Dietary supplement use and colorectal cancer risk: a systematic review and meta-analyses of prospective cohort studies

Folate intake and colorectal cancer risk according to genetic subtypes defined by targeted tumor sequencing

BACKGROUND

Folate is involved in multiple genetic, epigenetic, and metabolic processes, and inadequate folate intake has been associated with an increased risk of cancer.

OBJECTIVE

We examined whether folate intake is differentially associated with colorectal cancer (CRC) risk according to somatic mutations in genes linked to CRC using targeted sequencing.

DESIGN

Participants within two large CRC consortia with available information on dietary folate, supplemental folic acid, and total folate intake were included. Colorectal tumor samples from cases were sequenced for the presence of non-silent mutations in 105 genes and 6 signaling pathways (IGF2/PI3K, MMR, RTK/RAS, TGF-β, WNT, TP53/ATM). Multinomial logistic regression models were run comparing mutated/non-mutated CRC cases to controls to compute multivariable-adjusted odds ratios (ORs) with 95% confidence intervals (CI). Heterogeneity of associations of mutated versus non-mutated CRC cases was tested in case-only analyses using logistic regression. Analyses were performed separately in hypermutated and non-hypermutated tumors, as they exhibit different clinical behaviors.

RESULTS

We included 4,339 CRC cases (702 hypermutated tumors, 16.2%) and 11,767 controls. Total folate intake was inversely associated with CRC risk (OR=0.93, 95%CI=0.90-0.96). Among hypermutated tumors, 12 genes (AXIN2, B2M, BCOR, CHD1, DOCK3, FBLN2, MAP3K21, POLD1, RYR1, TET2, UTP20, ZNF521) showed nominal statistical significance (P<0.05) for heterogeneity by mutation status, but none remained significant after multiple testing correction. Among these genetic subtypes, the associations between folate variables and CRC were mostly inverse or towards the null, except for tumors mutated for DOCK3 (supplemental folic acid), CHD1 (total folate), and ZNF521 (dietary folate) that showed positive associations. We did not observe differential associations in analyses among non-hypermutated tumors, or according to the signaling pathways.

CONCLUSIONS

Folate intake was not differentially associated with CRC risk according to mutations in the genes explored. The nominally significant differential mutation effects observed in a few genes warrants further investigation.

Still too little evidence: the role of diet in colorectal cancer survivorship - a systematic review

Colorectal cancer incidence (CRC) is influenced by dietary factors, yet the impact of diet on CRC-specific mortality and recurrence-free survival (RFS) remains unclear. This review provides a narrative summary of existing research on dietary factors affecting CRC-specific mortality, RFS, and disease-free survival (DFS). This study searched electronic databases to identify cross-sectional/prospective research investigating dietary intake on CRC-specific mortality, RFS, or DFS. Twenty-eight studies were included in the corpus. Because of high study heterogeneity, we performed a narrative synthesis of studies. Limited, but suggestive evidence indicates beneficial effects of adhering to the American Cancer Society (ACS) guidelines and a plant rich low-carbohydrate diet on risk of CRC-specific mortality, potentially driven by fiber from cereals, vegetables, and wholegrains, but not fruit. For RFS and DFS, a Western dietary pattern, high intake of refined grains, and sugar sweetened beverages correlated with increased risk of CRC recurrence and development of disease/death. Conversely, greater adherence to the ACS dietary and alcohol guidelines, higher ω-3 polyunsaturated fatty acids, and dark fish consumption reduced risk. Our findings underscore the need for (i) standardized investigations into diet's role in CRC survivorship, including endpoints, and (ii) comprehensive analyses to isolate specific effects within correlated lifestyle components.

Genetic prediction of micronutrient levels and the risk of colorectal polyps: A mendelian randomization study

OBJECTIVE

Previous epidemiological and experimental studies have yielded conflicting results regarding the influence of human micronutrient levels on the risk of colorectal polyps (CP). In our study, we conducted a two-sample Mendelian randomization (MR) investigation to probe the link between 13 human micronutrients (calcium, selenium, magnesium, phosphorus, folate, vitamins B-6, B-12, C, D, beta-carotene, iron, zinc, and copper) and the genetic susceptibility to CP.

METHODS

Summary statistics for CP (n = 463,010) were obtained from pan-European genome-wide association studies, and instrumental variables for 13 micronutrients were screened from published genome-wide association studies (GWAS). After selecting suitable instrumental variables, we performed a two-sample MR study, deploying sensitivity analyses to judge heterogeneity and pleiotropy, using inverse variance weighted methods as our primary estimation tool.

RESULTS

Our study identified that a genetic predisposition to elevated toenail and circulating selenium or serum β-carotene concentrations lowers the risk of CP occurrence. However, no statistically significant association was observed between the other 11 micronutrients and the risk of CP.

CONCLUSION

The study findings provide evidence that the micronutrient selenium and β-carotene may confer protective effects against the development of CP.

Genetically Determined Circulating Lactase/Phlorizin Hydrolase Concentrations and Risk of Colorectal Cancer: A Two-Sample Mendelian Randomization Study

Previous research has found that milk is associated with a decreased risk of colorectal cancer (CRC). However, it is unclear whether the milk digestion by the enzyme lactase-phlorizin hydrolase (LPH) plays a role in CRC susceptibility. Our study aims to investigate the direct causal relationship of CRC risk with LPH levels by applying a two-sample Mendelian Randomization (MR) strategy. Genetic instruments for LPH were derived from the Fenland Study, and CRC-associated summary statistics for these instruments were extracted from the FinnGen Study, PLCO Atlas Project, and Pan-UK Biobank. Primary MR analyses focused on a cis-variant (rs4988235) for LPH levels, with results integrated via meta-analysis. MR analyses using all variants were also undertaken. This analytical approach was further extended to assess CRC subtypes (colon and rectal). Meta-analysis across the three datasets illustrated an inverse association between genetically predicted LPH levels and CRC risk (OR: 0.92 [95% CI, 0.89-0.95]). Subtype analyses revealed associations of elevated LPH levels with reduced risks for both colon (OR: 0.92 [95% CI, 0.89-0.96]) and rectal cancer (OR: 0.92 [95% CI, 0.87, 0.98]). Consistency was observed across varied analytical methods and datasets. Further exploration is warranted to unveil the underlying mechanisms and validate LPH's potential role in CRC prevention.

Interaction between vitamin E intake and a COMT gene variant on colorectal cancer risk among Korean adults: a case-control study

OBJECTIVES

Previous human trials have not supported the anticarcinogenic effect of vitamin E despite biological plausibility and considerable epidemiological evidence. A possible explanation for this inconsistency is the interactive effect of the catechol-O-methyltransferase (COMT) gene and supplemental vitamin E on cancer. We examined whether a COMT gene variant modulates the effect of dietary vitamin E intake on colorectal cancer (CRC) risk.

METHODS

In this case-control study of Korean adults (975 cases and 975 age- and sex-matched controls), dietary vitamin E density (mg/1,000 kcal) was measured using a semiquantitative food frequency questionnaire, COMT single nucleotide polymorphism (SNP) rs740603 (A>G) was genotyped, and CRC was verified histologically. We estimated odds ratios (ORs) and 95% confidence intervals (CIs) using unconditional logistic regression models with adjustments for potential confounders.

RESULTS

Higher vitamin E density was associated with a lower risk of CRC (highest vs. lowest quartiles: OR, 0.72; 95% CI, 0.55 to 0.96; p-for-trend=0.002). When stratified by COMT SNP rs740603 genotype, the inverse association between vitamin E density and CRC risk was confined to those with at least 1 A allele (≥median vs.

CONCLUSIONS

Our findings support a role for a genetic polymorphism in COMT in modifying the association between dietary vitamin E intake and CRC.

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Key Words

• Case-control studies
• Catechol-O-methyltransferase
• Colorectal cancer
• Gene-environment interaction
• Single nucleotide polymorphism
• Vitamin E

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MESH Headings

• Adult
• Humans
• Catechol O-Methyltransferase/genetics
• Case-Control Studies
• Polymorphism, Single Nucleotide
• Vitamin E
• Logistic Models
• Colorectal Neoplasms/epidemiology
• Colorectal Neoplasms/genetics
• Republic of Korea/epidemiology
• Risk Factors

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Grants

• National Research Foundation of Korea
• 2021R1A6A3A01087058 Ministry of Education
• 2021R1A2C2008439 Ministry of Science and ICT

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Affiliation(s)

Shinyoung Jun Department of Cancer Biomedical Science, National Cancer Center Graduate School of Cancer Science and Policy, Goyang, Korea
Madhawa Gunathilake Department of Cancer Biomedical Science, National Cancer Center Graduate School of Cancer Science and Policy, Goyang, Korea
Jeonghee Lee Department of Cancer Biomedical Science, National Cancer Center Graduate School of Cancer Science and Policy, Goyang, Korea
Jae Hwan Oh Center for Colorectal Cancer, National Cancer Center, Goyang, Korea
Hee Jin Chang Center for Colorectal Cancer, National Cancer Center, Goyang, Korea
Dae Kyung Sohn Center for Colorectal Cancer, National Cancer Center, Goyang, Korea
Aesun Shin Department of Preventive Medicine, Seoul National University College of Medicine, Seoul, Korea Cancer Research Institute, Seoul National University, Seoul, Korea
Jeongseon Kim Department of Cancer, AI & Digital Health, National Cancer Center Graduate School of Cancer Science and Policy, Goyang, Korea

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National and subnational incidence, mortality and associated factors of colorectal cancer in China: A systematic analysis and modelling study

Background

Due to their known variation by geography and economic development, we aimed to evaluate the incidence and mortality of colorectal cancer (CRC) in China over the past decades and identify factors associated with CRC among the Chinese population to provide targeted information on disease prevention.

Methods

We conducted a systemic review and meta-analysis of epidemiolocal studies on the incidence, mortality, and associated factors of CRC among the Chinese population, extracting and synthesising data from eligible studies retrieved from seven global and Chinese databases. We pooled age-standardised incidence rates (ASIRs) and mortality rates (ASMRs) for each province, subregion, and the whole of China, and applied a joinpoint regression model and annual per cent changes (APCs) to estimate the trends of CRC incidence and mortality. We conducted random-effects meta-analyses to assess the effect estimates of identified associated risk factors.

Results

We included 493 articles; 271 provided data on CRC incidence or mortality, and 222 on associated risk factors. Overall, the ASIR of CRC in China increased from 2.75 to 19.39 (per 100 000 person-years) between 1972 and 2019 with a slowed-down growth rate (APC1 = 5.75, APC2 = 0.42), while the ASMR of CRC decreased from 12.00 to 7.95 (per 100 000 person-years) between 1974 and 2020 with a slight downward trend (APC = -0.89). We analysed 62 risk factors with synthesized data; 16 belonging to the categories of anthropometrics factors, lifestyle factors, dietary factors, personal histories and mental health conditions were graded to be associated with CRC risk among the Chinese population in the meta-analysis limited to the high-quality studies.

Conclusions

We found substantial variation of CRC burden across regions and provinces of China and identified several associated risk factors for CRC, which could help to guide the formulation of targeted disease prevention and control strategies.

Registration

PROSPERO: CRD42022346558.

Food Intake and Colorectal Cancer

Colorectal cancer (CRC) accounts for considerable mortalities worldwide. Several modifiable risk factors, including a high intake of certain foods and beverages can cause CRC. This review summarized the latest findings on the intake of various foods, nutrients, ingredients, and beverages on CRC development, with the objective of classifying them as a risk or protective factor. High-risk food items include red meat, processed meat, eggs, high alcohol consumption, sugar-sweetened beverages, and chocolate candy. Food items that are protective include milk, cheese and other dairy products, fruits, vegetables (particularly cruciferous), whole grains, legumes (particularly soy beans), fish, tea (particularly green tea), coffee (particularly among Asians), chocolate, and moderate alcohol consumption (particularly wine). High-risk nutrients/ingredients include dietary fat from animal sources and industrial trans-fatty acids (semisolid/solid hydrogenated oils), synthetic food coloring, monosodium glutamate, titanium dioxide, and high-fructose corn sirup. Nutrients/ingredients that are protective include dietary fiber (particularly from cereals), fatty acids (medium-chain and odd-chain saturated fatty acids and highly unsaturated fatty acids, including omega-3 polyunsaturated fatty acids), calcium, polyphenols, curcumin, selenium, zinc, magnesium, and vitamins A, C, D, E, and B (particularly B6, B9, and B2). A combination of micronutrients and multi-vitamins also appears to be beneficial in reducing recurrent adenoma incidence.

Hormones and Aging: An Endocrine Society Scientific Statement

Multiple changes occur across various endocrine systems as an individual ages. The understanding of the factors that cause age-related changes and how they should be managed clinically is evolving. This statement reviews the current state of research in the growth hormone, adrenal, ovarian, testicular, and thyroid axes, as well as in osteoporosis, vitamin D deficiency, type 2 diabetes, and water metabolism, with a specific focus on older individuals. Each section describes the natural history and observational data in older individuals, available therapies, clinical trial data on efficacy and safety in older individuals, key points, and scientific gaps. The goal of this statement is to inform future research that refines prevention and treatment strategies in age-associated endocrine conditions, with the goal of improving the health of older individuals.

Interaction between retinol intake and ISX rs5755368 polymorphism in colorectal cancer risk: a case-control study in a Korean population

This study aimed to examine whether the ISX rs5755368 genotypes are associated with the effect of dietary retinol consumption on CRC risk. We recruited 923 CRC patients and 1846 controls to identify the association between dietary retinol and CRC risk. Dietary retinol intake was assessed using a semiquantitative food frequency questionnaire. Genotype data were available for 1419 patients (600 cases and 819 controls) of the total study population. Genotyping was performed using an Illumina MEGA Expanded Array. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated using unconditional logistic regression models. Retinol intake was inversely associated with CRC (OR = 0.49; 95% CI = 0.37-0.63). Participants with AA genotype showed lower CRC risk than subjects carrying the G allele (AG + GG) (OR = 0.76; 95% CI = 0.58-0.99). A 68% reduced risk of CRC was related to subjects who had the highest retinol intake and carrying AA genotype compared to the risk of participants consumed the lowest retinol intake and carrying the G allele (OR = 0.32; 95% CI = 0.20-0.53; P interaction = 0.026). Retinol intake could be a protective factor for CRC risk while this association could be strengthened among individuals carrying the homozygous AA genotype.

Metabolomic Analysis of Vitamin E Supplement Use in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial

The effects of vitamin E supplementation on cancer and other chronic diseases are not clear. We compared the serum metabolomic profile of differing vitamin E dosages in order to re-examine the previously observed changes in a novel C22 lactone sulfate compound, androgenic steroids, and other metabolites. A total of 3409 women and men previously selected for metabolomics studies in the PLCO Cancer Screening Trial were included in this investigation. Serum metabolites were profiled using ultrahigh-performance liquid and gas chromatography/tandem mass spectrometry. Seventy known metabolites including C22 lactone sulfate and androgens were significantly associated with vitamin E supplementation. In the sex-stratified analysis, 10 cofactors and vitamins (e.g., alpha-CEHC sulfate and alpha-CEHC glucuronide), two carbohydrates (glyceric and oxalic acids), and one lipid (glycocholenate sulfate) were significantly associated with vitamin E dose in both males and females (FDR-adjusted p-value < 0.01). However, the inverse association between C22 lactone sulfate and daily vitamin E supplementation was evident in females only, as were two androgenic steroids, 5-androstenediol and androsterone glucuronide. Our study provides evidence of distinct steroid hormone pathway responses based on vitamin E dosages. Further studies are needed to gain biological insights into vitamin E biochemical effects relevant to cancer and other chronic diseases.

Colorectal Cancer Chemoprevention: A Dream Coming True?

Colorectal cancer (CRC) is one of the deadliest forms of cancer worldwide. CRC development occurs mainly through the adenoma-carcinoma sequence, which can last decades, giving the opportunity for primary prevention and early detection. CRC prevention involves different approaches, ranging from fecal occult blood testing and colonoscopy screening to chemoprevention. In this review, we discuss the main findings gathered in the field of CRC chemoprevention, focusing on different target populations and on various precancerous lesions that can be used as efficacy evaluation endpoints for chemoprevention. The ideal chemopreventive agent should be well tolerated and easy to administer, with low side effects. Moreover, it should be readily available at a low cost. These properties are crucial because these compounds are meant to be used for a long time in populations with different CRC risk profiles. Several agents have been investigated so far, some of which are currently used in clinical practice. However, further investigation is needed to devise a comprehensive and effective chemoprevention strategy for CRC.

An overview of vitamins as epidrugs for colorectal cancer prevention

Gene expression altering epigenomic modifications such as DNA methylation, histone modification, and chromosome remodeling is crucial to regulating many biological processes. Several lifestyle factors, such as diet and natural, bioactive food compounds, such as vitamins, modify epigenetic patterns. However, epigenetic dysregulation can increase the risk of many diseases, including cancer. Various studies have provided supporting and contrasting evidence on the relationship between vitamins and cancer risk. Though there is a gap in knowledge about whether dietary vitamins can induce epigenetic modifications in the context of colorectal cancer (CRC), the possibility of using them as epidrugs for CRC treatment is being explored. This is promising because such studies might be informative about the most effective way to use vitamins in combination with DNA methyltransferase inhibitors and other approved therapies to prevent and treat CRC. This review summarizes the available epidemiological and observational studies involving dietary, circulating levels, and supplementation of vitamins and their relationship with CRC risk. Additionally, using available in vitro, in vivo, and human observational studies, the role of vitamins as potential epigenetic modifiers in CRC is discussed. This review is focused on the action of vitamins as modifiers of DNA methylation because aberrant DNA methylation, together with genetic alterations, can induce the initiation and progression of CRC. Although this review presents some studies with promising results, studies with better study designs are necessary. A thorough understanding of the underlying molecular mechanisms of vitamin-mediated epigenetic regulation of CRC genes can help identify effective therapeutic targets for CRC prevention and treatment.

Risk-Reducing Measures for Cancer Prevention

Cancer, or malignancy, continues to be one of the most serious health problems in the world, leading to death and disability. Unlike in previous years, where new cases of cancer were predominant in developed nations, the number of cases of cancer and the resultant deaths are increasing in low- and middle-income countries. This is partially attributable to the current trend of adopting a Western lifestyle, substantial urbanization, and the rise in infections, such as the human papillomavirus (HPV) and hepatitis B virus (HBV), which together account for over 30% of cancer cases in underdeveloped and developing nations. The deleterious impact of cancer, as cases multiply worldwide, is multi-dimensional. Cancer exerts serious physical, psychological, and monetary burdens, not only on cancer patients but also on their family members, close friends, health care systems, and society at large. Importantly, over half of all cancer types can be prevented globally by mitigating the risk and causative factors as well as prompt adherence to scientifically recommended prevention measures. This review provides various scientifically based and people-centered strategies that every individual could adopt to reduce their risk of developing cancer in the future. It is recommended that, for these cancer prevention strategies to be effective, there should be a strong political will from the governments of individual countries to enact specific laws and implement policies that will significantly reduce sedentary lifestyles and unhealthy eating among the general public. Likewise, HPV and HBV vaccines, as well as cancer screenings, should be made available, affordable, and accessible on a timely basis for those who are eligible to take them. Finally, intensified campaigns and numerous informative and educational programs that promote cancer prevention should be initiated globally.

Investigating Causal Associations of Diet-Derived Circulating Antioxidants with the Risk of Digestive System Cancers: A Mendelian Randomization Study

Molecular mechanisms and observational studies have found that diet-derived antioxidants are associated with digestive system cancers, whereas there is a lack of causal evidence from randomized clinical trials. In this study, we aimed to assess the causality of these associations through a Mendelian randomization (MR) study. Single nucleotide polymorphisms of diet-derived circulating antioxidants (i.e., α- and γ-tocopherol, ascorbate, retinol, β-carotene, lycopene, and urate), accessed by absolute levels and relative metabolite concentrations, were used as genetic instruments. Summary statistics for digestive system cancers were obtained from the UK Biobank and FinnGen studies. Two-sample MR analyses were performed in each of the two outcome databases, followed by a meta-analysis. The inverse-variance weighted MR was adopted as the primary analysis. Five additional MR methods (likelihood-based MR, MR-Egger, weighted median, penalized weighted median, and MR-PRESSO) and replicate MR analyses for outcomes from different sources were used as sensitivity analyses. Genetically determined antioxidants were not significantly associated with five digestive system cancers, after correcting for multiple tests. However, we found suggestive evidence that absolute ascorbate levels were negatively associated with colon cancer in UK Biobank-the odds ratio (OR) per unit increase in ascorbate was 0.774 (95% confidence interval [CI] 0.608-0.985, p = 0.037), which was consistent with the results in FinnGen, and the combined OR was 0.764 (95% CI 0.623-0.936, p = 0.010). Likewise, higher absolute retinol levels suggestively reduced the pancreatic cancer risk in FinnGen-the OR per 10% unit increase in ln-transformed retinol was 0.705 (95% CI 0.529-0.940, p = 0.017), which was consistent with the results in UK Biobank and the combined OR was 0.747 (95% CI, 0.584-0.955, p = 0.020). Sensitivity analyses verified the above suggestive evidence. Our findings suggest that higher levels of antioxidants are unlikely to be a causal protective factor for most digestive system cancers, except for the suggestive protective effects of ascorbate on colon cancer and of retinol on pancreatic cancer.

Allicin in Digestive System Cancer: From Biological Effects to Clinical Treatment

Allicin is the main active ingredient in freshly-crushed garlic and some other allium plants, and its anticancer effect on cancers of digestive system has been confirmed in many studies. The aim of this review is to summarize epidemiological studies and in vitro and in vivo investigations on the anticancer effects of allicin and its secondary metabolites, as well as their biological functions. In epidemiological studies of esophageal cancer, liver cancer, pancreatic cancer, and biliary tract cancer, the anticancer effect of garlic has been confirmed consistently. However, the results obtained from epidemiological studies in gastric cancer and colon cancer are inconsistent. In vitro studies demonstrated that allicin and its secondary metabolites play an antitumor role by inhibiting tumor cell proliferation, inducing apoptosis, controlling tumor invasion and metastasis, decreasing angiogenesis, suppressing Helicobacter pylori, enhancing the efficacy of chemotherapeutic drugs, and reducing the damage caused by chemotherapeutic drugs. In vivo studies further demonstrate that allicin and its secondary metabolites inhibit cancers of the digestive system. This review describes the mechanisms against cancers of digestive system and therapeutic potential of allicin and its secondary metabolites.

Plasma Circulating Vitamin C Levels and Risk of Endometrial Cancer: A Bi-Directional Mendelian Randomization Analysis

Background

Observational studies indicated that circulating vitamin C (VitC) levels may be correlated with the risk of endometrial cancer (EC). However, the causal effects and direction between them were still unclear.

Methods

In this study, 11 single nucleotide polymorphisms (SNPs) robustly correlated with plasma VitC levels were extracted from the latest genome-wide association study (GWAS), containing 52,018 individuals. Genetic data of EC were obtained from the Endometrial Cancer Association Consortium (ECAC) (12,906 cases and 108,979 controls). An inverse-variance weighted method was utilized as the primary analysis of Mendelian randomization (MR), supplemented by the weighted median, MR Pleiotropy Residual Sum and Outlier test (MR-PRESSO), and MR-Egger methods. Additional sensitivity analyses excluding 3 SNPs with secondary phenotypes were conducted to rule out the possible pleiotropic effects. Potential impacts of several risk factors of EC, such as obesity, body mass index (BMI), hypertension, and diabetes on VitC levels, were assessed. We additionally evaluated the effects of VitC on LDL cholesterol levels, HDL cholesterol levels, and triglycerides levels to probe into the possible mediators in the VitC-EC pathway.

Results

Genetically predicted higher plasma VitC levels (per 1 SD increase, approximately 20 μmol/L) were causally associated with an increased risk of EC overall [odds ratio (OR) 1.374, 95% CI 1.128–1.674, p = 0.0016], supported by complementary sensitivity analyses. In the subgroup analyses, genetically predicted higher levels of VitC were associated with a tendency of increased risks of both endometrioid (OR_SD 1.324, 95% CI 0.959–1.829, p = 0.0881) and non-endometrioid histology (OR_SD 1.392, 95% CI 0.873–2.220, p = 0.1647) while without statistical significance. The association remained significant after the exclusion of the three pleiotropic SNPs (OR_SD 1.394, 95% CI 1.090–1.784, p = 0.0082). The confounders and mediators were unlikely to affect the VitC-EC relationship. The causal effect of EC on VitC levels was not supported (OR 1.001, 95% CI 0.998–1.004, p = 0.4468).

Conclusions

This bi-directional MR study demonstrated a causal risk role of higher circulating VitC at physiological levels on an increased risk of EC, which was independent of confounders and mediators. Further studies are warranted to elucidate the possible mechanisms.

Vitamin C intake and multiple health outcomes: an umbrella review of systematic reviews and meta-analyses

The purpose of this article was to assess the existing systematic reviews and meta-analyses for the association between vitamin C intake and multiple health outcomes. A total of 76 meta-analyses (51 papers) of randomised controlled trials and observational studies with 63 unique health outcomes were identified. Dose-response analysis showed that vitamin C intake was associated with reduced risk of all-cause mortality, cardiovascular disease (CVD), oesophageal cancer, gastric cancer, cervical cancer and lung cancer with an increment of 50-100 mg per day. Beneficial associations were also identified for respiratory, neurological, ophthalmologic, musculoskeletal, renal and dental outcomes. Harmful associations were found for breast cancer and kidney stones for vitamin C supplement intake. The benefits of vitamin C intake outweigh the disadvantages for a range of health outcomes. However, the recommendation of vitamin C supplements needs to be cautious. More prospective studies and well-designed randomised controlled trials (RCTs) are needed.

Vitamin C Intake and Cancers: An Umbrella Review

Based on the existing systematic reviews and meta-analyses, we conducted this umbrella review aiming at evaluating the quality of evidence, validity and biases of the relationship between vitamin C (VC) intake and incidence and outcomes of multiple cancers. We identified 22 cancer outcomes within 3,562 articles. VC consumption was associated with lower incidence of bladder cancer, breast cancer, cervical tumors, endometrial cancer, esophageal cancer, gastric cancer, glioma, lung cancer, pancreatic cancer, prostate cancer, renal cell cancer, and total cancer occurrence. VC intake was also related to decreased risk of breast cancer prognosis (recurrence, cancer-specific mortality, and all-cause mortality).

Composite dietary antioxidant index and the risk of colorectal cancer: Findings from the Singapore Chinese Health Study

Colorectal cancer (CRC) is a major contributor to cancer death globally. Several studies showed some protections by certain individual dietary antioxidants against CRC development. Epidemiologic data on the composite dietary antioxidant index (CDAI) in relation to CRC risk are sparse. Using the Singapore Chinese Health Study, an ongoing prospective cohort consisting of 61 321 cancer-free participants aged 45 to 74 years at baseline, a food-based CDAI was calculated according to a previously established and validated method that included six food-sourced antioxidants including vitamins A, C and E, manganese, selenium and zinc. Cox proportional hazard regression method was used to estimate the hazard ratios (HRs) and their 95% confidence intervals (CIs) for CRC associated with various levels of CDAI with adjustment for multiple potential confounders. After an average of 17.5 years of follow-up, 2140 participants developed CRC. HRs (95% CIs) of CRC for quartiles 2, 3 and 4 of CDAI were 0.94 (0.83-1.07), 0.86 (0.75-1.00) and 0.80 (0.66-0.98), respectively, compared to the lowest quartile (P_trend  = .02). This inverse association between CDAI and CRC risk was more apparent in women or those without a history of diabetes, without family history of CRC, never smokers or overweight/obese individuals. However, none of the heterogeneity tests for the CDAI-CRC risk association reached statistical significance. Our findings suggest that food-based antioxidants may be beneficial for reducing the risk of CRC in the general population.

Effects of garlic intake on cancer: a systematic review of randomized clinical trials and cohort studies

BACKGROUND/OBJECTIVES

Due to the rapid increase of global cancer incidence and mortality and a high level of interest in cancer prevention, a systematic review of garlic intake and cancer risk is needed.

SUBJECTS/METHODS

We implemented a systematic review to examine the effects of varying levels of garlic intake on cancer. We conducted comprehensive literature searches in three electronic databases (MEDLINE, Embase, and Web of Science) for studies published between database inception and July or September of 2018. Two investigators independently screened abstracts and full-texts, extracted data, and assessed risk of bias (RoB). A total of one medium-quality randomized controlled trial (RCT) and 13 cohort studies graded as high RoB were included.

RESULTS

The 1-year follow-up results from a RCT showed that a significant decrease in the number and size of colorectal adenomas among participants with colorectal adenomas who received high-dose aged garlic extract (AGE) compared with those who received low-dose AGE (P < 0.05). The results of prospective observational studies provided inconsistent associations of colorectal cancer risk with garlic supplements and garlic intake as food.

CONCLUSIONS

In summary, the AGE was effective in reducing the number and magnitude of colorectal adenomas in one RCT, but there were inconsistent associations between garlic intake and colorectal cancer in cohort studies. Therefore, we could not draw a firm conclusion regarding the effects of garlic on cancer, because the current strength of evidence is inadequate due to a lack of number of high-quality RCTs.

The role of calcium and vitamin D dietary intake on risk of colorectal cancer: systematic review and meta-analysis of case-control studies

PURPOSE

The aim of this study is to analyze the current evidence about the relationships between calcium/vitamin D and CRC based on case-control studies according to sex, tumor location and continental region to complement the information obtained in meta-analyses of other designs.

METHODS

The articles were located in three databases (PUBMED, EMBASE and SCOPUS), they should be written in English language, with a case and control design and published between 1 January 1970 and 31 October 2019.

RESULTS

There were 37 selected studies, 32 for intake of calcium, that involved 24,353 CRC cases and 30,650 controls, and 23 for that of VIT D, with a total of 19,076 cases and 36.746 controls included. For dietary calcium intake, the overall OR was 0.94 (95% CI 0.92-0.97), suggesting a reducing effect with a 6% decrease in CRC risk for every 300 mg of calcium ingested daily. Regarding vitamin D intake a global OR of 0.96 (95% CI 0.93-0.98) was observed, what means a 4% decrease in the risk of CRC per 100 IU/day of vitamin D.

CONCLUSION

Higher dietary intakes of calcium and vitamin D are associated to a decreased risk of CRC.

Multivitamin Use and Overall and Site-Specific Cancer Risks in the National Institutes of Health-AARP Diet and Health Study

BACKGROUND

Multivitamins are among the most commonly used supplements in the United States, but their effectiveness in preventing cancer remains unclear.

OBJECTIVES

We prospectively examined the association between multivitamin use and risks of overall and site-specific cancer in a large, well-characterized cohort to ascertain potential preventive or harmful relationships.

METHODS

We examined 489,640 participants ages 50-71 in the NIH-American Association of Retired Persons (AARP) Diet and Health Study who were enrolled from 1995 to 1998. We linked to 11 state cancer registries in order to identify incident cancers. Multivitamin use was assessed by a baseline questionnaire. Cox proportional hazards regression models of multivitamin use were used to estimate HRs and 95% CIs for cancer risks in men and women, adjusted for potential confounders, including age, BMI, smoking, physical activity, the Healthy Eating Index 2015 score, and use of single-vitamin/-mineral supplements.

RESULTS

A slightly higher overall cancer risk was observed in men (but not women) who consumed 1 or more multivitamins daily compared to nonusers [HRs, 1.02 (95% CI: 1.01-1.04) and 1.03 (95% CI: 1.00-1.07), respectively; P-trend = 0.002]. The latter reflected higher risks for prostate cancer (HR, 1.04; 95% CI: 0.98-1.10; P-trend = 0.005), lung cancer (HR, 1.07; 95% CI: 0.96-1.20; P-trend = 0.003), and leukemia (HR, 1.26; 95% CI: 1.02-1.57; P-trend = 0.003). Taking more than 1 multivitamin daily was also strongly positively associated with the risk of oropharyngeal cancer in women (HR, 1.53, 95% CI: 1.04-2.24; P-trend < 0.0001). By contrast, daily multivitamin use was inversely associated with the colon cancer risk in both sexes (HR, 0.82; 95% CI: 0.73-0.93; P-trend = 0.0003).

CONCLUSIONS

We found little evidence to support a cancer-preventive role for multivitamin use, with the exception of colon cancer, in both sexes in the NIH-AARP Diet and Health Study. In addition, slightly higher risks of overall, prostate, and lung cancer, as well as leukemia, were observed for greater multivitamin use in men, with a higher oropharyngeal cancer risk in women.

Circulating vitamin C concentration and risk of cancers: a Mendelian randomization study

BACKGROUND

Circulating vitamin C concentrations have been associated with several cancers in observational studies, but little is known about the causal direction of the associations. This study aims to explore the potential causal relationship between circulating vitamin C and risk of five most common cancers in Europe.

METHODS

We used summary-level data for genetic variants associated with plasma vitamin C in a large vitamin C genome-wide association study (GWAS) meta-analysis on 52,018 Europeans, and the corresponding associations with lung, breast, prostate, colon, and rectal cancer from GWAS consortia including up to 870,984 participants of European ancestry. We performed two-sample, bi-directional Mendelian randomization (MR) analyses using inverse-variance-weighted method as the primary approach, while using 6 additional methods (e.g., MR-Egger, weighted median-based, and mode-based methods) as sensitivity analysis to detect and adjust for pleiotropy. We also conducted a meta-analysis of prospective cohort studies and randomized controlled trials to examine the association of vitamin C intakes with cancer outcomes.

RESULTS

The MR analysis showed no evidence of a causal association of circulating vitamin C concentration with any examined cancer. Although the odds ratio (OR) per one standard deviation increase in genetically predicted circulating vitamin C concentration was 1.34 (95% confidence interval 1.14 to 1.57) for breast cancer in the UK Biobank, this association could not be replicated in the Breast Cancer Association Consortium with an OR of 1.05 (0.94 to 1.17). Smoking initiation, as a positive control for our reverse MR analysis, showed a negative association with circulating vitamin C concentration. However, there was no strong evidence of a causal association of any examined cancer with circulating vitamin C. Sensitivity analysis using 6 different analytical approaches yielded similar results. Moreover, our MR results were consistent with the null findings from the meta-analysis exploring prospective associations of dietary or supplemental vitamin C intakes with cancer risk, except that higher dietary vitamin C intake, but not vitamin C supplement, was associated with a lower risk of lung cancer (risk ratio: 0.84, 95% confidence interval 0.71 to 0.99).

CONCLUSIONS

These findings provide no evidence to support that physiological-level circulating vitamin C has a large effect on risk of the five most common cancers in European populations, but we cannot rule out very small effect sizes.

Risk factors for early-onset colorectal cancer: a population-based case-control study in Ontario, Canada

Purpose

There has been an alarming increase in colorectal cancer (CRC) incidence among young adults aged < 50 years, and factors driving this upward trend are unknown. This study investigated associations between various medical, lifestyle, and dietary factors and risk of early-onset CRC (EO-CRC).

Methods

A population-based case–control study was conducted in Ontario, Canada during 2018–2019. EO-CRC cases aged 20–49 years (n = 175) were identified from the Ontario Cancer Registry; sex- and age group-matched controls (n = 253) were recruited through random digit dialing. Data on potential a priori risk factors were collected using a web-based self-reported questionnaire. Odds ratios (OR) and 95% confidence intervals (CI) were estimated using multivariable logistic regression.

Results

Family history of CRC in a first- or second-degree relative (OR 2.37; 95% CI 1.47–3.84), longer sedentary time (≥ 10 vs. < 5 h/day, OR 1.93; 95% CI 1.02–3.65), greater consumption of sugary drinks (≥ 7 vs. < 1 drinks/week, OR 2.99; 95% CI 1.57–5.68), and a more Westernized dietary pattern (quartile 4 vs. 1, OR 1.92; 95% CI 1.01–3.66) were each associated with an increased risk of EO-CRC. Conversely, calcium supplement use (OR 0.53; 95% CI 0.31–0.92), history of allergy or asthma (OR 0.62; 95% CI 0.39–0.98), and greater parity in females (≥ 3 vs. nulliparity, OR 0.29; 95% CI 0.11–0.76) were each associated with a reduced risk.

Conclusion

Modifiable factors, particularly sedentary behavior and unhealthy diet including sugary drink consumption, may be associated with EO-CRC risk. Our findings, if replicated, may help inform prevention strategies targeted at younger persons.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10552-021-01456-8.

Vitamin D Intake and the Risk of Colorectal Cancer: An Updated Meta-Analysis and Systematic Review of Case-Control and Prospective Cohort Studies

Simple Summary

Colorectal cancer (CRC) is the third most diagnosed cancer in men and the second in women worldwide, being the second most deadly cancer worldwide. The evidence coming from experimental studies suggest a protective effect of vitamin D intake on the risk of CRC. Different studies have shown that vitamin D may play a chemopreventive role in colorectal adenoma incidence, malignant transformation and progression. Our objective was to conduct an updated systematic review and meta-analysis of both case-control and prospective cohort studies on vitamin D intake and CRC. This manuscript provides a complete and updated state-of-the-art about vitamin D intake and CRC risk.

Abstract

Obesity, a sedentary lifestyle, high red meat consumption and alcohol, and tobacco are considered the driving factors behind colorectal cancer (CRC) worldwide. Both diet and lifestyle are recognized to play an important role in the prevention of CRC. Forty years later, the vitamin D–cancer hypothesis is considered consistent. However, the relationship between low vitamin D intake and CRC is still controversial. The aim of this meta-analysis is to determine the associations between Vitamin D intake and CRC. MEDLINE-PubMed and Cochrane databases were searched up to May 2020 for studies evaluating the association between vitamin D intake (from foods and supplements) and CRC. Two reviewers, working independently, screened all titles and abstracts to identify the studies that met the inclusion criteria (case-control or prospective cohort (PC) studies published in English). Data were pooled by the generic inverse variance method using a random or fixed effect model. Heterogeneity was identified using the Cochran Q-test and quantified by the I² statistic. A total of 31 original studies were included for the quantitative meta-analysis, comprising a total 47.540 cases and 70.567 controls in case-control studies, and a total of 14.676 CRC-incident cases (out of 808.130 subjects in PC studies) from 17 countries. A significant 25% lower risk was reported comparing the highest vs. the lowest dietary vitamin D consumption and CRC risk (odds ratio (95% confidence interval): 0.75 (0.67; 0.85)) in case-control studies, whereas a non-significant association was reported in case of prospective studies (hazard ratio (95% confidence interval): 0.94 (0.79; 1.11). The present meta-analysis demonstrates that high dietary vitamin D is associated to CRC prevention. However, larger and high-quality prospective studies and clinical trials are warranted to confirm this association.

Comprehensive Assessment of Diet Quality and Risk of Precursors of Early-Onset Colorectal Cancer

BACKGROUND

The role of poor diet quality in the rising incidence of colorectal cancer (CRC) diagnosed younger than age 50 years has not been explored. Based on molecular features of early-onset CRC, early-onset adenomas are emerging surrogate endpoints.

METHODS

In a prospective cohort study (Nurses' Health Study II), we evaluated 2 empirical dietary patterns (Western and prudent) and 3 recommendation-based indexes (Dietary Approaches to Stop Hypertension [DASH], Alternative Mediterranean Diet [AMED], and Alternative Healthy Eating Index [AHEI]-2010) with risk of early-onset adenoma overall and by malignant potential (high-risk: ≥1 cm, tubulovillous or villous histology, high-grade dysplasia, or ≥3 adenomas), among 29 474 women with 1 or more lower endoscopy before age 50 years (1991-2011). Multivariable logistic regressions were used to estimate odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

We documented 1157 early-onset adenomas with 375 at high risk. Western diet was positively associated, whereas prudent diet, DASH, AMED, and AHEI-2010 were inversely associated with risk of early-onset adenoma. The associations were largely confined to high-risk adenomas (the highest vs lowest quintile: Western, OR = 1.67, 95% CI = 1.18 to 2.37; prudent, OR = 0.69, 95% CI = 0.48 to 0.98; DASH, OR = 0.65, 95% CI = 0.45 to 0.93; AMED, OR = 0.55, 95% CI = 0.38 to 0.79; AHEI-2010, OR = 0.71, 95% CI = 0.51 to 1.01; all Ptrend ≤ .03), driven by those identified in the distal colon and rectum (all Ptrend ≤ .04, except AMED: Ptrend = .14).

CONCLUSION

Poor diet quality was associated with an increased risk of early-onset distal and rectal adenomas of high malignant potential. These findings provide preliminary but strong support to the role of diet in early-onset CRC.

Role of Diet in Colorectal Cancer Incidence: Umbrella Review of Meta-analyses of Prospective Observational Studies

IMPORTANCE

Several meta-analyses have summarized evidence for the association between dietary factors and the incidence of colorectal cancer (CRC). However, to date, there has been little synthesis of the strength, precision, and quality of this evidence in aggregate.

OBJECTIVE

To grade the evidence from published meta-analyses of prospective observational studies that assessed the association of dietary patterns, specific foods, food groups, beverages (including alcohol), macronutrients, and micronutrients with the incidence of CRC.

DATA SOURCES

MEDLINE, Embase, and the Cochrane Library were searched from database inception to September 2019.

EVIDENCE REVIEW

Only meta-analyses of prospective observational studies with a cohort study design were eligible. Evidence of association was graded according to established criteria as follows: convincing, highly suggestive, suggestive, weak, or not significant.

RESULTS

From 9954 publications, 222 full-text articles (2.2%) were evaluated for eligibility, and 45 meta-analyses (20.3%) that described 109 associations between dietary factors and CRC incidence were selected. Overall, 35 of the 109 associations (32.1%) were nominally statistically significant using random-effects meta-analysis models; 17 associations (15.6%) demonstrated large heterogeneity between studies (I2 > 50%), whereas small-study effects were found for 11 associations (10.1%). Excess significance bias was not detected for any association between diet and CRC. The primary analysis identified 5 (4.6%) convincing, 2 (1.8%) highly suggestive, 10 (9.2%) suggestive, and 18 (16.5%) weak associations between diet and CRC, while there was no evidence for 74 (67.9%) associations. There was convincing evidence of an association of intake of red meat (high vs low) and alcohol (≥4 drinks/d vs 0 or occasional drinks) with the incidence of CRC and an inverse association of higher vs lower intakes of dietary fiber, calcium, and yogurt with CRC risk. The evidence for convincing associations remained robust following sensitivity analyses.

CONCLUSIONS AND RELEVANCE

This umbrella review found convincing evidence of an association between lower CRC risk and higher intakes of dietary fiber, dietary calcium, and yogurt and lower intakes of alcohol and red meat. More research is needed on specific foods for which evidence remains suggestive, including other dairy products, whole grains, processed meat, and specific dietary patterns.

Dietary Factors Modulating Colorectal Carcinogenesis

The development of colorectal cancer, responsible for 9% of cancer-related deaths, is favored by a combination of genetic and environmental factors. The modification of diet and lifestyle may modify the risk of colorectal cancer (CRC) and prevent neoplasia in up to 50% of cases. The Western diet, characterized by a high intake of fat, red meat and processed meat has emerged as an important contributor. Conversely, a high intake of dietary fiber partially counteracts the unfavorable effects of meat through multiple mechanisms, including reduced intestinal transit time and dilution of carcinogenic compounds. Providing antioxidants (e.g., vitamins C and E) and leading to increased intraluminal production of protective fermentation products, like butyrate, represent other beneficial and useful effects of a fiber-rich diet. Protective effects on the risk of developing colorectal cancer have been also advocated for some specific micronutrients like vitamin D, selenium, and calcium. Diet-induced modifications of the gut microbiota modulate colonic epithelial cell homeostasis and carcinogenesis. This can have, under different conditions, opposite effects on the risk of CRC, through the production of mutagenic and carcinogenic agents or, conversely, of protective compounds. The aim of this review is to summarize the most recent evidence on the role of diet as a potential risk factor for the development of colorectal malignancies, as well as providing possible prevention dietary strategies.

Association Between Folate and Health Outcomes: An Umbrella Review of Meta-Analyses

Background: There is no study that has systematically investigated the breadth and validity of the associations of folate and multiple health outcomes. We aimed to evaluate the quantity, validity, and credibility of evidence regarding associations between folate and multiple health outcomes by using umbrella review of meta-analysis. Methods: We searched the MEDLINE, EMBASE, and Cochrane Library databases from inception to May 20, 2018, to identify potential meta-analyses that examined the association of folate with any health outcome. For each included meta-analysis, we estimated the summary effect size and their 95% confidence interval using the DerSimonian and Laird random-effects model. We used the AMSTAR 2 (A Measurement Tool to Assess Systematic Reviews) to assess methodological quality and the GRADE (Grading of Recommendations, Assessment, Development, and Evaluation working group classification) to assess the quality of evidence for each outcome included in the umbrella review. Results: Overall, 108 articles reporting 133 meta-analyses of observational studies and 154 meta-analyses of randomized controlled trials (RCTs) were included in the study. Among them, 108 unique exposure-outcome-population triplets (referred to as unique meta-analyses hereafter) of RCTs and 87 unique meta-analyses of observational studies were reanalyzed. Beneficial effects of folate were observed in the all-cause mortality rate and in a number of chronic diseases, including several birth/pregnancy outcomes, several cancers, cardiovascular disease and metabolic-related outcomes, neurological conditions, and several other diseases. However, adverse effects of folate were observed for prostate cancer, colorectal adenomatous lesions, asthma or wheezing, and wheezing as an isolated symptom and depression. Conclusions: Current evidence allows for the conclusion that folate is associated with decreased risk of all-cause mortality and a wide range of chronic diseases. However, folate may be associated with an increased risk of prostate cancer. Further research is warranted to improve the certainty of the estimates.

Genetically proxied milk consumption and risk of colorectal, bladder, breast, and prostate cancer: a two-sample Mendelian randomization study

BACKGROUND

Observational studies have shown that milk consumption is inversely associated with colorectal, bladder, and breast cancer risk, but positively associated with prostate cancer. However, whether the associations reflect causality remains debatable. We investigated the potential causal associations of milk consumption with the risk of colorectal, bladder, breast, and prostate cancer using a genetic variant near the LCT gene as proxy for milk consumption.

METHODS

We obtained genetic association estimates for cancer from the UK Biobank (n = 367,643 women and men), FinnGen consortium (n = 135,638 women and men), Breast Cancer Association Consortium (n = 228,951 women), and Prostate Cancer Association Group to Investigate Cancer Associated Alterations in the Genome consortium (n = 140,254 men). Milk consumption was proxied by a genetic variant (rs4988235 or rs182549) upstream of the gene encoding lactase, which catalyzes the breakdown of lactose.

RESULTS

Genetically proxied milk consumption was associated with a reduced risk of colorectal cancer. The odds ratio (OR) for each additional milk intake increasing allele was 0.95 (95% confidence interval [CI] 0.91-0.99; P = 0.009). There was no overall association of genetically predicted milk consumption with bladder (OR 0.99; 95% CI 0.94-1.05; P = 0.836), breast (OR 1.01; 95% CI 1.00-1.02; P = 0.113), and prostate cancer (OR 1.01; 95% CI 0.99-1.02; P = 0.389), but a positive association with prostate cancer was observed in the FinnGen consortium (OR 1.07; 95% CI 1.01-1.13; P = 0.026).

CONCLUSIONS

Our findings strengthen the evidence for a protective role of milk consumption on colorectal cancer risk. There was no or limited evidence that milk consumption affects the risk of bladder, breast, and prostate cancer.

Recent advances in clinical practice: colorectal cancer chemoprevention in the average-risk population

Colorectal cancer (CRC) is one of the most common and lethal malignancies in Western countries. Its development is a multistep process that spans more than 15 years, thereby providing an opportunity for prevention and early detection. The high incidence and mortality rates emphasise the need for prevention and screening. Many countries have therefore introduced CRC screening programmes. It is expected, and preliminary evidence in some countries suggests, that this screening effort will decrease CRC-related mortality rates. CRC prevention involves a healthy lifestyle and chemoprevention-more specifically, oral chemoprevention that can interfere with progression from a normal colonic mucosa to adenocarcinoma. This preventive effect is important for individuals with a genetic predisposition, but also in the general population. The ideal chemopreventive agent, or combination of agents, remains unknown, especially when considering safety during long-term use. This review evaluates the evidence across 80 meta-analyses of interventional and observational studies of CRC prevention using medications, vitamins, supplements and dietary factors. This review suggests that the following factors are associated with a decreased incidence of CRC: aspirin, non-steroidal anti-inflammatory drugs, magnesium, folate, a high consumption of fruits and vegetables, fibre and dairy products. An increased incidence of CRC was observed with frequent alcohol or meat consumption. No evidence of a protective effect for tea, coffee, garlic, fish and soy products was found. The level of evidence is moderate for aspirin, β-carotene and selenium, but is low or very low for all other exposures or interventions.

Bisphosphonates and risk of cancers: a systematic review and meta-analysis

Background

It is unclear whether bisphosphonates are associated with risk of cancers. Therefore, this meta-analysis aimed to evaluate the effect of bisphosphonates on overall cancers.

Methods

A search in Pubmed, Embase, Cochrane Library and Web of Science databases was conducted, from the inception date of each resource to September 26, 2019. The summarised effect estimates with 95% CIs were calculated using a random-effect model. Heterogeneity and publication bias were explored.

Results

Thirty-four articles were included in this study (4,508,261 participants; 403,196 cases). The results revealed that bisphosphonates significantly decreased the risk of colorectal cancer (RR = 0.89, 95% CI: 0.81–0.98), breast cancer (RR = 0.87, 95% CI: 0.82–0.93) and endometrial cancer (RR = 0.75, 95% CI: 0.61–0.94), but no significant association was observed in all-cause cancer. Furthermore, nitrogen-containing bisphosphonates only had protective effects both on breast cancer (RR = 0.94, 95% CI: 0.90–0.99) and endometrial cancer (RR = 0.70, 95% CI: 0.54–0.92). Non-nitrogen-containing bisphosphonates tended to increase the risk of liver cancer (RR = 2.14, 95% CI: 1.23–3.72) and pancreas cancer (RR = 1.75, 95% CI: 1.32–2.33).

Conclusion

Bisphosphonates are significantly associated with risk reduction of colorectal, breast and endometrial cancer, especially nitrogen-containing bisphosphonates. It should be noted that non-nitrogen-containing bisphosphonates might increase the risk of liver and pancreas cancer. Large prospective cohort studies are needed to find the causal association between bisphosphonates and risk of cancers.

The Incidence Rate of Colorectal Cancer in Saudi Arabia: An Observational Descriptive Epidemiological Analysis

Introduction

Colorectal cancer (CRC) is the third most commonly diagnosed malignancy and its incidence, as well as mortality rate, is increasing globally. In this paper, the epidemiological analysis of CRC which includes colon cancer (CC) and rectum cancer (RC) is done among the Saudi Arabian population based on the registered cases in the Saudi cancer registry between 2006 and 2016. The study describes the crude incidence rates (CIRs) and age-standardized incidence rates (ASIRs) of colorectal cancer by year of diagnosis, age group, and administrative regions to explore the spread, distribution, trend, and factual state of the disease in Saudi Arabia.

Methodology

For statistical analysis of data, t-test, sex ratio, descriptive statistics, and Kruskal–Wallis were done using IBM Statistical Package for the Social Sciences version 20.0 (SPSS). A total of 7849 and 5164 of colorectal cancer and rectum cancer cases were reported from January 2006 to December 2016, respectively.

Results

Results displayed that CRC is more frequent in males than females and have a high mean number and percentage in the old age group (60–75 and above). Riyadh (for CC and RC), Makkah (CC), and Eastern Province (RC) showed the highest mean CIR and ASIR for males. The highest CIR sex ratio was calculated in Jouf and Madinah for CC whereas Qassim, Jazan, and Tabuk were calculated highest for RC. Highest ASIR sex ratio reported in Jouf (CC) and Tabuk (RC). Lowest CIR and ASIR among males were reported in Baha (CC) and northern region (RC). In females, the highest mean CIR and ASIR were reported in Riyadh (CC and RC) and Makkah (CC). Lowest CIR and ASIR among females were reported in Jazan in both CC and RC.

Conclusion

Regions of Eastern Province, Northern Region, and Jouf showed the most significant changes of CIRs and ASIRs for both cancers, whereas the least significant change was reported in Jazan from 2006 to 2016.

Phytochemical compounds targeting on Nrf2 for chemoprevention in colorectal cancer

Colorectal cancer (CRC) has become one of the major factors of tumor-related morbidity and mortality in the world because of its poor prognosis and consequences of metastatic spread. Currently, chemoprevention has been considered as a way of preventing cancer who takes advantage of plant phytochemicals and synthetic compounds. Phytochemical compounds are receiving much considerable attention for their ability in chemoprevention due to low toxicity and cost. For strategies of chemoprevention, keeping the balance of internal and external environment in cells or tissues is important. Hence, it is particularly important to eliminate overmuch carcinogens and carcinogenic metabolites by phase 2 detoxifying enzymes and antioxidant enzymes such as glutathione S-transferase (GST), heme oxygenase-1(HO-1) and so on. Nuclear factor-erythroid 2-related factor 2 (Nrf2) plays a key role in regulating these enzymes via mediating antioxidant response elements (ARE). In this review, we collected recent studies of phytochemical compounds targeting on Nrf2 in CRC treatment. We summarized the mechanisms of these compounds in activating Nrf2, and their effects on chemotherapeutic agents.

Statin use and the risk of colorectal cancer in a population-based electronic health records study

There is extensive debate regarding the protective effect of 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors (statins) on colorectal cancer (CRC). We aimed to assess the association between CRC risk and exposure to statins using a large cohort with prescription data. We carried out a case-control study in Catalonia using the System for Development of Primary Care Research (SIDIAP) database that recorded patient diseases history and linked data on reimbursed medication. The study included 25 811 cases with an incident diagnosis of CRC between 2010 and 2015 and 129 117 frequency-matched controls. Subjects were classified as exposed to statins if they had ever been dispensed statins. Analysis considering mean daily defined dose, cumulative duration and type of statin were performed. Overall, 66 372 subjects (43%) were exposed to statins. There was no significant decrease of CRC risk associated to any statin exposure (OR = 0.98; 95% CI: 0.95–1.01). Only in the stratified analysis by location a reduction of risk for rectal cancer was observed associated to statin exposure (OR = 0.87; 95% CI: 0.81–0.92). This study does not support an overall protective effect of statins in CRC, but a protective association with rectal cancer merits further research.

The Association between Prebiotic Fiber Supplement Use and Colorectal Cancer Risk and Mortality in the Women's Health Initiative

BACKGROUND

Fiber-based prebiotic supplements are marketed for maintaining bowel health and promoting beneficial gut bacteria. However, the association between prebiotic supplement use and colorectal cancer risk and mortality is unknown.

METHODS

The association between prebiotic use and colorectal cancer risk and mortality was evaluated in postmenopausal women in the Women's Health Initiative study. Self-reported prebiotic use was documented at study enrollment. Adjudicated colorectal cancer cases and mortality were captured using medical and death records. Cox proportional hazards models were used to estimate the HR related to prebiotic use and colorectal cancer risk and mortality.

RESULTS

In total, 3,032 colorectal cancer cases were diagnosed during an average 15.4 years of follow-up. Overall, 3.7% of women used a prebiotic with psyllium, the major fiber type. Use of any prebiotic supplement was not associated with colorectal cancer risk or mortality. The type of prebiotic supplement (none vs. insoluble or soluble) was not associated with colorectal cancer risk; however, use of insoluble fiber prebiotics compared with none was associated with higher colorectal cancer mortality [HR, 2.79; 95% confidence interval (CI), 1.32-5.90; P = 0.007]. Likelihood ratio tests indicated no significant interactions between prebiotic use and other colorectal cancer risk factors, including metabolic syndrome.

CONCLUSIONS

Prebiotic fiber supplement use was not associated with colorectal cancer risk. Insoluble, but not soluble, prebiotic fiber use was associated with higher colorectal cancer mortality. These findings do not support the promotion of prebiotic fiber supplements to reduce colorectal cancer risk or colorectal cancer mortality.

IMPACT

Further investigation is warranted for findings regarding insoluble prebiotic fiber and higher colorectal cancer mortality in postmenopausal women.

Folate and Its Impact on Cancer Risk

PURPOSE OF REVIEW

Research has evaluated the potential impact of folate on cancer risk with conflicting findings. Studies have demonstrated increased risk, no effect, and decreased risk. This review summarizes findings of mixed results between folate intake, serum levels, gene polymorphisms, and cancer risk based on meta-analyses from the past five years.

RECENT FINDING

Low or deficient folate status is associated with increased risk of many cancers. Folic acid supplementation and higher serum levels are associated with increased risk of prostate cancer. Gene polymorphisms may impact risk in certain ethnic groups. Folate has been studied extensively due to its role in methylation and nucleotide synthesis. Further prospective studies are needed to clarify optimal levels for nutrient remediation and risk reduction in those at risk, as well as elucidate the association between high intake, high serum levels, and prostate cancer risk. Future considerations for cancer risk may include gene interactions with nutrients and environmental factors.

Sexual dimorphism in the incidence of human cancers

Background

Sex differences in the incidences of cancers become a critical issue in both cancer research and the development of precision medicine. However, details in these differences have not been well reported. We provide a comprehensive analysis of sexual dimorphism in human cancers.

Methods

We analyzed four sets of cancer incidence data from the SEER (USA, 1975–2015), from the Cancer Registry at Mayo Clinic (1970–2015), from Sweden (1970–2015), and from the World Cancer Report in 2012.

Results

We found that all human cancers had statistically significant sexual dimorphism with male dominance in the United States and mostly significant in the Mayo Clinic, Sweden, and the world data, except for thyroid cancer, which is female-dominant.

Conclusions

Sexual dimorphism is a clear but mostly neglected phenotype for most human cancers regarding the clinical practice of cancer. We expect that our study will facilitate the mechanistic studies of sexual dimorphism in human cancers. We believe that fully addressing the mechanisms of sexual dimorphism in human cancers will greatly benefit current development of individualized precision medicine beginning from the sex-specific diagnosis, prognosis, and treatment.

Electronic supplementary material

The online version of this article (10.1186/s12885-019-5902-z) contains supplementary material, which is available to authorized users.

No Interaction between Polymorphisms Related to Vitamin A Metabolism and Vitamin A Intake in Relation to Colorectal Cancer in a Prospective Danish Cohort

Although vitamin A is essential for gut immune cell trafficking (paramount for the intestinal immune system), epidemiological studies on the role of vitamin A in colorectal cancer (CRC) aetiology are conflicting. By using functional polymorphisms, gene–environment (GxE) interaction analyses may identify the biological effects (or “mechanism of action”) of environmental factors on CRC aetiology. Potential interactions between dietary or supplemental vitamin A intake and genetic variation in the vitamin A metabolic pathway genes related to risk of CRC were studied. We used a nested case-cohort design within the Danish “Diet, Cancer and Health” cohort, with prospectively collected lifestyle information from 57,053 participants, and the Cox proportional hazard models and likelihood ratio test. No statistically significant associations between the selected polymorphisms and CRC, and no statistically significant interactions between vitamin A intake and the polymorphisms were found. In conclusion, no support of an involvement of vitamin A in CRC aetiology was found.

Obesity and cancer risk: Emerging biological mechanisms and perspectives

Continuously rising trends in obesity-related malignancies render this disease spectrum a public health priority. Worldwide, the burden of cancer attributable to obesity, expressed as population attributable fraction, is 11.9% in men and 13.1% in women. There is convincing evidence that excess body weight is associated with an increased risk for cancer of at least 13 anatomic sites, including endometrial, esophageal, renal and pancreatic adenocarcinomas; hepatocellular carcinoma; gastric cardia cancer; meningioma; multiple myeloma; colorectal, postmenopausal breast, ovarian, gallbladder and thyroid cancers. We first synopsize current epidemiologic evidence; the obesity paradox in cancer risk and mortality; the role of weight gain and weight loss in the modulation of cancer risk; reliable somatometric indicators for obesity and cancer research; and gender differences in obesity related cancers. We critically summarize emerging biological mechanisms linking obesity to cancer encompassing insulin resistance and abnormalities of the IGF-I system and signaling; sex hormones biosynthesis and pathway; subclinical chronic low-grade inflammation and oxidative stress; alterations in adipokine pathophysiology; factors deriving from ectopic fat deposition; microenvironment and cellular perturbations including vascular perturbations, epithelial-mesenchymal transition, endoplasmic reticulum stress and migrating adipose progenitor cells; disruption of circadian rhythms; dietary nutrients; factors with potential significance such as the altered intestinal microbiome; and mechanic factors in obesity and cancer. Future perspectives regarding prevention, diagnosis and therapeutics are discussed. The aim of this review is to investigate how the interplay of these main potential mechanisms and risk factors, exerts their effects on target tissues provoking them to acquire a cancerous phenotype.

Differentially expressed genes ASPN, COL1A1, FN1, VCAN and MUC5AC are potential prognostic biomarkers for gastric cancer

Gastric cancer (GC) is one of the most common malignancies worldwide. To the best of our knowledge, no biomarkers have been widely accepted for the early diagnosis and prognostic prediction of GC. This study aimed to identify potential novel prognostic biomarkers for GC. The dataset GSE29272, which originates from the public database Gene Expression Omnibus, was employed in the present study. The online tool GEO2R was used to calculate the differentially expressed genes (DEGs) in GSE29272 between tumour tissues and adjacent tissues. CytoHubba and MCODE plugins of Cytoscape software were used to obtain hub genes and modules of DEGs. The online tools Database for Annotation, Visualisation and Integrated Discovery and Search Tool for the Retrieval of Interacting Genes were employed to conduct Gene Ontology (GO) enrichment analysis and Kyoto Encyclopedia of Genes and Genomes pathway analysis, and to construct protein-protein interaction networks. A total of 117 DEGs were extracted from GSE29272. In addition, 15 hub genes and seven modules were identified in the 117 DEGs. The enrichment analysis revealed that they were mainly enriched in GO biological process and cellular component domains, and the 'ECM-receptor interaction', 'focal adhesion', 'metabolism of xenobiotics by cytochrome P450' and 'drug metabolism' pathways. The hub genes asporin (ASPN), collagen type I α1 chain (COL1A1), fibronectin 1 (FN1), versican (VCAN) and mucin 5AC (MUC5AC) were demonstrated to have prognostic value for patients with GC. The ASPN and VCAN genes were significantly associated with overall survival and disease-free survival (log-rank P=0.025, 0.038, 0.0014 and 0.015, respectively). COL1A1 and FN1 were significantly associated with overall survival (log-rank P=0.013 and 0.05, respectively), and MUC5AC was significantly associated with disease-free survival (log-rank P=0.027). Results from the present study suggested that ASPN, COL1A1, FN1, VCAN and MUC5AC may represent novel prognostic biomarkers for GC.

Risk factors for advanced colorectal neoplasms in the proximal colon in 6218 subjects undergoing complete colonoscopy

BACKGROUND AND AIM

Proximal migration of colonic lesion has been observed; however, risk factors of lesions in the proximal colon remain uncertain. This study aimed to investigate risk factors of lesions in the proximal colon.

METHODS

Consecutive subjects with complete colonoscopy were included. The primary outcome was risk factors associated with advanced neoplasm (AN) and serrated lesion in the proximal colon. Age, gender, first-degree relative (FDR) with colorectal cancer (CRC), smoking, alcohol consumption, body mass index, hypertension, diabetes, ischemic heart disease, and the use of aspirin, non-steroidal anti-inflammatory drug, and anticoagulants were fitted into a regression model, with reference to subjects without colonic finding. Results were measured by odds ratio (OR) with 95% confidence interval (CI).

RESULTS

Among 6218 subjects (mean age 56.65 ± 6.15 years; 46.8% male), 352 (5.7%) had AN; 809 (13.0%) had serrated lesions, and 3648 (58.7%) had no colonic finding. There were 148 (2.4%) and 235 (3.8%) subjects having AN and serrated lesion in the proximal colon. Age ≥ 50 (OR: 13.30; 95% CI: 1.85-95.76), male gender (OR: 1.82; 95% CI: 1.26-2.62), FDR with CRC (OR: 2.12; 95% CI: 1.43-3.15), and hypertension (OR: 1.86; 95% CI: 1.30-2.68) were associated with AN in the proximal colon. Age ≥ 50 (OR: 5.72; 95% CI: 2.10-15.53), male gender (OR: 1.54; 95% CI: 1.15-2.05), and smoking (OR: 1.85; 95% CI: 1.23-2.79) increased risk of serrated lesions in the proximal colon.

CONCLUSION

Age ≥ 50 and male gender were associated with both proximally located AN and serrated lesion; FDR with CRC and hypertension increased the risk of proximal AN, while ever smoking increased the risk of proximal serrated lesion. FDR with CRC was not associated with serrated lesion.

Combined Mineral Intakes and Risk of Colorectal Cancer in Postmenopausal Women

BACKGROUND

Despite considerable biological plausibility, other than for calcium, there are few reported epidemiologic studies on mineral intake-colorectal cancer associations, none of which investigated multiple minerals in aggregate.

METHODS

Accordingly, we incorporated 11 minerals into a mineral score and investigated its association with incident colorectal cancer in the Iowa Women's Health Study, a prospective cohort study of 55- to 69-year-old women who completed a food frequency questionnaire in 1986. In the analytic cohort (n = 35, 221), 1,731 incident colorectal cancer cases were identified via the State Health Registry of Iowa. Participants' calcium, magnesium, manganese, zinc, selenium, potassium, and iodine intakes were ranked 1 to 5, with higher ranks indicating higher, potentially anticarcinogenic, intakes, whereas for iron, copper, phosphorus, and sodium intakes, the rankings were reversed to account for their possible procarcinogenic properties. The rankings were summed to create each woman's mineral score. The mineral score-incident colorectal cancer association was estimated using multivariable Cox proportional hazards regression.

RESULTS

There was decreasing risk with an increasing score (P _trend = 0.001). The hazard ratios and 95% confidence intervals (CI) for those in mineral score quintiles 2 to 5 relative to those in the lowest were 0.91 (CI, 0.88-1.08), 0.85 (CI, 0.75-0.95), 0.86 (CI, 0.75-0.97), and 0.75 (CI, 0.71-0.95), respectively.

CONCLUSIONS

Our findings suggest that a predominance of putative anti- relative to pro-colorectal carcinogenic mineral intakes may be inversely associated with colorectal cancer risk.

IMPACT

These results support further investigation of colorectal cancer etiology using composite mineral intake scores.

Retinol palmitate and ascorbic acid: Role in oncological prevention and therapy

Cancer development has been directly related to oxidative stress. During chemotherapy, some cancer patients use dietary antioxidants to avoid nutritional deficiencies due to cancer treatment. Among the antioxidants consumed, there are vitamins, including retinyl palmitate (PR) and ascorbic acid (AA), which have the capacity to reduce free radicals formation, protect cellular structures and maintain the cellular homeostasis. This systematic review evaluated the antioxidant and antitumor mechanisms of retinol palmitate (a derivative of vitamin A) and/or ascorbic acid (vitamin C) in cancer-related studies. Ninety-seven (97) indexed articles in the databases PubMed and Science Direct, published between 2013 and 2017, including 23 clinical studies (5 for every single compound while 13 in interaction) and 74 non-clinical studies (37 for retinol palmitate, 36 for ascorbic acid and 1 in interaction) were considered. Antioxidant and antitumor effects, with controversies over dosage and route of administration, were observed for the test compounds in their isolated form or associated in clinical studies. Prevention of cancer risks against oxidative damage was seen in lower doses of retinol palmitate and/or vitamin C. However, at high doses, they can generate reactive oxygen species, cytotoxicity and apoptosis in test systems. Non-clinical studies using cell lines have allowed understanding the mechanisms related to antioxidants and antitumor effects of the isolated compounds, however, studies on vitamin interactions, acting as antioxidants and/or antitumor are still rare and controversial. More studies, mainly related to modulation of antineoplastic drugs are needed for understanding the risks and benefits of their use during treatment in order to achieve effectiveness in cancer therapy and patient's quality of life.

Body mass index, calcium supplementation and risk of colorectal adenomas

Calcium supplementation (1,200 mg/day) did not significantly reduce colorectal adenomas in our recent randomized, controlled trial (Vitamin D/Calcium Polyp Prevention Study, VCPPS, 2004-2013) in contrast to our previous trial (Calcium Polyp Prevention Study, CPPS, 1988-1996). To reconcile these findings, we identified participant characteristics that differed between the study populations and modified the effect of calcium supplementation on adenomas or high-risk findings (advanced or multiple adenomas). Compared to the CPPS, more participants in the VCPPS were obese (body mass index (BMI) ≥30 kg/m² ; 37.5% vs. 24.4%) and fewer had normal BMI (BMI <25 kg/m² ; 18.5% vs. 31%). BMI appeared to modify the effect of calcium supplementation on adenomas and especially on high risk-findings: in the VCPPS, there was a 44% reduction in high-risk findings among individuals whose BMI was normal (RR = 0.56, 95% CI = 0.26-1.23), but not among overweight (RR = 1.09, 95% CI = 0.62-1.91) or obese (RR = 1.54, 95% CI = 0.92-2.57) individuals (p_interaction = 0.03). Similarly, in the CPPS, there was a 56% reduction in high-risk findings among individuals whose BMI was normal (RR = 0.44, 95% CI = 0.26-0.74), but not among overweight (RR = 0.87, 95% CI = 0.55-1.39) or obese (RR = 1.02, 95% CI = 0.57-1.82) individuals (p_interaction = 0.02). Standardization of each trial's findings to the BMI distribution in the other attenuated calcium's protective effect on adenomas in the CPPS but enhanced it in the VCPPS. In conclusion, 1,200 mg/day calcium supplementation may reduce risk of colorectal adenomas among those with normal BMI but not in overweight or obese individuals; and differences in BMI distribution partially account for the apparent difference in calcium efficacy between the two trials.