Low intake of vegetables and fruits and risk of colorectal cancer: the Japan Collaborative Cohort Study

A causality between fruit consumption and colorectal cancer: a two-sample Mendelian randomization analysis

Background

Colorectal cancer (CRC) significantly threatens human health with increasing incidence and mortality. A debate continues whether fruit consumption is associated with CRC, despite dietary habits having an impact on the disease. The study aims to examine the causal relationship between fruit consumption and CRC based on a two-sample Mendelian randomization method (MR).

Methods

Summary statistics for fruit consumption and CRC were obtained from the UK Biobank and the FinnGen Consortium, respectively. Analysis methods used in this study included the inverse-variance weighted (IVW), MR Egger, weighted median, simple mode, and weighted mode. Heterogeneity and horizontal pleiotropy were also assessed. Additionally, a leave-one-out analysis was performed to validate the robustness of the results.

Results

We found that fruit consumption was associated with a reduction in CRC risk by the IVW method (P = 0.021). This protective effect was predominantly observed in males (OR 0.374; 95% CI: 0.157-0.892; P = 0.027), while no protective effect was noted in females. However, causal correlations were not observed upon analyzing 16 individual types of fruits. Moreover, our results were unlikely to be influenced by horizontal pleiotropy and heterogeneity. Leave-one-out analysis confirmed the stability of the results.

Conclusion

Our findings suggest that a genetic predisposition for fruit consumption may be protective against CRC, underscoring the need for further research to elucidate the underlying mechanisms and dietary patterns involved.

Plant-based dietary patterns, genetic predisposition and risk of colorectal cancer: a prospective study from the UK Biobank

BACKGROUND

Plant-based dietary patterns may affect colorectal cancer (CRC) related outcomes, while risks differ in the quality of plant foods. We aimed to examine the association of plant-based diet quality with risks of CRC incidence and mortality and whether this association was modified by genetic risk.

METHODS

This prospective cohort study included 186,675 participants free of cancer when the last dietary recall was completed. We calculated three plant-based diet indices (PDIs), i.e., the overall plant-based diet index (PDI), the healthful plant-based diet index (hPDI), and the unhealthful plant-based diet index (uPDI) representing adherence to plant-based diets with diverse quality. Genetic risk was characterized using a weighted polygenic risk score (PRS), capturing overall risk variants associated with CRC. Hazard ratios (HR) and 95% confidential intervals (CI) were estimated by the cause-specific Cox proportional hazards model.

RESULTS

Over a follow-up of 9.5 years, 2163 cases and 466 deaths from CRC were documented. The HR of CRC incidence was 0.88 (95% CI, 0.81-0.96) and 0.91 (95% CI, 0.84-0.99) per 10-score increase in PDI and hPDI, respectively. Compared to the lowest quartile, PDI, hPDI, and uPDI in the highest quartile were associated with a 13% decrease, a 15% decrease, and a 14% increase in risk of incident CRC, respectively. We found a joint association of genetic risk and PDIs with incident CRC, with the highest hazard observed in those carrying higher PRS and adhering to lower-quality PDIs. The inverse association of PDI and hPDI with CRC mortality was pronounced in males.

CONCLUSIONS

Our results suggested that better adherence to overall and healthful plant-based diets was associated with a lower risk of CRC, whereas an unhealthful plant-based diet was associated with a higher CRC risk. Consumption of a higher-quality plant-based diet combined with decreased genetic risk conferred less susceptibility to CRC. Our findings highlighted the importance of food quality when adhering to a plant-based dietary pattern for CRC prevention in the general population.

Implications of estrogen and its receptors in colorectal carcinoma

Estrogens have been implicated in the pathogenesis of various cancer types, including colorectal carcinoma (CRC). Estrogen receptors such as ERα and ERβ activate intracellular signaling cascades followed by binding to estrogen, resulting in important changes in cellular behaviors. The nuclear estrogen receptors, i.e. ERβ and ERα are responsible for the genomic actions of estrogens, whereas the other receptor, such as G protein-coupled estrogen receptor (GPER) regulates rapid non-genomic actions, which lead to secondary gene expression changes in cells. ERβ, the predominant estrogen receptor expressed in both normal and non-malignant colonic epithelium, has protective roles in colon carcinogenesis. ERβ may exert the anti-tumor effect through selective activation of pro-apoptotic signaling, increasing DNA repair, inhibiting expression of oncogenes, regulating cell cycle progression, and also by changing the micro-RNA pool and DNA-methylation. Thus, a better understanding of the underlying mechanisms of estrogen and its receptors in CRC pathogenesis could provide a new horizon for effective therapeutic development. Furthermore, using synthetic or natural compounds as ER agonists may induce estrogen-mediated anti-cancer activities against colon cancer. In this study, we report the most recent pre-clinical and experimental evidences related to ERs in CRC development. Also, we reviewed the actions of naturally occurring and synthetic compounds, which have a protective role against CRC development by acting as ER agonist.

Vegetable and fruit intake and colorectal cancer risk by smoking status in adults: The Japan Public Health Center-based Prospective Study

BACKGROUND

Cigarette smoke contains many oxidants and free radicals which may affect the association between vegetable and fruit intake and colorectal cancer (CRC) risk. However, this relationship remains unclear.

OBJECTIVE

This study aimed to investigate the associations between vegetable and fruit intake and CRC risk by smoking status.

METHODS

The Japan Public Health Center-based Prospective Study is a population-based prospective cohort study. Participants completed a self-administered questionnaire in 1995-1999 (baseline survey) and were followed through to 2013. At the baseline survey, 89,283 residents (41,797 men and 47,486 women) aged 45-74 years were included. Participants were asked about their lifestyle and dietary habits. To investigate the association of vegetable and fruit intake with risk of CRC, Cox proportional hazard models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs). We analyzed the relationship between vegetable and fruit intake and CRC risk stratified by sex and smoking status.

RESULTS

During follow-up, 2261 participants were diagnosed with CRC. Overall, vegetable and fruit intake were not associated with CRC risk in either sex. When stratified by sex and smoking status, CRC risk among male never smokers was inversely associated with intake of vegetables and fruit combined (HR: 0.72; 95% CI: 0.53, 0.98; highest vs lowest quartile p trend = 0.01) and fruit alone (HR: 0.62; 95% CI: 0.45, 0.86; p trend < 0.01).

CONCLUSIONS

Cigarette smoking may affect the association between vegetable and fruit intake and CRC risk among men.

Renal cell carcinoma management: A step to nano-chemoprevention

Renal cell carcinoma (RCC) is one of the most common kidney cancers, responsible for nearly 90 % of all renal malignancies. Despite the availability of many treatment strategies, RCC still remains to be an incurable disease due to its resistivity towards conventional therapies. Nanotechnology is an emerging field of science that offers newer possibilities in therapeutics including cancer medicine, specifically by targeted delivery of anticancer drugs. Several phytochemicals are known for their anti-cancer properties and have been regarded as chemopreventive agents. However, the hydrophobic nature of many phytochemicals decreases its bioavailability and distribution, thus showing limited therapeutic effect. Application of nanotechnology to enhance chemoprevention is an effective strategy to increase the bioavailability of phytochemicals and thereby its therapeutic efficacy. The present review focuses on the utility of nanotechnology in RCC treatment and chemopreventive agents of RCC. We have also visualized the future prospects of nanomolecules in the prevention and cure of RCC.

Healthy and unhealthy plant-based diets in relation to the incidence of colorectal cancer overall and by molecular subtypes

BACKGROUND

Plant-based foods have been recommended for health. However, not all plant foods are healthy, and little is known about the association between plant-based diets and specific molecular subtypes of colorectal cancer (CRC). We examined the associations of healthy and unhealthy plant-based diets with the incidence of CRC and its molecular subtypes.

METHODS

While 123 773 participants of the Nurses' Health Study and the Health Professionals Follow-up Study had been followed up (3 143 158 person-years), 3077 of them had developed CRC. Healthy and unhealthy plant-based diet indices (hPDI and uPDI, respectively) were calculated using repeated food frequency questionnaire data. We determined the tumoural status of microsatellite instability (MSI), CpG island methylator phenotype (CIMP), and BRAF and KRAS mutations.

RESULTS

Higher hPDI was associated with lower CRC incidence (multivariable hazard ratio [HR] comparing extreme quartiles, 0.86, 95% confidence interval [CI]: 0.77, 0.96; P-trend = .04), whereas higher uPDI was associated with higher CRC incidence (multivariable HR comparing extreme quartiles, 1.16, 95% CI: 1.04, 1.29; P-trend = .005). The association of hPDI significantly differed by KRAS status (P-heterogeneity = .003) but not by other tumour markers. The hPDI was associated with lower incidence of KRAS-wildtype CRC (multivariable HR comparing extreme quartiles, 0.74, 95% CI: 0.57, 0.96; P-trend = .004) but not KRAS-mutant CRC (P-trend = .22).

CONCLUSIONS

While unhealthy plant-based diet enriched with refined grains and sugar is associated with higher CRC incidence, healthy plant-based diet rich in whole grains, fruits and vegetables is associated with lower incidence of CRC, especially KRAS-wildtype CRC.

Association between Low Fruit and Vegetable Consumption and Colorectal Polyps in Thailand

Objective:

This study aimed to evaluate the association between low fruit and vegetable consumption and colorectal polyps.

Methods:

A retrospective study was conducted among 1,228 participants aged 50-65 years who completed 2-time colonoscopy exams at the first and the fifth year of a colorectal screening program. Consuming less than one serving of fruit and vegetable daily was rated as low. Colorectal polyps from colonoscopy findings were recognized in 3 types: hyperplastic, low risk and high risk adenomatous polyps.

Results:

The findings demonstrated high prevalence of low fruit (93.6%) and low vegetable (85.8%) consumption. Exercising individuals were more likely to consume both fruit (OR 2.28, 95%CI 1.42-3.65) and vegetable (OR 1.40, 95%CI 1.00-1.96), while smoking history individuals tended to consume vegetable (OR 2.08, 95%CI 1.22-3.55). Low fruit consumption was strongly associated with high risk adenomatous polyps (OR 4.39, 95%CI 2.40-8.03), while low vegetable consumption was distinctively associated with low risk (OR 6.26, 95%CI 4.11-9.55) and high risk adenomatous polyps (OR 8.64, 95%CI 5.30-14.09).

Conclusion:

This study provides additional evidence of the association between low fruit and vegetable consumption and colorectal polyps. Enhancing people fiber eating behavior may help preventing colorectal cancer risk.

Behavioral, Nutritional, and Genetic Risk Factors of Colorectal Cancers in Morocco: Protocol for a Multicenter Case-Control Study

BACKGROUND

Colorectal cancer (CRC) has been reported as the third most commonly diagnosed cancer worldwide and is currently considered as a major public health concern. A peak increase in incidence has been noted in economically transitioning countries like Morocco where industrialization started shifting from a traditional lifestyle and diet toward a more westernized diet and lifestyle.

OBJECTIVE

This paper aims to present the protocol of a large-scale Moroccan case-control study that aims at investigating associations of diet, other lifestyle factors, and genetic traits with CRC risk in Morocco.

METHODS

A case-control study was conducted between 2009 and 2017, including 3032 case-control pairs (1516 cases and 1516 controls) matched on sex, age, and center in 5 major public health hospitals in Morocco. Questionnaires on sociodemographic data, lifestyle, family history of CRC, and nonsteroidal anti-inflammatory drugs (NSAIDs) were completed by trained investigators during face-to-face interviews. In addition, participants completed a semiquantitative food-frequency questionnaire, developed to assess food intake in the Moroccan population. Information regarding genetic factors was recorded for cases, and paraffin blocks (with embedded tumor tissues) are available in 3 collaborating hospitals. Conditional logistic regression analysis is planned to assess associations between diet and CRC risk. Binary logistic regression is considered to predict associations between mutations and nutritional risk factors including only CRC case series.

RESULTS

Altogether, 2966 cases-control pairs (1483 cases and 1483 controls) were considered eligible and included in this study. Both cases and controls did not differ significantly with respect to age (P=.36), sex (P=.51), center (P>.99), marital status (P=.30), and NSAID use (P=.08). However, participants in the control group were significantly more likely to have a high income level and live in urban areas and to have a high level of education than cases.

CONCLUSIONS

This is the first study investigating potential risk factors of CRC such as lifestyle, diet, and genetic factors, originating from a southern Mediterranean country with low but increasing CRC prevalence. Identified risk factors allow the establishment of evidence-based preventive actions regarding nutrition and other lifestyle habits adapted to the Moroccan context. In brief, this study will promote cancer research and prevention in Morocco.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

RR1-10.2196/13998.

Sulforaphane enhances apoptosis induced by Lactobacillus pentosus strain S-PT84 via the TNFα pathway in human colon cancer cells

Sulforaphane and Lactobacilli induce apoptosis in several cancer cells. Sulforaphane, a dietary isothiocyanate, is an attractive agent due to its potent anticancer effects. Sulforaphane suppresses the proliferation of various cancer cells in vitro and in vivo. The present study investigated the effect of sulforaphane and a co-culture with Lactobacillus-treated peripheral blood mononuclear cells (PBMCs) in human colon cancer cells. The combination markedly induced apoptosis in human colon cancer HCT116 and SW480 cells. A pan-caspase inhibitor markedly inhibited apoptosis, and a tumor necrosis factor (TNF) receptor/Fc chimera partially inhibited apoptosis in both cells. The amount of TNFα secretion in the culture supernatant was significantly increased by co-culture with Lactobacillus-treated normal human PBMCs. On the other hand, the expression of cellular inhibitor of apoptosis-2 (cIAP-2), an anti-apoptotic protein, was increased by co-culture with Lactobacillus-treated PBMCs in colon cancer cells, but sulforaphane treatment significantly suppressed the induction of cIAP-2. The present results revealed that sulforaphane enhances apoptosis in human colon cancer cells under co-culture with Lactobacillus-treated PBMCs via the TNFα signaling pathway.

Quercetin: A functional dietary flavonoid with potential chemo-preventive properties in colorectal cancer

Recently, an intense attention has been paid to the application of natural compounds as a novel therapeutic strategy for cancer treatment. Quercetin, a natural flavonol present in many commonly consumed food items, is widely demonstrated to exert inhibitory effects on cancer progression through various mechanisms. Since there is a strong association with diets containing abundant vegetables, fruits, and grains, and significant decline in the risk of colon cancer, accumulation studies have focused on the anticancer potential of quercetin in colorectal cancer. Cell cycle arrest, increase in apoptosis, antioxidant replication, modulation of estrogen receptors, regulation of signaling pathways, inhibition of and metastasis and angiogenesis are among various mechanisms underlying the chemo-preventive effects of quercetin in colorectal cancer. This review covers various therapeutic interactions of Quercetin as to how targets cellular involved in cancer treatment.

Dietary fibre for the prevention of recurrent colorectal adenomas and carcinomas

BACKGROUND

This is an update of the Cochrane review published in 2002.Colorectal cancer (CRC) is a major cause of morbidity and mortality in industrialised countries. Experimental evidence has supported the hypothesis that dietary fibre may protect against the development of CRC, although epidemiologic data have been inconclusive.

OBJECTIVES

To assess the effect of dietary fibre on the recurrence of colorectal adenomatous polyps in people with a known history of adenomatous polyps and on the incidence of CRC compared to placebo. Further, to identify the reported incidence of adverse effects, such as abdominal pain or diarrhoea, that resulted from the fibre intervention.

SEARCH METHODS

We identified randomised controlled trials (RCTs) from Cochrane Colorectal Cancer's Specialised Register, CENTRAL, MEDLINE and Embase (search date, 4 April 2016). We also searched ClinicalTrials.gov and WHO International Trials Registry Platform on October 2016.

SELECTION CRITERIA

We included RCTs or quasi-RCTs. The population were those having a history of adenomatous polyps, but no previous history of CRC, and repeated visualisation of the colon/rectum after at least two-years' follow-up. Dietary fibre was the intervention. The primary outcomes were the number of participants with: 1. at least one adenoma, 2. more than one adenoma, 3. at least one adenoma greater than or equal to 1 cm, or 4. a new diagnosis of CRC. The secondary outcome was the number of adverse events.

DATA COLLECTION AND ANALYSIS

Two reviewers independently extracted data, assessed trial quality and resolved discrepancies by consensus. We used risk ratios (RR) and risk difference (RD) with 95% confidence intervals (CI) to measure the effect. If statistical significance was reached, we reported the number needed to treat for an additional beneficial outcome (NNTB) or harmful outcome (NNTH). We combined the study data using the fixed-effect model if it was clinically, methodologically, and statistically reasonable.

MAIN RESULTS

We included seven studies, of which five studies with 4798 participants provided data for analyses in this review. The mean ages of the participants ranged from 56 to 66 years. All participants had a history of adenomas, which had been removed to achieve a polyp-free colon at baseline. The interventions were wheat bran fibre, ispaghula husk, or a comprehensive dietary intervention with high fibre whole food sources alone or in combination. The comparators were low-fibre (2 to 3 g per day), placebo, or a regular diet. The combined data showed no statistically significant difference between the intervention and control groups for the number of participants with at least one adenoma (5 RCTs, n = 3641, RR 1.04, 95% CI 0.95 to 1.13, low-quality evidence), more than one adenoma (2 RCTs, n = 2542, RR 1.06, 95% CI 0.94 to 1.20, low-quality evidence), or at least one adenoma 1 cm or greater (4 RCTs, n = 3224, RR 0.99, 95% CI 0.82 to 1.20, low-quality evidence) at three to four years. The results on the number of participants diagnosed with colorectal cancer favoured the control group over the dietary fibre group (2 RCTS, n = 2794, RR 2.70, 95% CI 1.07 to 6.85, low-quality evidence). After 8 years of comprehensive dietary intervention, no statistically significant difference was found in the number of participants with at least one recurrent adenoma (1 RCT, n = 1905, RR 0.97, 95% CI 0.78 to 1.20), or with more than one adenoma (1 RCT, n = 1905, RR 0.89, 95% CI 0.64 to 1.24). More participants given ispaghula husk group had at least one recurrent adenoma than the control group (1 RCT, n = 376, RR 1.45, 95% CI 1.01 to 2.08). Other analyses by types of fibre intervention were not statistically significant. The overall dropout rate was over 16% in these trials with no reasons given for these losses. Sensitivity analysis incorporating these missing data shows that none of the results can be considered as robust; when the large numbers of participants lost to follow-up were assumed to have had an event or not, the results changed sufficiently to alter the conclusions that we would draw. Therefore, the reliability of the findings may have been compromised by these missing data (attrition bias) and should be interpreted with caution.

AUTHORS' CONCLUSIONS

There is a lack of evidence from existing RCTs to suggest that increased dietary fibre intake will reduce the recurrence of adenomatous polyps in those with a history of adenomatous polyps within a two to eight year period. However, these results may be unreliable and should be interpreted cautiously, not only because of the high rate of loss to follow-up, but also because adenomatous polyp is a surrogate outcome for the unobserved true endpoint CRC. Longer-term trials with higher dietary fibre levels are needed to enable confident conclusion.

Fruit and vegetable intakes and risk of colorectal cancer and incident and recurrent adenomas in the PLCO cancer screening trial

The roles of fruits and vegetables in colorectal cancer development are unclear. Few prospective studies have assessed the association with adenoma, a known precursor to colorectal cancer. Our aim was to evaluate the association between fruit and vegetable intake and colorectal cancer development by evaluating the risk of incident and recurrent colorectal adenoma and colorectal cancer. Study participants were identified from the intervention arm of the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial. Fruit and vegetable intake was measured using a self-reported dietary questionnaire. Total fruit and vegetable intake was not associated with reduced incident or recurrent adenoma risk overall, but a protective association was observed for multiple adenomas (Odds ratio 3rd tertile vs. 1st tertile = 0.61, 95% confidence interval (CI): 0.38, 1.00). Higher fruit and vegetable intakes were associated with a borderline reduced risk of colorectal cancer (Hazard ratio (HR) 3rd tertile vs. 1st tertile = 0.82, 95% CI: 0.67, 1.01), which reached significance amongst individuals with high processed meat intakes (HR = 0.74, 95% CI: 0.55, 0.99). Our results suggest that increased fruit and vegetable intake may protect against multiple adenoma development and may reduce the detrimental effects of high processed meat intakes on colorectal cancer risk.

Vegetable consumption and colorectal cancer risk: an evaluation based on a systematic review and meta-analysis among the Japanese population

OBJECTIVE

The association between vegetable consumption and colorectal cancer risk remains unclear and may differ by region. We performed a systematic review and meta-analysis of epidemiologic studies on this issue among the Japanese population.

METHODS

A systematic review and meta-analysis was performed by searching MEDLINE through PubMed and the Ichushi database for cohort and case-control studies that were published by the end of December 2014. Associations were evaluated based on their magnitude and the strength of the evidence. Meta-analysis was performed by using the random effects model to estimate the summary relative risk with 95% confidence interval according to the study design. The final judgment was made based on a consensus of the research group members with consideration for both epidemiological evidence and biological plausibility.

RESULTS

We identified six cohort studies and 11 case-control studies on vegetable intake and colorectal cancer among the Japanese population. Of the cohort studies, one study showed a weak inverse association with colon cancer and another study showed a weak positive association with rectal cancer in men, but other studies found no associations between vegetable consumption and colon and rectal cancers. With regard to case-control studies, one study found a strong inverse association with colon cancer, and three studies showed a weak-to-strong inverse association with rectal cancer. In meta-analysis, the summary relative risk (95% confidence interval) for the highest vs. the lowest categories of vegetable consumption were 1.00 (0.92-1.10) and 0.75 (0.59-0.96) for cohort and case-control studies, respectively.

CONCLUSIONS

There was insufficient evidence to support an association between intake of vegetables and the risk of colorectal cancer among the Japanese population.