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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.

BACKGROUND: Antibiotics use may increase colorectal cancer (CRC) risk by altering the gut microbiota, with suggestive evidence reported. Our study aims to investigate antibiotics use in relation to subsequent CRC risk.

METHODS: This is a nationwide, population-based study with a matched case-control design (first primary CRC cases and 5 matched, cancer-free controls). Complete-population data, extracted from Swedish national registers for the period 2005-2016, were used to calculate odds ratios and 95% confidence intervals.

RESULTS: We included 40 545 CRC cases and 202 720 controls. Using the full dataset, we found a positive association between more frequent antibiotics use and CRC, excluding antibiotics prescribed within 2 years of diagnosis attenuated results toward the null. In site-specific analyses, excluding the 2-year washout, the positive association was confined to the proximal colon (adjusted odds ratio for very high use vs no use = 1.17, 95% confidence interval = 1.05 to 1.31). For rectal cancer, an inverse association, which appears to be driven by women, was observed. Quinolones and sulfonamides and/or trimethoprims were positively associated with proximal colon cancer, whereas a more general inverse association, across antibiotics classes, was observed for rectal cancer. We found no association between methenamine hippurate, a urinary tract antiseptic not affecting the gut microbiota, and CRC risk.

CONCLUSIONS: This register-based study covering the entire population of Sweden found a robust association between antibiotics use and higher risk of proximal colon cancer and an inverse association with rectal cancer in women. This study strengthens the evidence from previous investigations and adds important insight into site-specific colorectal carcinogenesis.

Background: Stress is a commonly perceived cause of cancer, but the evidence to date is limited and inconclusive. We examined work-related stress in relation to cancer incidence in a population-based cohort, with outcome data from Swedish national registries.

Methods: The study population included 113,057 participants in the Västerbotten Intervention Programme. HRs were estimated using Cox proportional hazards regression, for cancer overall and for types with ≥500 cases, and adjusting for several potential confounders. The primary exposure was prediagnostic work-related stress, using the well established Karasek job demand/control model. Demand and control variables were dichotomized at the median, and participants were classified according to combinations of these categories. We also considered social network and aspects of quality of life.

Results: "High-strain" work (high demand/low control) was not associated with cancer risk compared with "low-strain" work (low demand/high control): multivariable HR 1.01 [95% confidence interval (CI), 0.94-1.08] for men and 0.99 (95% CI, 0.92-1.07) for women. Results were also null for most cancer types assessed: prostate, breast, colorectal, lung, and gastrointestinal (GI). The risk of GI cancer was lower for "passive" (low demand/low control) versus "low-strain" work, particularly for colorectal cancer in women: multivariable HR 0.71 (95% CI, 0.55-0.91), but statistical significance was lost after adjustment for multiple testing.

Conclusions: The findings of this population-based, cohort study do not support a role for work-related stress in determining cancer risk.

Impact: This study helps fill an important knowledge gap given the common concern about stress as a risk factor for cancer.

Colorectal cancer prognosis is dependent on stage, and measures to improve early detection are urgently needed. Using prospectively collected plasma samples from the population-based Northern Sweden Health and Disease Study, we evaluated protein biomarkers in relation to colorectal cancer risk. Applying a two-tiered approach, we analyzed 160 proteins in matched sequential samples from 58 incident colorectal cancer case–control pairs. Twenty-one proteins selected from both this discovery phase and the literature were then analyzed in a validation set of 450 case–control pairs. Odds ratios were estimated by conditional logistic regression. LASSO regression and ROC analysis were used for multi-marker analyses. In the main validation analysis, no proteins retained statistical significance. However, exploratory subgroup analyses showed associations between FGF-21 and colon cancer risk (multivariable OR per 1 SD: 1.23 95% CI 1.03–1.47) as well as between PPY and rectal cancer risk (multivariable OR per 1 SD: 1.47 95% CI 1.12–1.92). Adding protein markers to basic risk predictive models increased performance modestly. Our results highlight the challenge of developing biomarkers that are effective in the asymptomatic, prediagnostic window of opportunity for early detection of colorectal cancer. Distinguishing between cancer subtypes may improve prediction accuracy. However, single biomarkers or small panels may not be sufficient for effective precision screening.

Body fatness increases the risk of colorectal cancer (CRC). Insulin resistance and altered adipokines are potential mechanisms, but previous biomarker studies have been inconsistent. Intertumoral heterogeneity might provide an explanation. We investigated insulin, C-peptide, adiponectin, and leptin in relation to CRC molecular subtypes using a nested case-control design (1010 cases, 1010 matched controls, median 12.3 years from baseline to CRC diagnosis) from the population-based Northern Sweden Health and Disease Study. Repeated samples were available from 518 participants. Risks of CRC and subtypes, defined by tumor BRAF and KRAS mutations and microsatellite instability (MSI) status, were estimated using conditional logistic regression and linear mixed models. Higher C-peptide and lower adiponectin were associated with increased CRC risk (odds ratios per standard deviation increase (95% CI): 1.11 (1.01, 1.23) and 0.91 (0.83, 1.00), respectively), though weakened when adjusted for body mass index. Insulin and leptin were not associated with CRC risk. Within-individual time trajectories were similar in cases and controls, and no subtype-specific relationships were identified (all Pheterogeneity > 0.1). Adiponectin was weakly inversely associated with the risk of KRAS-mutated (P = 0.08) but not BRAF-mutated or KRAS/BRAF-wildtype CRC, consistent with the one previous study. These findings contribute to an increased understanding of the complex role of body size in CRC.

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.

Background

Bilirubin, a byproduct of hemoglobin breakdown and purported anti-oxidant, is thought to be cancer preventive. We conducted complementary serological and Mendelian randomization (MR) analyses to investigate whether alterations in circulating levels of bilirubin are associated with risk of colorectal cancer (CRC). We decided a priori to perform analyses separately in men and women based on suggestive evidence that associations may differ by sex.

Methods

In a case-control study nested in the European Prospective Investigation into Cancer and Nutrition (EPIC), pre-diagnostic unconjugated bilirubin (UCB, the main component of total bilirubin) concentrations were measured by high-performance liquid chromatography in plasma samples of 1386 CRC cases and their individually matched controls. Additionally, 115 single-nucleotide polymorphisms (SNPs) robustly associated (P < 5 x 10(-8)) with circulating total bilirubin were instrumented in a 2-sample MR to test for a potential causal effect of bilirubin on CRC risk in 52,775 CRC cases and 45,940 matched controls in the Genetics and Epidemiology of Colorectal Cancer Consortium (GECCO), the Colon Cancer Family Registry (CCFR), and the Colorectal Transdisciplinary (CORECT) study.

Results

The associations between circulating UCB levels and CRC risk differed by sex (P-heterogeneity = 0.008). Among men, higher levels of UCB were positively associated with CRC risk (odds ratio [OR] = 1.19, 95% confidence interval [CI] = 1.04-1.36; per 1-SD increment of log-UCB). In women, an inverse association was observed (OR = 0.86 (0.76-0.97)). In the MR analysis of the mainUGT1A1SNP (rs6431625), genetically predicted higher levels of total bilirubin were associated with a 7% increase in CRC risk in men (OR = 1.07 (1.02-1.12);P = 0.006; per 1-SD increment of total bilirubin), while there was no association in women (OR = 1.01 (0.96-1.06);P = 0.73). Raised bilirubin levels, predicted by instrumental variables excluding rs6431625, were suggestive of an inverse association with CRC in men, but not in women. These differences by sex did not reach formal statistical significance (P-heterogeneity >= 0.2).

Conclusions

Additional insight into the relationship between circulating bilirubin and CRC is needed in order to conclude on a potential causal role of bilirubin in CRC development.

Background: Inflammation has been implicated in colorectal cancer etiology, but the relationship between C-reactive protein (CRP) and colorectal cancer risk is unclear. We aimed to investigate the association between prediagnostic plasma CRP concentrations and the risk of clinical and molecular colorectal cancer subtypes.

Methods: We used prospectively collected samples from 1,010 matched colorectal cancer case-control pairs from two population-based cohorts in Northern Sweden, including 259 with repeated samples. Conditional logistic regression and linear mixed models were used to estimate relative risks of colorectal cancer, including subtypes based on BRAF and KRAS mutations, microsatellite instability status, tumor location, stage, lag time, and (using unconditional logistic regression) body mass index.

Results: CRP was not associated with colorectal cancer risk, regardless of clinical or molecular colorectal cancer subtype. For participants with advanced tumors and blood samples <5 years before diagnosis, CRP was associated with higher risk [OR per 1 unit increase in natural logarithm (In) transformed CRP, 1.32; 95% confidence interval (CI), 1.01-1.73]. CRP levels increased over time, but average time trajectories were similar for cases and controls (P-interaction = 0.19).

Conclusions: Our results do not support intertumoral heterogeneity as an explanation for previous inconsistent findings regarding the role of CRP in colorectal cancer etiology. The possible association in the subgroup with advanced tumors and shorter follow-up likely reflects undiagnosed cancer at baseline. Impact: Future efforts to establish the putative role of chronic, low-grade inflammation in colorectal cancer development will need to address the complex relationship between systemic inflammatory factors and tumor microenvironment, and might consider larger biomarker panels than CRP alone.

Colorectal cancer (CRC) is a heterogeneous disease, with varying clinical presentations and patient prognosis. Different molecular subgroups of CRC should be treated differently and therefore, must be better characterized. Organoid culture has recently been suggested as a good model to reflect the heterogeneous nature of CRC. However, organoid cultures cannot be established from all CRC tumors. The study examines which CRC tumors are more likely to generate organoids and thus benefit from ex vivo organoid drug testing. Long-term organoid cultures from 22 out of 40 CRC tumor specimens were established. It was found that organoid cultures were more difficult to establish from tumors characterized as microsatellite instable (MSI), BRAF-mutated, poorly differentiated and/or of a mucinous type. This suggests that patients with such tumors are less likely to benefit from ex vivo organoid drug testing, but it may also suggest biological difference in tumor growth. RNA sequencing analysis of tumor sections revealed that the in vivo maintenance of these non-organoid-forming tumors depends on factors related to inflammation and pathogen exposure. Furthermore, using TCGA data we could show a trend towards a worse prognosis for patients with organoid-forming tumors, suggesting also clinical differences. Results suggest that organoids are more difficult to establish from tumors characterized as MSI, BRAF-mutated, poorly differentiated and/or of a mucinous type. We further suggest that the maintenance of cell growth of these tumors in vivo may be promoted by immune-related factors and other stromal components within the tumor microenvironment.

Background: Autism spectrum disorder (ASD) evolves from an interplay between genetic and environmental factors during prenatal development. Since identifying maternal biomarkers associated with ASD risk in offspring during early pregnancy might result in new strategies for intervention, we investigated maternal metabolic biomarkers in relation to occurrence of ASD in offspring using both univariate logistic regression and multivariate network analysis.

Methods: Serum samples from 100 women with an offspring diagnosed with ASD and 100 matched control women with typically developing offspring were collected at week 14 of pregnancy. Concentrations of 62 metabolic biomarkers were determined, including amino acids, vitamins (A, B, D, E, and K), and biomarkers related to folate (vitamin B9) metabolism, lifestyle factors, as well as C-reactive protein (CRP), the kynurenine-tryptophan ratio (KTR), and neopterin as markers of inflammation and immune activation.

Results: We found weak evidence for a positive association between higher maternal serum concentrations of folate and increased occurrence of ASD (OR per 1 SD increase: 1.70, 95% CI 1.22–2.37, FDR adjusted P = 0.07). Multivariate network analysis confirmed expected internal biochemical relations between the biomarkers. Neither inflammation markers nor vitamin D3 levels, all hypothesized to be involved in ASD etiology, displayed associations with ASD occurrence in the offspring.

Conclusions: Our findings suggest that high maternal serum folate status during early pregnancy may be associated with the occurrence of ASD in offspring. No inference about physiological mechanisms behind this observation can be made at the present time because blood folate levels may have complex relations with nutritional intake, the cellular folate status and status of other B-vitamins. Therefore, further investigations, which may clarify the potential role and mechanisms of maternal blood folate status in ASD risk and the interplay with other potential risk factors, in larger materials are warranted.