A cohort study of dietary iron and heme iron intake and risk of colorectal cancer in women

Emerging role of necroptosis, pyroptosis, and ferroptosis in breast cancer: New dawn for overcoming therapy resistance

Breast cancer (BC) is one of the primary causes of death in women worldwide. The challenges associated with adverse outcomes have increased significantly, and the identification of novel therapeutic targets has become increasingly urgent. Regulated cell death (RCD) refers to a type of cell death that can be regulated by several different biomacromolecules, which is distinctive from accidental cell death (ACD). In recent years, apoptosis, a representative RCD pathway, has gained significance as a target for BC medications. However, tumor cells exhibit avoidance of apoptosis and result in treatment resistance, which emphasizes further studies devoted to alternative cell death processes, namely necroptosis, pyroptosis, and ferroptosis. Here, in this review, we focus on summarizing the crucial signaling pathways of these RCD in BC. We further discuss the molecular mechanism and potentiality in clinical application of several prospective drugs, nanoparticles, and other small compounds targeting different RCD subroutines of BC. We also discuss the benefits of modulating RCD processes on drug resistance and the advantages of combining RCD modulators with conventional treatments in BC. This review will deepen our understanding of the relationship between RCD and BC, and shed new light on future directions to attack cancer vulnerabilities with RCD modulators for therapeutic purposes.

Observational Dose-Response Meta-Analysis Methods May Bias Risk Estimates at Low Consumption Levels: The Case of Meat and Colorectal Cancer

Observational studies of foods and health are susceptible to bias, particularly from confounding between diet and other lifestyle factors. Common methods for deriving dose-response meta-analysis (DRMA) may contribute to biased or overly certain risk estimates. We used DRMA models to evaluate the empirical evidence for colorectal cancer (CRC) association with unprocessed red meat (RM) and processed meats (PM), and the consistency of this association for low and high consumers under different modeling assumptions. Using the Global Burden of Disease project's systematic reviews as a start, we compiled a data set of studies of PM with 29 cohorts contributing 23,522,676 person-years and of 23 cohorts for RM totaling 17,259,839 person-years. We fitted DRMA models to lower consumers only [consumption < United States median of PM (21 g/d) or RM (56 g/d)] and compared them with DRMA models using all consumers. To investigate impacts of model selection, we compared classical DRMA models against an empirical model for both lower consumers only and for all consumers. Finally, we assessed if the type of reference consumer (nonconsumer or mixed consumer/nonconsumer) influenced a meta-analysis of the lowest consumption arm. We found no significant association with consumption of 50 g/d RM using an empirical fit with lower consumption (relative risk [RR] 0.93 (0.8-1.02) or all consumption levels (1.04 (0.99-1.10)), while classical models showed RRs as high as 1.09 (1.00-1.18) at 50g/day. PM consumption of 20 g/d was not associated with CRC (1.01 (0.87-1.18)) when using lower consumer data, regardless of model choice. Using all consumption data resulted in association with CRC at 20g/day of PM for the empirical models (1.07 (1.02-1.12)) and with as little as 1g/day for classical models. The empirical DRMA showed nonlinear, nonmonotonic relationships for PM and RM. Nonconsumer reference groups did not affect RM (P = 0.056) or PM (P = 0.937) association with CRC in lowest consumption arms. In conclusion, classical DRMA model assumptions and inclusion of higher consumption levels influence the association between CRC and low RM and PM consumption. Furthermore, a no-risk limit of 0 g/d consumption of RM and PM is inconsistent with the evidence.

Iron metabolism in colorectal cancer: a balancing act

BACKGROUND

Colorectal cancer (CRC) is the third most commonly diagnosed cancer and the second deadliest malignancy worldwide. Current dietary habits are associated with increased levels of iron and heme, both of which increase the risk of developing CRC. The harmful effects of iron overload are related to the induction of iron-mediated pro-tumorigenic pathways, including carcinogenesis and hyperproliferation. On the other hand, iron deficiency may also promote CRC development and progression by contributing to genome instability, therapy resistance, and diminished immune responses. In addition to the relevance of systemic iron levels, iron-regulatory mechanisms in the tumor microenvironment are also believed to play a significant role in CRC and to influence disease outcome. Furthermore, CRC cells are more prone to escape iron-dependent cell death (ferroptosis) than non-malignant cells due to the constitutive activation of antioxidant genes expression. There is wide evidence that inhibition of ferroptosis may contribute to the resistance of CRC to established chemotherapeutic regimens. As such, ferroptosis inducers represent promising therapeutic drugs for CRC.

CONCLUSIONS AND PERSPECTIVES

This review addresses the complex role of iron in CRC, particularly in what concerns the consequences of iron excess or deprivation in tumor development and progression. We also dissect the regulation of cellular iron metabolism in the CRC microenvironment and emphasize the role of hypoxia and of oxidative stress (e.g. ferroptosis) in CRC. Finally, we underline some iron-related players as potential therapeutic targets against CRC malignancy.

Association of meat consumption with the risk of gastrointestinal cancers: a systematic review and meta-analysis

BACKGROUND

The association between gastrointestinal cancer and types of meat consumption, including red meat, processed meat, or a combination of both, remains disputable. Therefore, we performed a systematic review and meta-analysis of prospective cohort studies to estimate the association between meat consumption and gastrointestinal cancer risk.

METHODS

PubMed, EmBase, and the Cochrane library databases were searched systematically for eligible studies that investigated the relation between meat consumption and the risk of developing gastrointestinal cancers, including esophageal cancer (EC), gastric cancer (GC), colorectal cancer (CRC), colon cancer (CC), rectal cancer (RC), pancreatic cancer (PC), and hepatocellular carcinoma (HCC) throughout February, 2023. The pooled relative risk (RR) with 95% confidence interval (CI) was assigned as an effect estimate and calculated using a random-effects model with inverse variance weighting.

RESULTS

Forty cohorts comprising 3,780,590 individuals were selected for the final quantitative analysis. The summary results indicated that a higher red meat consumption was associated with an increased risk of CRC (RR: 1.09; 95% CI: 1.02-1.16; P = 0.007) and CC (RR: 1.13; 95% CI: 1.03-1.25; P = 0.011). Moreover, a higher processed meat consumption was associated with an increased risk of CRC (RR: 1.19; 95% CI: 1.13-1.26; P < 0.001), CC (RR: 1.24; 95% CI: 1.13-1.26; P < 0.001), and RC (RR: 1.24; 95% CI: 1.08-1.42; P = 0.002). Furthermore, a higher total consumption of red and processed meat was associated with an increased risk of CRC (RR: 1.13; 95% CI: 1.06-1.20; P < 0.001), CC (RR: 1.17; 95% CI: 1.04-1.33; P = 0.012), and RC (RR: 1.20; 95% CI: 1.04-1.39; P = 0.016). Finally, the strength of higher consumption of total red and processed meat with the risk of GC, and higher consumption of red meat with the risk of RC in subgroup of high adjusted level was lower than subgroup of moderate adjusted level, while the strength of higher consumption of processed meat with the risk of RC and HCC in subgroup of follow-up ≥ 10.0 years was higher than subgroup of follow-up < 10.0 years.

CONCLUSIONS

This study found that meat consumption was associated with an increased risk of CRC, CC, and RC, and dietary intervention could be considered an effective strategy in preventing CRC.

Dietary intake of total, heme and non-heme iron and the risk of colorectal cancer in a European prospective cohort study

BACKGROUND

Iron is an essential micronutrient with differing intake patterns and metabolism between men and women. Epidemiologic evidence on the association of dietary iron and its heme and non-heme components with colorectal cancer (CRC) development is inconclusive.

METHODS

We examined baseline dietary questionnaire-assessed intakes of total, heme, and non-heme iron and CRC risk in the EPIC cohort. Sex-specific multivariable-adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) were computed using Cox regression. We modelled substitution of a 1 mg/day of heme iron intake with non-heme iron using the leave one-out method.

RESULTS

Of 450,105 participants (318,680 women) followed for 14.2 ± 4.0 years, 6162 (3511 women) developed CRC. In men, total iron intake was not associated with CRC risk (highest vs. lowest quintile, HRQ5vs.Q1:0.88; 95%CI:0.73, 1.06). An inverse association was observed for non-heme iron (HRQ5vs.Q1:0.80, 95%CI:0.67, 0.96) whereas heme iron showed a non-significant association (HRQ5vs.Q1:1.10; 95%CI:0.96, 1.27). In women, CRC risk was not associated with intakes of total (HRQ5vs.Q1:1.11, 95%CI:0.94, 1.31), heme (HRQ5vs.Q1:0.95; 95%CI:0.84, 1.07) or non-heme iron (HRQ5vs.Q1:1.03, 95%CI:0.88, 1.20). Substitution of heme with non-heme iron demonstrated lower CRC risk in men (HR:0.94; 95%CI: 0.89, 0.99).

CONCLUSIONS

Our findings suggest potential sex-specific CRC risk associations for higher iron consumption that may differ by dietary sources.

Association between gastric cancer and the intake of different types of iron and meats

BACKGROUND

Heme and non-heme irons are two forms of iron in the diet. Few studies have evaluated the association between heme iron intake and the risk of gastric cancer (GC). We aimed to investigate the association between heme, non-heme and total iron intake and risk of GC in Iran.

METHODS

In a hospital-based case-control study, nutritionists interviewed 178 pathologically confirmed GC patients and 276 controls using a valid Diet History Questionnaire. Multiple logistic regression model was used to estimate Odds Ratios (OR) and 95% Confidence Intervals (CIs) for iron intake and risk of GC.

RESULTS

Subjects in the highest tertile of total iron intake were 46% less likely to get GC than those in the lowest (OR = 0.54, 95% CI: 0.32-0.92), however, the associations were not significant for intake of heme and non-heme iron. The risk of GC in the highest tertile of total meat intake was 2.51 times higher than the lowest. We found significant associations between GC and chicken (OR = 2.95; 95% CI: 1.66-5.22) and fish intake (OR = 1.89; 95% CI: 1.09-3.27), However, we found no associations between the risk of GC and intake of red meat, salted fish, and liver.

CONCLUSION

Total iron intake was associated with a lower risk of GC which could be partly due to the high prevalence of anemia in Iran. Although, we could not find any significant association between the risk of GC and the intake of heme and non-hem iron among the Iranian population.

Supplementation with High or Low Iron Reduces Colitis Severity in an AOM/DSS Mouse Model

The relationship between colitis-associated colorectal cancer (CAC) and the dysregulation of iron metabolism has been implicated. However, studies on the influence of dietary iron deficiency on the incidence of CAC are limited. This study investigated the effects of dietary iron deficiency and dietary non-heme iron on CAC development in an azoxymethane/dextran sodium sulfate (AOM/DSS) mouse model. The four-week-old mice were divided into the following groups: iron control (IC; 35 ppm iron/kg) + normal (NOR), IC + AOM/DSS, iron deficient (ID; <5 ppm iron/kg diet) + AOM/DSS, and iron overload (IOL; approximately 2000 ppm iron/kg) + AOM/DSS. The mice were fed the respective diets for 13 weeks, and the AOM/DSS model was established at week five. FTH1 expression increased in the mice’s colons in the IC + AOM/DSS group compared with that observed in the ID and IOL + AOM/DSS groups. The reduced number of colonic tumors in the ID + AOM/DSS and IOL + AOM/DSS groups was accompanied by the downregulated expression of cell proliferation regulators (PCNA, cyclin D1, and c-Myc). Iron overload inhibited the increase in the expression of NF-κB and its downstream inflammatory cytokines (IL-6, TNFα, iNOS, COX2, and IL-1β), likely due to the elevated expression of antioxidant genes (SOD1, TXN, GPX1, GPX4, CAT, HMOX1, and NQO1). ID + AOM/DSS may hinder tumor development in the AOM/DSS model by inhibiting the PI3K/AKT pathway by increasing the expression of Ndrg1. Our study suggests that ID and IOL diets suppress AOM/DSS-induced tumors and that long-term iron deficiency or overload may negate CAC progression.

Priority Micronutrient Density in Foods

Background

Despite concerted efforts to improve diet quality and reduce malnutrition, micronutrient deficiencies remain widespread globally, especially in low- and middle-income countries and among population groups with increased needs, where diets are often inadequate in iron, zinc, folate, vitamin A, calcium, and vitamin B12. There is a need to understand the density of these micronutrients and their bioavailability across diverse foods and the suitability of these foods to help meet requirements for populations with high burdens of micronutrient malnutrition.

Objective

We aimed to identify the top food sources of these commonly lacking micronutrients, which are essential for optimal health, to support efforts to reduce micronutrient malnutrition among various populations globally.

Methods

We built an aggregated global food composition database and calculated recommended nutrient intakes for five population groups with varying requirements. An approach was developed to rate foods according to their density in each and all priority micronutrients for various population groups with different nutrient requirements.

Results

We find that the top sources of priority micronutrients are organs, small fish, dark green leafy vegetables, bivalves, crustaceans, goat, beef, eggs, milk, canned fish with bones, mutton, and lamb. Cheese, goat milk, and pork are also good sources, and to a lesser extent, yogurt, fresh fish, pulses, teff, and canned fish without bones.

Conclusion

The results provide insight into which foods to prioritize to fill common micronutrient gaps and reduce undernutrition.

Deciphering the involvement of iron targets in colorectal cancer: a network biology approach

Several studies suggested the role of heme iron, but not non-heme iron in colorectal cancer. A network and system biology-based approach was used to understand the role of heme and non-heme iron on colorectal cancer etiology. Heme and non-heme iron targets were screened in addition to CRC targets. The protein-protein interaction map of both iron targets was prepared with CRC targets. Moreover, functional enrichment analysis was performed in order to understand their role in cancer etiology. The heme iron is predicted to modulate several cancer-associated pathways. Our results indicate several targets and pathways, including IL-4/IL-13, ACE, and HIF-1 signaling, that may have an important role in heme iron-mediated CRC and must be given consideration for understanding their role in colorectal cancer.

The interplay of pineal hormones and socioeconomic status leading to colorectal cancer disparity

Colorectal cancer (CRC) is the third leading cause of cancer-related deaths in the United States. Despite increased screening options and state-of-art treatments offered in clinics, racial differences remain in CRC. African Americans (AAs) are disproportionately affected by the disease; the incidence and mortality are higher in AAs than Caucasian Americans (CAs). At the time of diagnosis, AAs more often present with advanced stages and aggressive CRCs, primarily accounting for the racial differences in therapeutic outcomes and mortality. The early incidence of CRC in AAs could be attributed to race-specific gene polymorphisms and lifestyle choices associated with socioeconomic status (SES). Altered melatonin-serotonin signaling, besides the established CRC risk factors (age, diet, obesity, alcoholism, and tobacco use), steered by SES, glucocorticoid, and Vitamin D status in AAs could also account for the early incidence in this racial group. This review focuses on how the lifestyle factors, diet, allelic variants, and altered expression of specific genes could lead to atypical serotonin and melatonin signaling by modulating the synthesis, secretion, and signaling of these pineal hormones in AAs and predisposing them to develop more aggressive CRC earlier than CAs. Crosstalk between gut microbiota and pineal hormones and its impact on CRC pathobiology is addressed from a race-specific perspective. Lastly, the status of melatonin-focused CRC treatments, the need to better understand the perturbed melatonin signaling, and the potential of pineal hormone-directed therapeutic interventions to reduce CRC-associated disparity are discussed.

Priority Micronutrient Density of Foods for Complementary Feeding of Young Children (6-23 Months) in South and Southeast Asia

Background: Given their high nutrient requirements and limited gastric capacity, young children during the complementary feeding period (6-23 months) should be fed nutrient-dense foods. However, complementary feeding diets in low- and middle-income countries are often inadequate in one or more essential micronutrients. In South and Southeast Asia infants' and young children's diets are commonly lacking in iron, zinc, vitamin A, folate, vitamin B12, and calcium, hereafter referred to as priority micronutrients. Objective: This study aimed to identify the top food sources of priority micronutrients among minimally processed foods for complementary feeding of children (6-23 months) in South and Southeast Asia. Methods: An aggregated regional food composition database for South and Southeast Asia was built, and recommended nutrient intakes (RNIs) from complementary foods were calculated for children aged 6-23 months. An approach was developed to classify foods into one of four levels of priority micronutrient density based on the calories and grams required to provide one-third (for individual micronutrients) or an average of one-third (for the aggregate score) of RNIs from complementary foods. Results: We found that the top food sources of multiple priority micronutrients are organs, bivalves, crustaceans, fresh fish, goat, canned fish with bones, and eggs, closely followed by beef, lamb/mutton, dark green leafy vegetables, cow milk, yogurt, and cheese, and to a lesser extent, canned fish without bones. Conclusions: This analysis provided insights into which foods to prioritize to fill common micronutrient gaps and reduce undernutrition in children aged 6-23 months in South and Southeast Asia.

Emerging Evidence on the Effects of Dietary Factors on the Gut Microbiome in Colorectal Cancer

Dietary factors have important role in modulating the gut microbiome, which in-turn regulates the molecular events in colonic mucosa. The composition and resulting metabolism of the gut microbiome are decisive factors in colorectal cancer (CRC) tumorigenesis. Altered gut microbiome is associated with impaired immune response, and the release of carcinogenic or genotoxic substances which are the major microbiome-induced mechanisms implicated in CRC pathogenesis. Diets low in dietary fibers and phytomolecules as well as high in red meat are important dietary changes which predispose to CRC. Dietary fibers which reach the colon in an undigested form are further metabolized by the gut microbiome into enterocyte friendly metabolites such as short chain fatty acid (SCFA) which provide anti-inflammatory and anti-proliferative effects. Healthy microbiome supported by dietary fibers and phytomolecules could decrease cell proliferation by regulating the epigenetic events which activate proto-oncogenes and oncogenic pathways. Emerging evidence show that predominance of microbes such as Fusobacterium nucleatum can predispose the colonic mucosa to malignant transformation. Dietary and lifestyle modifications have been demonstrated to restrict the growth of potentially harmful opportunistic organisms. Synbiotics can protect the intestinal mucosa by improving immune response and decreasing the production of toxic metabolites, oxidative stress and cell proliferation. In this narrative review, we aim to update the emerging evidence on how diet could modulate the gut microbial composition and revive colonic epithelium. This review highlights the importance of healthy plant-based diet and related supplements in CRC prevention by improving the gut microbiome.

Consumption of red meat and processed meat and cancer incidence: a systematic review and meta-analysis of prospective studies

Red meat and processed meat consumption has been hypothesized to increase risk of cancer, but the evidence is inconsistent. We performed a systematic review and meta-analysis of prospective studies to summarize the evidence of associations between consumption of red meat (unprocessed), processed meat, and total red and processed meat with the incidence of various cancer types. We searched in MEDLINE and EMBASE databases through December 2020. Using a random-effect meta-analysis, we calculated the pooled relative risk (RR) and 95% confidence intervals (CI) of the highest versus the lowest category of red meat, processed meat, and total red and processed meat consumption in relation to incidence of various cancers. We identified 148 published articles. Red meat consumption was significantly associated with greater risk of breast cancer (RR = 1.09; 95% CI = 1.03-1.15), endometrial cancer (RR = 1.25; 95% CI = 1.01-1.56), colorectal cancer (RR = 1.10; 95% CI = 1.03-1.17), colon cancer (RR = 1.17; 95% CI = 1.09-1.25), rectal cancer (RR = 1.22; 95% CI = 1.01-1.46), lung cancer (RR = 1.26; 95% CI = 1.09-1.44), and hepatocellular carcinoma (RR = 1.22; 95% CI = 1.01-1.46). Processed meat consumption was significantly associated with a 6% greater breast cancer risk, an 18% greater colorectal cancer risk, a 21% greater colon cancer risk, a 22% greater rectal cancer risk, and a 12% greater lung cancer risk. Total red and processed meat consumption was significantly associated with greater risk of colorectal cancer (RR = 1.17; 95% CI = 1.08-1.26), colon cancer (RR = 1.21; 95% CI = 1.09-1.34), rectal cancer (RR = 1.26; 95% CI = 1.09-1.45), lung cancer (RR = 1.20; 95% CI = 1.09-1.33), and renal cell cancer (RR = 1.19; 95% CI = 1.04-1.37). This comprehensive systematic review and meta-analysis study showed that high red meat intake was positively associated with risk of breast cancer, endometrial cancer, colorectal cancer, colon cancer, rectal cancer, lung cancer, and hepatocellular carcinoma, and high processed meat intake was positively associated with risk of breast, colorectal, colon, rectal, and lung cancers. Higher risk of colorectal, colon, rectal, lung, and renal cell cancers were also observed with high total red and processed meat consumption.

Intravenous iron is non-inferior to oral iron regarding cell growth and iron metabolism in colorectal cancer associated with iron-deficiency anaemia

Oral iron promotes intestinal tumourigenesis in animal models. In humans, expression of iron transport proteins are altered in colorectal cancer. This study examined whether the route of iron therapy alters iron transport and tumour growth. Colorectal adenocarcinoma patients with pre-operative iron deficiency anaemia received oral ferrous sulphate (n = 15), or intravenous ferric carboxymaltose (n = 15). Paired (normal and tumour tissues) samples were compared for expression of iron loading, iron transporters, proliferation, apoptosis and Wnt signalling using immunohistochemistry and RT-PCR. Iron loading was increased in tumour and distributed to the stroma in intravenous treatment and to the epithelium in oral treatment. Protein and mRNA expression of proliferation and iron transporters were increased in tumours compared to normal tissues but there were no significant differences between the treatment groups. However, intravenous iron treatment reduced ferritin mRNA levels in tumours and replenished body iron stores. Iron distribution to non-epithelial cells in intravenous iron suggests that iron is less bioavailable to tumour cells. Therefore, intravenous iron may be a better option in the treatment of colorectal cancer patients with iron deficiency anaemia due to its efficiency in replenishing iron levels while its effect on proliferation and iron metabolism is similar to that of oral iron treatment.

Probiotics: A Promising Candidate for Management of Colorectal Cancer

Colorectal cancer (CRC) is the World's third most frequently diagnosed cancer type. It accounted for about 9.4% mortality out of the total incidences of cancer in the year 2020. According to estimated facts by World Health Organization (WHO), by 2030, 27 million new CRC cases, 17 million deaths, and around 75 million people living with the disease will appear. The facts and evidence that establish a link between the intestinal microflora and the occurrence of CRC are quite intuitive. Current shortcomings of chemo- and radiotherapies and the unavailability of appropriate treatment strategies for CRC are becoming the driving force to search for an alternative approach for the prevention, therapy, and management of CRC. Probiotics have been used for a long time due to their beneficial health effects, and now, it has become a popular candidate for the preventive and therapeutic treatment of CRC. The probiotics adopt different strategies such as the improvement of the intestinal barrier function, balancing of natural gut microflora, secretion of anticancer compounds, and degradation of carcinogenic compounds, which are useful in the prophylactic treatment of CRC. The pro-apoptotic ability of probiotics against cancerous cells makes them a potential therapeutic candidate against cancer diseases. Moreover, the immunomodulatory properties of probiotics have created interest among researchers to explore the therapeutic strategy by activating the immune system against cancerous cells. The present review discusses in detail different strategies and mechanisms of probiotics towards the prevention and treatment of CRC.

The role of iron homeostasis and iron-mediated ROS in cancer

As an important trace element, iron plays an essential role in many biology processes like cell proliferation, metabolism, and mitochondrial function. However, the disruption of iron homeostasis tends to cells death and human diseases due to it servers as mediator to promote the production of reactive oxygen species (ROS). In this review, first we introduced the mechanism of complex iron-mediated ROS involved in apoptosis, necroptosis, ferroptosis and pyroptosis. Next, we discussed the controversial role of excess iron and iron deficiency in tumor. Finally, we discussed the anti-cancer effects of iron on both sides, and novel iron-related strategies. This review outlined the mechanisms and regulation of iron homeostasis and iron-mediated ROS in tumors, and discussed the iron-related treatments.

1,2,3-Triazole tethered 1,2,4‑trioxane trimer induces apoptosis in metastatic cancer cells and inhibits their proliferation, migration and invasion

Artemisinin (ART) has been in use against different cancer cells and its derivatives and conjugates are more cytotoxic to iron-rich cancer cells. It is desirable to develop easily achievable synthetic 1,2,4-trioxanes having the same pharmacophore as that of ART. To explore more efficient compounds, a 1,2,3-triazole tethered 1,2,4‑trioxane trimer (4T) was synthesized and the anti-cancer effects of ART and 4T on MDA-MB-435 and MDA-MB-231 cells were investigated concerning regulation of osteopontin (OPN) expression, which is associated with cancer progression and malignancy. ¹H NMR and ¹³C NMR, oxidative stress analysis, flow cytometry, western blot, Real-Time PCR, transfections, luciferase assay, cell viability, proliferation, migration and chemotactic invasion assays were used in this study. It was observed that the 4T induced apoptosis by inhibiting Bcl-2 (~0.6-fold) and cleavage of caspase-3 (intrinsic pathway) in these metastatic cancer cells, and also reduced colony formation, migration and invasion of these cancer cells. The treatment of 4T decreased the reduced glutathione level and increased the activities of glucose-6-phosphate dehydrogenase and glutathione reductase in the 4T treated cancer cells as compared to their respective controls. Further, the expression of OPN was diminished (~0.5-fold) by the 4T in these cell lines. It was also observed that the key mitogen-activated protein kinase pathway proteins, mitogen-activated protein kinase kinase1/2 (~1.8-fold) and extracellular signal-regulated kinase1/2 (~16-fold), were also activated following the treatment of the 4T. However, the phosphorylated c-Jun level, a component of activator protein-1, was significantly reduced in these cancer cells upon 4T treatment. Taken together, we hypothesize that 4T may be useful for controlling cancer progression and malignancy.

Emerging trends in colorectal cancer: Dysregulated signaling pathways (Review)

Colorectal cancer (CRC) is the third most frequently detected type of cancer, and the second most common cause of cancer‑related mortality globally. The American Cancer Society predicted that approximately 147,950 individuals would be diagnosed with CRC, out of which 53,200 individuals would succumb to the disease in the USA alone in 2020. CRC‑related mortality ranks third among both males and females in the USA. CRC arises from 3 major pathways: i) The adenoma‑carcinoma sequence; ii) serrated pathway; and iii) the inflammatory pathway. The majority of cases of CRC are sporadic and result from risk factors, such as a sedentary lifestyle, obesity, processed diets, alcohol consumption and smoking. CRC is also a common preventable cancer. With widespread CRC screening, the incidence and mortality from CRC have decreased in developed countries. However, over the past few decades, CRC cases and mortality have been on the rise in young adults (age, <50 years). In addition, CRC cases are increasing in developing countries with a low gross domestic product (GDP) due to lifestyle changes. CRC is an etiologically heterogeneous disease classified by tumor location and alterations in global gene expression. Accumulating genetic and epigenetic perturbations and aberrations over time in tumor suppressor genes, oncogenes and DNA mismatch repair genes could be a precursor to the onset of colorectal cancer. CRC can be divided as sporadic, familial, and inherited depending on the origin of the mutation. Germline mutations in APC and MLH1 have been proven to play an etiological role, resulting in the predisposition of individuals to CRC. Genetic alterations cause the dysregulation of signaling pathways leading to drug resistance, the inhibition of apoptosis and the induction of proliferation, invasion and migration, resulting in CRC development and metastasis. Timely detection and effective precision therapies based on the present knowledge of CRC is essential for successful treatment and patient survival. The present review presents the CRC incidence, risk factors, dysregulated signaling pathways and targeted therapies.

Colorectal Cancer Genetics, Incidence and Risk Factors: In Search for Targeted Therapies

Each year, colorectal cancers (CRCs) affect over a quarter of a million people. The risk of developing CRC in industrialized nations is approximately 5%. When the disease is localised, treatment success rates range from 70-90%; however, advanced CRC has a high mortality rate, consistently ranking in the top three causes of cancer-related deaths. There is a large geographic difference in global distribution, and CRC is predominantly associated with developed countries and a Western lifestyle and diet. As such, the developed world accounts for more than 63% of all cases of CRC. Geographic variations also predict cancer outcomes, which differ between racial and ethnic groups. This variation is due to inequalities in wealth, differences in the exposure to risk factors and barriers to high-quality cancer prevention, early detection and treatment. The aim of this paper was to review CRC in low- and middle-income countries such as South Africa, India, Brazil and China, and compare them with high-income countries such as the United States of America and the United Kingdom. It is important to note that these economically less developed countries, with historically low CRC rates, are experiencing an increased frequency of CRC. The review also discusses biological markers and genetic pathways involved in the development of colorectal cancer. Genes known to be responsible for the most common forms of inherited CRCs have also been identified but more remain to be identified. This would provide more candidate genes to be added to known biomarkers. CRC burden can be controlled through the widespread application of existing knowledge, such as reduced smoking habits, vaccination, early detection and promoting physical activity, accompanied by a healthy diet. An increased understanding of the molecular mechanisms and events underlying colorectal carcinogenesis will enable the development of new targets and therapeutic drugs.

Dietary Intakes of Calcium, Iron, Magnesium, and Potassium Elements and the Risk of Colorectal Cancer: a Meta-Analysis

The purpose of this study was to analyze the existing studies and to investigate the relationship between the risk of colorectal cancer (CRC) and intakes of four individual dietary elements calcium (Ca), iron (Fe), magnesium (Mg), and potassium (K). All relevant articles in both Chinese and English were searched and collected from PubMed, Web of Science, and Chinese National Knowledge Infrastructure databases up to December 17, 2017. There were 29 eligible literatures selected for further meta-analysis, including 14 cohort studies and 15 case-control studies. The meta-analysis of cohort studies indicated that the high intakes of dietary Ca and Mg were negatively associated with the risk of CRC, as the hazard ratios (HR) were 0.76 (95% confidence interval (CI) 0.72, 0.80) and 0.80 (95% CI 0.73, 0.87), respectively. Nevertheless, high intake of dietary heme Fe was positively correlated to the incidence of colon cancer (HR = 1.01, 95% CI 0.82, 1.19) and rectal cancer (HR = 1.04, 95% CI 0.67, 1.42). A meta-analysis of case-control studies indicated that high intakes of dietary Ca, Mg, and K were negatively related with the occurrence of CRC, because the odds ratios (OR) were 0.36 (95% CI 0.32, 0.40), 0.80 (95% CI 0.63, 0.98) and 0.97 (95% CI 0.74, 1.21), respectively. However, high Fe intake from diet was positively correlated with the rising increasing of CRC (OR = 1.04, 95% CI 0.91, 1.18). More research is needed to indicate the risk relationship between element intake and CRC.

Different forms and sources of iron in relation to colorectal cancer risk: a case-control study in China

Few studies have examined the association of various types of Fe with colorectal cancer risk. The aim of this study was to investigate different forms and sources of Fe in relation to colorectal cancer risk in a Chinese population. A total of 2138 patients with colorectal cancer and 2144 sex- and age-matched (5-year interval) controls were recruited from July 2010 to November 2017. Dietary information was assessed by face-to-face interviews using a validated FFQ. Multivariable logistic regression was used to estimate the OR and 95 % CI on models. Intake of Fe from plants and Fe from white meat were inversely associated with the risk of colorectal cancer, while haem Fe and Fe from red meat were positively associated with colorectal cancer risk. The multivariable OR for the highest quartile v. the lowest quartile were 0·72 (95 % CI 0·59, 0·87, P trend&lt;0·001) for Fe from plants, 0·54 (95 % CI 0·45, 0·66, P trend&lt;0·001) for Fe from white meat, 1·26 (95 % CI 1·04, 1·53, P trend=0·005) for haem Fe and 1·83 (95 % CI 1·49, 2·24, P trend&lt;0·001) for Fe from red meat intake, respectively. However, no significant association was found between the consumption of total dietary Fe, non-haem Fe, Fe from meat and colorectal cancer risk. This study showed that lower intake of Fe from plants and white meat, as well as higher intake of haem Fe and Fe from red meat, were associated with colorectal cancer risk in a Chinese population.

Gut Microbiota and Iron: The Crucial Actors in Health and Disease

Iron (Fe) is a highly ample metal on planet earth (~35% of the Earth’s mass) and is particularly essential for most life forms, including from bacteria to mammals. Nonetheless, iron deficiency is highly prevalent in developing countries, and oral administration of this metal is so far the most effective treatment for human beings. Notably, the excessive amount of unabsorbed iron leave unappreciated side effects at the highly interactive host–microbe interface of the human gastrointestinal tract. Recent advances in elucidating the molecular basis of interactions between iron and gut microbiota shed new light(s) on the health and pathogenesis of intestinal inflammatory diseases. We here aim to present the dynamic modulation of intestinal microbiota by iron availability, and conversely, the influence on dietary iron absorption in the gut. The central part of this review is intended to summarize our current understanding about the effects of luminal iron on host–microbe interactions in the context of human health and disease.

Foods and beverages and colorectal cancer risk: a systematic review and meta-analysis of cohort studies, an update of the evidence of the WCRF-AICR Continuous Update Project

Objective

As part of the World Cancer Research Fund International Continuous Update Project, we updated the systematic review and meta-analysis of prospective studies to quantify the dose-response between foods and beverages intake and colorectal cancer risk.

Data sources

PubMed and several databases up to 31 May 2015.

Study selection

Prospective studies reporting adjusted relative risk estimates for the association of specific food groups and beverages and risk of colorectal, colon and rectal cancer.

Data synthesis

Dose-response meta-analyses using random effect models to estimate summary relative risks (RRs).

Results

About 400 individual study estimates from 111 unique cohort studies were included. Overall, the risk increase of colorectal cancer is 12% for each 100 g/day increase of red and processed meat intake (95% CI = 4-21%, I2=70%, pheterogeneity (ph)<0.01) and 7% for 10 g/day increase of ethanol intake in alcoholic drinks (95% CI = 5-9%, I2=25%, ph = 0.21). Colorectal cancer risk decrease in 17% for each 90g/day increase of whole grains (95% CI = 11-21%, I2 = 0%, ph = 0.30, 6 studies) and 13% for each 400 g/day increase of dairy products intake (95% CI = 10-17%, I2 = 18%, ph = 0.27, 10 studies). Inverse associations were also observed for vegetables intake (RR per 100 g/day =0.98 (95% CI = 0.96-0.99, I2=0%, ph = 0.48, 11 studies) and for fish intake (RR for 100 g/day = 0.89 (95% CI = 0.80-0.99, I2=0%, ph = 0.52, 11 studies), that were weak for vegetables and driven by one study for fish. Intakes of fruits, coffee, tea, cheese, poultry and legumes were not associated with colorectal cancer risk.

Conclusions

Our results reinforce the evidence that high intake of red and processed meat and alcohol increase the risk of colorectal cancer. Milk and whole grains may have a protective role against colorectal cancer. The evidence for vegetables and fish was less convincing.

The association of diet, gut microbiota and colorectal cancer: what we eat may imply what we get

Despite the success of colonoscopy screening and recent advances in cancer treatment, colorectal cancer (CRC) still remains one of the most commonly diagnosed and deadly cancers, with a significantly increased incidence in developing countries where people are adapting to Western lifestyle. Diet has an important impact on risk of CRC. Multiple epidemiological studies have suggested that excessive animal protein and fat intake, especially red meat and processed meat, could increase the risk of developing CRC while fiber could protect against colorectal tumorigenesis. Mechanisms have been investigated by animal studies. Diet could re-shape the community structure of gut microbiota and influence its function by modulating the production of metabolites. Butyrate, one of the short-chain fatty acids (SCFAs), which act as a favorable source for colonocytes, could protect colonic epithelial cells from tumorigenesis via anti-inflammatory and antineoplastic properties through cell metabolism, microbiota homeostasis, antiproliferative, immunomodulatory and genetic/epigenetic regulation ways. In contrast, protein fermentation and bile acid deconjugation, which cause damage to colonic cells through proinflammatory and proneoplastic ways, lead to increased risk of developing CRC. In conclusion, a balanced diet with an increased abundance of fiber should be adopted to reduce the risk and prevent CRC.

Transcriptome analysis of genes associated with breast cancer cell motility in response to Artemisinin treatment

Background

Well-known anti-malarial drug artemisinin exhibits potent anti-cancerous activities. In-vivo and in-vitro studies showed its anti-tumor and immunomodulatory properties signifying it as a potent drug candidate for study. The studies of mechanisms of cell movement are relevant which can be understood by knowing the involvement of genes in an effect of a drug. Although cytotoxicity and anti-proliferative activity of artemisinin is evident, the genes participating in its anti-migratory and reduced invasive effect are not well studied. The present study reports the alteration in the expression of 84 genes involved in cell motility upon artemisinin treatment in MCF-7 breast cancer cells using pathway focused gene expression PCR array. In addition, the effect of artemisinin on epigenetic modifier HDACs is studied.

Methods

We checked the functional stimulus of artemisinin on cell viability, migration, invasion and apoptosis in breast cancerous cell lines. Using qRT-PCR and western blot, we validated the altered expression of relevant genes associated with proliferation, migration, invasion, apoptosis and mammary gland development.

Results

Artemisinin inhibited cell proliferation of estrogen receptor negative breast cancer cells with fewer efficacies in comparison to estrogen receptor positive ones. At the same time, cell viability and proliferation of normal breast epithelial MCF10A cells was un-affected. Artemisinin strongly inhibited cancer cell migration and invasion. Along with orphan nuclear receptors (ERRα, ERRβ and ERRγ), artemisinin altered the ERα/ERβ/PR/Her expression status of MCF-7 cells. The expression of genes involved in the signaling pathways associated with proliferation, migration, invasion and apoptosis was significantly altered which cooperatively resulted into reduced growth promoting activities of breast cancer cells. Interestingly, artemisinin exhibited inhibitory effect on histone deacetylases (HDACs).

Conclusions

Upregulated expression of tumor suppressor genes along with reduced expression of oncogenes significantly associated with growth stimulating signaling pathways in response to artemisinin treatment suggests its efficacy as an effective drug in breast cancer treatment.

Mechanisms Linking Colorectal Cancer to the Consumption of (Processed) Red Meat: A Review

Colorectal cancer (CRC) is the third most commonly diagnosed cancer in the world. The vast majority of CRC cases have been linked to environmental causes rather than to heritable genetic changes. Over the last decades, epidemiological evidence linking the consumption of red and, more convincingly, of processed red meat to CRC has accumulated. In parallel, hypotheses on carcinogenic mechanisms underlying an association between CRC and the intake of red and processed red meat have been proposed and investigated in biological studies. The hypotheses that have received most attention until now include (1) the presence of polycyclic aromatic hydrocarbons and heterocyclic aromatic amines, two groups of compounds recognized as carcinogenic, (2) the enhancing effect of (nitrosyl)heme on the formation of carcinogenic N-nitroso compounds and lipid peroxidation. However, none of these hypotheses completely explains the link between red and processed red meat intake and the CRC risk. Consequently, scientists have proposed additional mechanisms or refined their hypotheses. This review first briefly summarizes the development of CRC followed by an in-depth overview and critical discussion of the different potential carcinogenic mechanisms underlying the increased CRC risk associated with the consumption of red and processed red meat.

Dietary Iron and Colorectal Cancer Risk: A Review of Human Population Studies

Iron is an essential micronutrient that is involved in many redox processes and serves as an integral component in various physiological functions. However, excess iron can cause tissue damage through its pro-oxidative effects, potentiating the development of many diseases such as cancer through the generation of reactive oxidative species. The two major forms of iron in the diet are heme and nonheme iron, both of which are found in several different foods. In addition to natural food sources, intake of nonheme iron may also come from fortified foods or in supplement form. This review summarizes the results of human population studies that have examined the role of dietary iron (heme and nonheme), heme iron alone, and iron from supplements in colorectal carcinogenesis.

Pattern and Distribution of Colorectal Cancer in Tanzania: A Retrospective Chart Audit at Two National Hospitals

Background. Colorectal cancer (CRC) is a growing public health concern with increasing rates in countries with previously known low incidence. This study determined pattern and distribution of CRC in Tanzania and identified hot spots in case distribution. Methods. A retrospective chart audit reviewed hospital registers and patient files from two national institutions. Descriptive statistics, Chi square (χ²) tests, and regression analyses were employed and augmented by data visualization to display risk variable differences. Results. CRC cases increased sixfold in the last decade in Tanzania. There was a 1.5% decrease in incidences levels of rectal cancer and 2% increase for colon cancer every year from 2005 to 2015. Nearly half of patients listed Dar es Salaam as their primary residence. CRC was equally distributed between males (50.06%) and females (49.94%), although gender likelihood of diagnosis type (i.e., rectal or colon) was significantly different (P = 0.027). More than 60% of patients were between 40 and 69 years. Conclusions. Age (P = 0.0183) and time (P = 0.004) but not gender (P = 0.0864) were significantly associated with rectal cancer in a retrospective study in Tanzania. Gender (P = 0.0405), age (P = 0.0015), and time (P = 0.0075) were all significantly associated with colon cancer in this study. This retrospective study found that colon cancer is more prevalent among males at a relatively younger age than rectal cancer. Further, our study showed that although more patients were diagnosed with rectal cancer, the trend has shown that colon cancer is increasing at a faster rate.

Red Meat and Colorectal Cancer: A Quantitative Update on the State of the Epidemiologic Science

The potential relationship between red meat consumption and colorectal cancer (CRC) has been the subject of scientific debate. Given the high degree of resulting uncertainty, our objective was to update the state of the science by conducting a systematic quantitative assessment of the epidemiologic literature. Specifically, we updated and expanded our previous meta-analysis by integrating data from new prospective cohort studies and conducting a broader evaluation of the relative risk estimates by specific intake categories. Data from 27 independent prospective cohort studies were meta-analyzed using random-effects models, and sources of potential heterogeneity were examined through subgroup and sensitivity analyses. In addition, a comprehensive evaluation of potential dose-response patterns was conducted. In the meta-analysis of all cohorts, a weakly elevated summary relative risk was observed (1.11, 95% CI: 1.03-1.19); however, statistically significant heterogeneity was present. In general, summary associations were attenuated (closer to the null and less heterogeneous) in models that isolated fresh red meat (from processed meat), adjusted for more relevant factors, analyzed women only, and were conducted in countries outside of the United States. Furthermore, no clear patterns of dose-response were apparent. In conclusion, the state of the epidemiologic science on red meat consumption and CRC is best described in terms of weak associations, heterogeneity, an inability to disentangle effects from other dietary and lifestyle factors, lack of a clear dose-response effect, and weakening evidence over time. KEY TEACHING POINTS: •The role of red meat consumption in colorectal cancer risk has been widely contested among the scientific community.•In the current meta-analysis of red meat intake and colorectal cancer, we comprehensively examined associations by creating numerous sub-group stratifications, conducting extensive sensitivity analyses, and evaluating dose-response using several different methods.•Overall, all summary associations were weak in magnitude with no clear dose-response patterns.•Interpretation of findings from epidemiologic studies investigating diet and health outcomes involves numerous methodological considerations, such as accurately measuring food intake, dietary pattern differences across populations, food definitions, outcome classifications, bias and confounding, multicollinearity, biological mechanisms, genetic variation in metabolizing enzymes, and differences in analytical metrics and statistical testing parameters.

Nutrients, foods, and colorectal cancer prevention

Diet has an important role in the development of colorectal cancer. In the past few decades, findings from extensive epidemiologic and experimental investigations have linked consumption of several foods and nutrients to the risk of colorectal neoplasia. Calcium, fiber, milk, and whole grains have been associated with a lower risk of colorectal cancer, and red meat and processed meat have been associated with an increased risk. There is substantial evidence for the potential chemopreventive effects of vitamin D, folate, fruits, and vegetables. Nutrients and foods also may interact, as a dietary pattern, to influence colorectal cancer risk. Diet likely influences colorectal carcinogenesis through several interacting mechanisms. These include the direct effects on immune responsiveness and inflammation, and the indirect effects of overnutrition and obesity-risk factors for colorectal cancer. Emerging evidence also implicates the gut microbiota as an important effector in the relationship between diet and cancer. Dietary modification therefore has the promise of reducing colorectal cancer incidence.

Management of Iron Deficiency Anemia

Anemia affects one-fourth of the world's population, and iron deficiency is the predominant cause. Anemia is associated with chronic fatigue, impaired cognitive function, and diminished well-being. Patients with iron deficiency anemia of unknown etiology are frequently referred to a gastroenterologist because in the majority of cases the condition has a gastrointestinal origin. Proper management improves quality of life, alleviates the symptoms of iron deficiency, and reduces the need for blood transfusions. Treatment options include oral and intravenous iron therapy; however, the efficacy of oral iron is limited in certain gastrointestinal conditions, such as inflammatory bowel disease, celiac disease, and autoimmune gastritis. This article provides a critical summary of the diagnosis and treatment of iron deficiency anemia. In addition, it includes a management algorithm that can help the clinician determine which patients are in need of further gastrointestinal evaluation. This facilitates the identification and treatment of the underlying condition and avoids the unnecessary use of invasive methods and their associated risks.

Macro- and micronutrients consumption and the risk for colorectal cancer among Jordanians

OBJECTIVE

Diet and lifestyle have been reported to be important risk factors for the development of colorectal cancer (CRC). However, the association between total energy and nutrient intake and the risk of developing CRC has not been clearly explained. The aim of our study is to examine the relationship between total energy intake and other nutrients and the development of CRC in the Jordanian population.

RESEARCH METHODS AND PROCEDURES

Dietary data was collected from 169 subjects who were previously diagnosed with CRC, and 248 control subjects (matched by age, gender, occupation and marital status). These control subjects were healthy and disease free. Data was collected between January 2010 and December 2012, using interview-based questionnaires. Logistic regression was used to evaluate the association between quartiles of total energy, macro- and micronutrient intakes with the risk of developing CRC in our study population.

RESULTS

Total energy intake was associated with a higher risk of developing CRC (OR = 2.60 for the highest versus lowest quartile of intake; 95% CI: 1.21-5.56, p-trend = 0.03). Intakes of protein (OR = 3.62, 95% CI: 1.63-8.05, p-trend = 0.002), carbohydrates (OR = 1.41, 95% CI: 0.67-2.99, p-trend = 0.043), and percentage of energy from fat (OR = 2.10, 95% CI: 0.38-11.70, p-trend = 0.009) significantly increased the risk for the development of CRC. Saturated fat, dietary cholesterol and sodium intake showed a significant association with the risk of developing CRC (OR = 5.23, 95% CI: 2.33-11.76; OR = 2.48, 95% CI: 1.18-5.21; and OR = 3.42, 95% CI: 1.59-7.38, respectively), while vitamin E and caffeine intake were indicative of a protective effect against the development of CRC, OR = 0.002 (95% CI: 0.0003-0.011) and 0.023 (95%CI: 0.008-0.067), respectively.

CONCLUSION

Our results suggest an increased risk for the development of CRC in subjects with high dietary intake of energy, protein, saturated fat, cholesterol, and sodium, and diets high in vitamin E and caffeine were suggestive of a protective effect against the risk of developing CRC.

IMPACT

This is the first study in Jordan to suggest that it may be possible to reduce CRC risk by adjusting the intake of some macro-and micronutrients.

Nucleotide excision repair gene polymorphisms, meat intake and colon cancer risk

PURPOSE

Much of the DNA damage from colon cancer-related carcinogens, including heterocyclic amines (HCA) and polycyclic aromatic hydrocarbons (PAH) from red meat cooked at high temperature, are repaired by the nucleotide excision repair (NER) pathway. Thus, we examined whether NER non-synonymous single nucleotide polymorphisms (nsSNPs) modified the association between red meat intake and colon cancer risk.

METHODS

The study consists of 244 African-American and 311 white colon cancer cases and population-based controls (331 African Americans and 544 whites) recruited from 33 counties in North Carolina from 1996 to 2000. Information collected by food frequency questionnaire on meat intake and preparation methods were used to estimate HCA and benzo(a)pyrene (BaP, a PAH) intake. We tested 7 nsSNPs in 5 NER genes: XPC A499V and K939Q, XPD D312N and K751Q, XPF R415Q, XPG D1104H, and RAD23B A249V. Adjusted odds ratios (OR) and 95% confidence intervals (CI) were calculated using unconditional logistic regression.

RESULTS

Among African Americans, we observed a statistically significant positive association between colon cancer risk and XPC 499 AV+VV genotype (OR=1.7, 95% CI: 1.1, 2.7, AA as referent), and an inverse association with XPC 939 QQ (OR=0.3, 95%CI: 0.2, 0.8, KK as referent). These associations were not observed among whites. For both races combined, there was interaction between the XPC 939 genotype, well-done red meat intake and colon cancer risk (OR=1.5, 95% CI=1.0, 2.2 for high well-done red meat and KK genotype as compared to low well-done red meat and KK genotype, pinteraction=0.05).

CONCLUSIONS

Our data suggest that NER nsSNPs are associated with colon cancer risk and may modify the association between well-done red meat intake and colon cancer risk.

Dietary iron, iron homeostatic gene polymorphisms and the risk of advanced colorectal adenoma and cancer

Dietary iron intake and variation in iron homeostasis genes may affect colorectal neoplasia risk. We conducted two nested case-control studies within the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial: one of advanced colorectal adenoma (1205 cases; 1387 controls) and one of colorectal cancer (370 cases; 401 controls). Iron intake was estimated with a food frequency questionnaire and genotyping was performed for 21 genes. Unconditional logistic regression was used to estimate odds ratio (OR) and 95% confidence intervals (95% CIs) for colorectal neoplasia risk within quartiles of intake. Several single nucleotide polymorphisms (SNPs) modified the association between iron intake and the risk of adenoma or cancer. Dietary iron was positively associated with colorectal adenoma among three SNPs of HEPHL1, including carriers of the AA genotype at rs7946162 (ORQ4-Q1 = 2.22, 95% CI 1.15-4.27, Ptrend = 0.03; Pinteraction = 0.10), the TT genotype at rs2460063 (ORQ4-Q1 = 2.39, 95% CI 1.26-4.54, Ptrend = 0.02; Pinteraction = 0.04) and the GG genotype at rs7127348 (ORQ4-Q1 = 2.40, 95% CI 1.23-4.67, Ptrend = 0.02; Pinteraction = 0.09). Heme iron was positively associated with colorectal cancer among those with GG genotypes for ACO1 rs10970985 (ORQ4-Q 1 = 2.45, 95% CI 3.40-8.06, Ptrend = 0.004; Pinteraction = 0.05). However, none of the associations were statistically significant after adjustment for multiple comparisons. Future studies should target the specific genes and SNPs for which the association was significant prior to multiple comparison correction.

Epidemiological and nonclinical studies investigating effects of iron in carcinogenesis--a critical review

The efficacy and tolerability of intravenous (i.v.) iron in managing cancer-related anemia and iron deficiency has been clinically evaluated and reviewed recently. However, long-term data in cancer patients are not available; yet, long-term i.v. iron treatment in hemodialysis patients is not associated with increased cancer risk. This review summarizes epidemiological and nonclinical data on the role of iron in carcinogenesis. In humans, epidemiological data suggest correlations between certain cancers and increased iron exposure or iron overload. Nonclinical models that investigated whether iron can enhance carcinogenesis provide only limited evidence relevant for cancer patients since they were typically based on high iron doses as well as injection routes and iron formulations which are not used in the clinical setting. Nevertheless, in the absence of long-term outcome data from prospectively defined trials in i.v. iron-treated cancer patients, iron supplementation should be limited to periods of concomitant anti-tumor treatment.

Dietary heme iron and the risk of colorectal cancer with specific mutations in KRAS and APC

Red meat intake has been linked to increased colorectal cancer (CRC) risk. Although the underlying mechanisms remain unclear, experimental studies suggest a role for dietary heme iron. Because heme iron was shown to promote specific mutations, it would be insightful to link heme iron data to CRC with mutations in key genes in an observational, population-based study. We investigated the association between dietary heme iron intake and risk of CRC with mutations in APC (adenomatous polyposis coli) and KRAS (Kirsten ras) and P53 overexpression in the Netherlands Cohort Study. After 7.3 years of follow-up, excluding the first 2.3 years due to incomplete coverage of the pathology registry and to avoid preclinical disease, adjusted hazard ratios (including adjustment for total meat) and 95% confidence intervals were calculated, using 4026 subcohort members (aged 55-69 years at baseline), 435 colon and 140 rectal cancer patients. When comparing the highest with the lowest tertile of intake, heme iron intake was associated with an increased risk of CRC harboring activating mutations in KRAS (hazard ratio = 1.71, 95% confidence interval: 1.15-2.57; P for trend = 0.03) and CRC without truncating mutations in APC (hazard ratio = 1.79, 95% confidence interval: 1.23-2.60; P for trend = 0.003). We observed a positive association between heme iron intake and the risk of CRC with activating G>A mutations in KRAS (P for trend = 0.01) and overall G>A mutations in APC (P for trend = 0.005). No associations were found with CRC harboring G>T mutations in KRAS/APC. Heme iron intake was positively associated with the risk of P53 overexpressed tumors but not with tumors without P53 overexpression (Pheterogeneity = 0.12). Heme iron intake was associated with an increased risk of colorectal tumors harboring G>A transitions in KRAS and APC and overexpression of P53. These novel findings suggest that alkylating rather than oxidative DNA-damaging mechanisms are involved in heme-induced colorectal carcinogenesis.

A comparative overview of general risk factors associated with the incidence of colorectal cancer

Cancers found in colorectal region remain largely localized to the large intestine and rectum. They are derived from the epithelium and are considered to be among the most frequently detected cancers. They are known to occur in approximately 5 % population of the Western world. After metastasis, a patient's 5-year postsurgical survival chances unfortunately fall from 90 to 10 % or even less. Adenocarcinoma, the most common cell type of colon cancer, alone constitutes 95 % of the cases. Lymphoma and squamous cell carcinoma can also be found in some cases. Because 5 % of persons are predisposed to development of colorectal cancer, this disease has often been addressed as an important public health issue. Factors that are known in particular to increase a person's risk to develop this cancer are as follows: an individual's age, dietary habits, any complaint of obesity, diabetes, previous history of cancer or intestinal polyps, personal habit of alcohol consumption and smoking, family history of colon cancer, race, sex, and ethnicity. Since the risk of colorectal cancer is increasing steadily in Kashmir, India, like in some other corners of Asia, exhaustive efforts are being made to find the association of above given and other risk factors with the development of this gastrointestinal tract cancer. Adoption of Western life style, diet mimicry, together with a habit of having physically inactive life style and consumption of red meat in particular can be blamed as being active players to a considerable extent.

Iron metabolism and risk of cancer in the Swedish AMORIS study

Objectives

Pre-clinical studies have shown that iron can be carcinogenic, but few population-based studies investigated the association between markers of the iron metabolism and risk of cancer while taking into account inflammation. We assessed the link between serum iron (SI), total-iron binding capacity (TIBC), and risk of cancer by levels of C-reactive protein (CRP) in a large population-based study (n = 220,642).

Methods

From the Swedish Apolipoprotein Mortality Risk (AMORIS) study, we selected all participants (>20 years old) with baseline measurements of serum SI, TIBC, and CRP. Multivariate Cox proportional hazards regression was carried out for standardized and quartile values of SI and TIBC. Similar analyses were performed for specific cancers (pancreatic, colon, liver, respiratory, kidney, prostate, stomach, and breast cancer). To avoid reverse causation, we excluded those with follow-up <3 years.

Results

We found a positive association between standardized TIBC and overall cancer [HR 1.03 (95 % CI 1.01–1.05)]. No statistically significant association was found between SI and cancer risk except for postmenopausal breast cancer [HR for standardized SI 1.09 (95 % CI 1.02–1.15)]. The association between TIBC and specific cancer was only statistically significant for colon cancer [i.e., HR for standardized TIBC: 1.17 (95 % CI 1.08–1.28)]. A borderline interaction between SI and levels of CRP was observed only in stomach cancer.

Conclusions

As opposed to pre-clinical findings for serum iron and cancer, this population-based epidemiological study showed an inverse relation between iron metabolism and cancer risk. Minimal role of inflammatory markers observed warrants further study focusing on developments of specific cancers.

Intakes of heme iron and zinc and colorectal cancer incidence: a meta-analysis of prospective studies

BACKGROUND

Epidemiologic findings concerning the associations between intakes of heme iron and zinc and colorectal cancer (CRC) incidence yielded conflicting results. We aimed to investigate the associations by performing a meta-analysis of prospective studies.

METHODS

We conducted a literature search on PubMed and EMBASE databases up to December 2012 to identify the prospective studies that investigated the relationships between heme iron or zinc intake and risk of CRC. We also reviewed the bibliographies of the retrieved articles to identify additional studies. We used a random-effects model to calculate the summary relative risks (RRs) with 95 % confidence intervals (CIs).

RESULTS

Eight studies on heme iron intake and six studies on zinc intake met the inclusion criteria. The summary RR of CRC for the highest versus the lowest intake was 1.14 (95 % CI = 1.04-1.24) for heme iron and 0.83 (95 % CI = 0.72-0.94) for zinc, respectively. The observed associations were not significantly modified by subsites within the colorectum, sex, geographic area, study duration, the number of cases, or the range of intakes. In the dose-response analyses, the summary RR of CRC was 1.11 (95 % CI = 1.03-1.18) for heme iron intake of 1 mg/day, and 0.86 (95 % CI = 0.78-0.96) for zinc intake of 5 mg/day, respectively. There was little evidence of publication bias.

CONCLUSION

This meta-analysis suggests a significant positive dose-response association of heme iron intake and a significant inverse dose-response association of zinc intake with risk of CRC.

Associations between red meat and risks for colon and rectal cancer depend on the type of red meat consumed

Cancer prevention guidelines recommend limiting intake of red meat and avoiding processed meat; however, few studies have been conducted on the effects of specific red meat subtypes on colon cancer or rectal cancer risk. The study aim was to evaluate associations between intake of red meat and its subtypes, processed meat, fish, and poultry and risk for colon cancer or rectal cancer in the Danish Diet, Cancer and Health cohort study. We also evaluated whether fish or poultry should replace red meat intake to prevent colon cancer or rectal cancer. During follow-up (13.4 y), 644 cases of colon cancer and 345 cases of rectal cancer occurred among 53,988 participants. Cox proportional hazards models were used to compute incidence rate ratio (IRRs) and 95% CIs. No associations were found between intake of red meat, processed meat, fish, or poultry and risk for colon cancer or rectal cancer. The risk associated with specific red meat subtypes depended on the animal of origin and cancer subsite; thus, the risk for colon cancer was significantly elevated for higher intake of lamb [IRR(per 5g/d) = 1.07 (95% CI: 1.02-1.13)], whereas the risk for rectal cancer was elevated for higher intake of pork [IRR(per 25g/d) = 1.18 (95% CI: 1.02-1.36)]. Substitution of fish for red meat was associated with a significantly lower risk for colon cancer [IRR(per 25g/d) = 0.89 (95% CI: 0.80-0.99)] but not rectal cancer. Substitution of poultry for red meat did not reduce either risk. This study suggests that the risks for colon cancer and potentially for rectal cancer differ according to the specific red meat subtype consumed.

Long-term dietary heme iron and red meat intake in relation to endometrial cancer risk

BACKGROUND

Heme and total iron, present in meat, have been hypothesized to promote carcinogenesis. Few prospective studies have examined the associations between intakes of heme and total iron, types of meat, and endometrial cancer risk.

OBJECTIVE

We evaluated the associations between intakes of heme and total iron, types of meat, and risk of endometrial cancer in a large cohort of women.

DESIGN

Among 60,895 women in the Swedish Mammography Cohort, 720 endometrial cancer cases were confirmed during 21 y of follow-up. RRs and 95% CIs were calculated by Cox proportional hazards models.

RESULTS

A comparison of the highest with the lowest quartile showed a 20-30% higher risk of endometrial cancer for higher intakes of heme iron (RR: 1.24; 95% CI: 1.01, 1.53 for ≥1.63 compared with <0.69 mg/d), total iron (RR: 1.31; 95% CI: 1.07, 1.61 for ≥15.09 compared with <12.27 mg/d), and liver (RR: 1.29; 95% CI: 1.06, 1.56 for ≥100 compared with <100 g/wk). No statistically significant associations were observed between intakes of red and processed meats and endometrial cancer risk. RRs did not greatly differ when we stratified by BMI, parity, and intakes of alcohol, vitamin C, or zinc or when we excluded patients with diabetes.

CONCLUSIONS

Our study suggests a modest positive association between heme iron, total iron, and liver intakes and endometrial cancer risk; no statistically significant associations were observed for intakes of other red and processed meats and endometrial cancer risk.

Zinc and heme iron intakes and risk of colorectal cancer: a population-based prospective cohort study in Japan

BACKGROUND

Food sources and intakes of zinc and heme iron may differ between Western and Asian populations. However, all of the studies on the association between zinc and heme iron intakes and colorectal cancer have been conducted in Western populations.

OBJECTIVE

We investigated the association between zinc and heme iron intakes and colorectal cancer risk in a Japanese general population.

DESIGN

We conducted a large, population-based prospective study in 39,721 men and 45,376 women aged 45-74 y. Heme iron and zinc intakes were measured by using a validated food-frequency questionnaire in either 1995 or 1998.

RESULTS

During as many as 808,053 person-years of follow-up until the end of 2006, 1284 colorectal cancer cases were identified. In multivariate-adjusted models, zinc and heme iron intakes were not associated with colorectal cancer in either men or women. In comparison with the lowest quartile, the HRs (95% CIs) for developing colorectal cancer in the fourth quartile of zinc and heme iron intakes were 0.77 (0.58, 1.03; P-trend = 0.2) and 1.06 (0.79, 1.42; P-trend = 0.6), respectively, for men and 1.05 (0.77, 1.44; P-trend = 0.4) and 0.88 (0.61, 1.29; P-trend = 0.4), respectively, for women.

CONCLUSION

Our results in a Japanese population with lower intakes and different major food sources of zinc and heme iron in comparison with those of Western populations suggest that zinc and heme iron intakes are not associated with colorectal cancer.

Associations of dietary iron intake with mortality from cardiovascular disease: the JACC study

Background

We investigated the relationship between dietary iron intake and mortality from cardiovascular disease (CVD) in a population-based sample of Japanese adults.

Methods

The study cohort consisted of 58 615 healthy Japanese (23 083 men and 35 532 women), aged between 40 and 79 years, who had no history of stroke, coronary heart disease (CHD), or cancer at baseline. Dietary iron intake was assessed at baseline by a validated food frequency questionnaire administered between 1988 and 1990 as part of the Japan Collaborative Cohort (JACC) Study.

Results

We documented 2690 (1343 men and 1347 women) deaths from CVD: 1227 (607 men and 620 women) deaths from total stroke, 651 from ischemic stroke (355 men and 296 women), 459 (196 men and 263 women) from hemorrhagic stroke, and 557 (311 men and 246 women) from CHD. Dietary intake of total iron was positively associated with mortality from total and ischemic stroke and total CVD in men. The multivariable hazard ratio for the highest versus the lowest quintile of total iron intake was 1.43 (95% CI, 1.02–2.00; P for trend = 0.009) for total stroke and 1.27 (1.01–1.58; 0.023) for total CVD in men. Dietary total iron intake was not associated with mortality from other endpoints in men, and was not associated with any endpoints in women.

Conclusions

Dietary intake of total iron was positively associated with mortality from stroke and total CVD in Japanese men.