CI, 1.28-6.33) for the tumor front and center, respectively, after adjustment for sex, age at diagnosis, and tumor stage. The risk estimates were consistent after additional adjustment for several potential confounders. For CD3, no clear associations were found. CONCLUSIONS: Physical activity may promote the infiltration of CD8+ immune cells in the tumor microenvironment of colorectal cancer. IMPACT: The study provides some evidence on how physical activity may alter the prognosis in colorectal cancer.

Plasma Cotinine Is Positively Associated with Homocysteine in Smokers but Not in Users of Smokeless Tobacco.

Plasma total homocysteine (tHcy) is a risk marker, and smoking is an established risk factor for cardiovascular disease. It is unclear if the effect of smoked tobacco on homocysteine is mediated by nicotine or other combustion products in smoked tobacco. Snus (moist smokeless tobacco) is high nicotine-containing tobacco, and little is known about the effect of snus on plasma homocysteine. Therefore, we studied, in a cross-section of subjects (n = 1375) from the Northern Sweden Health and Disease Study, with strictly defined current smokers (n = 194) and snus users (n = 47), the impact of tobacco exposure on tHcy, assessed by self-reported tobacco habits and plasma cotinine concentrations. The snus users had higher cotinine concentrations than the smokers. Cotinine, creatinine, methylmalonic acid, and the methylenetetrahydrofolate reductase genotype (MTHFR) T allele were positively associated with tHcy among the smokers, but not among the snus users. No association was observed between tHcy and the number of cigarettes/day. There was a positive association between cotinine and tHcy in the smokers, but not among the snus users. This indicates that substances other than nicotine in tobacco smoke could be responsible for the differential effects on homocysteine status. Self-reported smoking should be complemented by a cotinine assay whenever possible.

Dietary Methyl-Group Donor Intake and Breast Cancer Risk in the European Prospective Investigation into Cancer and Nutrition (EPIC).

(1) Background: Methyl-group donors (MGDs), including folate, choline, betaine, and methionine, may influence breast cancer (BC) risk through their role in one-carbon metabolism; (2) Methods: We studied the relationship between dietary intakes of MGDs and BC risk, adopting data from the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort; (3) Results: 318,686 pre- and postmenopausal women were followed between enrolment in 1992-2000 and December 2013-December 2015. Dietary MGD intakes were estimated at baseline through food-frequency questionnaires. Multivariable Cox proportional hazards regression models were used to quantify the association between dietary intake of MGDs, measured both as a calculated score based on their sum and individually, and BC risk. Subgroup analyses were performed by hormone receptor status, menopausal status, and level of alcohol intake. During a mean follow-up time of 14.1 years, 13,320 women with malignant BC were identified. No associations were found between dietary intakes of the MGD score or individual MGDs and BC risk. However, a potential U-shaped relationship was observed between dietary folate intake and overall BC risk, suggesting an inverse association for intakes up to 350 µg/day compared to a reference intake of 205 µg/day. No statistically significant differences in the associations were observed by hormone receptor status, menopausal status, or level of alcohol intake; (4) Conclusions: There was no strong evidence for an association between MGDs involved in one-carbon metabolism and BC risk. However, a potential U-shaped trend was suggested for dietary folate intake and BC risk. Further research is needed to clarify this association.

A comparison of complementary measures of vitamin B6 status, function, and metabolism in the European Prospective Investigation into Cancer and Nutrition (EPIC) study.

BACKGROUND: Vitamin B6 insufficiency has been linked to increased risk of cancer and other chronic diseases. The circulating concentration of pyridoxal 5'-phosphate (PLP) is a commonly used measure of vitamin B6 status. Ratios of substrates indicating PLP coenzymatic function and metabolism may be useful complementary measures to further explore the role of vitamin B6 in health. OBJECTIVES: We explored the sensitivity of 5 outcomes, namely PLP concentration, homocysteine:cysteine (Hcy:Cys), cystathionine:cysteine (Cysta:Cys), the 3´-hydroxykynurenine ratio (HKr), and the 4-pyridoxic acid ratio (PAr) to vitamin B6 intake as well as personal and lifestyle characteristics. MEDTHODS: Dietary intake and biomarker data were collected from participants from 3 nested case-control studies within the European Prospective Investigation into Cancer and Nutrition (EPIC). Bayesian regression models assessed the associations of the 5 biomarker outcomes with vitamin B6 intake and personal and lifestyle covariates. Analogous models examined the relations of Hcy:Cys, Cysta:Cys, and HKr with PLP. RESULTS: In total, 4608 participants were included in the analyses. Vitamin B6 intake was most strongly associated with PLP, moderately associated with Hcy:Cys, Cysta:Cys, and HKr, and not associated with PAr (fold change in marker given a doubling of vitamin B6 intake: PLP 1.60 [95% credible interval (CrI): 1.50, 1.71]; Hcy:Cys 0.87 [95% CrI: 0.84, 0.90]; Cysta:Cys 0.89 [95% CrI: 0.84, 0.94]; HKr 0.88 [95% CrI: 0.85, 0.91]; PAr 1.00 [95% CrI: 0.95, 1.05]). PAr was most sensitive to age, and HKr was least sensitive to BMI and alcohol intake. Sex and menopause status were strongly associated with all 5 markers. CONCLUSIONS: We found that 5 different markers, capturing different aspects of vitamin B6-related biological processes, varied in their associations with vitamin B6 intake and personal and lifestyle predictors.

Prediagnostic Blood Selenium Status and Mortality among Patients with Colorectal Cancer in Western European Populations.

A higher selenium (Se) status has been shown to be associated with lower risk for colorectal cancer (CRC), but the importance of Se in survival after CRC diagnosis is not well studied. The associations of prediagnostic circulating Se status (as indicated by serum Se and selenoprotein P (SELENOP) measurements) with overall and CRC-specific mortality were estimated using multivariable Cox proportional hazards regression among 995 CRC cases (515 deaths, 396 from CRC) in the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort. Se and SELENOP serum concentrations were measured on average 46 months before CRC diagnosis. Median follow-up time was 113 months. Participants with Se concentrations in the highest quintile (≥100 µg/L) had a multivariable-adjusted hazard ratio (HR) of 0.73 (95% CI: 0.52-1.02; Ptrend = 0.06) for CRC-specific mortality and 0.77 (95% CI: 0.57-1.03; Ptrend = 0.04) for overall mortality, compared with the lowest quintile (≤67.5 µg/L). Similarly, participants with SELENOP concentrations in the highest (≥5.07 mg/L) compared with the lowest quintile (≤3.53 mg/L) had HRs of 0.89 (95% CI: 0.64-1.24; Ptrend = 0.39) for CRC-specific mortality and 0.83 (95% CI: 0.62-1.11; Ptrend = 0.17) for overall mortality. Higher prediagnostic exposure to Se within an optimal concentration (100-150 µg/L) might be associated with improved survival among CRC patients, although our results were not statistically significant and additional studies are needed to confirm this potential association. Our findings may stimulate further research on selenium's role in survival among CRC patients especially among those residing in geographic regions with suboptimal Se availability.