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Metabolic syndrome and liver-related events: a systematic review and meta-analysis.
Ren, H, Wang, J, Gao, Y, Yang, F, Huang, W
BMC endocrine disorders. 2019;19(1):40
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Liver cancer is one of the most common cancers worldwide and chronic liver disease a major cause of death in the US. Viral hepatitis and excessive alcohol intake are important risk factors, but do not explain many cases. Non-alcoholic fatty liver disease (NAFLD) is associated with insulin resistance and several metabolic abnormalities, suggesting a link between metabolic factors and cancer of the liver. This review and meta-analysis pooled data from 19 epidemiological studies, involving 1,561,457 participants, to evaluate the risk of metabolic syndrome for liver related events (LREs). 16 of the 19 studies showed an increased risk of LREs for people with metabolic syndrome, whilst 3 found a negative association. The meta-analysis found that people with metabolic syndrome had increased risks of 76% for liver cancer and of 421% for death from liver related causes. The risk of any LRE was increased by 49%. The risks were higher for people with hepatitis B infection and lower for people living in Asia. The authors state that the mechanisms are not fully understood and hypothesise that people with metabolic syndrome likely share risk factors for cancer, such as low physical activity, oxidative stress and dietary factors such as high caloric food, high fat and low fibre intake. The authors conclude that metabolic syndrome is an important risk factor for liver disease.
Abstract
BACKGROUND Previous studies have suggested that metabolic syndrome (MetS) and its component conditions are linked to the development of many benign or malignant diseases. Some studies have described relationships among metabolic syndrome or diabetes and liver cancer, but not many articles described the relationships between MetS and cirrhosis, acute hepatic failure, end-stage liver disease, and even death. However, liver cancers, cirrhosis, acute hepatic failure, end-stage liver disease, and liver-related mortality-collectively described as liver-related events (LREs)-may have different relationships with MetS. We undertook this meta-analysis to examine the association between MetS and LREs, and to determine whether geographic region or hepatitis B virus (HBV) positivity might influence the association. METHODS Relevant studies were identified from PubMed, EMBASE, and the Cochrane database. Two reviewers independently searched records from January 1980 to December 2017. The search terms included 'metabolic syndrome', 'diabetes mellitus', 'insulin resistance syndrome', and 'metabolic abnormalities', combined with 'cirrhosis', 'hepatic fibrosis ', 'hepatocellular carcinoma', 'complication', 'LRE', 'HCC', 'liver-related events', and 'liver cancer'. No language restriction was applied to the search. We chose the studies reporting an association between MetS and LREs. We used Begg's and Egger's tests and visually examined a funnel plot to assess publication bias. All analyses were conducted in Stata 14.0 software. RESULTS There were 19 studies (18 cohort and 1 case-control) included in the analysis, with a total of 1,561,457 participants. The subjects' ages ranged from 18 to 84 years. The combined analysis showed an overall 86% increase risk of LREs in cases with MetS (RR: 1.86,95% CI: 1.56-2.23). The funnel plot was asymmetrical, and the Egger's test p values showed a publication bias in this meta analysis. However, through the trim and fill method, we obtained a new RR value for LREs with MetS of 1.49 (95% CI: 1.40-1.58, p = 0.000). There was no obvious difference with the two answers, so we concluded that the results were robust. For hepatitis B positive patients, the RR for MetS and LREs was 2.15 (95% CI:1.02-4.53, p = 0.038), but for the hepatitis B negative patients, the RR was 1.85 (95% CI:1.53-2.24, p = 0.000). And for non-Asians, the RR for MetS and LREs was 2.21 (95% CI: 1.66-2.69, p = 0.000), while for Asians, the RR was 1.73 (95% CI: 1.35-2.22, p = 0.000). CONCLUSIONS This meta-analysis showed that MetS is associated with a moderately increased risk of LREs prevalence. Patients with MetS together with hepatitis B are more likely to develop hepatic events. For non-Asians, MetS is more likely to increase the incidence of LREs.
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Exposure to glyphosate-based herbicides and risk for non-Hodgkin lymphoma: A meta-analysis and supporting evidence.
Zhang, L, Rana, I, Shaffer, RM, Taioli, E, Sheppard, L
Mutation research. Reviews in mutation research. 2019;781:186-206
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Glyphosate is a highly effective broad-spectrum herbicide that is typically applied in mixtures known as glyphosate-based herbicides (GBHs). Glyphosate and its metabolites persist in food, water, and dust, potentially indicating that everyone may be exposed ubiquitously. The objective of this study was to focus on an a priori hypothesis - the highest biologically relevant exposure to GBHs, i.e., higher levels, longer durations and/or with sufficient lag and latency, will lead to increased risk of non-Hodgkin lymphoma (NHL) in humans. This study is a meta-analysis of six studies (one cohort and five case-control control studies) with almost 65,000 participants. Results demonstrated a significantly increased NHL risk in highly GBH-exposed individuals. Authors conclude that the overall evidence from human, animal, and mechanistic studies presented in this study, supports a compelling link between exposures to GBHs and increased risk for NHL.
Abstract
Glyphosate is the most widely used broad-spectrum systemic herbicide in the world. Recent evaluations of the carcinogenic potential of glyphosate-based herbicides (GBHs) by various regional, national, and international agencies have engendered controversy. We investigated whether there was an association between high cumulative exposures to GBHs and increased risk of non-Hodgkin lymphoma (NHL) in humans. We conducted a new meta-analysis that includes the most recent update of the Agricultural Health Study (AHS) cohort published in 2018 along with five case-control studies. Using the highest exposure groups when available in each study, we report the overall meta-relative risk (meta-RR) of NHL in GBH-exposed individuals was increased by 41% (meta-RR = 1.41, 95% confidence interval, CI: 1.13-1.75). For comparison, we also performed a secondary meta-analysis using high-exposure groups with the earlier AHS (2005), and we calculated a meta-RR for NHL of 1.45 (95% CI: 1.11-1.91), which was higher than the meta-RRs reported previously. Multiple sensitivity tests conducted to assess the validity of our findings did not reveal meaningful differences from our primary estimated meta-RR. To contextualize our findings of an increased NHL risk in individuals with high GBH exposure, we reviewed publicly available animal and mechanistic studies related to lymphoma. We documented further support from studies of malignant lymphoma incidence in mice treated with pure glyphosate, as well as potential links between glyphosate / GBH exposure and immunosuppression, endocrine disruption, and genetic alterations that are commonly associated with NHL or lymphomagenesis. Overall, in accordance with findings from experimental animal and mechanistic studies, our current meta-analysis of human epidemiological studies suggests a compelling link between exposures to GBHs and increased risk for NHL.
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Environmental Factors and the Risk of Brain Tumours in Young People: A Systematic Review.
Zumel-Marne, A, Castano-Vinyals, G, Kundi, M, Alguacil, J, Cardis, E
Neuroepidemiology. 2019;53(3-4):121-141
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Brain tumours (BT) are the second most common cancer type in children and young adults. The aim of this study was to review and summarize the scientific literature about exposure to environmental factors and BT risk. This study is a systematic review of 70 articles of which 69% (n = 49) had >200 cases recruited. Results indicate a possible association between exposure to heavy metals, passive smoking, water and air pollutants, use of pesticides and living on a farm with farm animals, meat consumption during preconception, pregnancy or early infancy and an increased risk of BT in children and young adults. Authors conclude that larger scale studies with better exposure assessment are needed to evaluate possible associations between environmental risk factors and BT in young people.
Abstract
BACKGROUND Brain tumours (BT) are one of the most frequent tumour types in young people, although little is known about their risk factors. OBJECTIVE The objective of the current work was to review and summarize the scientific literature concerning exposure to environmental factors and BT risk in young people (<25 years old). METHODS PUBMED, Embase, Cochrane Library, Scopus, IME-Biomedina (bibliographic database of Consejo Superior de Investigaciones Científicas) and Web of science databases were searched. A score to assess the quality of the methodological information was created. RESULTS Some possible associations between BT risk in young people were reported for cadmium, consumption of well water, presence of nitrate or nitrate-nitrogen in tap water, mother's passive smoking, air pollution, parental handling of pesticides at home and/or professional pesticide treatment within houses, living on a farm and/or with farm animals, some parental occupations and high amount of meat consumption. CONCLUSIONS Although many of the studies reviewed suggest associations between the environmental exposures and BT in children and young adults, at present no reliable conclusion can be drawn as most results are based on small number of cases and exposure assessment is limited. Large-scale studies with better exposure assessment are needed to shed light on these possible associations, especially on exposure to heavy metals, tab water consumption, pesticides and parental smoking.
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Change in physical activity and quality of life in endometrial cancer survivors receiving a physical activity intervention.
Robertson, MC, Lyons, EJ, Song, J, Cox-Martin, M, Li, Y, Green, CE, Pinto, BM, Carmack, CL, Harrison, C, Baum, G, et al
Health and quality of life outcomes. 2019;17(1):91
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Endometrial cancer survivors suffer from high rates of obesity and physical activity-related co-morbidities that are related to cancer-specific and overall mortality. The aim of this study was to investigate how change in physical activity over time related to change in multiple, specific measures of quality of life for endometrial cancer survivors receiving a physical activity intervention. This study was a one-group, pre-post design which recruited 100 women diagnosed with stage I, II, or IIIa endometrial cancer. Each participant received a customized exercise prescription that was based on the results of baseline fitness tests. Results indicate change in physical activity was positively associated with change in SF-36 (Short Form Health Survey) subscale scores for role limitations due to physical health and general health. Furthermore, change in physical activity was negatively associated with change in pain and somatic distress. Authors conclude that increasing physical activity was positively associated with improvements in role limitation due to physical health, general health, pain, and somatic distress.
Abstract
BACKGROUND Endometrial cancer survivors are at an increased risk of poor quality of life outcomes. Physical activity is positively associated with general quality of life in this population, however, little is known about how changes in physical activity may be associated with changes in specific aspects of quality of life. The aim of this secondary data analysis was to explore the relationships between change in physical activity and change in physical, mental, social, and other aspects of quality of life in endometrial cancer survivors receiving a physical activity intervention. METHODS Endometrial cancer survivors (N = 100) participated in a telephone-based physical activity intervention for six months. At baseline and post-intervention we measured physical activity via accelerometry and ecological momentary assessment, and quality of life via the Short Form Health Survey (SF-36), the Quality of Life of Adult Cancer Survivors instrument, the Brief Symptom Inventory, the Pittsburgh Sleep Quality Index, and the Perceived Stress Scale. We conducted structural equation modeling path analyses to investigate how physical activity post-intervention was associated with the quality of life measures' subscales post-intervention, adjusting for baseline levels and potentially confounding covariates. RESULTS Increasing physical activity was positively associated with improvements in general health (p = .044), role limitation due to physical health (p = .005), pain (p = .041), and somatic distress (p = .023). There was no evidence to indicate that change in physical activity was associated with change in other aspects of quality of life. CONCLUSIONS Endometrial cancer survivors are at higher risk for suffering from challenges to physical quality of life, and findings from this study suggest that increasing physical activity may alleviate some of these problems. Further research is needed to determine whether other aspects of quality of life are linked to change in physical activity. TRIAL REGISTRATION Trial registration number: NCT00501761 Name of registry: clinicaltrials.gov Date of registration: July 16, 2007. Date of enrollment: June 16, 2005.
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A phase II randomized controlled trial of three exercise delivery methods in men with prostate cancer on androgen deprivation therapy.
Alibhai, SMH, Santa Mina, D, Ritvo, P, Tomlinson, G, Sabiston, C, Krahn, M, Durbano, S, Matthew, A, Warde, P, O'Neill, M, et al
BMC cancer. 2019;19(1):2
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Most men diagnosed with prostate cancer receive androgen deprivation therapy (ADT) and they commonly experience adverse side effects. Exercise is one of the most effective interventions to counter ADT side effects. The main aim of this study was to determine the feasibility of conducting a large multi-centre non-inferiority RCT of three exercise delivery models in men with prostate cancer on ADT. The study is a randomized phase II non-inferiority trial recruited 59 patients who were diagnosed with prostate cancer at any stage. The study compared 1:1, site-based personal training with two less-resource-intense approaches: group, site-training and individual home-based training. Results indicate that exercise adherence, as measured through attendance, was high for supervised sessions but under 50% by self-report and accelerometery. There was no difference between the three groups in terms of satisfaction. Authors conclude that both group, site-training and individual home-based training interventions in men with prostate cancer on ADT appeared to be similar to 1:1, site-based personal training for multiple efficacy outcomes.
Abstract
BACKGROUND Existing evidence demonstrates that 1:1 personal training (PT) improves many adverse effects of androgen deprivation therapy (ADT). Whether less resource-intensive exercise delivery models are as effective remains to be established. We determined the feasibility of conducting a multi-center non-inferiority randomized controlled trial comparing PT with supervised group (GROUP) and home-based (HOME) exercise programs, and obtained preliminary efficacy estimates for GROUP and HOME compared to PT on quality of life (QOL) and physical fitness. METHODS Men with prostate cancer on ADT were recruited from one of two experienced Canadian centres and randomized 1:1:1 to PT, GROUP, or HOME. Randomization was stratified by length of ADT use and site. Participants completed moderate intensity aerobic and resistance exercises 4-5 days per week for 6 months with a target 150 min per week of exercise. Exercise prescriptions were individualized and progressed throughout the trial. Feasibility endpoints included recruitment, retention, adherence, and participant satisfaction. The efficacy endpoints QOL, fatigue, and fitness (VO2 peak, grip strength, and timed chair stands) in GROUP and HOME were compared for non-inferiority to PT. Descriptive analyses were used for feasibility endpoints. Between-group differences for efficacy endpoints were examined using Bayesian linear mixed effects models. RESULTS Fifty-nine participants (mean age 69.9 years) were enrolled. The recruitment rate was 25.4% and recruitment was slower than projected. Retention was 71.2%. Exercise adherence as measured through attendance was high for supervised sessions but under 50% by self-report and accelerometry. Satisfaction was high and there was no difference in this measure between all three groups. Between-group differences (comparing both GROUP and HOME to PT) were smaller than the minimum clinically important difference on most measures of QOL, fatigue, and fitness. However, two of six outcomes for GROUP and four of six outcomes for HOME had a > 20% probability of being inferior for GROUP. CONCLUSIONS Feasibility endpoints were generally met. Both GROUP and HOME interventions in men with PC on ADT appeared to be similar to PT for multiple efficacy outcomes, although conclusions are limited by a small sample size and cost considerations have not been incorporated. Efforts need to be targeted to improving recruitment and adherence. A larger trial is warranted. TRIAL REGISTRATION ClinicalTrials.gov: NCT02046837 . Date of registration: January 20, 2014.
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Salmonella Infection in Chronic Inflammation and Gastrointestinal Cancer.
Zha, L, Garrett, S, Sun, J
Diseases (Basel, Switzerland). 2019;7(1)
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Salmonella is a group of bacteria that is normally associated with food poisoning. In 2% to 5% of people with Salmonella food poisoning, the bacteria remain in the body, leading to long-term infection, which has been linked to various health problems. This literature review looked at the link between Salmonella infection and the development of diseases such as inflammatory bowel disease (IBD), gall bladder cancer and colon cancer. The authors describe how long-term Salmonella infection plays a role in several biological processes, such as stem cell maintenance, host cell transformation, and gut dysbiosis. Leaky gut, dysbiosis and inflammation are induced by the bacteria and contribute to the development of cancer. The authors conclude that more studies are needed to further understand the relationship between Salmonella infections and the risk of colon cancer.
Abstract
Salmonella not only causes acute infections, but can also cause patients to become chronic "asymptomatic" carriers. Salmonella has been verified as a pathogenic factor that contributes to chronic inflammation and carcinogenesis. This review summarizes the acute and chronic Salmonella infection and describes the current research progress of Salmonella infection contributing to inflammatory bowel disease and cancer. Furthermore, this review explores the underlying biological mechanism of the host signaling pathways manipulated by Salmonella effector molecules. Using experimental animal models, researchers have shown that Salmonella infection is related to host biological processes, such as host cell transformation, stem cell maintenance, and changes of the gut microbiota (dysbiosis). Finally, this review discusses the current challenges and future directions in studying Salmonella infection and its association with human diseases.
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Poor Dietary Polyphenol Intake in Childhood Cancer Patients.
Liu, A, Cohen, J, Vittorio, O
Nutrients. 2019;11(11)
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The Mediterranean diet is associated with reduced cancer risk due to the presence of antioxidants, primarily polyphenols, which are found in fruits, vegetables, and olive oil. This small-sample 2017 study of 59 paediatric cancer patients estimated their polyphenol intake (using a 24hr recall food diary) and explored the potential beneficial effects that a diet rich in polyphenols could have on survival, based on relapse rates in a 2019 follow-up. Overall 55.9% of the patients were diagnosed with acute lymphatic leukaemia, 90% were undergoing chemotherapy, and BMI varied with 7% overweight and 15.8% obese. The mean and median polyphenol intakes were 173.31 +/- 141.02 and 114.29 mg/day respectively (considered low). The polyphenols consumed by the children mainly came from fruits (26.6%), beverages (17.98%), and cereals (16.24%) with a distinct lack of vegetables. Twelve percent of patients had relapsed or died three years after the study recruitment. There was no difference between the relapse status and polyphenol intake but a general trend towards higher polyphenols in the non-relapse groups. The study concludes that polyphenol intake was low in participants compared to other age groups. This may be influenced by challenges in eating as an adverse effect to treatment, thus placing them at greater risk. Cancer treatment in children has been linked with the depletion of their bodies’ stores of antioxidants. Improving the dietary intake of polyphenols may have the potential to reduce their treatment-related side effects and improve treatment outcomes
Abstract
Emerging research demonstrates polyphenol-rich diets like the Mediterranean diet may play a role in improving the outcomes of adult cancer therapy. To date, there are no trials assessing the intake or efficacy of polyphenol-rich diets in childhood cancer patients. In this study we collected dietary data on 59 childhood cancer patients on treatment using a three-pass 24-h dietary recall (24-HDR), which is based on a validated and structured three-part methodology. Polyphenol consumption was calculated by matching the food consumption data with polyphenol content extracted from the most updated Phenol-Explorer database. The mean total polyphenol intake was 173.31 ± 141.02 mg/day. The major food sources of polyphenols were fruits, beverages, and cereals. There were no significant associations with time since diagnosis, body mass index (BMI) z-score, types of cancer, treatment intensity, food-related symptoms, relapse, and total daily polyphenol intake. Further investigation with larger studies will facilitate the steps in assessing the value of polyphenol-rich dietary patterns in future nutritional interventions for childhood cancer patients.
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Precision Nutrition and Cancer Relapse Prevention: A Systematic Literature Review.
Reglero, C, Reglero, G
Nutrients. 2019;11(11)
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This article looks at the role food plays in precision medicine and nutrition therapies targeting cancers, specifically the mechanistic role of bioactive phytochemicals and their interaction with tumour progression, metastasis, and chemo-resistance. The term precision medicine represents the advances in genomics, metabolomics, and proteomics which have made cancer treatments more targeted and ‘precise’. Lung, breast, prostate and colon cancers account for a 49.2% mortality rate amongst cancers. Relapses worsen the prognosis of patients. This review aims to provide a better understanding of metabolic variation between nutrients, metabolism, microbiota, and related genes, which may help to develop adjuvant cancer therapies for the above cancers. 35 studies from 2017-2019 were selected: 20 on polyphenols, 3 on lipids (omega 3) and 12 on bioactive plant extracts. Epigallocatechin-gallate (EGCG), a flavonoid present in green tea, is shown to inhibit tumour cell growth. Curcumin modulates gene expression and critical anti-apoptotic effectors and enhances the effect of some targeted drugs used in cancer treatment. Bioactive lipid docosahexaenoic acid (DHA) induces apoptosis and has inhibitory effects on breast cancer cells growth. Ginger is shown to have an antiproliferative impact on cancer cell growth. Grape seed extract was associated with antitumor effect in colon cancer in combination with curcumin. Bioavailability of these extracts is discussed as a barrier to clinical use. Precision nutritional therapies are seen as a new era in the treatment of cancer and precision medicine but the review concludes that more research is necessary.
Abstract
Cancer mortality rates are undergoing a global downward trend; however, metastasis and relapse after surgery and adjuvant treatments still correlate with poor prognosis and represent the most significant challenges in the treatment of this disease. Advances in genomics, metabolomics, and proteomics are improving our understanding regarding cancer metabolic diversity, resulting in detailed classifications of tumors and raising the effectiveness of precision medicine. Likewise, the growing knowledge of interactions between nutrients and the expression of certain genes could lead to cancer therapies based on precision nutrition strategies. This review aims to identify the recent advances in the knowledge of the mechanistic role of bioactive phytochemicals in foodstuffs in tumor progression, metastasis, and chemo-resistance in order to assess their potential use in precision nutrition therapies targeting relapse in lung, breast, colon, and prostate cancer, and leukemia. A considerable number of bioactive phytochemicals in foodstuffs were identified in the literature with proven effects modulating tumor growth, progression, and metastasis. In addition, the use of foodstuffs in cancer, and specifically in relapse therapies, is being reinforced by the development of different formulations that significantly increase the therapeutic efficiency of these products. This can open the possibility for testing combinations of bioactive phytochemicals with cancer relapse treatments as a potential prevention strategy.
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Chemopreventive and anticancer activity of flavonoids and its possibility for clinical use by combining with conventional chemotherapeutic agents.
Kikuchi, H, Yuan, B, Hu, X, Okazaki, M
American journal of cancer research. 2019;9(8):1517-1535
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Novel therapies for cancer treatment using herbs and edible components of plants are continuously being studied as an adjunct to conventional cancer therapies: antitumor drugs and radiation. Resistance to drugs, and tumour recurrence rates suggest that new therapies are needed. This 2019 review discusses the possible strategy of combining flavonoids, nutraceuticals and conventional chemotherapeutic agents to minimise adverse effects, and improve quality of life of patients undergoing traditional treatments. Flavonoids, such as EGCG, Quercetin, Luteolin, Glabridin and Naringin demonstrate several clinically interesting mechanisms: anti-angiogenic and anti-metastatic properties, apoptosis and autophagy promoting activities, and immunomodulatory effects. On the downside there are questions over the low bioavailability of flavonoids from foods. The widely accepted consensus is that combination treatments which embrace novel therapies alongside traditional treatment are clinically safe. The interest in flavonoids is principally for improving chemotherapy sensitivity and minimizing the adverse side effects of these treatments. The molecular mechanisms underlying flavonoids multiple pharmacological effects make them a potential adjunctive agent for cancer chemoprevention although more clinical trials are needed.
Abstract
Cancer is a diverse class of diseases characterized by uncontrolled cell growth with the potential to invade and spread to other parts of the body, and continues to be one of the leading causes of death worldwide. Conventional cancer treatment modalities include antitumor drugs, surgical resection, locally targeted therapies such as radiation therapy. Along with improved understanding of the molecular pathogenesis of various cancers, generation and the use of smart targeted anti-cancer drugs have been challenged. The need for novel therapeutic strategies remains paramount given the sustained development of drug resistance, tumor recurrence, and metastasis. Development of new strategies aimed at improving chemotherapy sensitivity and minimizing the adverse side effects is thus essential for obtaining satisfied therapeutic outcomes for patients and enhancing their quality of life. Emerging evidence has reported that many cancer patients use either herbs employed in complementary therapies or dietary agents that influence cellular signaling worldwide. Numerous components of edible plants, collectively termed phytochemicals that have beneficial effects for health, are being reported increasingly in the scientific literature. Of those, flavonoids have attracted much attention by virtue of its wide variety of biological functions including antioxidant, anti-inflammatory, and anticancer activity. In this review, we highlight the molecular mechanisms underlying its multiple pharmacological effects, especially focusing on cancer chemoprevention. We further discuss possible strategies to develop anticancer therapy by combining flavonoids nutraceuticals and conventional chemotherapeutic agents. We also highlight numerous pharmacokinetic challenges such as bioavailability, drug-drug interactions, which are still fundamental questions concerning its future clinical application.
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Glycemic Index, Glycemic Load and Cancer Risk: An Updated Meta-Analysis.
Turati, F, Galeone, C, Augustin, LSA, La Vecchia, C
Nutrients. 2019;11(10)
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This 2019 meta-analysis is an update of an earlier 2015 study on the relationship between high Glycemic Index (GI) and Glycemic load (GL) diets and cancer risk. Twenty new epidemiological reports were added to the original seventy-five studies covering a total of 169,00 cancer cases. The theory is that elevated insulin levels, triggered by a high GI diet, increase bioactive chemicals which promote cancer development by inhibiting cell apoptosis and stimulating cell proliferation. This study collated cancers into 3 subgroups of hormonal cancers (breast, endometrium, ovary and prostate), digestive tract cancers (cancers, stomach, colorectum and pancreas) and other (lung, bladder and kidney). The combined results showed that the risk ratio for hormonal-related cancers and GI/GL were modestly elevated but not significant except for a possible moderate positive association between GL and endometrial cancer (RR1.12). There was a positive significant association between high GI intake and colorectal cancer risk (RR 1.20) but not with the other digestive-tract cancers. A high GI was associated with small increased risks of bladder (RR 1.25) and kidney (RR 1.16) cancers. The researchers conclude that the high number of studies and cancer types included provide high statistical power. Although the results show only moderate association this may be relevant at population level given the high incidence of cancers.
Abstract
Diets high in glycemic index (GI) and glycemic load (GL) have been related to an increased risk of selected cancers, but additional quantification is required. We updated a systematic review and meta-analysis published in 2015 to May 2019 to provide quantitative information on GI/GL and cancer risk. Relative risks (RR) and the corresponding 95 % confidence intervals (CI) for the highest versus the lowest categories of GI and GL were extracted from selected studies and pooled using random-effects models. Twenty reports (>22,000 cancer cases) have become available after January 2015, and 15 were added to the meta-analyses by cancer sites, which considered a total of 88 investigations. The five additional reports were reviewed, but not included in the meta-analyses, since data were inadequate to be pooled. For hormone-related cancers, summary RRs for the highest versus lowest GI and GL intakes were moderately increased. They ranged from 1.04 (breast) to 1.12 (endometrium) for GI and from 1.03 (prostate) to 1.22 (ovary) for GL, of borderline significance. High GI was associated with small increased risks of colorectal (summary RR for GI: 1.20, 95% CI, 1.07-1.34-GL: 1.09, 95% CI, 0.97-1.22, 19 studies), bladder (GI: 1.25, 95% CI, 1.11-1.41-GL: 1.10, 95% CI, 0.85-1.42, four studies) and kidney cancers (GI: 1.16, 95% CI, 1.02-1.32-GL: 1.14, 95% CI, 0.81-1.60, five studies). GL was not significantly related to those cancer sites. Stomach, prostate and lung cancers were not associated with GI and GL. The present analysis, based on an updated comprehensive evaluation of the epidemiological literature, indicates moderate unfavorable effects of high versus low GI on colorectal, and possibly bladder and kidney cancers, and a possible moderate positive association between GL and endometrial cancer.