Epithelial overexpression of IL-33 induces eosinophilic esophagitis dependent on IL-13.

BACKGROUND: Eosinophilic esophagitis (EoE) is an increasingly common inflammatory condition of the esophagus; however, the underlying immunologic mechanisms remain poorly understood. The epithelium-derived cytokine IL-33 is associated with type 2 immune responses and elevated in esophageal biopsy specimens from patients with EoE. OBJECTIVE: We hypothesized that overexpression of IL-33 by the esophageal epithelium would promote the immunopathology of EoE. METHODS: We evaluated the functional consequences of esophageal epithelial overexpression of a secreted and active form of IL-33 in a novel transgenic mouse, EoE33. EoE33 mice were analyzed for clinical and immunologic phenotypes. Esophageal contractility was assessed. Epithelial cytokine responses were analyzed in three-dimensional organoids. EoE33 phenotypes were further characterized in ST2-/-, eosinophil-deficient, and IL-13-/- mice. Finally, EoE33 mice were treated with dexamethasone. RESULTS: EoE33 mice displayed ST2-dependent, EoE-like pathology and failed to thrive. Esophageal tissue remodeling and inflammation included basal zone hyperplasia, eosinophilia, mast cells, and TH2 cells. Marked increases in levels of type 2 cytokines, including IL-13, and molecules associated with immune responses and tissue remodeling were observed. Esophageal organoids suggested reactive epithelial changes. Genetic deletion of IL-13 in EoE33 mice abrogated pathologic changes in vivo. EoE33 mice were responsive to steroids. CONCLUSIONS: IL-33 overexpression by the esophageal epithelium generated immunopathology and clinical phenotypes resembling human EoE. IL-33 may play a pivotal role in the etiology of EoE by activating the IL-13 pathway. EoE33 mice are a robust experimental platform for mechanistic investigation and translational discovery.

Associations between pathological features and risk of metachronous colorectal cancer.

Survivors of colorectal cancer (CRC) are at risk of developing another primary colorectal cancer - metachronous CRC. Understanding which pathological features of the first tumour are associated with risk of metachronous CRC might help tailor existing surveillance guidelines. Population-based CRC cases were recruited from the United States, Canada and Australia between 1997 and 2012 and followed prospectively until 2022 by the Colon Cancer Family Registry. Metachronous CRC was defined as a new primary CRC diagnosed at least 1 year after the initial CRC. Those with the genetic cancer predisposition Lynch syndrome or MUTYH mutation carriers were excluded. Cox regression models were fitted to estimate hazard ratios (HRs) and corresponding 95% confidence intervals (CIs) for the associations. Of 6085 CRC cases, 138 (2.3%) were diagnosed with a metachronous CRC over a median follow-up time of 12 years (incidence: 2.0 per 1000 person-years). CRC cases with a synchronous CRC were 3.4-fold more likely to develop a metachronous CRC (adjusted HR: 3.36, 95% CI: 1.89-5.98) than those without a synchronous tumour. CRC cases with MMR-deficient tumours had a 72% increased risk of metachronous CRC (adjusted HR: 1.72, 95% CI: 1.11-2.64) compared to those with MMR-proficient tumours. Compared to cases who had an adenocarcinoma histologic type, those with an undifferentiated histologic type were 77% less likely to develop a metachronous CRC (adjusted HR: 0.23, 95% CI: 0.06-0.94). Existing surveillance guidelines for CRC survivors could be updated to include increased surveillance for those whose first CRC was diagnosed with a synchronous CRC or was MMR-deficient.

Circulating white blood cell traits and colorectal cancer risk: A Mendelian randomisation study.

Observational studies have suggested a protective role for eosinophils in colorectal cancer (CRC) development and implicated neutrophils, but the causal relationships remain unclear. Here, we aimed to estimate the causal effect of circulating white blood cell (WBC) counts (N = ~550 000) for basophils, eosinophils, monocytes, lymphocytes and neutrophils on CRC risk (N = 52 775 cases and 45 940 controls) using Mendelian randomisation (MR). For comparison, we also examined this relationship using individual-level data from UK Biobank (4043 incident CRC cases and 332 773 controls) in a longitudinal cohort analysis. The inverse-variance weighted (IVW) MR analysis suggested a protective effect of increased basophil count and eosinophil count on CRC risk [OR per 1-SD increase: 0.88, 95% CI: 0.78-0.99, P = .04; OR: 0.93, 95% CI: 0.88-0.98, P = .01]. The protective effect of eosinophils remained [OR per 1-SD increase: 0.88, 95% CI: 0.80-0.97, P = .01] following adjustments for all other WBC subtypes, to account for genetic correlation between the traits, using multivariable MR. A protective effect of increased lymphocyte count on CRC risk was also found [OR: 0.84, 95% CI: 0.76-0.93, P = 6.70e-4] following adjustment. Consistent with MR results, a protective effect for eosinophils in the cohort analysis in the fully adjusted model [RR per 1-SD increase: 0.96, 95% CI: 0.93-0.99, P = .02] and following adjustment for the other WBC subtypes [RR: 0.96, 95% CI: 0.93-0.99, P = .001] was observed. Our study implicates peripheral blood immune cells, in particular eosinophils and lymphocytes, in CRC development, highlighting a need for mechanistic studies to interrogate these relationships.

Allometric versus traditional body-shape indices and risk of colorectal cancer: a Mendelian randomization analysis.

BACKGROUND: Traditional body-shape indices such as Waist Circumference (WC), Hip Circumference (HC), and Waist-to-Hip Ratio (WHR) are associated with colorectal cancer (CRC) risk, but are correlated with Body Mass Index (BMI), and adjustment for BMI introduces a strong correlation with height. Thus, new allometric indices have been developed, namely A Body Shape Index (ABSI), Hip Index (HI), and Waist-to-Hip Index (WHI), which are uncorrelated with weight and height; these have also been associated with CRC risk in observational studies, but information from Mendelian randomization (MR) studies is missing. METHODS: We used two-sample MR to examine potential causal cancer site- and sex-specific associations of the genetically-predicted allometric body-shape indices with CRC risk, and compared them with BMI-adjusted traditional body-shape indices, and BMI. Data were obtained from UK Biobank and the GIANT consortium, and from GECCO, CORECT and CCFR consortia. RESULTS: WHI was positively associated with CRC in men (OR per SD: 1.20, 95% CI: 1.03-1.39) and in women (1.15, 1.06-1.24), and similarly for colon and rectal cancer. ABSI was positively associated with colon and rectal cancer in men (1.27, 1.03-1.57; and 1.40, 1.10-1.77, respectively), and with colon cancer in women (1.20, 1.07-1.35). There was little evidence for association between HI and colon or rectal cancer. The BMI-adjusted WHR and HC showed similar associations to WHI and HI, whereas WC showed similar associations to ABSI only in women. CONCLUSIONS: This large MR study provides strong evidence for a potential causal positive association of the allometric indices ABSI and WHI with CRC in both sexes, thus establishing the association between abdominal fat and CRC without the limitations of the traditional waist size indices and independently of BMI. Among the BMI-adjusted traditional indices, WHR and HC provided equivalent associations with WHI and HI, while differences were observed between WC and ABSI.

Cronkhite-Canada Syndrome: A Rare Cause of Gastrointestinal Polyposis With Response to Emerging Therapy.

A 70-year-old man presented to the clinic with a 6-month history of dysgeusia, followed by chronic, non-bloody diarrhea and 45 lb unintentional weight loss. Esophagogastroduodenoscopy discovered confluent nodularity in the gastric antrum and examined duodenum, but a normal esophagus. Colonoscopy uncovered patches of polypoid nodular mucosa throughout the entire colon. Biopsies of the nodular mucosa were consistent with hamartomatous polyps while biopsies of the intervening, normal-appearing mucosa demonstrated edema with crypt architectural distortion. Other hereditary polyposis syndromes were excluded with genetic testing, confirming a diagnosis of Cronkhite-Canada syndrome. Adalimumab therapy was initiated with clinical improvement after nonresponse to prednisone.

Reliability of an Expanded Non-alcoholic Steatohepatitis Grading and Staging System for Assessment of Disease Activity and Fibrosis.

The nonalcoholic steatohepatitis clinical research network (NASH-CRN) system is commonly used for histologic assessment of disease activity and fibrosis in NASH. Despite this, the system does not fully capture the range of disease activity and fibrosis. As such, an expanded NAS (E-NAS) grading and staging system with a calculated E-NAS index was developed by our group. In this follow up study, we aim to revalidate the E-NAS system and compare its reliability to existing systems. Hematoxylin and eosin and trichrome stained sections from 40 liver biopsies were reviewed digitally by four hepatopathologists and assessed using the NASH-CRN and E-NAS systems as well as a modified Ishak fibrosis stage. The pathologist's gestalt impression of disease activity and fibrosis was scored on a Visual Analogue Scale (VAS), which ranged from 0 (no activity/fibrosis) to 100 (the worst activity/fibrosis ever seen). Inter-rater reliability was assessed, and Spearman correlation coefficients were calculated. The E-NAS index had higher inter-rater agreement versus the NAS score (ICC 0.70 vs 0.61). The inter-rater agreement for ballooning in the E-NAS system was also higher at 0.67 compared to the NAS (ICC 0.60). ICCs for fibrosis were comparable between all the systems assessed (0.78 to 0.88). Finally, the calculated E-NAS index was higher with increasing stage of fibrosis compared to the NAS suggesting that it associates better with fibrosis. In summary, the E-NAS system demonstrates substantial inter-rater reliability as well as improved correlation with disease activity VAS and fibrosis compared to the NAS score.

Hepatitis and Vasodilatory Shock due to an Unsuspected Culprit: A Rare Presentation of Multisystem Langerhans Cell Histiocytosis.

Introduction: Langerhans cell histiocytosis (LCH) is a rare hematologic condition which can affect multiple organ systems and has variable presentation. LCH is more commonly seen as a malignancy of childhood. LCH in adulthood can have poor outcomes depending on the involvement of critical organs. Case Presentation: We report a case of a 71-year-old female who presented with progressive weakness, weight loss, diarrhea, and jaundice, and had been undergoing outpatient workup for elevated liver enzymes for the last 2 years. She required admission to the intensive care unit for vasodilatory shock, requiring vasopressor and chronotropic support. Imaging showed an underlying multiorgan process involving the gastrointestinal tract, liver, spleen, and central nervous system. A repeat liver biopsy after a prior inconclusive one revealed the diagnosis of multisystem LCH presenting as secondary sclerosing cholangitis. Conclusion: The uniqueness of this multisystem LCH case lies not only in its rarity but also in the diagnostic journey that necessitated a repeat biopsy for a conclusive diagnosis. Early identification and targeted intervention can help in ensuring better patient outcomes, especially when the presentation can overlap with various other possible conditions.

Population-Level Identification of Patients With Lynch Syndrome for Clinical Care, Quality Improvement, and Research.

PURPOSE: Identification of those at risk of hereditary cancer syndromes using electronic health record (EHR) data sources is important for clinical care, quality improvement, and research. We describe diagnostic processes, previously seldom reported, for a common hereditary cancer syndrome, Lynch syndrome (LS), using EHR data within a community-based, multicenter, demographically diverse health system. METHODS: Within a retrospective cohort enrolled between 2015 and 2020 at Kaiser Permanente Northern California, we assessed electronic diagnostic domains for LS including (1) family history of LS-associated cancer; (2) personal history of LS-associated cancer; (3) LS screening via mismatch repair deficiency (MMRD) testing of newly diagnosed malignancy; (4) germline genetic test results; and (5) clinician-entered diagnostic codes for LS. We calculated proportions and overlap for each diagnostic domain descriptively. RESULTS: Among 5.8 million individuals, (1) 28,492 (0.49%) had a family history of LS-associated cancer of whom 3,635 (13%) underwent genetic testing; (2) 100,046 (1.7%) had a personal history of a LS-associated cancer; and (3) 8,711 (0.1%) were diagnosed with colorectal cancer of whom 7,533 (86%) underwent MMRD screening and of the positive screens (486), 130 (27%) underwent germline testing. One thousand seven hundred and fifty-seven (0.03%) were diagnosed with endometrial cancer of whom 1,613 (92%) underwent MMRD screening and of the 195 who screened positive, 55 (28%) underwent genetic testing. (4) 30,790 (0.05%) had LS germline genetic testing with 707 (0.01%) testing positive; and (5) 1,273 (0.02%) had a clinician-entered diagnosis of LS. CONCLUSION: It is feasible to electronically characterize the diagnostic processes of LS. No single data source comprehensively identifies all LS carriers. There is underutilization of LS genetic testing for those eligible and underdiagnosis of LS. Our work informs similar efforts in other settings for hereditary cancer syndromes.

Histologic assessments in ulcerative colitis: the evidence behind a new endpoint in clinical trials.

INTRODUCTION: Treatment goals for ulcerative colitis (UC) are evolving from the achievement of clinical remission to more rigorous goals defined by endoscopic and histologic healing. Achievement of deeper remission targets aims to reduce the risk of colectomy, hospitalizations, and colorectal cancer. AREAS COVERED: This review covers histologic assessments, histologic remission as a clinical trial endpoint, and the association between histologic disease activity and clinical outcomes. Future directions are also discussed, including the use of advanced imaging and artificial intelligence technologies, as well as potential future treatment targets beyond histologic remission. EXPERT OPINION: Histologic assessments are used for their sensitivity in measuring mucosal inflammatory changes in UC. Due to correlation with disease activity, histologic assessments may support clinical decision-making regarding treatment decisions as such assessments can be associated with rates of clinical relapse, hospitalization, colectomy, and neoplasia. While histologic remission is limited by varying definitions and multiple histologic indices, work is ongoing to create a consensus on the use of histologic assessments in clinical trials. As research advances, aspirational targets beyond histologic remission, such as molecular healing and disease clearance, are being explored.

Ulcerative colitis (UC) is the most common inflammatory bowel disease and often results in bloody diarrhea, frequent bowel movements, and bowel urgency. Patients with UC are at greater risk for hospitalization, surgery, and colorectal cancer. To reduce these risks, the goals of UC treatment are changing from mainly addressing symptoms to reducing inflammation at a deeper histologic, or microscopic, level. The inflammation in UC causes distinct microscopic changes in the colon, which can be assessed after collecting biopsies or tissue samples. This review provides an overview of histologic remission (when no signs of inflammation are seen in tissue samples viewed under a microscope) as a treatment goal in UC.Histologic remission has been shown to be associated with lower rates of relapse, hospitalization, surgical removal of the colon, and colorectal cancer. However, using histologic remission as a treatment target can be difficult due to varying definitions and the many different scoring assessments available to healthcare providers. Updated guidance from regulatory agencies and academic organizations has helped align definitions of histologic remission and how to assess histologic healing in clinical trials.The introduction of targeted advanced therapies has allowed for deeper healing with the potential for histologic resolution. This enables clinicians and researchers to aim for treatment targets that are harder to achieve but have a greater impact for patients in the course of their disease. New technologies such as artificial intelligence, high-resolution endoscopy, and digital pathology have also led to targets beyond histologic healing, aiming to restore the function of the colon's mucosal barrier and disease clearance.

Identification of immune cell markers associated with ulcerative colitis histological disease activity in colonic biopsies.

AIMS: Accurate determination of histological activity in ulcerative colitis (UC) is essential given its diagnostic and prognostic importance. Data on the relationship between histology and immune cell markers are limited. We aimed to evaluate the association between histological disease activity and immune cell marker concentration in colonic biopsies from patients with UC. METHODS: Sigmoid colon biopsies from 20 patients with UC were retrospectively assessed using the Robarts Histopathology Index (RHI). Targeted mass spectrometry determined the concentration of 18 immune cell markers (cluster of differentiation (CD) 4, CD8, CD19, CD20, CD40, CD56, CD68, CD103, forkhead box p3 (FOXP3), human leucocyte antigen, DR alpha chain (HLA-DRA), interleukin 10 (IL-10), IL-23 subunit alpha (IL-23A), IL-23 receptor (IL-23R), IL-2 receptor alpha chain (IL-2RA), Ki67, lymphocyte-activation gene 3 (LAG-3), programmed cell death protein 1 (PD-1) and PD ligand 1 (PD-L1)). The association between RHI score and immune cell marker concentration was quantified using Spearman's rank correlation coefficient (ρ) and related 95% CIs. RESULTS: Fourteen of the 18 immune cell marker proteins were detected, with tissue concentration ranging from 0.003 to 11.53 fmol/µg. The overall RHI score was positively correlated with CD19, CD20, CD40, FOXP3, LAG-3, PD-1 and PD-L1 concentration (ρ=0.596-0.799) and negatively correlated with CD56 concentration (ρ=-0.460). There was no significant association between RHI score and CD4, CD8, CD68, CD103, HLA-DRA or Ki67 concentration. CONCLUSIONS: This study provides insight into the correlation between immune cell marker expression and histological disease activity and the possible molecular and immunological determinants underlying microscopic disease activity in UC.

Causal relationships between risk of venous thromboembolism and 18 cancers: a bidirectional Mendelian randomization analysis.

BACKGROUND: People with cancer experience high rates of venous thromboembolism (VTE). Risk of subsequent cancer is also increased in people experiencing their first VTE. The causal mechanisms underlying this association are not completely understood, and it is unknown whether VTE is itself a risk factor for cancer. METHODS: We used data from large genome-wide association study meta-analyses to perform bidirectional Mendelian randomization analyses to estimate causal associations between genetic liability to VTE and risk of 18 different cancers. RESULTS: We found no conclusive evidence that genetic liability to VTE was causally associated with an increased incidence of cancer, or vice versa. We observed an association between liability to VTE and pancreatic cancer risk [odds ratio for pancreatic cancer: 1.23 (95% confidence interval: 1.08-1.40) per log-odds increase in VTE risk, P = 0.002]. However, sensitivity analyses revealed this association was predominantly driven by a variant proxying non-O blood group, with inadequate evidence to suggest a causal relationship. CONCLUSIONS: These findings do not support the hypothesis that genetic liability to VTE is a cause of cancer. Existing observational epidemiological associations between VTE and cancer are therefore more likely to be driven by pathophysiological changes which occur in the setting of active cancer and anti-cancer treatments. Further work is required to explore and synthesize evidence for these mechanisms.

Improved Risk-Stratification Scheme for Mismatch-Repair Proficient Stage II Colorectal Cancers Using the Digital Pathology Biomarker QuantCRC.

PURPOSE: There is a need to improve current risk stratification of stage II colorectal cancer to better inform risk of recurrence and guide adjuvant chemotherapy. We sought to examine whether integration of QuantCRC, a digital pathology biomarker utilizing hematoxylin and eosin-stained slides, provides improved risk stratification over current American Society of Clinical Oncology (ASCO) guidelines. EXPERIMENTAL DESIGN: ASCO and QuantCRC-integrated schemes were applied to a cohort of 398 mismatch-repair proficient (MMRP) stage II colorectal cancers from three large academic medical centers. The ASCO stage II scheme was taken from recent guidelines. The QuantCRC-integrated scheme utilized pT3 versus pT4 and a QuantCRC-derived risk classification. Evaluation of recurrence-free survival (RFS) according to these risk schemes was compared using the log-rank test and HR. RESULTS: Integration of QuantCRC provides improved risk stratification compared with the ASCO scheme for stage II MMRP colorectal cancers. The QuantCRC-integrated scheme placed more stage II tumors in the low-risk group compared with the ASCO scheme (62.5% vs. 42.2%) without compromising excellent 3-year RFS. The QuantCRC-integrated scheme provided larger HR for both intermediate-risk (2.27; 95% CI, 1.32-3.91; P = 0.003) and high-risk (3.27; 95% CI, 1.42-7.55; P = 0.006) groups compared with ASCO intermediate-risk (1.58; 95% CI, 0.87-2.87; P = 0.1) and high-risk (2.24; 95% CI, 1.09-4.62; P = 0.03) groups. The QuantCRC-integrated risk groups remained prognostic in the subgroup of patients that did not receive any adjuvant chemotherapy. CONCLUSIONS: Incorporation of QuantCRC into risk stratification provides a powerful predictor of RFS that has potential to guide subsequent treatment and surveillance for stage II MMRP colorectal cancers.

Large-scale integration of omics and electronic health records to identify potential risk protein biomarkers and therapeutic drugs for cancer prevention and intervention.

Identifying risk protein targets and their therapeutic drugs is crucial for effective cancer prevention. Here, we conduct integrative and fine-mapping analyses of large genome-wide association studies data for breast, colorectal, lung, ovarian, pancreatic, and prostate cancers, and characterize 710 lead variants independently associated with cancer risk. Through mapping protein quantitative trait loci (pQTL) for these variants using plasma proteomics data from over 75,000 participants, we identify 365 proteins associated with cancer risk. Subsequent colocalization analysis identifies 101 proteins, including 74 not reported in previous studies. We further characterize 36 potential druggable proteins for cancers or other disease indications. Analyzing >3.5 million electronic health records, we uncover five drugs (Haloperidol, Trazodone, Tranexamic Acid, Haloperidol, and Captopril) associated with increased cancer risk and two drugs (Caffeine and Acetazolamide) linked to reduced colorectal cancer risk. This study offers novel insights into therapeutic drugs targeting risk proteins for cancer prevention and intervention.

Use of Deep Learning to Evaluate Tumor Microenvironmental Features for Prediction of Colon Cancer Recurrence.

Deep learning may detect biologically important signals embedded in tumor morphologic features that confer distinct prognoses. Tumor morphologic features were quantified to enhance patient risk stratification within DNA mismatch repair (MMR) groups using deep learning. Using a quantitative segmentation algorithm (QuantCRC) that identifies 15 distinct morphologic features, we analyzed 402 resected stage III colon carcinomas [191 deficient (d)-MMR; 189 proficient (p)-MMR] from participants in a phase III trial of FOLFOX-based adjuvant chemotherapy. Results were validated in an independent cohort (176 d-MMR; 1,094 p-MMR). Association of morphologic features with clinicopathologic variables, MMR, KRAS, BRAFV600E, and time-to-recurrence (TTR) was determined. Multivariable Cox proportional hazards models were developed to predict TTR. Tumor morphologic features differed significantly by MMR status. Cancers with p-MMR had more immature desmoplastic stroma. Tumors with d-MMR had increased inflammatory stroma, epithelial tumor-infiltrating lymphocytes (TIL), high-grade histology, mucin, and signet ring cells. Stromal subtype did not differ by BRAFV600E or KRAS status. In p-MMR tumors, multivariable analysis identified tumor-stroma ratio (TSR) as the strongest feature associated with TTR [HRadj 2.02; 95% confidence interval (CI), 1.14-3.57; P = 0.018; 3-year recurrence: 40.2% vs. 20.4%; Q1 vs. Q2-4]. Among d-MMR tumors, extent of inflammatory stroma (continuous HRadj 0.98; 95% CI, 0.96-0.99; P = 0.028; 3-year recurrence: 13.3% vs. 33.4%, Q4 vs. Q1) and N stage were the most robust prognostically. Association of TSR with TTR was independently validated. In conclusion, QuantCRC can quantify morphologic differences within MMR groups in routine tumor sections to determine their relative contributions to patient prognosis, and may elucidate relevant pathophysiologic mechanisms driving prognosis. SIGNIFICANCE: A deep learning algorithm can quantify tumor morphologic features that may reflect underlying mechanisms driving prognosis within MMR groups. TSR was the most robust morphologic feature associated with TTR in p-MMR colon cancers. Extent of inflammatory stroma and N stage were the strongest prognostic features in d-MMR tumors. TIL density was not independently prognostic in either MMR group.

Identifying metabolic features of colorectal cancer liability using Mendelian randomization.

Background: Recognizing the early signs of cancer risk is vital for informing prevention, early detection, and survival. Methods: To investigate whether changes in circulating metabolites characterize the early stages of colorectal cancer (CRC) development, we examined the associations between a genetic risk score (GRS) associated with CRC liability (72 single-nucleotide polymorphisms) and 231 circulating metabolites measured by nuclear magnetic resonance spectroscopy in the Avon Longitudinal Study of Parents and Children (N = 6221). Linear regression models were applied to examine the associations between genetic liability to CRC and circulating metabolites measured in the same individuals at age 8 y, 16 y, 18 y, and 25 y. Results: The GRS for CRC was associated with up to 28% of the circulating metabolites at FDR-P < 0.05 across all time points, particularly with higher fatty acids and very-low- and low-density lipoprotein subclass lipids. Two-sample reverse Mendelian randomization (MR) analyses investigating CRC liability (52,775 cases, 45,940 controls) and metabolites measured in a random subset of UK Biobank participants (N = 118,466, median age 58 y) revealed broadly consistent effect estimates with the GRS analysis. In conventional (forward) MR analyses, genetically predicted polyunsaturated fatty acid concentrations were most strongly associated with higher CRC risk. Conclusions: These analyses suggest that higher genetic liability to CRC can cause early alterations in systemic metabolism and suggest that fatty acids may play an important role in CRC development. Funding: This work was supported by the Elizabeth Blackwell Institute for Health Research, University of Bristol, the Wellcome Trust, the Medical Research Council, Diabetes UK, the University of Bristol NIHR Biomedical Research Centre, and Cancer Research UK. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. This work used the computational facilities of the Advanced Computing Research Centre, University of Bristol - http://www.bristol.ac.uk/acrc/.

Colorectal cancer, or bowel cancer, is the fourth most common cause of death from cancer worldwide. Understanding how the cancer develops and recognizing early signs is essential, as people who receive treatment early on have higher survival rates. One way to boost early detection and disease survival rates is through identifying early colorectal cancer biomarkers. For example, metabolites produced when cells process nutrients have been shown to play a role in the development of colon cancer. Certain metabolites could therefore serve as biomarkers, which can be detected in routine blood tests. But first, scientists need to identify the exact metabolic processes involved in cancer development. Bull, Hazelwood et al. show that fat metabolites during early adulthood may help predict colorectal cancer risk. In the experiments, the team assessed the link between an individual's genetic risk for developing colorectal cancer and metabolites in their blood. By looking at data from over 6,000 individuals living in the UK, followed from early life into adulthood, they found higher fatty acid and low-density lipoprotein levels in young adults at risk of colorectal cancer. However, the results could not be replicated in a separate cohort study of middle-aged adults. Bull, Hazelwood et al. noted that many individuals in this older age group use fat-targeting drugs called statins, which may have obscured this connection. The study of Bull, Hazelwood et al. shows that colorectal cancer risk indicators may be present from adolescence to around 40 years, before most individuals are diagnosed. The results suggest this may be a window for early detection and preventive interventions. It also highlights that differences in fat metabolism, possibly linked to genetic differences, may underlie colorectal cancer risk. More studies are needed to better understand how and whether interventions targeting fat levels may help prevent colorectal cancer development.