Smoking is associated with hypermethylation of the APC 1A promoter in colorectal cancer: the ColoCare Study

Smoking tobacco is a known risk factor for the development of colorectal cancer and for mortality associated with the disease. Smoking has been reported to be associated with changes in DNA methylation in blood and in lung tumour tissues, although there has been scant investigation of how epigenetic factors may be implicated in the increased risk of developing colorectal cancer. To identify epigenetic changes associated with smoking behaviours, we performed epigenome-wide analysis of DNA methylation in colorectal tumours from 36 never-smokers, 47 former smokers, and 13 active smokers, and in adjacent mucosa from 49 never-smokers, 64 former smokers, and 18 active smokers. Our analyses identified 15 CpG sites within the APC 1A promoter that were significantly hypermethylated and 14 CpG loci within the NFATC1 gene body that were significantly hypomethylated (pLIS < 1 × 10^-5 ) in the tumours of active smokers. The APC 1A promoter was hypermethylated in 7 of 36 tumours from never-smokers (19%), 12 of 47 tumours from former smokers (26%), and 8 of 13 tumours from active smokers (62%). Promoter hypermethylation was positively associated with duration of smoking (Spearman rank correlation, ρ = 0.26, p = 0.03) and was confined to tumours, with hypermethylation never being observed in adjacent mucosa. Further analysis of adjacent mucosa revealed significant hypomethylation of four loci associated with the TNXB gene in tissue from active smokers. Our findings provide exploratory evidence for hypermethylation of the key tumour suppressor gene APC being implicated in smoking-associated colorectal carcinogenesis. Further work is required to establish the validity of our observations in independent cohorts. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Colorectal Cancer in Inflammatory Bowel Diseases: A Population-Based Study in Utah

BACKGROUND AND AIMS

The molecular, endoscopic, and histological features of IBD-associated CRC differ from sporadic CRC. The objective of this study was to describe the prevalence, clinical features, and prognosis of IBD-associated CRC compared to patients with sporadic CRC in a US statewide population-based cohort.

METHODS

All newly diagnosed cases of CRC between 1996 and 2011 were obtained from Utah Cancer Registry. IBD was identified using a previously validated algorithm, from statewide databases of Intermountain Healthcare, University of Utah Health Sciences, and the Utah Population Database. Logistic regression was performed to identify risk factors associated with IBD-associated cancer and Cox regression for differences in survival.

RESULTS

Among 12,578 patients diagnosed with CRC, 101 (0.8%) had a prior history of IBD (61 ulcerative colitis and 40 Crohn's disease). The mean age at CRC diagnosis was greater for patients without IBD than those with IBD (67.1 vs 52.8 years, P < 0.001). Individuals with IBD-associated CRC were more likely to be men (odds ratio [OR] 1.90, 95% CI 1.23-2.92), aged less than 65 years (OR 6.77, 95% CI 4.06-11.27), and have CRC located in the proximal colon (OR 2.79, 95% CI 1.85-4.20) than those with sporadic CRC. Nearly 20% of the IBD-associated CRCs had evidence of primary sclerosing cholangitis. After adjustment for age, gender, and stage at diagnosis, the excess hazard of death after CRC diagnosis was 1.7 times higher in IBD than in non-IBD patients (95% CI 1.27-2.33).

CONCLUSIONS

The features of patients with CRC and IBD differ significantly from those without IBD and may be associated with increased mortality.

Abstract SY28-02: The adipose-cancer link: From microenvironment to metabolomics

This presentation will showcase the interface of systemic and localized disturbances in metabolism with tumor development, specifically focusing on colorectal cancer. Colorectal cancer is the second leading cause of cancer-related death worldwide among both men and women. Risk and preventive factors are well established and include, among others, lack of physical activity and obesity (risk) as well as aspirin use and screening (prevention). Adipose tissue is emerging as a key player in carcinogenesis through the secretion of proinflammatory cytokines and adipokines. The colon is surrounded by adipose tissue, which supports the direct (paracrine) adipose-colon crosstalk and influence as a tumor microenvironment, as well as systemic influences on colon carcinogenesis factors secreted into the bloodstream. As part of the ColoCare cohort, an international, multicenter cohort of colorectal cancer patients, we have investigated adipose tissue distribution, composition, characteristics, and possible influence on colorectal tumors. In an integrated analysis of the transcriptome and metabolome of visceral and subcutaneous adipose tissue (VAT and SAT, respectively), we showed that there are distinct differences that may play a central role in driving carcinogenesis (1). These analyses are ongoing and have been extended to blood-based measures of the inflammasome and metabolome, as well as tumor characteristics. Adipose tissue biology can also be directly affected by weight-loss interventions through diet and exercise. As part of the Nutrition and Exercise in Women (NEW) study, we showed that weight loss results in changes in adipose tissue gene expression as well as corresponding reductions in biomarkers, including inflammatory biomarkers (2, 3).

References

1. Liesenfeld DB, Grapov D, Fahrmann JF, Salou M, Scherer D, Toth R, et al. Metabolomics and transcriptomics identify pathway differences between visceral and subcutaneous adipose tissue in colorectal cancer patients: the ColoCare study. Am J Clin Nutr 2015;102(2):433-43.

2. Imayama I, Ulrich CM, Alfano CM, Wang C, Xiao L, Wener MH, et al. Effects of a caloric restriction weight loss diet and exercise on inflammatory biomarkers in overweight/obese postmenopausal women: a randomized controlled trial. Cancer Res 2012;72(9):2314-26.

3. Campbell KL, Foster-Schubert KE, Makar KW, Kratz M, Hagman D, Schur EA, et al. Gene expression changes in adipose tissue with diet- and/or exercise-induced weight loss. Cancer Prev Res 2013;6(3):217-31.

Citation Format: Cornelia M. Ulrich. The adipose-cancer link: From microenvironment to metabolomics [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr SY28-02. doi:10.1158/1538-7445.AM2017-SY28-02

Genetic Variants in Epigenetic Pathways and Risks of Multiple Cancers in the GAME-ON Consortium

Background: Epigenetic disturbances are crucial in cancer initiation, potentially with pleiotropic effects, and may be influenced by the genetic background.Methods: In a subsets (ASSET) meta-analytic approach, we investigated associations of genetic variants related to epigenetic mechanisms with risks of breast, lung, colorectal, ovarian and prostate carcinomas using 51,724 cases and 52,001 controls. False discovery rate-corrected P values (q values < 0.05) were considered statistically significant.Results: Among 162,887 imputed or genotyped variants in 555 candidate genes, SNPs in eight genes were associated with risk of more than one cancer type. For example, variants in BABAM1 were confirmed as a susceptibility locus for squamous cell lung, overall breast, estrogen receptor (ER)-negative breast, and overall prostate, and overall serous ovarian cancer; the most significant variant was rs4808076 [OR = 1.14; 95% confidence interval (CI) = 1.10-1.19; q = 6.87 × 10-5]. DPF1 rs12611084 was inversely associated with ER-negative breast, endometrioid ovarian, and overall and aggressive prostate cancer risk (OR = 0.93; 95% CI = 0.91-0.96; q = 0.005). Variants in L3MBTL3 were associated with colorectal, overall breast, ER-negative breast, clear cell ovarian, and overall and aggressive prostate cancer risk (e.g., rs9388766: OR = 1.06; 95% CI = 1.03-1.08; q = 0.02). Variants in TET2 were significantly associated with overall breast, overall prostate, overall ovarian, and endometrioid ovarian cancer risk, with rs62331150 showing bidirectional effects. Analyses of subpathways did not reveal gene subsets that contributed disproportionately to susceptibility.Conclusions: Functional and correlative studies are now needed to elucidate the potential links between germline genotype, epigenetic function, and cancer etiology.Impact: This approach provides novel insight into possible pleiotropic effects of genes involved in epigenetic processes. Cancer Epidemiol Biomarkers Prev; 26(6); 816-25. ©2017 AACR.

Endocrine and metabolic diseases among colorectal cancer survivors in a population-based cohort

10074

Background: Colorectal cancer is the third most common cancer among men and women in the United States. As of 2016, there were an estimated 1.4 million colorectal cancer survivors. Research on endocrine and metabolic diseases over the long term in colorectal cancer survivors is limited. Obesity is a risk factor for colorectal cancer, thus it is of interest to investigate diseases that may share this risk factor such as diabetes for long term health effects among survivors. Methods: A total of 7,077 colorectal cancer patients who were diagnosed between 1997 to 2012 were identified in the Utah Population Database. A general population cohort of 35,354 individuals was matched on birth year, sex, birth state and follow-up time as a comparison group. Late effects were identified using electronic medical records and statewide ambulatory and inpatient data and were assessed over three time periods of 1-5 years, 5-10 years, and > 10 years. Cox proportional hazard models were used to estimate the risk of late effects after adjusting for matching factors, race, baseline body mass index, and the baseline Charlson Comorbidity Index. Results: Across all three time periods, late effects risk for endocrine diseases and metabolic disorders was significantly greater for colorectal cancer survivors compared to the general population cohort. Risk for diabetes mellitus with complications was significantly increased for survivors and risk was greatest for uncontrolled diabetes (HR = 5.04, 99%CI = 2.38, 10.67) and diabetes with neurological manifestations (HR = 4.10, 99%CI = 2.08, 8.26). Higher risk was also observed for thyroid disorders (HR = 3.09, 99%CI = 2.34, 4.08) and nutritional deficiencies (HR = 4.98, 99%CI = 3.47, 7.17). The risk of obesity in survivors was greatest 1-5 years post cancer diagnosis (HR = 5.04, 99%CI = 2.91, 8.75), but remained significantly increased at all follow-up time periods. Conclusions: Endocrine and metabolic diseases were significantly higher in colorectal cancer survivors across the follow-up periods. As the number of colorectal cancer survivors increases, understanding the long term multimorbidity trajectory is critical for improved survivorship care.

ASAMET: A randomized, 2x2 biomarker prevention trial of low-dose aspirin and metformin in colorectal cancer

TPS1591

Background: Epidemiological studies and cardiovascular prevention trials have shown that low-dose aspirin (ASA) can inhibit colorectal cancer (CRC) incidence and mortality, including inhibition of distant metastases. Metformin (MET) has also been associated with decreased CRC incidence and mortality in meta-analyses of epidemiological studies in diabetics and has been shown to decrease by 40% colorectal adenoma recurrence in a randomized trial. Recent studies have shown that ASA is an inhibitor of mTOR/S6K1 and an activator of AMPK, targeting regulators of intracellular energy homeostasis and metabolism, and that the combination of ASA and MET, another AMPK activator and S6K1 inhibitor, has a striking additive effect on AMPK activation and mTOR inhibition, with increased autophagy and decreased cell growth in CRC cell lines. While both drugs are being tested as single agents, their combination has not been tested in clinical trials. Methods: This is a randomized, placebo-controlled, double-blind, 2x2 biomarker trial of ASA and MET to test the activity of either agent alone and the potential synergism of their combination on a set of surrogate biomarkers of colorectal carcinogenesis. After surgery, 160 patients with stage I-III CRC will randomly be assigned in a 4-arm trial to either ASA, 100mg qd, MET 850mg bid, their combination, or placebo for 1 year. The primary endpoint is the change, defined as the difference between pre- and post-treatment expression, of NFκBin the unaffected mucosa of proximal and distal colon obtained by multiple biopsies in paired colonoscopies one year apart. Additional biomarkers will include: 1) the genomic profile of candidate genes, pathways, and overall genomic patterns in tissue biopsies by genome-wide gene expression arrays; 2) the IHC expression of tissue pS6K, p53, beta-catenin, PI3K; 3) the associations of mutations and SNPs with treatment response by NGS of primary tumors; 4) the measurement of circulating IL-6, CRP and VEGF, and 5) plasma and colonic MET concentrations and their correlation with biomarker profiles. A favorable biomarker modulation may provide important clues for a subsequent phase III adjuvant trial. Clinical trial information: EudraCT Number: 2015-004824-77.

Cost-effectiveness of genotype-guided aspirin use for colorectal cancer prevention

e18318

Background: Colonoscopy is the “gold standard” for colorectal cancer (CRC) screening. However, adherence rates are low and detection is not optimal. Concomitant aspirin chemoprevention is recommended by US Preventive Task Force, but bleeding complications can be limiting. Variant genotypes in aspirin metabolism can modify CRC and adenoma risk. Genotype guided aspirin (ggASA) use will identify a targeted average-risk population for maximal aspirin benefit while minimizing adverse events rates compared to the general population. We conducted a cost-effectiveness analysis (CEA) of primary chemoprevention in CRC using ggASA compared to no intervention, and colonoscopy ±general aspirin in healthy average-risk individuals. Methods: Our Markov decision analytical model consisted of 5 possible health states: no CRC/polyps, adenoma, pre-clinical CRC, CRC, and death. Model probabilities for CRC and its prevalence were estimated using SEER database and published literature. A microsimulation of 10,000 individuals aged 50-64 years was used to estimate cost-effectiveness from US payer perspective over lifetime. One way and probabilistic sensitivity analyses and model validation results will be reported in the final poster. Results: Our results suggest that compared to colonoscopy and no intervention, ggASA was associated with fewer CRC cases, and CRC-related deaths and MI cases. Compared to colonoscopy + general aspirin, ggASA was associated with fewer bleeding events, similar rates of CRC and CRC-related deaths, and fewer MI cases prevented. From a cost-effectiveness standpoint, ggASA use over a lifetime had the lowest costs and highest quality adjusted life years gained compared to other strategies, if testing costs were ignored. Once genetic testing costs exceeds $63, colonoscopy + general aspirin becomes the most cost effective strategy. Between genetic testing cost of $63-283, the costs of using ggASA per quality adjusted life year gained is below $100,000. Conclusions: Genotype-guided aspirin use precisely identifies an average-risk population, and lowers adverse events rates compared to general aspirin. The economic value of genotype-guided aspirin is dependent on the genetic testing costs.

Abstract A26: Body fatness and adipose tissue subtypes are associated with circulating biomarkers of inflammation and angiogenesis in colorectal cancer patients: The ColoCare Study

Background: Adiposity has been linked to both risk and prognosis of colorectal cancer; however, the impact of different compartments of adipose tissue (visceral vs. subcutaneous) is unclear. In healthy individuals, adiposity is associated with elevated biomarkers of inflammation, which provides a mechanistic link between adiposity and cancer risk. For prognosis, the downstream effects of inflammation on angiogenesis may be central. We investigated associations between adiposity and biomarkers of inflammation, as well as angiogenesis, in colorectal cancer patients enrolled in the ColoCare Study, an international multicenter patient cohort.

Methods: We utilized preoperatively obtained serum samples of patients with newly diagnosed colorectal cancer [n=164; (stage I-IV)] from the ColoCare Study in Heidelberg, Germany, with available diagnostic multi-detector-CT images for adipose tissue quantification. Abdominal adipose tissue was assessed by area-based quantification of visceral (VAT), and subcutaneous adipose tissue (SAT), as well as their ratio (VAT/SAT) on levels L3/L4 and L4/L5. Body mass index (BMI) was calculated (kg/m2) and demographic and clinical-surgical data were abstracted from medical records. Circulating CRP, SAA, VEGF-A, VEGF-D, sICAM-1 and sVCAM-1 levels were assessed on the Meso Scale Discoveries platform with V-plex assays at the Huntsman Cancer Institute (average intra-plate CVs 2.9%, inter-plate CVs 7.9%). Partial correlations and regression analyses, adjusting for age, sex and tumor stage were performed.

Results: While overall obesity (BMI) was only significantly associated with sVCAM (r=0.23, p=0.006), visceral adiposity (VAT) was associated with both CRP and SAA (r=0.21, p=0.01 and r=0.17, p=0.04, respectively). There was no association between SAT and the measured biomarkers. Most predictive was the ratio of VAT/SAT on level L3/L4, which was associated with CRP (r=0.18, p=0.04), SAA (r=0.24, p=0.006), sICAM-1 (r=0.18, p=0.04), and particularly VEGF-A (r=0.28, p=0.0008). Similar associations were observed for the VAT/SAT ratio on level L4/5.

Conclusions: We demonstrated a link between specifically visceral adiposity and biomarkers of inflammation in colorectal cancer patients. In addition, we showed that visceral adiposity also affects circulating VEGF-A levels. This protein has various effects, including the induction of angiogenesis, vasculogenesis and endothelial cell growth, as well as the promotion of cell migration, and the inhibition of apoptosis. Our findings support a mechanistic role of visceral adipose tissue in colorectal cancer risk and potentially prognosis.

Citation Format: Cornelia M. Ulrich, Jürgen Böhm, Christy Warby, Tengda Lin, Mariam Salou, Biljana Gigic, Dominique Scherer, Johanna Nattenmueller, Jennifer Ose, Lin Zielske, Petra Schrotz-King, Torsten Kölsch, Erin Siegel, Christopher Li, Alexis Ulrich, Hanno Glimm, Jewel Samadder, Stephen Hursting, Hans-Ulrich Kauczor. Body fatness and adipose tissue subtypes are associated with circulating biomarkers of inflammation and angiogenesis in colorectal cancer patients: The ColoCare Study. [abstract]. In: Proceedings of the AACR Special Conference: Improving Cancer Risk Prediction for Prevention and Early Detection; Nov 16-19, 2016; Orlando, FL. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2017;26(5 Suppl):Abstract nr A26.

Cardiorespiratory fitness and muscle strength in pancreatic cancer patients

PURPOSE

Cancer patients frequently experience reduced physical fitness due to the disease itself as well as treatment-related side effects. However, studies on physical fitness in pancreatic cancer patients are missing. Therefore, we assessed cardiorespiratory fitness and muscle strength of pancreatic cancer patients.

METHODS

We included 65 pancreatic cancer patients, mostly after surgical resection. Cardiorespiratory fitness was assessed using cardiopulmonary exercise testing (CPET) and 6-min walk test (6MWT). Hand-held dynamometry was used to evaluate isometric muscle strength. Physical fitness values were compared to reference values of a healthy population. Associations between sociodemographic and clinical variables with patients' physical fitness were analyzed using multiple regression models.

RESULTS

Cardiorespiratory fitness (VO₂peak, 20.5 ± 6.9 ml/min/kg) was significantly lower (-24%) compared to healthy reference values. In the 6MWT pancreatic cancer patients nearly reached predicted values (555 vs. 562 m). Maximal voluntary isometric contraction (MVIC) of the upper (-4.3%) and lower extremities (-13.8%) were significantly lower compared to reference values. Overall differences were larger in men than those in women. Participating in regular exercise in the year before diagnosis was associated with greater VO₂peak (p < .05) and MVIC of the knee extensors (p < .05).

CONCLUSIONS

Pancreatic cancer patients had significantly impaired physical fitness with regard to both cardiorespiratory function and isometric muscle strength, already in the early treatment phase (median 95 days after surgical resection). Our findings underline the need to investigate exercise training in pancreatic cancer patients to counteract the loss of physical fitness.

Muscle strength in breast cancer patients receiving different treatment regimes

BACKGROUND

Muscle dysfunction and sarcopenia have been associated with poor performance status, an increased mortality risk, and greater side effects in oncologic patients. However, little is known about how performance is affected by cancer therapy. We investigated muscle strength in breast cancer patients in different adjuvant treatment settings and also compared it with data from healthy individuals.

METHODS

Breast cancer patients (N = 255) from two randomized controlled exercise trials, staged 0-III and aged 54.4 ± 9.4 years, were categorized into four groups according to their treatment status. In a cross-sectional design, muscle function was assessed bilaterally by isokinetic dynamometry (0°, 60°, 180°/s) as maximal voluntary isometric contraction (MVIC) and maximal isokinetic peak torque (MIPT) in shoulder rotators and knee flexors and extensors. Additionally, muscular fatigue index (FI%) and shoulder flexibility were evaluated. Healthy women (N = 26), aged 53.3 ± 9.8 years, were tested using the same method. Analysis of covariance was used to estimate the impact of different cancer treatments on skeletal muscle function with adjustment for various clinical and socio-demographic factors.

RESULTS

Consistently, lower muscle strength was measured in shoulder and knee strength in patients after chemotherapy. On average, patients had up to 25% lower strength in lower extremities and 12-16% in upper extremities in MVIC and MIPT during cancer treatment compared with healthy women. No substantial difference between patient groups in shoulder strength, but significantly lower shoulder flexibility in patients with radical mastectomy was measured. Chemotherapy-treated patients had consistently higher FI%. No serious adverse events were reported.

CONCLUSIONS

Breast cancer patients showed markedly impaired muscle strength and joint dysfunctions before and after anticancer treatment. The significant differences between patients and healthy individuals underline the need of exercise therapy as early as possible in order to prevent or counteract the loss of muscle function after curative surgery as well as the consequences of neo-/adjuvant chemotherapy.

Self-reported physical activity behavior of breast cancer survivors during and after adjuvant therapy: 12 months follow-up of two randomized exercise intervention trials

BACKGROUND

Exercise during and after breast cancer treatment has shown several health benefits. However, little is known about the courses, patterns, and determinants of physical activity of breast cancer patients, and the role of exercise interventions on their physical activity behavior in the long run.

MATERIAL AND METHODS

Self-reported physical activity was assessed in 227 breast cancer survivors before, during, and three, six, and 12 months post-intervention within two randomized resistance exercise trials performed during adjuvant chemo- or radiotherapy, respectively, with similar designs. Multiple ordinal logistic regression analyses were performed to identify determinants of physical activity at these time points.

RESULTS

While the intervention group exercised a median 1.8 h/week during adjuvant therapy (interquartile range 1.4-2.5), 68% of controls did not engage in any exercise. At 12-months follow-up 32% of patients did not engage in any exercise irrespective of the intervention. Of the patients who cycled for transportation pre-diagnosis about half stopped cycling in the long term in both groups. In contrast, walking was maintained over time. Major determinants of low levels of exercise at 12-months follow-up were low pre-diagnosis levels of exercise, lower education, being postmenopausal, and having breast problems or depressive symptoms. Further, the intervention appeared to influence the type of sports performed, with strength exercise being the most common type of exercise at follow-up in the exercise group, more frequently compared to the control group.

CONCLUSION

The exercise intervention effectively countervailed the decrease in physical activity during cancer therapy and boosted strength exercise in the months following the intervention, but in the longer term many survivors were insufficiently active. Breast cancer survivors may need continued motivation and practical support tailored to their individual characteristics and physical activity history to incorporate exercise in everyday routine in the long term.

Plasma 25-Hydroxyvitamin D3 Levels in Colorectal Cancer Patients and Associations with Physical Activity

Physical activity (PA) and vitamin D are thought to affect colorectal cancer prognosis. The present study investigates associations between 25(OH)D₃ and PA in prospectively followed colorectal cancer patients in the ColoCare study. At 6, 12, and 24 mo after surgery, patients donated a blood sample, wore an accelerometer for 10 consecutive days, and completed a PA questionnaire. Plasma 25-hydroxyvitamin D₃ (25(OH)D₃) levels were measured by high-performance liquid chromatography. We tested associations using partial correlations and multivariate linear regression analysis, adjusted for season, age, and body mass index. A total of 137 assessments of 25(OH)D₃ levels and PA were conducted (58 at 6 mo, 51 at 12 mo, and 28 at 24 mo). More than 60% of the patients were vitamin D-deficient (25(OH)D₃ ≤20 ng/ml), independent of study time point. At 6-mo follow-up, accelerometry-based vigorous and moderate-to-vigorous PAs were positively associated with 25(OH)D₃ levels (P = 0.04; P = 0.006,). PA together with season was a significant predictor of elevated 25(OH)D₃ levels. Our results suggest that the majority of colorectal cancer patients may suffer from vitamin D deficiency. Engaging in PA may be an effective approach to increase their 25(OH)D₃ levels.

Effects of Intentional Weight Loss on Markers of Oxidative Stress, DNA Repair and Telomere Length - a Systematic Review

BACKGROUND

Altered levels of markers of oxidative stress, DNA repair, and telomere integrity have been detected in obese individuals and may underlie the pathogenesis of obesity-related diseases. However, whether or not such effects are reversed by intentional weight loss has not been systematically reviewed.

METHODS

A literature search in PubMed/Medline identified 2,388 articles of which 21 studies (randomized controlled trial (RCT) (n = 10) and non-randomized intervention studies (n = 11)) were classified as testing the effects of intentional weight loss on i) oxidative stress (n = 15), ii) DNA repair (n = 2), and iii) telomere length (n = 4).

RESULTS

Across a broad range of intervention designs, diet-, exercise-, surgery-, balloon-induced weight loss regimens decreased oxidative stress measures. Studies investigating DNA repair capacity or telomere length as endpoints after weight loss were less common in number and yielded null or inconsistent results, respectively.

CONCLUSION

While this systematic review supports a role for intentional weight loss in reducing obesity-associated oxidative stress, it is not clear whether the effects are primary outcomes or secondary to improvement in obesity-associated insulin resistance and/or chronic inflammation. Although the lack of effect of intentional weight loss on DNA repair capacity might be anticipated given that oxidative stress is reduced, additional studies are needed. The inconsistent effects of weight loss on telomere length or DNA repair suggest the need for a re-assessment of intervention designs and assay methodology to definitively address this topic.

Telomere structure and maintenance gene variants and risk of five cancer types

Telomeres cap chromosome ends, protecting them from degradation, double-strand breaks, and end-to-end fusions. Telomeres are maintained by telomerase, a reverse transcriptase encoded by TERT, and an RNA template encoded by TERC. Loci in the TERT and adjoining CLPTM1L region are associated with risk of multiple cancers. We therefore investigated associations between variants in 22 telomere structure and maintenance gene regions and colorectal, breast, prostate, ovarian, and lung cancer risk. We performed subset-based meta-analyses of 204,993 directly-measured and imputed SNPs among 61,851 cancer cases and 74,457 controls of European descent. Independent associations for SNP minor alleles were identified using sequential conditional analysis (with gene-level p value cutoffs ≤3.08 × 10-5 ). Of the thirteen independent SNPs observed to be associated with cancer risk, novel findings were observed for seven loci. Across the DCLRE1B region, rs974494 and rs12144215 were inversely associated with prostate and lung cancers, and colorectal, breast, and prostate cancers, respectively. Across the TERC region, rs75316749 was positively associated with colorectal, breast, ovarian, and lung cancers. Across the DCLRE1B region, rs974404 and rs12144215 were inversely associated with prostate and lung cancers, and colorectal, breast, and prostate cancers, respectively. Near POT1, rs116895242 was inversely associated with colorectal, ovarian, and lung cancers, and RTEL1 rs34978822 was inversely associated with prostate and lung cancers. The complex association patterns in telomere-related genes across cancer types may provide insight into mechanisms through which telomere dysfunction in different tissues influences cancer risk.

A systematic review of the interrelation between diet- and surgery-induced weight loss and vitamin D status

Obesity is a major global health problem and has been associated with vitamin D deficiency. Intentional weight loss may alter vitamin D status and, conversely, vitamin D supplementation has been hypothesized to aid in weight loss. A systematic literature search in PubMed/Medline identified 3173 articles of which 37 studies (randomized controlled trials (RCT) [n=17], non-RCTs [n=20]) are summarized as effect of: (I) diet-induced weight loss on vitamin D status (n=7), (II) vitamin D supplementation on diet-induced weight loss (n=11), (III) surgery-induced weight loss on vitamin D status (n=15), and (IV) vitamin D supplementation after surgery-induced weight loss on vitamin D status (n=5). While all studies on the effect of diet-induced weight loss on vitamin D status have consistently reported increased vitamin D levels, the targeted percentage of weight loss that is necessary for an increase has varied between 5% and >10%. N=11 RCTs testing the effect of vitamin D supplementation observe that vitamin D supplementation does not result in increased weight loss, but may affect body fat loss. Vitamin D deficiency and subsequent hyperparathyroidism have been detected in post-surgery patients, and there is evidence that vitamin D supplementation improves these post-surgery complications. We review the current evidence addressing the role of vitamin D status and supplementation in diet- and surgery-induced weight loss. Subsequently, we highlight gaps in current research and suggest directions for future research including differences in vitamin D supplementation dosages, indoor vs. outdoor exercise, and the assessment of vitamin D status in different body pools.

Discovery of novel plasma proteins as biomarkers for the development of incisional hernias after midline incision in patients with colorectal cancer: The ColoCare study

BACKGROUND

Ventral incisional hernia is the most common long-term complication after an abdominal operation. Among newly diagnosed colorectal cancer patients, we screened the preoperative plasma proteome to explore predictive markers for the development of an incisional hernia.

METHODS

We utilized preoperative plasma samples of 72 newly diagnosed colorectal cancer patients who underwent midline incision for tumor resection between 2010 and 2013. A total of 21 patients with incisional hernia occurrence were matched with 51 patients with at least 18 months follow-up without an incisional hernia by sex, age, and body mass index. To assess predictive markers of incisional hernia risk, we screened the plasma proteome for >2,000 distinct proteins using a well-validated antibody microarray test. Paired t tests were used to compare protein levels between cases and controls. A gene-set-enrichment analysis (Gene Ontology and Kyoto Encyclopedia of Genes and Genomes) was applied to test for differences in signaling pathways between the 2 groups.

RESULTS

The proteome screen identified 25 proteins that showed elevated or reduced plasma levels in the hernia group compared to the control group (nominal P values < .05). Several proteins were in pathways associated with wound healing (CCL21, SHBG, BRF2) or cell adhesion (PCDH15, CDH3, EPCAM).

CONCLUSION

Our study shows that there are multiple individual and groups of plasma proteins that could feasibly predict the personal hernia risk prior to undergoing an operation. Further investigations in larger, independent sample sets are warranted to replicate findings and validate clinical utility of potential biomarkers. After validation, such a biomarker could be incorporated into a multifactorial risk model to guide clinical decision-making.

The effects of intermittent calorie restriction on metabolic health: Rationale and study design of the HELENA Trial

Mechanistic studies suggest benefits of intermittent calorie restriction (ICR) in chronic disease prevention that may exceed those of continuous calorie restriction (CCR), even at equal net calorie intake. Despite promising results from first trials, it remains largely unknown whether ICR-induced metabolic alterations reported from experimental studies can also be observed in humans, and whether ICR diets are practicable and effective in real life situations. Thus, we initiated the HELENA Trial to test the effects of ICR (eu-caloric diet on five days and very low energy intake on two days per week) on metabolic parameters and body composition over one year. We will assess the effectiveness of ICR compared to CCR and a control diet over a 12-week intervention, 12-week maintenance phase and 24-week follow-up in 150 overweight or obese non-smoking adults (50 per group, 50% women). Our primary endpoint is the difference between ICR and CCR with respect to fold-changes in expression levels of 82 candidate genes in abdominal subcutaneous adipose tissue biopsies (SATb) during the intervention phase. The candidate genes represent pathways, which may link obesity-related metabolic alterations with the risk for major chronic diseases. In secondary and exploratory analyses, changes in metabolic, hormonal, inflammatory and metagenomic parameters measured in different biospecimens (SATb, blood, urine, stool) are investigated and effects of ICR/CCR/control on imaging-based measures of subcutaneous, visceral and hepatic fat are evaluated. Our study is the first randomized trial over one year testing the effects of ICR on metabolism, body composition and psychosocial factors in humans.