Hemochromatosis Gene Mutations, Body Iron Stores, Dietary Iron, and Risk of Colorectal Adenoma in Women

Serum ferritin and risk of colonic neoplasia: Implications for the workup and treatment of iron deficiency

Iron deficiency is the most common extraintestinal sign of colonic neoplasia, including colorectal cancer (CRC) and other lower gastrointestinal pathology. Both upper endoscopy and colonoscopy is usually recommended in the work-up of patients with unexplained iron deficiency, particularly in men and postmenopausal women. As the incidence of early-onset CRC (age <50 years) rises in the United States, there is an increasing need to identify risk predictors to aid in the early detection of CRC. It remains unknown if serum ferritin (SF), and what specific threshold, can be used as a marker to stratify those at risk for CRC and other lower gastrointestinal pathology. In this current review of the literature, we aimed to review guidelines for diagnostic workup of colonic neoplasia in the setting of iron deficiency and examine the association and specific thresholds of SF and risk of CRC by age. Some of the published findings are conflicting, and conclusions specific to younger patients are limited. Though further investigation is warranted, the cumulative findings suggest that SF, in addition to considering the clinical context and screening guidelines, may have potential utility in the assessment of colonic neoplasia.

MRI Appearance of Focal Lesions in Liver Iron Overload

Liver iron overload is defined as an accumulation of the chemical element Fe in the hepatic parenchyma that exceeds the normal storage. When iron accumulates, it can be toxic for the liver by producing inflammation and cell damage. This can potentially lead to cirrhosis and hepatocellular carcinoma, as well as to other liver lesions depending on the underlying condition associated to liver iron overload. The correct assessment of liver iron storage is pivotal to drive the best treatment and prevent complication. Nowadays, magnetic resonance imaging (MRI) is the best non-invasive modality to detect and quantify liver iron overload. However, due to its superparamagnetic properties, iron provides a natural source of contrast enhancement that can make challenging the differential diagnosis between different focal liver lesions (FLLs). To date, a fully comprehensive description of MRI features of liver lesions commonly found in iron-overloaded liver is lacking in the literature. Through an extensive review of the published literature, we aim to summarize the MRI signal intensity and enhancement pattern of the most common FLLs that can occur in liver iron overload.

Associations of Human Colorectal Adenoma with Serum Biomarkers of Body Iron Stores, Inflammation and Antioxidant Protein Thiols

Red and processed meat consumption and obesity are established risk factors for colorectal adenoma (CRA). Adverse changes in biomarkers of body iron stores (total serum iron, ferritin, transferrin and transferrin saturation), inflammation (high-sensitivity C-reactive protein [hs-CRP]) and anti-oxidative capacity (total of thiol groups (-S-H) of proteins [SHP]) might reflect underlying mechanisms that could explain the association of red/processed meat consumption and obesity with CRA. Overall, 100 CRA cases (including 71 advanced cases) and 100 CRA-free controls were frequency-matched on age and sex and were selected from a colonoscopy screening cohort. Odds ratios (OR) and 95% confidence intervals (95%CI) for comparisons of top and bottom biomarker tertiles were derived from multivariable logistic regression models. Ferritin levels were significantly positively associated with red/processed meat consumption and hs-CRP levels with obesity. SHP levels were significantly inversely associated with obesity. Transferrin saturation was strongly positively associated with overall and advanced CRA (ORs [95%CIs]: 3.05 [1.30-7.19] and 2.71 [1.03-7.13], respectively). Due to the high correlation with transferrin saturation, results for total serum iron concentration were similar (but not statistically significant). Furthermore, SHP concentration was significantly inversely associated with advanced CRA (OR [95%CI]: 0.29 [0.10-0.84]) but not with overall CRA (OR [95%CI]: 0.65 [0.27-1.56]). Ferritin, transferrin, and hs-CRP levels were not associated with CRA. High transferrin saturation as a sign of iron overload and a low SHP concentration as a sign of redox imbalance in obese patients might reflect underlying mechanisms that could in part explain the associations of iron overload and obesity with CRA.

Morbidity, risk of cancer and mortality in 3645 HFE mutations carriers

BACKGROUND & AIMS

Mutations in the HFE gene can lead to hereditary haemochromatosis (HH) and have been suggested to increase the risk of extra-hepatic diseases, especially breast and colorectal cancer. Here we investigated long-term outcomes of Swedish patients with HFE mutations.

METHODS

We identified 3645 patients with a homozygous p.C282Y (62%) or a compound heterozygous p.C282Y/p.H63D (38%) mutation from eight centres in Sweden between 1997 and 2017. These were matched 1:10 by age, sex and county of residence to reference individuals from the general population. We ascertained incident outcomes until the end of 2017 by linkage to national registers. Studied outcomes were HH, cirrhosis, hepatocellular carcinoma (HCC), breast cancer (in women), colorectal cancer, type 1 and 2 diabetes, hypothyroidism, Parkinson's disease and mortality. Cox proportional hazards regression was used to estimate hazard ratios for these outcomes.

RESULTS

Median age at diagnosis was 52 years, 44% were females. During a mean follow-up of 7.9 years, we found an increased risk for HCC, HH, cirrhosis, type 2 diabetes, osteoarthritis and death. Excess mortality was only seen in men. No increased risk was seen for colorectal or breast cancer. Liver-related outcomes were rare, with a cumulative incidence of <1%.

CONCLUSIONS

Individuals found to be HFE mutation carriers in a university hospital setting had an increased risk for mortality in men, along with increased risks of cirrhosis, HCC, diabetes type 2, and osteoarthritis. In general, the absolute risk for adverse outcomes was low and no increased risk for colon or breast cancer was observed.

Hereditary hemochromatosis promotes colitis and colon cancer and causes bacterial dysbiosis in mice

Hereditary hemochromatosis (HH), an iron-overload disease, is a prevalent genetic disorder. As excess iron causes a multitude of metabolic disturbances, we postulated that iron overload in HH disrupts colonic homeostasis and colon–microbiome interaction and exacerbates the development and progression of colonic inflammation and colon cancer. To test this hypothesis, we examined the progression and severity of colitis and colon cancer in a mouse model of HH (Hfe^−/−), and evaluated the potential contributing factors. We found that experimentally induced colitis and colon cancer progressed more robustly in Hfe^−/− mice than in wild-type mice. The underlying causes were multifactorial. Hfe^−/− colons were leakier with lower proliferation capacity of crypt cells, which impaired wound healing and amplified inflammation-driven tissue injury. The host/microflora axis was also disrupted. Sequencing of fecal 16S RNA revealed profound changes in the colonic microbiome in Hfe^−/− mice in favor of the pathogenic bacteria belonging to phyla Proteobacteria and TM7. There was an increased number of bacteria adhered onto the mucosal surface of the colonic epithelium in Hfe^−/− mice than in wild-type mice. Furthermore, the expression of innate antimicrobial peptides, the first-line of defense against bacteria, was lower in Hfe^−/− mouse colon than in wild-type mouse colon; the release of pro-inflammatory cytokines upon inflammatory stimuli was also greater in Hfe^−/− mouse colon than in wild-type mouse colon. These data provide evidence that excess iron accumulation in colonic tissue as happens in HH promotes colitis and colon cancer, accompanied with bacterial dysbiosis and loss of function of the intestinal/colonic barrier.

Association between red and processed meat intake and colorectal adenoma incidence and recurrence: a systematic review and meta-analysis

The associations between red and processed meat intake and colorectal adenoma (CRA) incidence and recurrence are inconclusive. We performed a systematic review and meta-analysis to analysis these associations. We conducted a systematic search of PubMed, EMBASE and Web of Science up to December 2016. The relative risks (RRs) and 95% confidence intervals (CIs) were assessed. Subgroup analyses, dose-response-analyses, subtype analyses and analyses of CRA locations were also conducted. Twenty-seven studies that involved 208,117 participants and 19,150 cases met criteria. The RRs of the highest versus lowest intakes for CRA incidence were 1.23 (1.15–1.31) for red meat and 1.15 (1.07–1.24) for processed meat. Dose-response analyses for meat per 100 g/day yielded the results were consistent with the original analyses, with 1.14 (1.07–1.20) for red meat and 1.27 (1.03–1.50) for processed meat. Additionally, there were no associations between red and processed meat intake and CRA recurrence, including total CRA (P > 0.05), advanced CRA (P > 0.05) and multiple CRA (P > 0.05). In conclusion, our findings support the hypothesis that red and processed meat intake was associated with an increased CRA incidence but not for CRA recurrence.

Duodenal cytochrome b (Cybrd1) ferric reductase functional studies in cells

Dietary non-heme ferric iron is reduced by the ferric reductase enzyme, duodenal cytochrome b (Dcytb), before absorption by the divalent metal transporter 1 (DMT1). A single nucleotide polymorphism (SNP rs10455 mutant) that is located in the last exon of the Dcytb gene was reported in C282Y haemochromatosis HFE subjects. The present work therefore investigated the phenotype of this mutant Dcytb in Chinese hamster ovary (CHO) cells. These cultured cells were transfected with either wild type (WT) or the SNP vector plasmids of Dcytb. Ferric reductase assays were performed in Dcytb transgenic CHO cells using the ferrozine spectrophometric assay protocol. The Dcytb SNP rs10455 showed a gain-of-function capability since ferric reductase activity increased significantly (p < 0.01) in the transgenic cells. Varying ferric reductase activity was found when CHO cells were pretreated with modulators of Dcytb protein expression. Although ferric reductase in endogenous CHO cells increased with deferoxamine or CoCl₂, iron loading with ferric ammonium citrate (FAC) had the opposite effect. Taken together, the study reveals a gain-of-function phenotype for Dcytb rs10455 mutation that could be a putative modifier of colorectal cancer risk, with attendant variability in penetrance among human HFE C282Y homozygotes.

Meat intake and risk of colorectal polyps: results from a large population-based screening study in Germany

Background: Red and processed meats have been shown to be associated with colorectal adenomas in many, but not all, studies, and the association according to the type of colorectal adenoma or the location in the colorectum is unclear.Objectives: We investigated the association of meat intake in relation to colorectal polyps and further investigated the association according to histologic subtypes and subsites in a large population-based screening study in Germany.Design: In this cross-sectional study, 15,950 participants aged ≥55 y underwent a screening colonoscopy. We calculated prevalence ratios (PRs) and 95% CIs for associations between meat intake and the most-advanced findings from a colonoscopy with the use of log binomial regression.Results: Overall, 3340 participants (20.4%) had nonadvanced adenomas, 1643 participants (10.0%) had advanced adenomas, and 189 participants (1.2%) had colorectal cancer. We observed no statistically significant association between red or processed meat consumption and the prevalence of any adenomas or advanced adenomas [highest compared with lowest: red meat, PR: 1.07 (95% CI: 0.83, 1.37); processed meat, PR: 1.11 (95% CI: 0.91, 1.36)]. In site-specific analyses, although no dose-response relation was observed, processed meat was positively associated with the prevalence of advanced adenomas in the rectum only (multiple times per day compared with <1 time/wk, PR: 1.87; 95% CI: 1.19, 2.95). Poultry intake was not associated with any outcome.Conclusions: On the basis of this large colonoscopy-based study, there are no significant associations between red or processed meat intake and the prevalence of any adenomas or advanced adenomas. However, processed meat may be positively associated with the prevalence of advanced adenomas in the rectum, but prospective cohort studies are needed to further clarify this association. There is no association between poultry consumption and the prevalence of colorectal polyps in this study.

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.

Serum Ferritin as a Prognostic Biomarker for Survival in Relapsed or Refractory Metastatic Colorectal Cancer

Background: This study investigated the prognostic impact of serum ferritin for survival in patients with relapsed or refractory metastatic colorectal cancer (mCRC).

Methods: This retrospective cohort study reviewed clinicopathological characteristics and laboratory biomarkers in 120 mCRC patients being treated with Korean Medicine (KM). The overall survival (OS) of patients was calculated using the Kaplan-Meier method, and statistical significance was assessed using the log-rank test. Univariate and multivariate analyses of Cox proportional hazards regression were used to evaluate the prognostic impact for survival in relapsed or refractory mCRC patients.

Results: Of the patients, 62.5% had liver metastases, 74.1% underwent greater than second-line chemotherapy, and 80.8% underwent surgery. Median OS was 7.6 months for all patients after the initiation of KM treatment, which was begun 13.7 months, on average, after mCRC diagnosis. Concerning prognostic factors such as the presence of liver metastasis (p = 0.024), high carcinoembryonic antigen level (CEA > 5 ng/mL, p = 0.044), elevated C-reactive protein (CRP ≥ 10.0 mg/L, p = 0.000), high absolute monocyte count (AMC > 413.3 cells/μL, p = 0.034), elevated serum ferritin (ferritin ≥ 150 ng/mL, p = 0.002), low hemoglobin level (Hb < 12 g/dL, p = 0.026) and low albumin (albumin < 3.5 g/dL, p = 0.003) were associated with increased hazard ratios and poor survival. According to the multivariate proportional hazards model with backward and forward manners, albumin (albumin < 3.5 g/dL; hazard ratio (HR) 2.218, 95% confidence interval (CI) 1.135 - 3.990, p = 0.019), CRP (CRP ≥ 10.0 mg/L; HR 2.506, 95% CI 1.644 - 3.822, p = 0.000), CEA (CEA > 5 ng/mL; HR 2.040, 95% CI 1.203 - 3.460, p = 0.008), and serum ferritin (ferritin ≥ 150 ng/mL; HR 1.763, 95% CI 1.169 - 2.660, p = 0.007) were independent prognostic biomarkers of survival in mCRC patients.

Conclusions: These results indicate that serum ferritin acts as an independent prognostic biomarker for survival in relapsed or refractory mCRC patients.

Heme Iron Intake, Dietary Antioxidant Capacity, and Risk of Colorectal Adenomas in a Large Cohort Study of French Women

BACKGROUND

Nitrosylated and non-nitrosylated heme iron from red processed and nonprocessed meat have been associated with increased colorectal carcinogenesis. Mechanisms include oxidative processes. It has been hypothesized that dietary antioxidants could counteract the effects of heme iron. We investigated the relationships between heme iron intake and the risk of colorectal adenomas, and a potential interaction with the dietary antioxidant capacity, in the E3N prospective cohort study.

METHODS

The study included 17,397 women, who underwent at least one colonoscopy. Among them, 1,409 were diagnosed with at least one first colorectal adenoma during the 103,253 person-years of follow-up. Dietary intake was measured by a semiquantitative food history questionnaire. HR estimates and 95% confidence intervals (CI) were obtained from Cox proportional hazards models, adjusted for potential confounders.

RESULTS

Heme iron intake was positively associated with colorectal and colon adenoma risks [HR for the fourth vs. first quartile: HR4 = 1.36 (1.13-1.65), Ptrend = 0.001 and HR4 = 1.49; 95% CI, 1.19-1.87; Ptrend = 0.0003, respectively]. Nonnitrosylated and nitrosylated heme iron intakes were, respectively, associated with advanced distal and proximal adenoma risks. There was a dose-effect relationship between the heme iron to total dietary antioxidant capacity ratio and colorectal adenoma risk.

CONCLUSION

In this prospective cohort study, the association between heme iron and colorectal adenoma risk was found to depend on site, nitrosylation or not, and the ratio with the NEAC.

IMPACT

These results emphasize the need for a global assessment of diet when considering nutritional prevention of colorectal carcinogenesis. Cancer Epidemiol Biomarkers Prev; 25(4); 640-7. ©2016 AACR.

Gender and plasma iron biomarkers, but not HFE gene mutations, increase the risk of colorectal cancer and polyps

A cohort study of patients included in the Basque Country colorectal cancer (CRC) screening programme was carried out to assess the risk of adenomatous polyps and CRC (P-CRC) associated with HFE gene mutations, with gender and with iron biomarkers (serum ferritin (SF), iron (Fe) and transferrin saturation index (TSI)). Among 432 included patients (mean age 59.8 years), 263 were men (60.9 %) and 169 women (39.1 %). P-CRC were identified in 221 patients (51.2 %) and no polyps (NP) in 211 patients (48.8 %). HFE mutations were identified in 43.8 % of the patients. C282Y/wt genotypic frequency was 6.8 % in the P-CRC group and 1.4 % in the NP group (p < 0.05). The allelic frequency was 3.8 versus 1.2 % (p < 0.05). For laboratory, all three iron biomarkers showed a statistically significant difference: mean Fe, 91.29 ± 34 for P-CRC and 80.81 ± 30.59 for NP group. Mean TSI for P-CRC was 24.95 ± 8.90 and 22.74 ± 8.79 for NP group. Mean SF 308.09 ± 536.32 for P-CRC and 177.55 ± 159.95 for NP group. In a multivariate logistic regression analysis, only male gender (odds ratio (OR) = 2.04, 1.29-3.22), SF (OR = 1.001, 1.0004-1.003) and Fe (OR = 1.01, 1.004-1.02) were related with the presence of CRC and adenoma. Men gender and raised serum iron biomarkers increase the risk of P-CRC.

Evidence for the Influence of the Iron Regulatory MHC Class I Molecule HFE on Tumor Progression in Experimental Models and Clinical Populations

Proteins involved in iron regulation are modifiers of cancer risk and progression. Of these, the HFE protein (high iron gene and its protein product) is of particular interest because of its interaction with both iron handling and immune function and the high rate of genetic polymorphisms resulting in a mutant protein. Clinical studies suggest that HFE polymorphisms increase the risk of certain cancers, but the inconsistent outcomes suggest a more nuanced effect, possibly interacting with other genetic or environmental factors. Some basic science research has been conducted to begin to understand the implications of variant HFE genotype on cancer, but the story is far from complete. In particular, putative mechanisms exist for HFE to affect tumor progression through its role in iron handling and its major histocompatibility complex class I structural features. In this review, the current understanding of the role of HFE in cancer is described and models for future directions are identified.

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.

The significance of ferritin in cancer: anti-oxidation, inflammation and tumorigenesis

The iron storage protein ferritin has been continuously studied for over 70years and its function as the primary iron storage protein in cells is well established. Although the intracellular functions of ferritin are for the most part well-characterized, the significance of serum (extracellular) ferritin in human biology is poorly understood. Recently, several lines of evidence have demonstrated that ferritin is a multi-functional protein with possible roles in proliferation, angiogenesis, immunosuppression, and iron delivery. In the context of cancer, ferritin is detected at higher levels in the sera of many cancer patients, and the higher levels correlate with aggressive disease and poor clinical outcome. Furthermore, ferritin is highly expressed in tumor-associated macrophages which have been recently recognized as having critical roles in tumor progression and therapy resistance. These characteristics suggest ferritin could be an attractive target for cancer therapy because its down-regulation could disrupt the supportive tumor microenvironment, kill cancer cells, and increase sensitivity to chemotherapy. In this review, we provide an overview of the current knowledge on the function and regulation of ferritin. Moreover, we examine the literature on ferritin's contributions to tumor progression and therapy resistance, in addition to its therapeutic potential.

Health effects of different dietary iron intakes: a systematic literature review for the 5th Nordic Nutrition Recommendations

BACKGROUND

The present literature review is part of the NNR5 project with the aim of reviewing and updating the scientific basis of the 4th edition of the Nordic Nutrition Recommendations (NNR) issued in 2004.

OBJECTIVE

The objective of this systematic literature review was to assess the health effects of different intakes of iron, at different life stages (infants, children, adolescents, adults, elderly, and during pregnancy and lactation), in order to estimate the requirement for adequate growth, development, and maintenance of health.

METHODS

The initial literature search resulted in 1,076 abstracts. Out of those, 276 papers were identified as potentially relevant. Of those, 49 were considered relevant and were quality assessed (A, B, or C). An additional search on iron and diabetes yielded six articles that were quality assessed. Thus, a total of 55 articles were evaluated. The grade of evidence was classified as convincing (grade 1), probable (grade 2), suggestive (grade 3), and inconclusive (grade 4).

RESULTS

There is suggestive evidence that prevention or treatment of iron deficiency (ID) and iron deficiency anemia (IDA) improves cognitive, motoric, and behavioral development in young children, and that treatment of IDA improves attention and concentration in school children and adult women. There is insufficient evidence to show negative health effects of iron intakes in doses suggested by the NNR 4. There is insufficient evidence to suggest that normal birth weight, healthy, exclusively breast-fed infants need additional dietary iron before 6 months of life in the Nordic countries. An iron concentration of 4-8 mg/L in infant formulas seems to be safe and effective for normal birth weight infants. There is probable evidence that iron supplements (1-2 mg/kg/day) given up to 6 months of age to infants with low birth weight (<2,500 g) prevents IDA and possibly reduce the risk of behavioral problems later on. There is probable evidence that ID and IDA in pregnant women can be effectively prevented by iron supplementation at a dose of 40 mg/day from week 18-20 of gestation. There is probable evidence that a high intake of heme iron, but not total dietary, non-heme or supplemental iron, is associated with increased risk of type 2 diabetes (T2D) and gestational diabetes.

CONCLUSIONS

Overall, the evidence does not support a change of the iron intakes recommended in the NNR 4. However, one could consider adding recommendations for infants below 6 months of age, low birth weight infants and pregnant women.

Intestinal iron homeostasis and colon tumorigenesis

Colorectal cancer (CRC) is the third most common cause of cancer-related deaths in industrialized countries. Understanding the mechanisms of growth and progression of CRC is essential to improve treatment. Iron is an essential nutrient for cell growth. Iron overload caused by hereditary mutations or excess dietary iron uptake has been identified as a risk factor for CRC. Intestinal iron is tightly controlled by iron transporters that are responsible for iron uptake, distribution, and export. Dysregulation of intestinal iron transporters are observed in CRC and lead to iron accumulation in tumors. Intratumoral iron results in oxidative stress, lipid peroxidation, protein modification and DNA damage with consequent promotion of oncogene activation. In addition, excess iron in intestinal tumors may lead to increase in tumor-elicited inflammation and tumor growth. Limiting intratumoral iron through specifically chelating excess intestinal iron or modulating activities of iron transporter may be an attractive therapeutic target for CRC.

HFE gene C282Y variant is associated with colorectal cancer in Caucasians: a meta-analysis

The HFE gene has been suggested to play an important role in the pathogenesis of colorectal cancer. However, the results have been conflicting. In this study, we performed a meta-analysis to clarify the association of HFE gene C282Y variant with colorectal cancer. PubMed and Embase were retrieved to identify the potential literature. Pooled odds ratio (OR) with 95 % confidence interval (CI) was calculated using fixed- or random-effects model. A total of eight papers including nine studies (7,588 colorectal cancer cases and 81,571 controls) for HFE gene C282Y variant were included in the meta-analysis. The result indicated that HFE gene C282Y variant was significantly associated with colorectal cancer under recessive model (OR = 2.00, 95 % CI = 1.32-3.04), with no evidence of between-study heterogeneity (I (2) = 0.2 %, p = 0.432). Further subgroup analysis by number of cases suggested the effect was significant in studies with more than 500 cases (OR = 2.51, 95 % CI = 1.58-3.98, I (2) = 0.0 %, p = 0.921), but not in studies with less than 500 cases (OR = 0.75, 95 % CI = 0.28-1.97, I (2) = 0.0 %, p = 0.622). The current meta-analysis supported the positive association of HFE gene C282Y variant with colorectal cancer. Further large-scale studies with the consideration for gene-gene/gene-environment interactions should be conducted to investigate the association.

Hemochromatosis (HFE) gene mutations and risk of gastric cancer in the European Prospective Investigation into Cancer and Nutrition (EPIC) study

Hereditary hemochromatosis (HH) is a strong risk factor for hepatocellular cancer, and mutations in the HFE gene associated with HH and iron overload may be related to other tumors, but no studies have been reported for gastric cancer (GC). A nested case-control study was conducted within the European Prospective Investigation into Cancer and Nutrition (EPIC), including 365 incident gastric adenocarcinoma and 1284 controls matched by center, sex, age and date of blood collection. Genotype analysis was performed for two functional polymorphisms (C282Y/rs1800562 and H63D/rs1799945) and seven tagSNPs of the HFE genomic region. Association with all gastric adenocarcinoma, and according to anatomical localization and histological subtype, was assessed by means of the odds ratio (OR) and 95% confidence interval (CI) estimated by unconditional logistic regression adjusted for the matching variables. We observed a significant association for H63D with OR (per rare allele) of 1.32 (CI = 1.03-1.69). In subgroup analyses, the association was stronger for non-cardia anatomical subsite (OR = 1.60, CI = 1.16-2.21) and intestinal histological subtype (OR = 1.82, CI = 1.27-2.62). Among intestinal cases, two tagSNPs (rs1572982 and rs6918586) also showed a significant association that disappeared after adjustment for H63D. No association with tumors located in the cardia or with diffuse subtype was found for any of the nine SNPs analyzed. Our results suggest that H63D variant in HFE gene seems to be associated with GC risk of the non-cardia region and intestinal type, possibly due to its association with iron overload although a role for other mechanisms cannot be entirely ruled out.

Red and processed meat intake and risk of colorectal adenomas: a systematic review and meta-analysis of epidemiological studies

BACKGROUND

Current evidence indicates that red and processed meat intake increases the risk of colorectal cancer; however, the association with colorectal adenomas is unclear.

OBJECTIVE

To conduct a systematic review and meta-analysis of epidemiological studies of red and processed meat intake and risk of colorectal adenomas as part of the Continuous Update Project of the World Cancer Research Fund.

DESIGN

PubMed and several other databases were searched for relevant studies from their inception up to 31 December 2011. Summary relative risks (RRs) were estimated using a random effects model.

RESULTS

Nineteen case-control studies and seven prospective studies were included in the analyses. The summary RR per 100 g/day of red meat was 1.27 (95 % CI 1.16-1.40, I (2) = 5 %, n = 16) for all studies combined, 1.20 (95 % CI 1.06-1.36, I (2) = 0 %, n = 6) for prospective studies, and 1.34 (95 % CI 1.12-1.59, I (2) = 31 %, n = 10) for case-control studies. The summary RR per 50 g/day of processed meat intake was 1.29 (95 % CI 1.10-1.53, I (2) = 27 %, n = 10) for all studies combined, 1.45 (95 % CI 1.10-1.90, I (2) = 0 %, n = 2) for prospective studies, and 1.23 (95 % CI 0.99-1.52, I (2) = 37 %, n = 8) for case-control studies. There was evidence of a nonlinear association between red meat (p nonlinearity < 0.001) and processed meat (p nonlinearity = 0.01) intake and colorectal adenoma risk.

CONCLUSION

These results indicate an elevated risk of colorectal adenomas with intake of red and processed meat, but further prospective studies are warranted.

Exploring the relationship between maternal iron status and offspring's blood pressure and adiposity: a Mendelian randomization study

Background

Iron deficiency is the most common micronutrient deficiency worldwide. Experimental animal studies suggest that mothers deficient in iron during pregnancy are more likely to have offspring who become obese with high blood pressure. C282Y mutation carriers are more likely to have higher iron stores.

Methods

We undertook an instrumental variable (IV) analysis, using maternal C282Y as an indicator for the mother’s iron status, to examine its association with offspring blood pressure (BP), waist circumference (WC), and body mass index (BMI), and compared the results to that of ordinary least squares (OLS) regression. Offspring of a sub-cohort of mothers from the UK Women’s Cohort Study (UKWCS) were recruited in 2009–2010 (n = 348, mean age = 41 years). Their blood pressure, height, and weight were measured at their local general medical practice, and they were asked to self-measure their waist circumference. About half were offspring of C282Y carriers. Maternal ferritin was used as a biomarker of maternal iron status.

Results

Maternal C282Y was strongly associated with maternal ferritin (mean difference per allele = 84 g/L, 95% confidence interval: 31–137, P = 0.002). Using IV analyses, maternal ferritin was not linked to offspring’s BP, BMI, or WC. The first stage F-statistic for the strength of the instrument was 10 (Kleibergen–Paap rk LM P = 0.009). Maternal ferritin was linked to offspring diastolic BP, WC, and BMI in univariable, but not in multivariable OLS analysis. There was no difference between the OLS and the IV models coefficients for any of the outcomes considered.

Conclusion

We found no association between maternal iron status and adult offspring’s BP and adiposity using both multivariable OLS and IV modeling. To our knowledge, this is the first study examining this relationship. Further exploration in larger studies that have genetic variation assessed in both mother and offspring should be considered.

Blood donation and colorectal cancer incidence and mortality in men

Background

Although blood donations may reduce body iron stores, to date, prospective data on frequent blood donation and colorectal cancer risk are limited.

Methodology/Principal Findings

We tested whether frequent blood donation is associated with a lower risk of colorectal cancer in the Health Professionals Follow-up Study. We prospectively followed 35,121men who provide the information on lifetime number of blood donations in 1992 through 2008. Serum ferritin levels were measured in a random sample of 305 men. Cox proportional hazard regression models were used to calculate the multivariable relative risks (RRs, 95%CIs) after adjusting for age and other established colorectal cancer risk factors. We documented 684 incident colorectal cancer cases and 224 deaths from colorectal cancer. The mean serum ferritin levels varied from 178 µg/L for men who did not donate blood to 98 µg/L for men who had at least 30 donations. Age-adjusted results for both incidence and mortality were essentially the same as the multivariable-adjusted results. Comparing with non-donors, the multivariable RRs (95%CIs) for colorectal cancer incidence were 0.92 (0.77, 1.11) for 1–5 donation, 0.85 (0.64, 1.11) for 6–9 donations, 0.96 (0.73, 1.26) for 10–19 donations, 0.91 (0.63, 1.32) for 20–29 donations, and 0.97 (0.68, 1.38) for at least 30 donations (P_trend = 0.92). The multivariable RRs for colorectal cancer mortality were 0.99 (0.72, 1.36) for 1–5 donation, 0.93 (0.57, 1.51) for 6–9 donations, 0.85 (0.50, 1.42) for 10–19 donations, and 1.14 (0.72, 1.83) for at least 20 donations (P_trend = 0.82). The results did not vary by cancer sub-sites, intake levels of total iron, heme iron, or family history of colorectal cancer.

Conclusions/Significance

Frequent blood donations were not associated with colorectal cancer incidence and mortality in men. Our results do not support an important role of body iron stores in colorectal carcinogenesis.

Meat consumption and the risk of incident distal colon and rectal adenoma

Background:

Most studies of meat and colorectal adenoma have investigated prevalent events from a single screening, thus limiting our understanding of the role of meat and meat-related exposures in early colorectal carcinogenesis.

Methods:

Among participants in the screening arm of the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial who underwent baseline and follow-up sigmoidoscopy (n=17 072), we identified 1008 individuals with incident distal colorectal adenoma. We calculated odds ratios (ORs) and 95% confidence intervals (95% CIs) for associations between meat and meat-related components and incident distal colorectal adenoma using multivariate logistic regression.

Results:

We observed suggestive positive associations for red meat, processed meat, haeme iron, and nitrate/nitrite with distal colorectal adenoma. Grilled meat (OR=1.56, 95% CI=1.04–2.36), well or very well-done meat (OR=1.59, 95% CI=1.05–2.43), 2-amino-1-methyl-6-phenyl-imidazo[4,5-b]pyridine (PhIP) (OR=1.75, 95% CI=1.17–2.64), benzo[a]pyrene (OR=1.53, 95% CI=1.06–2.20), and total mutagenic activity (OR=1.57, 95% CI=1.03–2.40) were positively associated with rectal adenoma. Total iron (diet and supplements) (OR=0.69, 95% CI=0.56–0.86) and iron from supplements (OR=0.65, 95% CI=0.44–0.97) were inversely associated with any distal colorectal adenoma.

Conclusion:

Our findings indicate that several meat-related components may be most relevant to early neoplasia in the rectum. In contrast, total iron and iron from supplements were inversely associated with any distal colorectal adenoma.

Iron homeostasis and distal colorectal adenoma risk in the prostate, lung, colorectal, and ovarian cancer screening trial

Red meat consumption has been positively associated with colorectal cancer; however, the biological mechanism underlying this relationship is not understood. Red meat is a major source of iron, which may play a role in colorectal carcinogenesis via increased crypt cell proliferation, cytotoxicity, and endogenous N-nitrosation. In a nested case-control study within the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial, we prospectively evaluated multiple iron exposure parameters, including dietary intake and serum measures of iron, ferritin, transferrin, total iron binding capacity (TIBC), and unsaturated iron binding capacity (UIBC) in relation to incident colorectal adenoma in 356 cases and 396 matched polyp-free controls. We also investigated variation in eight key genes involved in iron homeostasis in relation to colorectal adenoma in an additional series totaling 1,126 cases and 1,173 matched controls. We observed a positive association between red meat intake and colorectal adenoma [OR comparing extreme quartiles (OR(q4-q1)) = 1.59, 95% CI = 1.02-2.49, P(trend) = 0.03]. Serum TIBC and UIBC were inversely associated with colorectal adenoma (OR(q4-q1) = 0.57, 95% CI = 0.37-0.88, P(trend) = 0.03; and OR(q4-q1) = 0.62, 95% CI = 0.40-0.95, P(trend) = 0.04, respectively). Colorectal adenoma was not associated with serum ferritin, iron, or transferrin saturation or with polymorphisms in genes involved in iron homeostasis. Serum TIBC and UIBC, parameters that have a reciprocal relationship with overall iron load, were inversely related to colorectal adenoma, suggesting that individuals with lower iron status have a reduced risk of developing colorectal adenoma.

Primary prevention of colorectal cancer

Colorectal cancer has been strongly associated with a Western lifestyle. In the past several decades, much has been learned about the dietary, lifestyle, and medication risk factors for this malignancy. Although there is controversy about the role of specific nutritional factors, consideration of dietary pattern as a whole appears useful for formulating recommendations. For example, several studies have shown that high intake of red and processed meats, highly refined grains and starches, and sugars is related to increased risk of colorectal cancer. Replacing these factors with poultry, fish, and plant sources as the primary source of protein; unsaturated fats as the primary source of fat; and unrefined grains, legumes and fruits as the primary source of carbohydrates is likely to lower risk of colorectal cancer. Although a role for supplements, including vitamin D, folate, and vitamin B6, remains uncertain, calcium supplementation is likely to be at least modestly beneficial. With respect to lifestyle, compelling evidence indicates that avoidance of smoking and heavy alcohol use, prevention of weight gain, and maintenance of a reasonable level of physical activity are associated with markedly lower risks of colorectal cancer. Medications such as aspirin and nonsteroidal anti-inflammatory drugs and postmenopausal hormones for women are associated with substantial reductions in colorectal cancer risk, though their utility is affected by associated risks. Taken together, modifications in diet and lifestyle should substantially reduce the risk of colorectal cancer and could complement screening in reducing colorectal cancer incidence.

HFE C282Y homozygotes are at increased risk of breast and colorectal cancer

The evidence that mutations in the HFE gene for hemochromatosis are associated with increased cancer risk is inconsistent. The Melbourne Collaborative Cohort Study is a prospective cohort study that commenced recruitment in 1990. Participants born in Australia, New Zealand, the United Kingdom, or Ireland (n = 28,509) were genotyped for the HFE C282Y (substitution of tyrosine for cysteine at amino acid 282) variant. Incident cancers were ascertained from Australian cancer registries during an average of 14 years follow-up. Hazard ratios (HRs), confidence intervals (CIs), and P values were obtained from separate Cox regression analyses for colorectal, breast, and prostate cancers, all other solid cancers, and all cancers. Compared to those with no C282Y variant, C282Y homozygotes were at increased risk of colorectal cancer (HR = 2.28; 95% CI = 1.22, 4.25; P = 0.01) and female C282Y homozygotes were at increased risk of developing breast cancer (HR = 2.39; 95% CI = 1.24, 4.61; P = 0.01), but male C282Y homozygotes were not at increased risk for prostate cancer (HR = 0.96; 95% CI = 0.43, 2.15; P = 0.92). C282Y/H63D compound heterozygotes were not at increased risk for colorectal cancer (HR = 1.27; 95% CI = 0.80, 2.01), breast cancer (HR = 1.16; 95% CI = 0.74, 1.84), or prostate cancer (HR = 1.08; 95% CI = 0.68, 1.70).

CONCLUSION

HFE C282Y homozygotes have twice the risk of colorectal and breast cancer compared with those individuals without the C282Y variant.

Iron: An emerging factor in colorectal carcinogenesis

The carcinogenic potential of iron in colorectal cancer (CRC) is not fully understood. Iron is able to undergo reduction and oxidation, making it important in many physiological processes. This inherent redox property of iron, however, also renders it toxic when it is present in excess. Iron-mediated generation of reactive oxygen species via the Fenton reaction, if uncontrolled, may lead to cell damage as a result of lipid peroxidation and oxidative DNA and protein damage. This may promote carcinogenesis through increased genomic instability, chromosomal rearrangements as well as mutations of proto-oncogenes and tumour suppressor genes. Carcinogenesis is also affected by inflammation which is exacerbated by iron. Population studies indicate an association between high dietary iron intake and CRC risk. In this editorial, we examine the link between iron-induced oxidative stress and inflammation on the pathogenesis of CRC.

The effect of dietary iron intake on the development of iron overload among homozygotes for haemochromatosis

Objective

To quantify the role of dietary Fe in total body Fe (TBI) accumulation among homozygotes for theHFEgene associated with haemochromatosis.

Design

A Monte Carlo model was built to simulate Fe accumulation based on findings from human feeding experiments and national dietary surveys. A hypothetical cohort of 1000 homozygotes with starting age 25 years was used in 39-year simulations. The impact of reducing dietary Fe intake on Fe accumulation was tested.

Results

In the baseline model without any dietary intervention, by age 64, the percentage of males with TBI > 10 g, >15 g and >20 g was 93·2 %, 49·6 % and 14·7 %, respectively. When the Fe intake of individuals in the cohort was reduced to ≤200 % of the recommended dietary allowance (RDA), the corresponding percentages were 92·0 %, 40·5 % and 10·2 %, respectively. The corresponding figures were 91·0 %, 40·0 % and 9·3 % for Fe defortification and 70·3 %, 21·3 % and 4·1 % when Fe intake was capped at 100 % RDA. Similar trends were seen with sexes combined, although the impact of interventions was less. Sensitivity analysis revealed that the rate of Fe accumulation and the impact of dietary interventions are highly dependent on assumptions concerning Fe absorption rates.

Conclusions

Variation in Fe intake as currently observed in the USA contributes to variation in Fe accumulation among homozygotes, when continued over an extended period. Lifelong dietary habits and national fortification policy can affect the rate of Fe accumulation, although the magnitude of the effect varies by gender, the TBI level of interest and factors affecting the Fe absorption rate.

Haemochromatosis HFE gene polymorphisms as potential modifiers of hereditary nonpolyposis colorectal cancer risk and onset age

Hereditary nonpolyposis colorectal cancer (HNPCC) is characterized by germline mutations in DNA mismatch repair genes; however, variation in disease expression suggests that there are potential modifying factors. Polymorphisms of the HFE gene, which cause the iron overload disorder hereditary haemochromatosis, have been proposed as potential risk factors for the development of colorectal cancer (CRC). To understand the relationship between HNPCC disease phenotype and polymorphisms of the HFE gene, a total of 362 individuals from Australia and Poland with confirmed causative MMR gene mutations were genotyped for the HFE C282Y and H63D polymorphisms. A significantly increased risk of developing CRC was observed for H63D homozygotes when compared with combined wild-type homozygotes and heterozygotes (hazard ratio = 2.93, p = 0.007). Evidence for earlier CRC onset was also observed in H63D homozygotes with a median age of onset 6 years earlier than wild type or heterozygous participants (44 vs. 50 years of age). This effect was significant by all tests used (log-rank test p = 0.026, Wilcoxon p = 0.044, Tarone-Ware p = 0.035). No association was identified for heterozygosity of either polymorphism and limitations on power-prevented investigation of C282Y homozygosity or compound C282Y/H63D heterozygosity. In the Australian sample only, women had a significantly reduced risk of developing CRC when compared with men (hazard ratio = 0.58, p = 0.012) independent of HFE genotype for either single nucleotide polymorphisms. In conclusion, homozygosity for the HFE H63D polymorphism seems to be a genetic modifier of disease expression in HNPCC. Understanding the mechanisms by which HFE interrelates with colorectal malignancies could lead to reduction of disease risk in HNPCC.

Dietary meat intake in relation to colorectal adenoma in asymptomatic women

OBJECTIVES

No previous study has concurrently assessed the associations between meat intake, meat-cooking methods and doneness levels, meat mutagens (heterocyclic amines (HCAs) and polycyclic aromatic hydrocarbons), heme iron, and nitrite from meat and colorectal adenoma in asymptomatic women undergoing colonoscopy.

METHODS

Of the 807 eligible women in a cross-sectional multicenter colonoscopy screening study, 158 prevalent colorectal adenoma cases and 649 controls satisfactorily completed the validated food frequency and meat questionnaires. Using an established meat mutagen database and new heme iron and nitrite databases, we comprehensively investigated the components of meat that may be involved in carcinogenesis. Using logistic regression, we estimated odds ratios (ORs) and 95% confidence intervals (CIs) within quartiles of meat-related variables.

RESULTS

Red meat was associated positively with colorectal adenoma (OR fourth vs. first quartile = 2.02; 95% CI = 1.06-3.83; P trend = 0.38). Intake of pan-fried meat (OR = 1.72; 95% CI = 0.96-3.07; P trend = 0.01) and the HCA: 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) (OR = 1.90; 95% CI = 1.05-3.42; P trend = 0.07) were also associated with an increased risk of colorectal adenoma. The new databases yielded lower estimates of heme iron and nitrite than previous assessment methods, although the two methods were highly correlated for both exposures. Although not statistically significant, there were positive associations between iron and heme iron from meat and colorectal adenoma.

CONCLUSIONS

In asymptomatic women undergoing colonoscopy, colorectal adenomas were associated with high intake of red meat, pan-fried meat, and the HCA MeIQx. Other meat-related exposures require further investigation.

Large-scale evaluation of genetic variants in candidate genes for colorectal cancer risk in the Nurses' Health Study and the Health Professionals' Follow-up Study

Advances in genomics offer new strategies for assessing the association of common genetic variations at multiple loci and risk of many diseases, including colorectal cancer. Low-penetrance alleles of genes in many biological pathways, such as DNA repair, metabolism, inflammation, cell cycle, apoptosis, and Wnt signaling, may influence the risk of nonfamilial colorectal cancer. To identify susceptibility genes for colorectal cancer, we designed a large-scale case-control association study nested within the Nurses' Health Study (190 cases and 190 controls) and the Health Professionals' Follow-up Study (168 cases and 168 controls). We used a custom GoldenGate (Illumina) oligonucleotide pool assay including 1,536 single nucleotide polymorphisms (SNP) selected in candidate genes from cancer-related pathways, which have been sequenced and genotyped in the SNP500Cancer project; 1,412 of the 1,536 (92%) of the SNPs were genotyped successfully within 388 genes. SNPs in high linkage disequilibrium (r(2) >/= 0.90) with another assayed SNP were excluded from further analyses. As expected by chance (and not significant compared with a corrected Bonferroni P = 0.00004), in the additive model, 11 of 1,253 (0.9%) SNPs had a P(trend) < 0.01 and 38 of 1,253 (3.0%) SNPs had a P(trend) >/= 0.01 and P(trend) < 0.05. Of note, the MGMT Lys(178)Arg (rs2308237) SNP, in linkage disequilibrium with the previously reported MGMT Ile(143)Val SNP, had an inverse association with colorectal cancer risk (MGMT Lys(178)Arg: odds ratio, 0.52; 95% confidence interval, 0.35-0.78; unadjusted P(trend) = 0.0003 for the additive model; gene-based test global P = 0.00003). The SNP500Cancer database and the Illumina GoldenGate Assay allowed us to test a larger number of SNPs than previously possible. We identified several SNPs worthy of investigation in larger studies.

Iron intake, oxidative stress-related genes (MnSOD and MPO) and prostate cancer risk in CARET cohort

Iron overload may increase prostate cancer risk through stimulation of oxidative stress, and endogenous pro- and antioxidant capabilities, i.e. manganese superoxide dismutase (MnSOD) and myeloperoxidase (MPO), may modify these associations. We investigated this hypothesis in the Carotene and Retinol Efficacy Trial cohort in a nested case-control study. Although there was no association between iron intake and risk overall, there was a suggestion of increased risk of clinically aggressive prostate cancer with higher iron intake [odds ratio (OR) = 1.4, 95% confidence interval (CI) = 0.9-2.0]. Associations were most notable for men with aggressive prostate cancer who were below the median consumption of total fruits and vegetables (OR = 1.8, 95% CI = 1.1-3.2). Associations between MPO -463 G to A genotype (rs2333227) and prostate cancer risk were only noted among men with aggressive cancer, with more than a 2-fold risk reduction among men with AA genotypes (OR = 0.4, 95% CI = 0.2-1.0); MnSOD was not associated with risk overall, but the MnSOD T to C (Val-9Ala, rs4880) polymorphism modified associations between risk of clinically aggressive prostate cancer and dietary iron intake (P for interaction = 0.02). Among aggressive cancer cases with the TT genotype, higher iron intake level was associated with >2-fold increase in risk (OR = 2.3, 95% CI = 1.0-4.9), whereas there was no association among men with CC genotypes (OR = 0.9, 95% CI = 0.4-2.3). Although interactions were not significant, there were similar patterns for MPO genotype, iron intake and risk. These findings suggest that higher iron intake may be associated with risk of clinically aggressive prostate cancer, and that endogenous antioxidant capabilities may modify these associations.

Blood mononucleocytes are sensitive to the DNA damaging effects of iron overload--in vitro and ex vivo results with human and rat cells

Iron exposure enhances colorectal carcinogeneis, by producing reactive oxygen species, which damage lipids, proteins and DNA. We recently demonstrated that ferric-nitrilotriacetate (Fe-NTA) damages DNA of human colon cells in different stages of malignant transformation. Opposed to this, little is known on systemic effects of iron and it is still difficult to determine the border between essential iron supplementation and iron overload in humans. The aim of this study was to determine whether Fe-NTA causes global and specific DNA damage in peripheral leucocytes. Human leucocytes were treated in vitro with Fe-NTA for 30 min at 37 degrees C. Male Sprague Dawley rats were fed (6 weeks) with an iron-overload diet (9.9 g Fe/kg DM) and whole blood was collected. DNA damage was measured in human and rat blood cells using the alkaline version of the Comet Assay with repair specific enzymes. In human cells the distribution of TP53 in the comet images was detected using fluorescence in situ hybridization (Comet FISH) to measure DNA damage in the region of the TP53 gene. Fe-NTA (10-500 microM) was clearly genotoxic in human leucocytes in vitro, and also in leucocytes of rats fed the iron overload diet. The induced damage in human leucocytes was approximately two-fold that observed previously in human colon cells. Oxidized bases were induced by iron in rat leucocytes in vivo, while they were not induced in human leucocytes in vitro. Fe-NTA enhanced the migration of TP53 signals into the comet tail of human leucocytes, indicating a high susceptibility of this tumour-relevant gene towards DNA damage induced by iron overload. In conclusion, iron markedly induced DNA damage in human and rat leucocytes, which shows that these white blood cells are sufficiently sensitive to assess exposure to iron. The measurement of DNA damage in human leucocytes could be used as a sensitive biomarker to study iron overload in vivo in humans and thus to determine whether supplementation results in genotoxic risk.

Dietary animal-derived iron and fat intake and breast cancer risk in the Shanghai Breast Cancer Study

BACKGROUND

Dietary fats and other constituents have been studied extensively in relation to breast cancer risk. Iron, an essential micronutrient with pro-oxidant properties, has received little attention, and specific fats may augment its toxicity. We investigated the effects of iron and fats from various food sources on the risk of breast cancer.

METHODS

Participants in a population-based case-control study, 3,452 breast cancer cases, and 3,474 age-frequency-matched controls, completed in-person interviews, including a detailed food-frequency questionnaire. Plant- and animal-derived iron and fat intakes were derived from dietary intake data and food composition tables. Unconditional logistic regression models were used to study the independent and interactive effects of different forms of iron and fats on breast cancer risk.

RESULTS

Animal-derived (largely heme) iron intake was positively associated with breast cancer risk (P (trend) < 0.01; OR = 1.49 in the highest vs. lowest quartile, 95% confidence interval [CI] 1.25-1.78) after adjustment for known risk factors, antioxidant vitamin and isoflavone intake, and vitamin supplement use. The effect of animal-derived iron was similar in pre- and postmenopausal women. Intake of animal-derived fats was also associated with increased risk (adjusted OR = 1.34, 95% CI 1.14-1.58), particularly after menopause. A significant interaction between iron and fat from animal sources was observed (P < 0.01).

CONCLUSIONS

A high intake of animal-derived (heme) iron may be associated with an increased risk of primary breast cancer in Chinese women, and saturated and mono-unsaturated fats that are also derived from animal sources may augment this effect. Combined reductions in animal-derived iron and fat consumption have the potential to reduce breast cancer risk.

Dietary folate and APC mutations in sporadic colorectal cancer

Folate deficiency has been associated with colorectal cancer risk and may be involved in colorectal carcinogenesis through increased chromosome instability, gene mutations, and aberrant DNA methylation. Within the Netherlands Cohort Study on diet and cancer, we investigated the associations between dietary folate intake and colorectal cancer risk with (APC(+)) and without (APC(-)) truncating APC mutations, accounting for hMLH1 expression and K-ras mutations. In total, 528 cases and 4200 subcohort members were available for data analyses of the study cohort (n = 120,852) from a follow-up period between 2.3 and 7.3 y after baseline. Adjusted gender-specific incidence rate ratios (RR) over tertiles of folate intake were calculated in case-cohort analyses for colon and rectal cancer. Although relatively high folate intake was not associated with overall colorectal cancer risk, it reduced the risk of APC(-)colon tumors in men (RR 0.58, 95% CI 0.32-1.05, P(trend) = 0.06 for the highest vs. lowest tertile of folate intake). In contrast, it was positively associated with APC(+) colon tumors in men (highest vs. lowest tertile: RR 2.77, 95% CI 1.29-5.95, P(trend) = 0.008) and was even stronger when the lack of hMLH1 expression and K-ras mutations were excluded (RR 3.99, 95% CI 1.43-11.14, P(trend) = 0.007). Such positive associations were not observed among women; nor was folate intake associated with rectal cancer when APC mutation status was taken into account. Relatively high folate consumption reduced the risk of APC(-) colon tumors, but folate intake was positively associated with APC(+) colon tumors among men. These opposite results may indicate that folate enhances colorectal carcinogenesis through a distinct APC mutated pathway.

Hemochromatosis (HFE) gene mutations and peripheral neuropathy during antiretroviral therapy

OBJECTIVE

Peripheral neuropathy (PN) often complicates nucleoside reverse transcriptase inhibitor (NRTI) therapy of HIV infection and may involve mitochondrial dysfunction. Since iron deficiency is associated with some types of PN, and iron is essential for mitochondrial function, we tested the hypothesis that hemochromatosis (HFE) gene mutations influence susceptibility to NRTI-induced PN.

DESIGN

Case-control study involving multicenter, AIDS Clinical Trials Group (ACTG) protocol 384 and ACTG Human DNA Repository specimens.

METHODS

Study participants were randomized to receive three- or four-drug antiretroviral therapy with didanosine (ddI) plus stavudine (d4T) or zidovudine plus lamivudine, given with efavirenz, nelfinavir, or both, with up to three years of follow-up. PN was ascertained based on signs and symptoms. HFE C282Y and H63D genotypes were determined, and associations with PN were assessed using logistic regression.

RESULTS

: Of 509 participants, 147 (29%) developed PN, 73% of whom had been randomized to receive ddI plus d4T. Among ddI/d4T-ever-treated individuals, HFE C282Y heterozygotes developed PN on ddI/d4T significantly less often than C282Y non-carriers, adjusting for age, CD4 lymphocyte count and viral load at baseline, and concomitant antiretroviral drugs [6% vs. 35%, respectively, in whites; adjusted odds ratio (OR), 0.17; 95% confidence interval (CI) 0.03-0.83; P = 0.021]. Regardless of race/ethnicity, ddI/d4T-associated PN was uncommon in C282Y heterozygotes [race-adjusted OR, 0.30; 95% CI 0.09-0.96); P = 0.042].

CONCLUSIONS

Iron-loading HFE mutations such as C282Y are associated with a decreased risk of PN during antiretroviral therapy. This finding has potential implications for the prediction and prevention of NRTI-associated PN, particularly in populations at risk of iron deficiency.

Effect of Native American ancestry on iron-related phenotypes of Alabama hemochromatosis probands with HFE C282Y homozygosity

BACKGROUND

In age-matched cohorts of screening study participants recruited from primary care clinics, mean serum transferrin saturation values were significantly lower and mean serum ferritin concentrations were significantly higher in Native Americans than in whites. Twenty-eight percent of 80 Alabama white hemochromatosis probands with HFE C282Y homozygosity previously reported having Native American ancestry, but the possible effect of this ancestry on hemochromatosis phenotypes was unknown.

METHODS

We compiled observations in these 80 probands and used univariate and multivariate methods to analyze associations of age, sex, Native American ancestry (as a dichotomous variable), report of ethanol consumption (as a dichotomous variable), percentage transferrin saturation and loge serum ferritin concentration at diagnosis, quantities of iron removed by phlebotomy to achieve iron depletion, and quantities of excess iron removed by phlebotomy.

RESULTS

In a univariate analysis in which probands were grouped by sex, there were no significant differences in reports of ethanol consumption, transferrin saturation, loge serum ferritin concentration, quantities of iron removed to achieve iron depletion, and quantities of excess iron removed by phlebotomy in probands who reported Native American ancestry than in those who did not. In multivariate analyses, transferrin saturation (as a dependent variable) was not significantly associated with any of the available variables, including reports of Native American ancestry and ethanol consumption. The independent variable quantities of excess iron removed by phlebotomy was significantly associated with loge serum ferritin used as a dependent variable (p < 0.0001), but not with reports of Native American ancestry or reports of ethanol consumption. Loge serum ferritin was the only independent variable significantly associated with quantities of excess iron removed by phlebotomy used as a dependent variable (p < 0.0001) (p < 0.0001; ANOVA of regression).

CONCLUSION

We conclude that the iron-related phenotypes of hemochromatosis probands with HFE C282Y homozygosity are similar in those with and without Native American ancestry reports.