Statin use and the risk of colorectal adenoma: A meta-analysis

Trans-ancestry analysis in over 799,000 individuals yields new insights into the genetic etiology of colorectal cancer

BACKGROUND

Recent studies have demonstrated the relevance of circulating factors in the occurrence and development of colorectal cancer (CRC); however, the causal relationship remains unclear.

METHODS

Summary-level data for CRC were obtained from the UK Biobank (5,657 cases and 372,016 controls), FinnGen cohort (3,022 cases and 215,770 controls), and BioBank Japan Project (BBJ, 7,062 cases and 195,745 controls). Thirty-two peripheral markers with consistent definitions were collected from the three biobanks. Mendelian randomization (MR) was used to evaluate the causal effect of circulating factors on CRC. The effects from the three consortiums were combined using trans-ancestry meta-analysis methods.

RESULTS

Our analysis provided compelling evidence for the causal association of higher genetically predicted eosinophil cell count (EOS, odds ratio [OR], 0.8639; 95% confidence interval [CI] 0.7922-0.9421) and red cell distribution width (RDW, OR, 0.9981; 95% CI, 0.9972-0.9989) levels with a decreased risk of CRC. Additionally, we found suggestive evidence indicating that higher levels of total cholesterol (TC, OR, 1.0022; 95% CI, 1.0002-1.0042) may increase the risk of CRC. Conversely, higher levels of platelet count (PLT, OR, 0.9984; 95% CI, 0.9972-0.9996), total protein (TP, OR, 0.9445; 95% CI, 0.9037-0.9872), and C-reactive protein (CRP, OR, 0.9991; 95% CI, 0.9983-0.9999) may confer a protective effect against CRC. Moreover, we identified six ancestry-specific causal factors, indicating the necessity of considering patients' ancestry backgrounds before formulating prevention strategies.

CONCLUSIONS

MR findings support the independent causal roles of circulating factors in CRC, which might provide a deeper insight into early detection of CRC and supply potential preventative strategies.

Optimal glycaemic control and the reduced risk of colorectal adenoma and cancer in patients with diabetes: a population-based cohort study

OBJECTIVE

Whether varying degrees of glycaemic control impact colonic neoplasm risk in patients with diabetes mellitus (DM) remains uncertain.

DESIGN

Patients with newly diagnosed DM were retrieved from 2005 to 2013. Optimal glycaemic control at baseline was defined as mean haemoglobin A1c (HbA1c)<7%. Outcomes of interest included colorectal cancer (CRC) and colonic adenoma development. We used propensity score (PS) matching with competing risk models to estimate subdistribution HRs (SHRs). We further analysed the combined effect of baseline and postbaseline glycaemic control based on time-weighted mean HbA1c during follow-up.

RESULTS

Of 88 468 PS-matched patients with DM (mean (SD) age: 61.5 (±11.7) years; male: 47 127 (53.3%)), 1229 (1.4%) patients developed CRC during a median follow-up of 7.2 (IQR: 5.5-9.4) years. Optimal glycaemic control was associated with lower CRC risk (SHR 0.72; 95% CI 0.65 to 0.81). The beneficial effect was limited to left-sided colon (SHR 0.71; 95% CI 0.59 to 0.85) and rectum (SHR 0.71; 95% CI 0.57 to 0.89), but not right-sided colon (SHR 0.86; 95% CI 0.67 to 1.10). Setting suboptimal glycaemic control at baseline/postbaseline as a reference, a decreased CRC risk was found in optimal control at postbaseline (SHR 0.79), baseline (SHR 0.71) and both time periods (SHR 0.61). Similar associations were demonstrated using glycaemic control as a time-varying covariate (HR 0.75). A stepwise greater risk of CRC was found (Ptrend<0.001) with increasing HbA1c (SHRs 1.34, 1.30, 1.44, 1.58 for HbA1c 7.0% to <7.5%, 7.5% to <8.0%, 8.0% to <8.5% and ≥8.5%, respectively). Optimal glycaemic control was associated with a lower risk of any, non-advanced and advanced colonic adenoma (SHRs 0.73-0.87).

CONCLUSION

Glycaemic control in patients with DM was independently associated with the risk of colonic adenoma and CRC development with a biological gradient.

Big data approach in the field of gastric and colorectal cancer research

Big data is characterized by three attributes: volume, variety,, and velocity. In healthcare setting, big data refers to vast dataset that is electronically stored and managed in an automated manner and has the potential to enhance human health and healthcare system. In this review, gastric cancer (GC) and postcolonoscopy colorectal cancer (PCCRC) will be used to illustrate application of big data approach in the field of gastrointestinal cancer research. Helicobacter pylori (HP) eradication only reduces GC risk by 46% due to preexisting precancerous lesions. Apart from endoscopy surveillance, identifying medications that modify GC risk is another strategy. Population-based cohort studies showed that long-term use of proton pump inhibitors (PPIs) associated with higher GC risk after HP eradication, while aspirin and statins associated with lower risk. While diabetes mellitus conferred 73% higher GC risk, metformin use associated with 51% lower risk, effect of which was independent of glycemic control. Nonetheless, nonsteroidal anti-inflammatory drugs (NA-NSAIDs) are not associated with lower GC risk. CRC can still occur after initial colonoscopy in which no cancer was detected (i.e. PCCRC). Between 2005 and 2013, the rate of interval-type PCCRC-3y (defined as CRC diagnosed between 6 and 36 months of index colonoscopy which was negative for CRC) was 7.9% in Hong Kong, with >80% being distal cancers and higher cancer-specific mortality compared with detected CRC. Certain clinical and endoscopy-related factors were associated with PCCRC-3 risk. Medications shown to have chemopreventive effects on PCCRC include statins, NA-NSAIDs, and angiotensin-converting enzyme inhibitors/angiotensin receptor blockers.

BRAFV600E-mutated serrated colorectal neoplasia drives transcriptional activation of cholesterol metabolism

BRAF mutations occur early in serrated colorectal cancers, but their long-term influence on tissue homeostasis is poorly characterized. We investigated the impact of short-term (3 days) and long-term (6 months) expression of BrafV600E in the intestinal tissue of an inducible mouse model. We show that BrafV600E perturbs the homeostasis of intestinal epithelial cells, with impaired differentiation of enterocytes emerging after prolonged expression of the oncogene. Moreover, BrafV600E leads to a persistent transcriptional reprogramming with enrichment of numerous gene signatures indicative of proliferation and tumorigenesis, and signatures suggestive of metabolic rewiring. We focused on the top-ranking cholesterol biosynthesis signature and confirmed its increased expression in human serrated lesions. Functionally, the cholesterol lowering drug atorvastatin prevents the establishment of intestinal crypt hyperplasia in BrafV600E-mutant mice. Overall, our work unveils the long-term impact of BrafV600E expression in intestinal tissue and suggests that colorectal cancers with mutations in BRAF might be prevented by statins.

Metformin, Statin Use, and Female Colorectal Cancer: A Population-Based Cohort Study in Taiwan

In the last few years, the incidence of colorectal cancer (CRC) in women has gradually increased. However, epidemiological studies on the relationship between type II diabetes mellitus (T2DM) and female CRC and the effect of metformin or statins on female CRC are insufficient. To determine their association, we conducted a population-based cohort study on women in Taiwan. We collected data on a total of 396,521 women aged 40 to 64 years old from 1 January 2007 to 31 December 2009 from the National Health Insurance Research Database. We followed up on all participants in the cohort until the occurrence of CRC, the date for all death, or 31 December 2015. Full development of CRC was identified using the International Classification of Disease (ICD), 9th Revision, code 153. We estimated hazard ratios (HRs) and corresponding 95% confidence intervals (CIs) using the Cox proportional hazards model. Both metformin (adjusted hazard ratio, aHR = 1.12; 95% CI: 0.934–1.335, p = 0.227) and statin (aHR = 1.03; 95% CI: 0.906–1.172, p = 0.645) use showed no association with female CRC in a multivariate analysis. The findings indicate that metformin and statin use showed no protective effect against female colorectal cancer (CRC). An additional randomized trial is necessary to investigate the effect of metformin and statin use in CRC prevention.

Molecular targets of statins and their potential side effects: Not all the glitter is gold

Statins are a class of drugs widely used worldwide to manage hypercholesterolemia and the prevention of secondary heart attacks. Currently, available statins vary in terms of their pharmacokinetic and pharmacodynamic profiles. Although the primary target of statins is the inhibition of HMG-CoA reductase (HMGR), the rate-limiting enzyme in cholesterol biosynthesis, statins exhibit many pleiotropic effects downstream of the mevalonate pathway. These pleiotropic effects include the ability to reduce myocardial fibrosis, pathologic cardiac disease states, hypertension, promote bone differentiation, anti-inflammatory, and antitumor effects through multiple mechanisms. Although these pleiotropic effects of statins may be a cause for enthusiasm, there are many adverse effects that, for the most part, are unappreciated and need to be highlighted. These adverse effects include myopathy, new-onset type 2 diabetes, renal and hepatic dysfunction. Although these adverse effects may be relatively uncommon, considering the number of people worldwide who use statins daily, the actual number of people affected becomes quite large. Also, co-administration of statins with several other medications, herbal agents, and foods, which interact through common enzymatic pathways, can have untoward clinical consequences. In this review, we address these concerns.

Lipoproteins and cancer: The role of HDL-C, LDL-C, and cholesterol-lowering drugs

Cholesterol is an amphipathic sterol molecule that is vital for maintaining normal physiological homeostasis. It is a relatively complicated molecule with 27 carbons whose synthesis starts with 2-carbon units. This in itself signifies the importance of this molecule. Cholesterol serves as a precursor for vitamin D, bile acids, and hormones, including estrogens, androgens, progestogens, and corticosteroids. Although essential, high cholesterol levels are associated with cardiovascular and kidney diseases and cancer initiation, progression, and metastasis. Although there are some contrary reports, current literature suggests a positive association between serum cholesterol levels and the risk and extent of cancer development. In this review, we first present a brief overview of cholesterol biosynthesis and its transport, then elucidate the role of cholesterol in the progression of some cancers. Suggested mechanisms for cholesterol-mediated cancer progression are plentiful and include the activation of oncogenic signaling pathways and the induction of oxidative stress, among others. The specific roles of the lipoprotein molecules, high-density lipoprotein (HDL) and low-density lipoprotein (LDL), in this pathogenesis, are also reviewed. Finally, we hone on the potential role of some cholesterol-lowering medications in cancer.

Long-Term Statin Use, Total Cholesterol Level, and Risk of Colorectal Cancer: A Prospective Cohort Study

INTRODUCTION

Statin use has been examined as a potential chemopreventive strategy against colorectal cancer (CRC). Previous studies have not been able to investigate this topic with adequate follow-up time or disentangle the effects of statin use and total cholesterol level. We investigated prospectively this topic.

METHODS

Eligible participants (100,300 women and 47,991 men) in the Nurses' Health Study and Health Professionals Follow-Up Study were followed for up to 24 years. Cox proportional hazards models were used to estimate hazard ratios and 95% confidence intervals.

RESULTS

We documented 2,924 incident CRC cases during follow-up. In fully adjusted analyses, longer duration of statin use was associated with higher risk of colon cancer (hazard ratios, the 95% confidence interval was 1.09, 0.95-1.25 for 1-5 years; 1.16, 0.99-1.36 for 6-10 years; 1.08, 0.81-1.44 for 11-15 years; 1.85, 1.30-2.61 for >15 years; vs never users, P = 0.004 for trend) rather than rectal cancer. The risk elevation was driven by proximal colon cancer (1.16, 0.98-1.38 for 1-5 years; 1.19, 0.98-1.45 for 6-10 years; 1.25, 0.89-1.74 for 11-15 years; 2.17, 1.46-3.24 for >15 years; vs never users, P = 0.001 for trend) rather than distal colon cancer. The results remained robust in analyses among participants with hypercholesterolemia or who never received screening. Total cholesterol level was not associated with CRC risk.

DISCUSSION

This study does not support benefit of statin use in CRC chemoprevention or any association between total cholesterol level and CRC risk. On the contrary, long-term statin use may be associated with increased colon cancer risk (driven by proximal colon cancer).

AGA Clinical Practice Update on Chemoprevention for Colorectal Neoplasia: Expert Review

DESCRIPTION

The purpose of this expert review is to describe the role of medications for the chemoprevention of colorectal neoplasia. Neoplasia is defined as precancerous lesions (e.g., adenoma and sessile serrated lesion) or cancer. The scope of this review excludes dietary factors and high-risk individuals with hereditary syndromes or inflammatory bowel disease.

METHODS

The best practice advice statements are based on a review of the literature to provide practical advice. A formal systematic review and rating of the quality of evidence or strength of recommendation were not performed. BEST PRACTICE ADVICE 1: In individuals at average risk for CRC who are (1) younger than 70 years with a life expectancy of at least 10 years, (2) have a 10-year cardiovascular disease risk of at least 10%, and (3) not at high risk for bleeding, clinicians should use low-dose aspirin to reduce CRC incidence and mortality. BEST PRACTICE ADVICE 2: In individuals with a history of CRC, clinicians should consider using aspirin to prevent recurrent colorectal neoplasia. BEST PRACTICE ADVICE 3: In individuals at average risk for CRC, clinicians should not use non-aspirin NSAIDs to prevent colorectal neoplasia because of a substantial risk of cardiovascular and gastrointestinal adverse events. BEST PRACTICE ADVICE 4: In individuals with type 2 diabetes, clinicians may consider using metformin to prevent colorectal neoplasia. BEST PRACTICE ADVICE 5: In individuals with CRC and type 2 diabetes, clinicians may consider using metformin to reduce mortality. BEST PRACTICE ADVICE 6: Clinicians should not use calcium or vitamin D (alone or together) to prevent colorectal neoplasia. BEST PRACTICE ADVICE 7: Clinicians should not use folic acid to prevent colorectal neoplasia. BEST PRACTICE ADVICE 8: In individuals at average risk for CRC, clinicians should not use statins to prevent colorectal neoplasia. BEST PRACTICE ADVICE 9: In individuals with a history of CRC, clinicians should not use statins to reduce mortality.

Statins in risk-reduction and treatment of cancer

Statins, which are competitive inhibitors of 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase, reduce cholesterol blood levels and the risk of developing cardiovascular diseases and their related complications. In addition to this main activity, statins show pleiotropic effects such as antioxidant, anti-inflammatory and antiproliferative properties, with applications in many pathologies. Based on their antiproliferative properties, in vitro and in vivo studies have investigated their effects on various types of cancer (i.e., breast cancer, prostate cancer, colorectal cancer, ovarian cancer, lung cancer) with different genetic and molecular characteristics. Many positive results were obtained, but they were highly dependent on the physiochemical properties of the statins, their dose and treatment period. Combined therapies of statins and cytotoxic drugs have also been tested, and synergistic or additive effects were observed. Moreover, observational studies performed on patients who used statins for different pathologies, revealed that statins reduced the risk of developing various cancers, and improved the outcomes for cancer patients. Currently, there are many ongoing clinical trials aimed at exploring the potential of statins to lower the mortality and the disease-recurrence risk. All these results are the foundation of new treatment directions in cancer therapy.

Difference in Physician- and Patient-Dependent Factors Contributing to Adenoma Detection Rate and Serrated Polyp Detection Rate

BACKGROUND

Adenoma detection rate (ADR) is correlated with the risk of interval colorectal cancer and is considered as a quality benchmark for colonoscopy. Serrated polyp detection rate (SPDR) might be a more stringent indicator of quality in polyp detection.

AIMS

To evaluate in a 2-year monocentric observational study patient-dependent and endoscopist-dependent factors influencing ADR and SPDR in daily practice.

METHODS

We determined ADR and SPDR. We collected patient-dependent factors and endoscopist-dependent factors. Links between these data and detection rates were assessed by uni- and multivariate analysis.

RESULTS

A total of 11682 colonoscopies were performed (female: 54.3%; male: 45.7%; median age 58) by 30 endoscopists (female: 9; male: 21). ADR and SPDR were 29.2% and 8%, respectively. In multivariate analysis, ADR was associated with patient-dependent factors: age (OR 1.044, CI 95% 1.040-1.048), male gender (OR 1.7, CI 95% 1.56-1.85), personal history of polyp/cancer (OR 1.53, CI 95% 1.3-1.9), and positive fecal immunochemical test (OR 2.47, CI 95% 2.0-3.1). In multivariate analysis, SPDR was associated with withdrawal time (OR 1.25, CI 95% 1.17-1.32), low volume activity (OR 1.3, CI 95% 1.1-1.52), and personal history of polyp/cancer (OR 1.61, CI 95% 1.15-2.25).

CONCLUSION

In this large series of routine colonoscopies, we found that ADR was mainly driven by patient-dependent conditions, i.e., age, male gender, colonoscopy indication for positive FIT, and a personal history of polyp or cancer. In contrast, SPDR was mainly related to endoscopist-dependent factor, i.e., withdrawal time and low volume activity.

Statins reduce the progression of non-advanced adenomas to colorectal cancer: a postcolonoscopy study in 187 897 patients

BACKGROUND AND AIMS

Postcolonoscopy colorectal cancer (PCCRC) accounts for up to 9% of all CRCs. Statins have been shown to be associated with a lower CRC risk. We aimed to investigate whether PCCRC risk was also lower among statin users.

METHODS

This is a retrospective cohort study using a territory-wide electronic healthcare database in Hong Kong including patients aged 40 years or above who had undergone colonoscopies between 2005 and 2013. Exclusion criteria included prior colorectal cancer (CRC), inflammatory bowel disease, prior colectomy and CRC detected within 6 months of index colonoscopy. We defined statin use as at least 90-day use before index colonoscopy. Medication use was traced up to 5 years before index colonoscopy. PCCRC-3y was defined as cancer diagnosed between 6 and 36 months after index colonoscopy. Sites of CRC were categorised as proximal (proximal to splenic flexure) and distal cancer. The subdistribution HR (SHR) of PCCRC-3y with statin use was derived by propensity score matching based on covariates (including patient factors, concurrent medication use and endoscopy centre's performance).

RESULTS

Of 187 897 eligible subjects, 854 (0.45%) were diagnosed with PCCRC-3y. Statin use was associated with a lower PCCRC-3y risk (SHR: 0.72; 95% CI 0.55 to 0.95; p=0.018). Subgroup analysis shows that SHRs were 0.50 (95% CI 0.28 to 0.91; p=0.022) for proximal and 0.80 (95% CI 0.59 to 1.09; p=0.160) for distal cancer. Older (>60 years) patients, women and those without diabetes mellitus or polyps appeared to benefit more from statins.

CONCLUSIONS

Statins were associated with a lower PCCRC risk, particularly for proximal cancer.

Statin Exposure Is Not Associated with Reduced Prevalence of Colorectal Neoplasia in Patients with Inflammatory Bowel Disease

Background/Aims

Statins have been postulated to lower the risk of colorectal neoplasia. No studies have examined any possible chemopreventive effect of statins in patients with inflammatory bowel disease (IBD) undergoing colorectal cancer (CRC) surveillance. This study examined the association of statin exposure with dysplasia and CRC in patients with IBD undergoing dysplasia surveillance colonoscopies.

Methods

A cohort of patients with IBD undergoing colonoscopic surveillance for dysplasia and CRC at a single academic medical center were studied. The inclusion criteria were IBD involving the colon for 8 years (or any colitis duration if associated with primary sclerosing cholangitis [PSC]) and at least two colonoscopic surveillance exams. The exclusion criteria were CRC or high-grade dysplasia (HGD) prior to or at enrollment, prior colectomy, or limited (<30%) colonic disease. The primary outcome was the frequency of dysplasia and/or CRC in statin-exposed versus nonexposed patients.

Results

A total of 642 patients met the inclusion criteria (57 statin-exposed and 585 nonexposed). The statin-exposed group had a longer IBD duration, longer follow-up period, and more colonoscopies but lower inflammatory scores, less frequent PSC and less use of thiopurines and biologics. There were no differences in low-grade dysplasia, HGD, or CRC development during the follow-up period between the statin-exposed and nonexposed groups (21.1%, 5.3%, 1.8% vs 19.2%, 2.9%, 2.9%, respectively). Propensity score analysis did not alter the overall findings.

Conclusions

In IBD patients undergoing surveillance colonoscopies, statin use was not associated with reduced dysplasia or CRC rates. The role of statins as chemopreventive agents in IBD remains controversial.

Statin uses and mortality in colorectal cancer patients: An updated systematic review and meta-analysis

BACKGROUND

Colorectal cancer (CRC) remains one of the most common types of cancer and a leading cause of death worldwide. Previous studies indicated that statins may have a potential protective effect on CRC.

METHODS

We conducted this meta-analysis to systematically assess the overall and cancer-specific survival benefit of statin uses on CRC patients. Related references were identified through PubMed, the Cochrane Library, Web of Science, EMBASE, and SCOPUS from inception to August 2017. Adjusted hazard ratios (HRs) were adopted to calculate summary hazard ratios (HRs) with 95% confidence intervals (95% CIs), using a random-effects model.

RESULTS

Total fourteen studies involving 130 994 patients were included in this meta-analysis. Six studies reported the association between pre-diagnosis statin uses and CRC mortality, while 11 studies investigated mortality in patients using statins after CRC diagnosis. For pre-diagnosis statin uses, the pooled HR of all-cause mortality (ACM) was 0.85 (95% CI, 0.79-0.92) and the pooled HR of cancer-specific mortality (CSM) was 0.82 (95% CI, 0.79-0.86). In terms of post-diagnosis statin uses, the pooled HR of ACM was 0.86 (95% CI, 0.76-0.98), and the pooled HR of CSM was 0.79 (95% CI, 0.70-0.89). For post-diagnosis statin uses, there is no difference in ACM when stratified by KRAS gene (KRAS) mutation status. Results of ACM and CSM did not markedly alter in other subgroup analyses.

CONCLUSION

Our meta-analysis demonstrates that both pre-diagnosis and post-diagnosis statin uses are associated with reduced ACM and CSM for CRC patients.

Differential preventive activity of sulindac and atorvastatin in Apc+/Min-FCCCmice with or without colorectal adenomas

OBJECTIVE

The response of subjects to preventive intervention is heterogeneous. The goal of this study was to determine if the efficacy of a chemopreventive agent differs in non-tumour-bearing animals versus those with colorectal tumours. Sulindac and/or atorvastatin was administered to Apc^+/Min-FCCC mice with known tumour-bearing status at treatment initiation.

DESIGN

Male mice (6-8 weeks old) underwent colonoscopy and received control chow or chow with sulindac (300 ppm), atorvastatin (100 ppm) or sulindac/atorvastatin. Tissues were collected from mice treated for 14 weeks (histopathology) or 7 days (gene expression). Cell cycle analyses were performed on SW480 colon carcinoma cells treated with sulindac, atorvastatin or both.

RESULTS

The multiplicity of colorectal adenomas in untreated mice bearing tumours at baseline was 3.6-fold higher than that of mice that were tumour free at baseline (P=0.002). Atorvastatin completely inhibited the formation of microadenomas in mice that were tumour free at baseline (P=0.018) and altered the expression of genes associated with stem/progenitor cells. Treatment of tumour-bearing mice with sulindac/atorvastatin led to a 43% reduction in the multiplicity of colorectal adenomas versus untreated tumour-bearing mice (P=0.049). Sulindac/atorvastatin increased the expression of Hoxb13 and Rprm significantly, suggesting the importance of cell cycle regulation in tumour inhibition. Treatment of SW480 cells with sulindac/atorvastatin led to cell cycle arrest (G0/G1).

CONCLUSIONS

The tumour status of animals at treatment initiation dictates response to therapeutic intervention. Atorvastatin eliminated microadenomas in tumour-free mice. The tumour inhibition observed with Sul/Atorva in tumour-bearing mice was greater than that achieved with each agent.

Aspirin alone and combined with a statin suppresses eicosanoid formation in human colon tissue

Eicosanoids, including prostaglandins (PGs) and thromboxanes, are broadly bioactive lipid mediators and increase colon tumorigenesis possibly through chronic inflammatory mechanisms. Epidemiological and experimental data suggest that acetylsalicylic acid (ASA) helps prevent colorectal cancer (CRC), possibly through cyclooxygenase (COX)-mediated suppression of eicosanoid, particularly PGE2, formation. Recent studies suggest that statins prevent CRC and improve survival after diagnosis. We identified patients on ASA and/or statin treatment undergoing routine colonoscopy and measured eicosanoid levels in colonic mucosa with targeted metabolomics technology (LC-MS/MS). ASA-treated individuals (n = 27) had significantly lower tissue eicosanoid levels of most COX-derived metabolites than untreated individuals (n = 31). In contrast, COX-derived lipid metabolites tended to be higher in patients with statin treatment (n = 7) as compared with those not receiving statins (n = 24). This effect was not discernible in subjects treated with ASA and statins (n = 11): Individuals treated with both drugs showed a pronounced suppression of COX-derived eicosanoids in colon tissue, even compared with subjects treated with ASA alone. Our data from a routine clinical setting support the hypothesis that ASA and statins could inhibit CRC development via lipid mediator modification. Further studies should directly investigate the effect of dual ASA and statin treatment on colon tumorigenesis in humans.

The dichotomous role of H2S in cancer cell biology? Déjà vu all over again

Nitric oxide (NO) a gaseous free radical is one of the ten smallest molecules found in nature, while hydrogen sulfide (H2S) is a gas that bears the pungent smell of rotten eggs. Both are toxic yet they are gasotransmitters of physiological relevance. There appears to be an uncanny resemblance between the general actions of these two gasotransmitters in health and disease. The role of NO and H2S in cancer has been quite perplexing, as both tumor promotion and inflammatory activities as well as anti-tumor and antiinflammatory properties have been described. These paradoxes have been explained for both gasotransmitters in terms of each having a dual or biphasic effect that is dependent on the local flux of each gas. In this review/commentary, I have discussed the major roles of NO and H2S in carcinogenesis, evaluating their dual nature, focusing on the enzymes that contribute to this paradox and evaluate the pros and cons of inhibiting or inducing each of these enzymes.

Targeting of stress response pathways in the prevention and treatment of cancer

The hallmarks of tumor tissue are not only genetic aberrations but also the presence of metabolic and oxidative stress as a result of hypoxia and lactic acidosis. The stress activates several prosurvival pathways including metabolic remodeling, autophagy, antioxidant response, mitohormesis, and glutaminolysis, whose upregulation in tumors is associated with a poor survival of patients, while their activation in healthy tissue with statins, metformin, physical activity, and natural compounds prevents carcinogenesis. This review emphasizes the dual role of stress response pathways in cancer and suggests the integrative understanding as a basis for the development of rational therapy targeting the stress response.

Additional Benefits of Routine Drugs on Gastrointestinal Cancer: Statins, Metformin, and Proton Pump Inhibitors

BACKGROUND

Commonly used medications including statins, metformin, and proton pump inhibitors (PPIs) effectively reduce the risk of esophageal, gastric, and colorectal cancer (CRC).

SUMMARY

A number of observational studies and meta-analyses have shown that long-term statin use significantly reduces the incidence of gastrointestinal (GI) cancer. Moreover, statin use after GI cancer diagnosis has been significantly associated with better prognosis in large-scale cohort studies. Metformin was rigorously evaluated in a population-based study and meta-analysis, and was found to have an unexpected benefit in the prevention and prolonged survival of CRC patients with type 2 diabetes mellitus. In contrast, few studies have demonstrated the chemopreventive effect of metformin for esophageal and gastric cancer. Recent observational studies have demonstrated that PPIs effectively reduce the progression of nondysplastic Barrett's esophagus into esophageal adenocarcinoma in a dose-dependent manner. However, the association between chronic PPI use and CRC or gastric cancer risk is still controversial. It was expected that these 3 routinely used medicines would show a synergistic effect with conventional systemic chemotherapy in advanced GI cancers. However, recent phase III studies failed to show significantly better outcomes. Key Messages: Further studies are needed to identify "additional" anticancer effects of these commonly used medicines.

Mendelian randomisation implicates hyperlipidaemia as a risk factor for colorectal cancer

While elevated blood cholesterol has been associated with an increased risk of colorectal cancer (CRC) in observational studies, causality is uncertain. Here we apply a Mendelian randomisation (MR) analysis to examine the potential causal relationship between lipid traits and CRC risk. We used single nucleotide polymorphisms (SNPs) associated with blood levels of total cholesterol (TC), triglyceride (TG), low-density lipoprotein (LDL), and high-density lipoprotein (HDL) as instrumental variables (IV). We calculated MR estimates for each risk factor with CRC using SNP-CRC associations from 9,254 cases and 18,386 controls. Genetically predicted higher TC was associated with an elevated risk of CRC (odds ratios (OR) per unit SD increase = 1.46, 95% confidence interval [CI]: 1.20-1.79, p = 1.68 × 10-4 ). The pooled ORs for LDL, HDL, and TG were 1.05 (95% CI: 0.92-1.18, p = 0.49), 0.94 (95% CI: 0.84-1.05, p = 0.27), and 0.98 (95% CI: 0.85-1.12, p = 0.75) respectively. A genetic risk score for 3-hydoxy-3-methylglutaryl-coenzyme A reductase (HMGCR) to mimic the effects of statin therapy was associated with a reduced CRC risk (OR = 0.69, 95% CI: 0.49-0.99, p = 0.046). This study supports a causal relationship between higher levels of TC with CRC risk, and a further rationale for implementing public health strategies to reduce the prevalence of hyperlipidaemia.

Alpha-glucosidase inhibitor use is associated with decreased colorectal neoplasia risk in patients with type 2 diabetes mellitus receiving colonoscopy: a retrospective study

Purpose

The purpose of this study was to clarify the factors that influence the incidence of colorectal neoplasia in patients with type 2 diabetes mellitus (DM).

Study Design and Setting

Among a total of 1176 patients who underwent total colonoscopy at our hospital, we retrospectively analyzed 168 patients with type 2 DM. Univariate and multivariate logistic regression analyses were then performed to identify the risk factors associated with colorectal neoplasia.

Results

A multivariate analysis of these patients demonstrated that male gender (odds ratio [OR] = 4.04, 95% confidence interval [CI] = 1.67-10.37, p = 0.002), taking statins (OR = 4.59, 95% CI = 1.69-13.43, p = 0.003), taking alpha glucosidase inhibitor (α-GI) (OR = 0.35, 95% CI = 0.13-0.87, p = 0.023) and taking low-dose aspirin (LDA) (OR = 0.32, 95% CI = 0.10-0.95, p = 0.040) were independent factors associated with an increased (male gender and statins) or decreased (α-GI and LDA) risk of colorectal neoplasia.

Conclusions

While male gender and taking statins are risk factors, taking α-GI as well as LDA may reduce the risk of colorectal neoplasia in patients with type2 DM.

Role of second-look endoscopy and prophylactic hemostasis after gastric endoscopic submucosal dissection: A systematic review and meta-analysis

BACKGROUND

Although several studies have shown that second-look endoscopy does not affect the incidence of bleeding after gastric endoscopic submucosal dissection (ESD), the potential roles of second-look endoscopy have not been fully evaluated. This study aimed to determine the role of second-look endoscopy after ESD through a systematic review and meta-analysis.

METHODS

This study conducted a systematic literature search of MEDLINE, EMBASE, and the Cochrane Library through March 2016 using the keywords "second-look," "prophylactic hemostasis," "prophylactic haemostasis," "prevention," "prophylaxis," and "endoscopic submucosal dissection." Studies were included if they evaluated the incidence of post-ESD bleeding according to second-look endoscopy or prophylactic hemostasis during second-look endoscopy.

RESULTS

Four randomized controlled trials on post-ESD bleeding between second-look endoscopy and no second-look endoscopy and 12 non-randomized studies with a cohort design on post-ESD bleeding were included. On meta-analysis, second-look endoscopy did not affect delayed post-ESD bleeding (odds ratio [95% confidence interval] = 1.27 [0.80-2.00], I²  = 0%). During second-look endoscopy, patients who were considered as high-risk for post-ESD bleeding underwent prophylactic hemostasis. Delayed post-ESD bleeding was more common in patients who were treated with hemostasis during second-look endoscopy compared with those who were not (odds ratio [95% confidence interval] = 3.40 [1.87-6.18], I²  = 62%). In patients who underwent prophylactic hemostasis, the number needed to prolong a hospitalization period to avoid one additional post-ESD bleeding after discharge was 25.

CONCLUSION

Second-look endoscopy after ESD could not reduce the risk of delayed post-ESD bleeding. Delayed post-ESD bleeding was more common in patients who underwent prophylactic hemostasis than in those who did not.