Alcohol and the risk of colon and rectal cancer with mutations in the K-ras gene

Associations between nutritional factors and KRAS mutations in colorectal cancer: a systematic review

BACKGROUND

Between 30 and 50% of colon tumors have mutations in the Kirsten-ras (KRAS) gene, which have a large nutritional attributable risk. Despite its high frequency in colorectal cancer (CRC), data to support specific associations between KRAS mutations in CRC and diet are sparse. Here, we conducted a systematic review to summarize the current epidemiological evidence on the association between various dietary factors and KRAS mutations.

METHODS

PubMed, Science Direct, and Cochrane databases were searched for relevant studies published until December 31, 2019, using inclusion and exclusion criteria in accordance with PRISMA guidelines. We analyzed the studies to find associations between nutritional factors and CRC tumors with KRAS mutations in humans.

RESULTS

We identified 28 relevant studies to include in this systematic review. In-depth analyses showed unclear associations between nutritional factors and KRAS mutations in CRC. Most epidemiological studies in the same nutrient or food often reported conflicting and/or inconclusive findings, whereas for some dietary factors, the results were homogeneous.

CONCLUSIONS

Further research using a more robust prospective cohort study is needed to lend more credence to the epidemiological associations found between KRAS mutations and dietary factors.

Smoking, alcohol consumption and colorectal cancer risk by molecular pathological subtypes and pathways

Background

Smoking and alcohol increase risk for colorectal malignancies. However, colorectal cancer (CRC) is a heterogenic disease and associations with the molecular pathological pathways are unclear.

Methods

This population-based case–control study includes 2444 cases with first-diagnosis CRC and 2475 controls. Tumour tissue was analysed for MSI (microsatellite instability), CIMP (CpG island methylator phenotype), BRAF (B-Raf proto-oncogene serine/threonine kinase gene) and KRAS (Kirsten rat sarcoma viral oncogene homologue gene) mutations. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were estimated for associations between alcohol and smoking and CRC molecular subtypes and pathways.

Results

Current smoking showed higher ORs for MSI-high (OR = 2.79, 95% CI: 1.86–4.18) compared to MSS (OR = 1.41, 1.14–1.75, p-heterogeneity (p-het) = 0.001), BRAF-mutated (mut) (OR = 2.40, 1.41–4.07) compared to BRAF-wild type (wt) (OR = 1.52, 1.24–1.88, p-het = 0.074), KRAS-wt (OR = 1.70, 1.36–2.13) compared to KRAS-mut (OR = 1.26, 0.95–1.68, p-het = 0.039) and CIMP-high (OR = 2.01, 1.40–2.88) compared to CIMP-low/negative CRC (OR = 1.50, 1.22–1.85, p-het=0.101). Current smoking seemed more strongly associated with sessile serrated pathway (CIMP-high + BRAF-mut; OR = 2.39, 1.27–4.52) than with traditional pathway CRC (MSS + CIMP-low/negative + BRAF-wt; OR = 1.50, 1.16–1.94) and no association was observed with alternate pathway CRC (MSS + CIMP-low/negative + KRAS-wt; OR = 1.08, 0.77–1.43). No heterogeneity was observed in alcohol consumption association by molecular subtypes.

Conclusions

In this large case–control study, smoking was more strongly associated with MSI-high and KRAS-wt CRC and with cases showing features of the sessile serrated pathway. Association patterns were less clear for alcohol consumption.

Substance Use among Economically Disadvantaged African American Older Adults; Objective and Subjective Socioeconomic Status

Purpose. This study investigated the effects of objective and subjective socioeconomic status (SES) indicators on two health behaviors, cigarette smoking and alcohol drinking, among African American older adults. Methods. This community-based study recruited 619 economically disadvantaged African American older adults (age ≥ 65 years) residing in South Los Angeles. Structured face-to-face interviews were conducted to collect data. Data on demographic factors (age and gender), subjective SES (financial difficulties), objective SES (educational attainment), living arrangement, marital status, healthcare access (insurance), and health (number of chronic medical conditions, self-rated health, sick days, depression, and chronic pain) and health behaviors (cigarette smoking and alcohol drinking) were collected from participants. Logistic regressions were used to analyze the data. Results. High financial difficulties were associated with higher odds of smoking cigarettes and drinking alcohol, independent of covariates. Educational attainment did not correlate with our outcomes. Similar patterns emerged for cigarette smoking and alcohol drinking. Conclusion. Subjective SES indicators such as financial difficulties may be more relevant than objective SES indicators such as educational attainment to health risk behaviors such as cigarette smoking and alcohol drinking among African American older adults in economically constrain urban environments. Smoking and drinking may serve as coping mechanisms with financial difficulty, especially among African American older adults. In line with the minorities' diminished returns (MDR) theory, and probably due to discrimination against racial minorities, educational attainment has a smaller protective effect among economically disadvantaged African American individuals against health risk behaviors.

Cigarette Smoking among Economically Disadvantaged African-American Older Adults in South Los Angeles: Gender Differences

The current study aims to explore gender differences in the risk of cigarette smoking among African-American (AA) older adults who live in economically disadvantaged urban areas of southern Los Angeles. This cross-sectional study enrolled 576 older AA adults (age range between 65 and 96 years) who were residing in Service Planning Area 6 (SPA 6), one of the most economically challenged areas in southern Los Angeles. All participants had cardiometabolic disease (CMD). Data were collected using structured face-to-face interviews. Demographic factors (age and gender), socioeconomic status (educational attainment and financial difficulty), health (number of comorbid medical conditions and depressive symptoms), and health behaviors (current alcohol drinking and current smoking) were measured. Logistic regressions were used to analyze the data without and with interaction terms between gender and current drinking, depressive symptoms, and financial difficulty. AA men reported more smoking than AA women (25.3% versus 9.3%; p < 0.05). Drinking showed a stronger association with smoking for AA men than AA women. Depressive symptoms, however, showed stronger effects on smoking for AA women than AA men. Gender did not interact with financial difficulty with regard to current smoking. As AA older men and women differ in psychological and behavioral determinants of cigarette smoking, gender-specific smoking cessation interventions for AA older adults who live in economically deprived urban areas may be more successful than interventions and programs that do not consider gender differences in determinants of smoking. Gender-tailored smoking cessation programs that address drinking for AA men and depression for AA women may help reduce the burden of smoking in AA older adults in economically disadvantaged urban areas. Given the non-random sampling, there is a need for replication of these findings in future studies.

Lifestyle, Diet, and Colorectal Cancer Risk According to (Epi)genetic Instability: Current Evidence and Future Directions of Molecular Pathological Epidemiology

Purpose of Review

In this review, we describe molecular pathological epidemiology (MPE) studies from around the world that have studied diet and/or lifestyle factors in relation to molecular markers of (epi)genetic pathways in colorectal cancer (CRC), and explore future perspectives in this realm of research. The main focus of this review is diet and lifestyle factors for which there is evidence for an association with CRC as identified by the World Cancer Research Fund reports. In addition, we review promising hypotheses, that warrant consideration in future studies.

Recent Findings

Associations between molecular characteristics of CRC have been published in relation to smoking, alcohol consumption; body mass index (BMI); waist:hip ratio; adult attained height; physical activity; early life energy restriction; dietary acrylamide, fiber, fat, methyl donors, omega 3 fatty acids; meat, including total protein, processed meat, and heme iron; and fruit and vegetable intake.

Summary

MPE studies help identify where associations between diet, lifestyle, and CRC risk may otherwise be masked and also shed light on how timing of exposure can influence etiology. Sample size is often an issue, but this may be addressed in the future by pooling data.

Significance of Serum Total Oxidant/Antioxidant Status in Patients with Colorectal Cancer

Oxidative stress is involved in a variety of diseases. Prospective studies investigating the relationship between oxidative stress biomarkers and the status and development of colorectal cancer (CRC) are scarce; previous studies have failed to establish a relationship between the serum total oxidant/antioxidant status and CRC. Therefore, we compared the total serum oxidant/antioxidant levels of CRC patients and healthy subjects, and analyzed their clinical significance in the CRC. Fasting blood samples from 132 CRC patients and 64 healthy subjects were collected. Oxidative stress parameters, including total oxidant status (TOS) and total antioxidant status (TAS), were measured, and the oxidative stress index (OSI) was calculated. The TOS and OSI levels increased significantly (P<0.001) and the TAS level significantly decreased (P<0.001) in the CRC group compared to those in the healthy control group. Oxidative stress parameters differed significantly depending on the patient's smoking and drinking status (P<0.05). The preoperative and postoperative levels of TOS, TAS, and OSI did not differ significantly between primary sites (colon/rectum) and clinical stages (P>0.05).However, the levels of TOS, TAS, and OSI were significantly different between patients with no metastasis and those with metastases to two organs (P<0.05) Finally, the parameters are affected by smoking and drinking, and subsequent research should be conducted excluding the relevant influencing factors.

Polymorphisms in alcohol metabolism genes ADH1B and ALDH2, alcohol consumption and colorectal cancer

BACKGROUND

Colorectal cancer (CRC) is a leading cause of cancer death worldwide. Epidemiological risk factors for CRC included alcohol intake, which is mainly metabolized to acetaldehyde by alcohol dehydrogenase and further oxidized to acetate by aldehyde dehydrogenase; consequently, the role of genes in the alcohol metabolism pathways is of particular interest. The aim of this study is to analyze the association between SNPs in ADH1B and ALDH2 genes and CRC risk, and also the main effect of alcohol consumption on CRC risk in the study population.

METHODOLOGY/PRINCIPAL FINDINGS

SNPs from ADH1B and ALDH2 genes, included in alcohol metabolism pathway, were genotyped in 1694 CRC cases and 1851 matched controls from the Molecular Epidemiology of Colorectal Cancer study. Information on clinicopathological characteristics, lifestyle and dietary habits were also obtained. Logistic regression and association analysis were conducted. A positive association between alcohol consumption and CRC risk was observed in male participants from the Molecular Epidemiology of Colorectal Cancer study (MECC) study (OR = 1.47; 95%CI = 1.18-1.81). Moreover, the SNPs rs1229984 in ADH1B gene was found to be associated with CRC risk: under the recessive model, the OR was 1.75 for A/A genotype (95%CI = 1.21-2.52; p-value = 0.0025). A path analysis based on structural equation modeling showed a direct effect of ADH1B gene polymorphisms on colorectal carcinogenesis and also an indirect effect mediated through alcohol consumption.

CONCLUSIONS/SIGNIFICANCE

Genetic polymorphisms in the alcohol metabolism pathways have a potential role in colorectal carcinogenesis, probably due to the differences in the ethanol metabolism and acetaldehyde oxidation of these enzyme variants.

Alcohol consumption and rectal tumor mutations and epigenetic changes

PURPOSE

An association between alcohol and rectal cancer has been reported in the epidemiological literature. In this study we further explore the association by examining specific tumor markers with alcohol consumption as well as types of alcoholic beverages consumed.

METHODS

We assessed alcohol consumption with CpG Island Methylator Phenotype, TP53, and KRAS2 mutations in incident rectal cancer cases and compared them with population-based controls. We evaluated type, long-term, and recent alcohol consumption.

RESULTS

We observed a trend toward increasing risk of CpG Island Methylator Phenotype positive tumors and long-term alcohol consumption. In contrast, after adjusting for total alcohol intake, recent high beer consumption significantly increased the odds of having a TP53 mutation compared with those who did not drink beer (odds ratio, 1.97; 95% CI 1.24, 3.12). We observed a nonstatistically significant reduced risk of a TP53 mutation among those who drank wine (in particular, red wine) vs nonconsumers of wine. The association between TP53 mutations and recent beer consumption was strongest for transversion mutations.

CONCLUSIONS

These data suggest that both alcohol and specific constituents of alcoholic beverages contribute to rectal cancer risk among unique disease pathways.

Lifetime history of alcohol consumption and K-ras mutations in pancreatic ductal adenocarcinoma

BACKGROUND

In pancreatic ductal adenocarcinoma (PDA), evidence on the etiopathogenic role of alcohol consumption in the occurrence of K-ras mutations is scant, and the role of alcohol in pancreatic carcinogenesis is not well established. We analyzed the relation between lifetime consumption of alcohol and mutations in codon 12 of the K-ras oncogene in patients with PDA.

METHODS

Incident cases of PDA were prospectively identified and interviewed face-to-face during hospital admission about lifetime alcohol consumption and other lifestyle factors. Logistic regression was used to compare PDA cases (N = 107) with mutated and wild-type K-ras tumors (case-case study).

RESULTS

Mutated cases were moderate or heavy drinkers more frequently than wild-type cases: the odds ratio adjusted by age, sex, smoking, and history of pancreatitis (ORa) was 3.18 (95% confidence interval: 1.02-9.93; P = 0.046). Total grams of alcohol and years of consumption were higher in mutated than in wild-type cases: the ORa for lifetime alcohol consumption over 507,499 g was 3.35 (95% CI: 0.81-13.88); and for more than 40 years of alcohol consumption it was 4.47 (95% CI: 1.05-19.02). Age at onset of alcohol consumption and years of abstinence were also associated with the presence of K-ras mutations. There were no significant differences in alcohol dependency.

CONCLUSIONS

Alcohol consumption is weakly associated with an increased risk of having a K-ras mutated PDA. To confirm or to refute the hypothesis that ethanol, acetaldehyde or other alcohol-related substances might influence the acquisition or persistence of K-ras mutations in the pancreatic epithelium, large and unselected studies are warranted.