Caloric intake, body weight, and cancer: a review

Sirtuins (SIRTs) As a Novel Target in Gastric Cancer

Gastric cancer is a major health burden worldwide. Among all neoplasms, gastric cancer is the fifth most common and the third most deadly type of cancer. It is known that sirtuins (SIRTs), are NAD⁺-dependent histone deacetylases regulating important metabolic pathways. High expression of SIRTs in the human body can regulate metabolic processes; they prevent inflammation but also resist cell death and aging processes. The seven members of this family enzymes can also play a fundamental role in process of carcinogenesis by influencing cell viability, apoptosis and metastasis. This review collects and discusses the role of all seven sirtuins (SIRT1-SIRT7) in the pathogenesis of gastric cancer (GC).

Hepatic macrophage mediated immune response in liver steatosis driven carcinogenesis

Obesity confers an independent risk for carcinogenesis. Classically viewed as a genetic disease, owing to the discovery of tumor suppressors and oncogenes, genetic events alone are not sufficient to explain the progression and development of cancers. Tumor development is often associated with metabolic and immunological changes. In particular, obesity is found to significantly increase the mortality rate of liver cancer. As its role is not defined, a fundamental question is whether and how metabolic changes drive the development of cancer. In this review, we will dissect the current literature demonstrating that liver lipid dysfunction is a critical component driving the progression of cancer. We will discuss the involvement of inflammation in lipid dysfunction driven liver cancer development with a focus on the involvement of liver macrophages. We will first discuss the association of steatosis with liver cancer. This will be followed with a literature summary demonstrating the importance of inflammation and particularly macrophages in the progression of liver steatosis and highlighting the evidence that macrophages and macrophage produced inflammatory mediators are critical for liver cancer development. We will then discuss the specific inflammatory mediators and their roles in steatosis driven liver cancer development. Finally, we will summarize the molecular pattern (PAMP and DAMP) as well as lipid particle signals that are involved in the activation, infiltration and reprogramming of liver macrophages. We will also discuss some of the therapies that may interfere with lipid metabolism and also affect liver cancer development.

Clinical and Imaging Characteristics of Cancer Patients with COVID-19: A Pilot Study

Background: Malignancy is a known risk factor of coronavirus disease 2019 (COVID-19) severe involvement. Information about this infection in patients with cancer is limited. Objectives: This study aimed at reporting the clinical and imaging characteristics of COVID-19 infection in patients with cancer. Methods: All the patients were known cases of a solid tumor with COVID-19 infection in one center, between February and May 2020. Clinical presentation and imaging involvement of COVID-19 infection in addition to cancer features were documented from medical records/patient interviews. Results: Thirty-one patients with solid tumors and COVID-19 involvement were included. The most prevalet presentation was fever, cough, and myalgia. Breast and gastrointestinal malignancies were the most common cancer types. The mortality rate was 22.5% and all deceased patients suffered from stage 4 of their underlying cancer disease. Lung computed tomography scan (CT scan) features in these patients were not different from the non-cancer patients with COVID-19. Conclusions: COVID-19 involvement in patients with cancer seems to be more severe with higher mortality rates especially in patients with other comorbidity and in metastatic cases. Treatment modifications during the pandemic era sound to be logical in decreasing the infection rate.

Association between obesity and abnormal Papanicolau(Pap) smear cytology results in a resource-poor Nigerian setting

Background

Though obesity is associated with some malignancies, its association with cervical cancer is still inconclusive. This study was aimed at determining if there was an association between obesity and cervical epithelial cell abnormalities (CEA).

Methods

This was a cross-sectional comparative study of obese and non-obese women at the Cervical Cancer Screening Clinic, University of Nigeria Teaching Hospital (UNTH), Enugu between January, 2012 and June, 2013. The participants whose body mass index (BMI) were ≥ 30 kg/m² were classified as obese (200 women) while those whose BMI were < 30 kg/m² were classified as non-obese (200 women) and the two groups were consecutively recruited at the ratio of 1:1. Pap smear cytology, random blood sugar (RBS) and human immune-deficiency virus (HIV) screening was done for all the participants. Data was analyzed with SPSS version 20. Categorical variables were analyzed using McNemar’s test and Chi-squared test. Logistic regression analysis was used to determine the influence of socio-demographic characteristics on cervical epithelial cell abnormalities. The level of significance was set at ≤0.05.

Results

Among the obese women, 152(76%) had negative for intra-epithelial lesion or malignancy (NILM) while 48(24%) had cervical epithelial cell abnormalities (CEA). Also 182(91%) non-obese women had NILM while the remaining 18(9%) had CEA. The prevalence of CEA among all the study participants was 16.5%. There was an association between obesity and CEA[OR (95%CI) = 1.353(1.013–1.812); P-value = 0.04].CEA were significantly more common among women who were 40 years and above and single/separated women as well as widows (P-value = < 0.05).

Conclusion

There was an association between obesity and CEA. This underscores the need for a positive behavioural change among women in order to stem the tide of this public health problem.

Administration of repeatedly heated coconut oil alters lipid levels and antioxidant status in cholesterol fed rats

BACKGROUND: Oxidation products generated during repeated heating of cooking oils can participate in the development of cardiovascular diseases. OBJECTIVE: The purpose of the study was to investigate the effects of administration of high fat diet with and without cholesterol and to compare the effects of fresh and repeatedly heated coconut oil in rats. The effects of various diets containing coconut oil on lipid levels in serum and tissues, oxidative damage and antioxidant status in tissues were studied. METHODS: Coconut oil was heated at 210 ± 10°C for fifteen hours. Male Sprague Dawley rats were divided into four groups of six animals each and were fed the experimental diet for sixty days. RESULTS: Results revealed that rats fed high fat – cholesterol enriched diet significantly influenced the lipid levels and antioxidant status in experimental animals. The results indicate that repeated heating of coconut oil increased the lipid levels and oxidative stress in cholesterol fed rats. CONCLUSIONS: Study demonstrates that thermally stressed dietary oil increases the atherosclerotic tendency in experimental animals by inducing oxidative stress in addition to those induced by dietary cholesterol.

Dietary Factors Associated with Pancreatic Cancer Risk in Minia, Egypt: Principal Component Analysis

Background:

Pancreatic cancer (PC) is a serious and rapidly progressing malignancy. Identifying risk factors including dietary elements is important to develop preventive strategies. This study focused on possible links between diet and PC.

Methods:

We conducted a case-control study including all PC patients diagnosed at Minia Cancer Center and controls from general population from June 2014 to December 2015. Dietary data were collected directly through personal interviews. Principal component analysis (PCA) was performed to identify dietary groups. The data were analyzed using crude odds ratios (ORs) and multivariable logistic regression with adjusted ORs and 95% confidence intervals (CIs).

Results:

A total of 75 cases and 149 controls were included in the study. PCA identified six dietary groups, labeled as cereals and grains, vegetables, proteins, dairy products, fruits, and sugars. Bivariate analysis showed that consumption of vegetables, fruits, sugars, and total energy intake were associated with change in PC risk. In multivariable-adjusted models comparing highest versus lowest levels of intake, we observed significant lower odds of PC in association with vegetable intake (OR 0.24; 95% CI, 0.07-0.85, P=0.012) and a higher likelihood with the total energy intake (OR 9.88; 95% CI, 2.56-38.09, P<0.0001). There was also a suggested link between high fruit consumption and reduced odds of PC.

Conclusions:

The study supports the association between dietary factors and the odds of PC development in Egypt. It was found that higher energy intake is associated with an increase in likelihood of PC, while increased vegetable consumption is associated with a lower odds ratio.

Effect of Weight Gain and Weight Loss on In Vivo Colonocyte Proliferation Rate in People with Obesity

OBJECTIVE

To evaluate the effects of diet-induced changes in energy balance and body weight on in vivo colonocyte fractional proliferation rates (FPR) in people with obesity.

METHODS

In vivo colonocyte FPR was assessed in 31 men and women with obesity (BMI: 35.4 ± 4.0 kg/m2 , age: 52.6 ± 8.9 years) before and after diet-induced weight loss, weight gain, or weight maintenance. Subjects ingested aliquots of 2 H2 O (heavy water) daily for 4 to 7 days, followed by flexible sigmoidoscopy with colon biopsies to assess the incorporation of 2 H into the DNA of dividing colonocytes.

RESULTS

Colonocyte FPR averaged 12.7% ± 3.8% per day and correlated directly with intra-abdominal adipose tissue (IAAT) volume (r = 0.364, P = 0.044). Colonocyte FPR decreased in the weight loss group, did not change in the weight maintenance group, and increased in the weight gain group. The change in colonocyte FPR correlated directly with the percent change in body weight (r = 0.409, P = 0.028) and IAAT volume (r = 0.598, P = 0.001).

CONCLUSIONS

A high-calorie diet and weight gain increase, whereas a low-calorie diet and weight loss decrease, in vivo colonocyte proliferation rate in people with obesity. These results suggest that changes in energy balance influence the risk of developing colon cancer in people with obesity by regulating colonic mucosal growth rates.

Wnt/β-catenin activation and macrophage induction during liver cancer development following steatosis

Obesity confers an independent risk for carcinogenesis. In the liver, steatosis often proceeds cancer formation; however, the mechanisms by which steatosis promotes carcinogenesis is unknown. We hypothesize that steatosis alters the microenvironment to promote proliferation of tumor initiating cells (TICs) and carcinogenesis. We used several liver cancer models to address the mechanisms underlying the role of obesity in cancer and verified these findings in patient populations. Using bioinformatics analysis and verified by biochemical assays, we identified that hepatosteatosis resulting from either Pten deletion or transgenic expression of HCV core/NS5A proteins, promotes the activation of Wnt/β-catenin. We verified that high fat diet lipid accumulation is also capable of inducing Wnt/β-catenin. Caloric restriction inhibits hepatosteatosis, reduces Wnt/β-catenin activation and blocks the expansion of TICs leading to complete inhibition of tumorigenesis without affecting the phosphatase and tensin homologue deleted on chromosome 10 (PTEN) loss regulated protein kinase B (AKT) activation. Pharmacological inhibition or loss of the Wnt/β-catenin signal represses TIC growth in vitro, and decreases the accumulation of TICs in vivo. In human liver cancers, ontology analysis of gene set enrichment analysis (GSEA)-defined Wnt signature genes indicates that Wnt signaling is significantly induced in tumor samples compared with healthy livers. Indeed, Wnt signature genes predict 90% of tumors in a cohort of 558 patient samples. Selective depletion of macrophages leads to reduction of Wnt and suppresses tumor development, suggesting infiltrating macrophages as a key source for steatosis-induced Wnt expression. These data established Wnt/β-catenin as a novel signal produced by infiltrating macrophages induced by steatosis that promotes growth of tumor progenitor cells, underlying the increased risk of liver tumor development in obese individuals.

Historical review of the causes of cancer

In the early 1900s, numerous seminal publications reported that high rates of cancer occurred in certain occupations. During this period, work with infectious agents produced only meager results which seemed irrelevant to humans. Then in the 1980s ground breaking evidence began to emerge that a variety of viruses also cause cancer in humans. There is now sufficient evidence of carcinogenicity in humans for human T-cell lymphotrophic virus, human immunodeficiency virus, hepatitis B virus, hepatitis C virus, human papillomavirus, Epstein-Barr virus, and human herpes virus 8 according to the International Agency for Research on Cancer (IARC). Many other causes of cancer have also been identified by the IARC, which include: Sunlight, tobacco, pharmaceuticals, hormones, alcohol, parasites, fungi, bacteria, salted fish, wood dust, and herbs. The World Cancer Research Fund and the American Institute for Cancer Research have determined additional causes of cancer, which include beta carotene, red meat, processed meats, low fibre diets, not breast feeding, obesity, increased adult height and sedentary lifestyles. In brief, a historical review of the discoveries of the causes of human cancer is presented with extended discussions of the difficulties encountered in identifying viral causes of cancer.

Obesity and thyroid cancer

Many studies have provided observational data on the association of obesity and thyroid cancers, but only few of them propose mechanisms that would permit a better understanding of the causal molecular mechanisms of this association. Considering that there is an increasing incidence of both obesity and thyroid cancers, we need to summarize and link recent studies in order to characterize and understand the contribution of obesity-related factors that might affect thyroid cancer development and progression. Adipose tissue is involved in many vital processes, including insulin sensitivity, angiogenesis, regulation of energy balance, activation of the complement system, and responses such as inflammation. Although these processes have their own molecular pathways, they involve the same molecules through which obesity and adipose tissue might exert their roles in carcinogenesis, not only affecting MAPK and PI3K or even insulin pathways, but also recruiting local inflammatory responses that could result in disease formation and progression. This review describes five important issues that might explain the link between excessive weight and thyroid cancer: thyroid hormones, insulin resistance, adipokines, inflammation, and sexual hormones.

Effects of calorie restriction and diet-induced obesity on murine colon carcinogenesis, growth and inflammatory factors, and microRNA expression

Obesity is an established colon cancer risk factor, while preventing or reversing obesity via a calorie restriction (CR) diet regimen decreases colon cancer risk. Unfortunately, the biological mechanisms underlying these associations are poorly understood, hampering development of mechanism-based approaches for preventing obesity-related colon cancer. We tested the hypotheses that diet-induced obesity (DIO) would increase (and CR would decrease) colon tumorigenesis in the mouse azoxymethane (AOM) model. In addition, we established that changes in inflammatory cytokines, growth factors, and microRNAs are associated with these energy balance-colon cancer links, and thus represent mechanism-based targets for colon cancer prevention. Mice were injected with AOM once a week for 5 weeks and randomized to: 1) control diet; 2) 30% CR diet; or 3) DIO diet. Mice were euthanized at week 5 (n = 12/group), 10 (n = 12/group), and 20 (n = 20/group) after the last AOM injection. Colon tumors were counted, and cytokines, insulin-like growth factor 1 (IGF-1), IGF binding protein 3 (IGFBP-3), adipokines, proliferation, apoptosis, and expression of microRNAs (miRs) were measured. The DIO diet regimen induced an obese phenotype (∼36% body fat), while CR induced a lean phenotype (∼14% body fat); controls were intermediate (∼26% body fat). Relative to controls, DIO increased (and CR decreased) the number of colon tumors (p = 0.01), cytokines (p<0.001), IGF-1 (p = 0.01), and proliferation (p<0.001). DIO decreased (and CR increased) IGFBP-3 and apoptosis (p<0.001). miRs including mir-425, mir-196, mir-155, mir-150, mir-351, mir-16, let-7, mir34, and mir-138 were differentially expressed between the dietary groups. We conclude that the enhancing effects of DIO and suppressive effects of CR on colon carcinogenesis are associated with alterations in several biological pathways, including inflammation, IGF-1, and microRNAs.

Epidemiological association between body fat percentage and cervical cancer: a cross-sectional population-based survey from Mexico

BACKGROUND AND AIMS

Various studies have reported a direct association of cervical cancer risk with obesity and weight but not with the body fat percentage (BFP). The aim of this study was to analyze various anthropometric measures as potential risk factors for cervical cancer.

METHODS

A total of 20,236 women were included in a cross-sectional population-based survey. Obesity was defined according to the World Health Organization criteria, and central obesity was ≥80 cm; the BFP was defined using the Deurenberg equation (BFP = 1.2 [BMI] + 0.23 [age] - 10.8 [sex] - 5.4). The odds ratio (OR) was estimated from the chi square test and logistic regression models.

RESULTS

The prevalence of cervical cancer increased from 514 (95% confidence interval [CI] 321, 707) and 680 (95% CI 494, 866) to 732 (95% CI 535, 928) per 100,000 inhabitants in subjects with a normal weight, subjects who were overweight and subjects who were obese, respectively. Moreover, an association between cervical cancer and BFP (OR 1.027; CI 95% 1.006, 1.048; p = 0.012) was observed, and the risk increased with a BFP ≥45% (OR 2.369; CI 95% 1.284, 4.369; p = 0.006).

CONCLUSIONS

These data suggest a trend between the body mass index and the increasing prevalence of cervical cancer. In addition, the data showed a significant association between the BFP and cervical cancer, and this epidemiological association was higher as the BFP increased.

Secular trends of salted fish consumption and nasopharyngeal carcinoma: a multi-jurisdiction ecological study in 8 regions from 3 continents

BACKGROUND

Despite salted fish being a classical risk factor of Nasopharyngeal Carcinoma (NPC), whether secular trends in salted fish consumption worldwide accounted for changes in NPC rates were unknown. The relationship between vegetable and cigarette consumption to NPC risk worldwide were also largely uncertain. We investigated the longitudinal trends in standardised NPC incidence/mortality rates across 8 regions and their associations with secular trends in salted fish, vegetable and tobacco consumptions.

METHODS

Age standardised mortality rate (ASMR) and age standardised incidence rate (ASIR) of NPC were obtained from the WHO cancer mortality database and Hong Kong Cancer Registry. Per capita consumption of salted fish, tobacco and vegetables in Hong Kong and 7 countries (China, Finland, Japan, Portugal, Singapore, United Kingdom and United States) were obtained from the Food and Agriculture Organization of the United Nation (FAO) and Hong Kong Trade and Census Statistics. Pearson correlation and multivariate analysis were performed to examine both crude and adjusted associations.

RESULTS

There were markedly decreasing trends of NPC ASIR and ASMR in Hong Kong over the past three decades, which were correlated with corresponding secular changes in salted fish consumption per capita (Pearson r for 10 cumulative years : ASIR = 0.729 (male), 0.674 (female); ASMR = 0.943 (male), 0.622 (female), all p < 0.05 except for female ASMR). However such associations no longer correlated with adjustments for decreasing tobacco and increasing vegetable consumption per capita (Pearson r for 10 cumulative years: ASIR = 2.007 (male), 0.339 (female), ASMR = 0.289 (male), 1.992 (female), all p > 0.05). However, there were no clear or consistent patterns in relations between NPC ASIR and ASMR with salted fish consumption across 7 regions in 3 continents.

CONCLUSIONS

Our results do not support the notion that changes in salted fish consumption had played an important role in explaining secular trends of NPC rates in Hong Kong and worldwide. Further studies should explore other lifestyle and genetic factors. However, our findings do support the potentially protective effects of vegetable consumption against NPC.

Fluid intake, genetic variants of UDP-glucuronosyltransferases, and bladder cancer risk

Background:

Results of studies of fluid consumption and its association with bladder cancer have been inconsistent. Few studies have considered modification effects from genetic variants that may interact with the type of consumed fluids. UDP-glucuronosyltransferases (UGTs), which are membrane-bound conjugating enzymes, catalyse the transformation of hydrophobic substrates to more water-soluble glucuronides to facilitate renal or biliary excretion. Whether genetic variants in UGTs could modulate the association between fluid intake and bladder cancer has not been studied.

Methods:

We conducted a case–control study with 1007 patients with histopathologically confirmed bladder cancer and 1299 healthy matched controls. Fluid intake and epidemiologic data were collected via in-person interview. Multivariate unconditional logistic regression was used to estimate odds ratios (ORs) and the 95% confidence intervals (95% CI).

Results:

After adjustment for potential confounders, high quantity of total fluid intake (⩾2789 vs <1696 ml per day) conferred a 41% increased risk of bladder cancer (OR=1.41; 95% CI=1.10–1.81). Specific fluids such as regular soft drinks and decaffeinated coffee were also associated with increased risks, whereas tea, wine, and liquor were associated with decreased risks. Among 83 single-nucleotide polymorphisms in the UGT gene family, 18 were significantly associated with bladder cancer risk. The most significant one was rs7571337, with the variant genotype conferring a 29% reduction in risk (OR=0.71; 95% CI=0.56–0.90).

Conclusions:

Total and specific fluid intakes are associated with bladder cancer risk in the study population and that genetic variants of UGT genes could modulate the effects. These results facilitate identification of high-risk individuals and have important implications in bladder cancer prevention.

Adults with greater weight satisfaction report more positive health behaviors and have better health status regardless of BMI

BACKGROUND

Prior studies suggest that weight satisfaction may preclude changes in behavior that lead to healthier weight among individuals who are overweight or obese.

OBJECTIVE

To gain a better understanding of complex relationships between weight satisfaction, weight-related health behaviors, and health outcomes.

DESIGN

Cross-sectional analysis of data from the Aerobics Center Longitudinal Study (ACLS).

PARTICIPANTS

Large mixed-gender cohort of primarily white, middle-to-upper socioeconomic status (SES) adults with baseline examination between 1987 and 2002 (n = 19,003).

MAIN OUTCOME VARIABLES

Weight satisfaction, weight-related health behaviors, chronic health conditions, and clinical health indicators.

STATISTICAL ANALYSES PERFORMED

Chi-square test, t-tests, and linear and multivariate logistic regression.

RESULTS

Compared to men, women were more likely to be dieting (32% women; 18% men) and had higher weight dissatisfaction. Men and women with greater weight dissatisfaction reported more dieting, yo-yo dieting, and snacking and consuming fewer meals, being less active, and having to eat either more or less than desired to maintain weight regardless of weight status. Those who were overweight or obese and dissatisfied with their weight had the poorest health.

CONCLUSION

Greater satisfaction with one's weight was associated with positive health behaviors and health outcomes in both men and women and across weight status groups.

The effects of body mass index on complications and survival outcomes in patients with cervical carcinoma undergoing curative chemoradiation therapy

BACKGROUND

The effect of body mass index (BMI) on treatment outcomes for patients with locally advanced cervical carcinoma who receive definitive chemoradiation is unclear.

METHODS

The cohort in this study included all patients with cervical carcinoma (n = 404) who had stage IB(1) disease and positive lymph nodes or stage ≥IB(2) disease and received treatment at the authors' facility between January 1998 and January 2008. The mean follow-up was 47.2 months. BMI was calculated using the National Institute of Health online calculator. BMI categories were created according to the World Health Organization classification system. Primary outcomes were overall survival, disease-free survival, and complication rate. Univariate and multivariate analyses were performed. Kaplan-Meier survival curves were generated and compared using Cox proportional hazard models.

RESULTS

On multivariate analysis, compared with normal weight (BMI 18.5-24.9 kg/m(2) ), a BMI <18.5 kg/m(2) was associated with decreased overall survival (hazard ratio, 2.37; 95% confidence interval, 1.28-4.38; P < .01). The 5-year overall survival rate was 33%, 60%, and 68% for a of BMI <18.5 kg/m(2) , a BMI from 18.5 kg/m(2) to 24.9 kg/m(2) , and a BMI >24.9 kg/m(2) , respectively. A BMI <18.5 kg/m(2) was associated with increased risk of grade 3 or 4 complications compared with a BMI >24.9 kg/m(2) (radiation enteritis: 16.7% vs 13.6%, respectively; P = .03; fistula: 11.1% vs 8.8%, respectively; P = .05; bowel obstruction: 33.3% vs 4.4%, respectively; P < .001; lymphedema: 5.6% vs 1.2%, respectively; P = .02).

CONCLUSIONS

Underweight patients (BMI <18.5 kg/m(2) ) with locally advanced cervical cancer had diminished overall survival and more complications than normal weight and obese patients.

Cancer as a metabolic disease

Emerging evidence indicates that impaired cellular energy metabolism is the defining characteristic of nearly all cancers regardless of cellular or tissue origin. In contrast to normal cells, which derive most of their usable energy from oxidative phosphorylation, most cancer cells become heavily dependent on substrate level phosphorylation to meet energy demands. Evidence is reviewed supporting a general hypothesis that genomic instability and essentially all hallmarks of cancer, including aerobic glycolysis (Warburg effect), can be linked to impaired mitochondrial function and energy metabolism. A view of cancer as primarily a metabolic disease will impact approaches to cancer management and prevention.

Gene expression profiling of the short-term adaptive response to acute caloric restriction in liver and adipose tissues of pigs differing in feed efficiency

Residual feed intake (RFI) is a measure of feed efficiency, in which low RFI denotes improved feed efficiency. Caloric restriction (CR) is associated with feed efficiency in livestock species and to human health benefits, such as longevity and cancer prevention. We have developed pig lines that differ in RFI, and we are interested in identifying the genes and pathways that underlie feed efficiency. Prepubertal Yorkshire gilts with low RFI (n = 10) or high RFI (n = 10) were fed ad libitum or fed at restricted intake of 80% of maintenance energy requirements for 8 days. We measured serum metabolites and hormones and generated transcriptional profiles of liver and subcutaneous adipose tissue on these animals. Overall, 6,114 genes in fat and 305 genes in liver were differentially expressed (DE) in response to CR, and 311 genes in fat and 147 genes in liver were DE due to RFI differences. Pathway analyses of CR-induced DE genes indicated a dramatic switch to a conservation mode of energy usage by down-regulating lipogenesis and steroidogenesis in both liver and fat. Interestingly, CR altered expression of genes in immune and cell cycle/apoptotic pathways in fat, which may explain part of the CR-driven lifespan enhancement. In silico analysis of transcription factors revealed ESR1 as a putative regulator of the adaptive response to CR, as several targets of ESR1 in our DE fat genes were annotated as cell cycle/apoptosis genes. The lipid metabolic pathway was overrepresented by down-regulated genes due to both CR and low RFI. We propose a common energy conservation mechanism, which may be controlled by PPARA, PPARG, and/or CREB in both CR and feed-efficient pigs.

Results based on 124 cases of breast cancer and 97 controls from Taiwan suggest that the single nucleotide polymorphism (SNP309) in the MDM2 gene promoter is associated with earlier onset and increased risk of breast cancer

Background

It has been suggested that the single nucleotide polymorphism 309 (SNP309, T -> G) in the promoter region of the MDM2 gene is important for tumor development; however, with regards to breast cancer, inconsistent associations have been reported worldwide. It is speculated that these conflicting results may have arisen due to different patient subgroups and ethnicities studied. For the first time, this study explores the effect of the MDM2 SNP309 genotype on Taiwanese breast cancer patients.

Methods

Genomic DNA was obtained from the whole blood of 124 breast cancer patients and 97 cancer-free healthy women living in Taiwan. MDM2 SNP309 genotyping was carried out by restriction fragment length polymorphism (RFLP) assay. The multivariate logistic regression and the Kaplan-Meier method were used for analyzing the risk association and significance of age at diagnosis among different MDM2 SNP309 genotypes, respectively.

Results

Compared to the TT genotype, an increased risk association with breast cancer was apparent for the GG genotype (OR = 3.05, 95% CI = 1.04 to 8.95), and for the TG genotype (OR = 2.12, 95% CI = 0.90 to 5.00) after adjusting for age, cardiovascular disease/diabetes, oral contraceptive usage, and body mass index, which exhibits significant difference between cases and controls. Furthermore, the average ages at diagnosis for breast cancer patients were 53.6, 52 and 47 years for those harboring TT, TG and GG genotypes, respectively. A significant difference in median age of onset for breast cancer between GG and TT+TG genotypes was obtained by the log-rank test (p = 0.0067).

Conclusion

Findings based on the current sample size suggest that the MDM2 SNP309 GG genotype may be associated with both the risk of breast cancer and an earlier age of onset in Taiwanese women.

Body Mass Index and Lung Cancer Risk in Women

BACKGROUND

Studies have suggested that leanness in adulthood may be a risk factor for lung cancer; however, there is justifiable concern that the observed association may be due to residual confounding by smoking, preclinical weight loss, competing causes of death, or some combination of these.

METHODS

To examine this association we used data from the Canadian National Breast Screening Study, which included 89,835 women ages 40-59 years at recruitment between 1980 and 1985. During a mean of 16 years of follow-up, we observed 750 incident lung cancer cases. We used Cox proportional hazards models to estimate hazard ratios and 95% confidence intervals for the association between body mass index (BMI) and lung cancer.

RESULTS

After adjustment for pack-years of smoking and other covariates, there was some evidence for inverse associations in current smokers (hazard ratio for highest BMI quintile relative to the lowest = 0.63; 95% confidence interval = 0.48-0.83) and in former smokers (0.69; 0.39-1.23), whereas in never-smokers, BMI was positively associated with lung cancer (2.19; 1.00-4.80). The results for current and former smokers were not altered by exclusion of cases diagnosed within the first 5 years of follow-up; however, in never-smokers the strength of the association was reduced.

CONCLUSIONS

The present study contributes to the aggregate evidence suggesting that there may be an inverse association between BMI and lung cancer among smokers. However, the contrasting pattern of associations between BMI and lung cancer seen in ever-smokers and never-smokers in this study requires explanation.

Transient caloric restriction and cancer risk (The Netherlands)

Over the past century, many animal experiments have shown that caloric restriction can reduce the risk of cancer, a finding that proved to be highly reproducible. Many papers have been published on its potential for human health, but until know little evidence is available on its actual effects in humans. In Utrecht, The Netherlands, we have been investigating the effects of the 1944–1945 Dutch famine on breast cancer risk factors and breast cancer risk, and paradoxically the relatively short-term famine seemed to be related to increased breast cancer risk in later life. One of the differences between the famine situation and the large body of evidence from animal experiments is the duration of caloric restriction. Almost all animal experiments investigated sustained caloric restriction and information on the effects of short-term transient caloric restriction is very scarce. A search in the literature identified some animal experiments on short-term transient caloric restriction and these seemed to be at least supportive to the famine findings. Because caloric restriction in humans for preventive health measures would be mostly short-term, it is important to extend animal research on short-term caloric restriction.

Body Size and Risk for Breast Cancer in Relation to Estrogen and Progesterone Receptor Status in Japan

PURPOSE

The aim of this study is to examine the association of height, weight, and body mass index (BMI) with breast cancer and its hormone receptor-defined subtype in a low-risk population.

METHODS

We identified 441 newly diagnosed cases of breast cancer during a 9.9-year follow-up of a population-based cohort consisting of 55,537 women aged 40 to 69 years. Body size was assessed by using a self-administered questionnaire.

RESULTS

We found a significant positive association of height and marginally significant positive associations of weight and BMI with breast cancer in postmenopausal women. Weight and BMI were associated more strongly with estrogen receptor-positive (ER+) than ER-negative (ER-) breast cancer in postmenopausal women. BMI was related significantly to increased risk for ER+ (hazard ratio [HR] per BMI increment of 1 kg/m2, 1.08; 95% confidence interval [CI], 1.01-1.15), but not ER- breast cancer (HR per BMI increment of 1 kg/m2, 0.95; 95% CI, 0.84-1.06; p for difference of HRs=0.048).

CONCLUSIONS

The present study suggests that height, weight, and BMI are associated with increased risk for breast cancer among postmenopausal women in Japan. The positive association of weight and BMI might be limited to ER+ breast cancer.

Work, obesity, and occupational safety and health

There is increasing evidence that obesity and overweight may be related, in part, to adverse work conditions. In particular, the risk of obesity may increase in high-demand, low-control work environments, and for those who work long hours. In addition, obesity may modify the risk for vibration-induced injury and certain occupational musculoskeletal disorders. We hypothesized that obesity may also be a co-risk factor for the development of occupational asthma and cardiovascular disease that and it may modify the worker's response to occupational stress, immune response to chemical exposures, and risk of disease from occupational neurotoxins. We developed 5 conceptual models of the interrelationship of work, obesity, and occupational safety and health and highlighted the ethical, legal, and social issues related to fuller consideration of obesity's role in occupational health and safety.

Diet and body mass, and oral and oropharyngeal squamous cell carcinomas: analysis from the IARC multinational case-control study

Tobacco and alcohol use are the main risk factors for oral and oropharyngeal cancers, yet, dietary habits may also be of importance. Data from a series of case-control studies conducted in 9 countries worldwide (1,670 cases and 1,732 controls) were used to investigate the role of several food groups and body mass index (BMI). Low BMI significantly increased the odds ratio (OR) of cancer more than 2-fold among ever- and never-tobacco users and ever- and never-alcohol drinkers. After adjustment for potential confounders, high intake of fruits and vegetables significantly reduced the OR of cancer compared to low intake among ever-tobacco users (OR 0.4, 95% confidence interval [CI] 0.3-0.6), although not among never-tobacco users (OR 1.1, 95% CI 0.6-2.0). Similarly, the protective effect of high fruit and vegetable consumption was present among ever-drinkers (OR 0.4, 95% CI 0.3-0.6), but not among never-drinkers (OR 1.0, 95% CI 0.6-1.6). In conclusion, low BMI increases the risk of oral cancer, and vegetables and fruits may modulate the carcinogenic effects of tobacco and alcohol.

The impact of obesity on the incidence and treatment of gynecologic cancers: a review

Sixty-five percent of the adult population in the United States is overweight and 30% of the population is obese. There is mounting evidence that obesity is a risk factor for gynecologic cancers and may also adversely impact survival. The objectives of this review were to systematically evaluate and discuss the impact of overweight and obesity on endometrial, ovarian, and cervical cancer incidence and to review the data on the impact of obesity on treatment of these same gynecologic cancers. A PUBMED literature search was performed to identify articles in the English language that focused on the impact of obesity on cancer incidence and treatment. References of identified articles were also used to find additional related articles. Obesity profoundly increases the incidence of endometrial cancer, predominantly through the effects of unopposed estrogen. Although the data are less compelling in ovarian and cervical cancer, obesity may modestly increase the incidence of premenopausal ovarian cancer and might potentially increase cervical cancer incidence, perhaps as a result of the impact on glandular cancers or decreased screening compliance. Obese women with cancer have decreased survival; this may be disease-specific, the result of comorbid illnesses, or response to treatment. Obese women have increased surgical complications, may also have increased radiation complications, and there is no current consensus regarding appropriate chemotherapy dosing in the obese patient. Obesity is a serious health problem with significant effects on the incidence and treatment of the gynecologic malignancies.

TARGET AUDIENCE

Obstetricians & Gynecologists, Family Physicians.

LEARNING OBJECTIVES

After completion of this article, the reader should be able to summarize the clear evidence that obesity is a risk factor for many cancers, including gynecologic malignancies; describe the role of unopposed estrogen in gynecologic cancers; and explain that obese women overall have a poorer survival rate when afflicted with cancer.

Energy restriction and the risk of spontaneous mammary tumors in mice: a meta-analysis

Our meta-analysis was aimed at providing a systematic review of the literature regarding the effect of energy restriction on spontaneous mammary tumors in mice and at providing a more precise pooled (summary) estimate of the risk of mammary tumors. A sensitivity analysis was conducted to obtain insight in potential heterogeneity between the animal studies. A literature search was conducted with the following terms to identify relevant articles: animal studies, mammary tumors, fat restricted, dietary carbohydrates, energy restriction and calorie restriction. A criteria list for the assessment of quality items (i.e., study characteristics) in animal experiments was developed that was intended to quantitatively assess potential factors that underlie heterogeneous results of different animal experiments. Incidence figures were used to calculate the risk difference. The pooled risk difference was calculated by random effects meta regression analysis. Fourteen animal experiments were included in this meta-analysis. Publication bias could not be identified. The pooled risk difference for the 14 studies was -0.55 with a narrow 95% confidence interval (-0.69; -0.41), implying that the energy-restricted animal groups developed 55% less mammary tumors than the control groups. No heterogeneity could be detected between the studies based on study characteristics that included the age of mice at the start of intervention, duration of intervention, allocation of the mice, use of ad libitum control group, fertility of the mice and the type of energy-providing nutrient (fat, carbohydrate or protein). This meta-analysis confirms that energy restriction in itself consistently protects against the development of mammary tumor in mice, irrespective of the type of restricted nutrient or other study characteristics.

Obesity as a potential risk factor for adenocarcinomas and squamous cell carcinomas of the uterine cervix

BACKGROUND

Hormonal factors may play a more prominent role in cervical adenocarcinoma than squamous cell carcinoma. The authors evaluated whether obesity, which can influence hormone levels, was associated with adenocarcinoma and squamous cell carcinoma.

METHODS

This case-control study included 124 patients with adenocarcinoma, 139 matched patients with squamous cell carcinoma, and 307 matched community control participants. All participants completed interviews and provided cervicovaginal samples for human papillomavirus (HPV) testing. Polytomous logistic regression-generated odds ratios (ORs) and 95% confidence intervals (95% CIs) for self-reported height and weight, body mass index (BMI; kg/m(2)), and measured waist-to-hip ratio (WHR) for both histologic types were adjusted and stratified for HPV and other confounders.

RESULTS

Height, weight, BMI, and WHR were positively associated with adenocarcinoma. BMI >or= 30 kg/m(2) (vs. BMI < 25 kg/m(2); OR, 2.1 and 95% CI, 1.1-3.8) and WHR in the highest tertile (vs. the lowest tertile; OR, 1.8 and 95% CI, 0.97-3.3) were associated with adenocarcinoma. Neither height nor weight was found to be associated with squamous cell carcinoma, and associations for BMI >or= 30 kg/m(2) (OR, 1.6) and WHR in the highest tertile (OR, 1.6) were weaker and were not statistically significant. Analyses using only HPV positive controls showed similar associations. The data were adjusted for and stratified by screening, but higher BMI and WHR were associated with higher disease stage at diagnosis, even among recently and frequently screened patients with adenocarcinoma. Thus, residual confounding by screening could not be excluded as an explanation for the associations.

CONCLUSIONS

Obesity and body fat distribution were associated more strongly with adenocarcinoma than with squamous cell carcinoma. Although questions about screening remain, obesity may have a particular influence on the risk of glandular cervical carcinoma.

Obesity and height in urban Nigerian women with breast cancer

PURPOSE

To examine the relationship between obesity, height, and breast cancer in an urban Nigerian population.

METHODS

Between March 1998 and August 2000, we conducted a case-control study of hospital-based breast cancer patients (n = 234) and population-based controls (n = 273) using nurse interviewers in urban Southwestern Nigeria.

RESULTS

The study did not find a significant association between obesity (BMI >/= 30) and breast cancer among all women (OR = 1.51, 95% CI = 0.87-2.62) pre- (OR = 1.21, 95% CI = 0.56-2.60) and post-menopausal breast cancer patients (OR = 1.82, 95% CI = 0.78-4.31) in multivariate logistic regression analysis, while increasing height was positively associated with the risk of breast cancer among all women (OR = 1.05, 1.01 - 1.08), pre- (1.06, 1.01-1.10) and post-menopausal women (1.07, 1.01-1.13) for each cm. Age, irregular period, and early age of onset of periods were also found to be significantly associated with breast cancer risk.

CONCLUSION

This study failed to demonstrate an association between breast cancer risk and obesity while showing that height is positively associated with risk of breast cancer in urbanized Nigerian women.

Does dietary sugar and fat influence longevity?

Simultaneous consideration of the influence of the different types of carbohydrates and fats in human diets on mortality rates (especially the diseases of aging), and the probable retardation of such diseases by caloric restriction (CR) leads to the hypothesis that restriction of foods with a high glycemic index and saturated or hydrogenated fats would avoid or delay many diseases of aging and might result in life extension. Many of the health benefits of CR might thereby be available to humans without the side effects or unacceptability of semi-starvation diets.

[Diet and prostate cancer]

Prostate cancer is the first neoplasia in the United States accounting the second in cancer deaths. With all the treatments strategies in debate because of their side effects, is very important try to elucidate prevention mechanisms that may be implicate in the development of this disease, between these, nutrients have been of mayor importance. In the present review we tried to study the most important nutritional factors implicated in the development and prevention of prostate carcinoma. We focus our attention over the polyphenols of the red wine, which influence over cellular proliferation and apoptosis in LNCaP cells have been studied in our Department.

Mujeres felices por ser saludables: a breast cancer risk reduction program for Latino women

BACKGROUND

Breast cancer is the most commonly diagnosed cancer and the most common cause of cancer mortality among Latino women. Several behavioral factors such as early detection and dietary practices could help decrease morbidity and mortality associated with breast cancer in this population. Unfortunately, there are few data regarding the efficacy of health-related interventions for young Latino women.

METHODS

Mujeres Felices por ser Saludables is a randomized intervention project designed to assess breast cancer risk reduction behavior among Latino women ages 20-40 years. The primary objectives of the project were to determine whether an 8-month integrated dietary/breast health intervention could lead to a greater reduction in dietary fat, increase in dietary fiber, increase in the frequency and proficiency of breast self examination (BSE), and reduction in anxiety related to BSE compared to controls. Herein we describe the overall design of the project and present baseline characteristics of the 256 randomized women.

RESULTS

Our results suggest that the average daily intake of dietary fat (percentage of total energy) was slightly below 30% (percentage of total energy) among the women randomized. While over half of these women reported that they practice BSE, and few reported anxiety related to BSE, less than 27% of women were proficient in the recommended BSE technique.

CONCLUSIONS

There are few data on the dietary and breast health behaviors of young low-acculturated Latino women. This study documents the feasibility of recruiting, randomizing, and obtaining both baseline dietary and breast health data on this unique and underserved population.

Leanness and lung cancer risk: fact or artifact?

BACKGROUND

More than a dozen studies have examined the association between leanness and increased lung cancer risk. None of the prospective studies has been large enough to allow exclusion of smokers or persons with preexisting disease, two factors that cause both leanness and poor survival and thus may cause a spurious association between low body mass index and fatal lung cancer.

METHODS

Using Cox proportional hazards models, we examined this issue in a cohort of 941,105 U.S. adults enrolled in an American Cancer Society prospective study in 1982. During 14 years of follow-up, 14,066 people died of lung cancer.

RESULTS

In analyses restricted to lifelong nonsmokers who did not report preexisting disease, leanness was not substantially associated with lung cancer mortality in men (rate ratio = 0.9; 95% confidence interval = 0.3-3.1) or in women (rate ratio = 1.2; 95% confidence interval = 0.7-2.1). However, leanness was associated with increased lung cancer risk in analyses that attempted to control for, rather than exclude, smokers and persons with preexisting disease.

CONCLUSIONS

These data suggest that the association between leanness and lung cancer mortality is not causal but rather is an artifact of the effects of smoking and preexisting disease.

Leanness and squamous cell oesophageal cancer

BACKGROUND

Squamous cell oesophageal cancer is one of the few neoplasms inversely related to body mass index (BMI). However, it is not clear whether this is due to cancer-related weight loss or to other correlates of leanness.

PATIENTS AND METHODS

395 incident, histologically confirmed cases of squamous cell oesophageal cancer and 1,066 controls, admitted for acute, non-neoplastic diseases, in Italy and Switzerland. Odds ratios (ORs) were derived from multiple logistic regression, including terms for education, tobacco. alcohol, non-alcohol energy, fruit and vegetable intake.

RESULTS

The ORs for the lowest vs. the highest quartile of BMI in the year before diagnosis were 2.0 in men, 1.6 in women, and 1.9 (95% confidence interval: 1.3-2.9) in both sexes combined. The association with leanness was stronger in heavy smokers, but was not accounted for by smoking and drinking, nor by differences in diet. Weight change in the decade prior to diagnosis showed no linear association with risk. However, cases were not leaner than controls at age 30 (OR = 0.6 for the lowest BMI quartile) and 50 (OR = 1.1).

CONCLUSIONS

Leanness appears to be an indicator of squamous cell oesophageal carcinogenesis. However, low BMI in the distant past was unrelated to oesophageal cancer risk.

Leanness as early marker of cancer of the oral cavity and pharynx

BACKGROUND

It is not clear whether the purported association of leanness with cancer of the oral cavity and pharynx was due to cancer-related weight loss or to the influence of factors associated with leanness.

PATIENTS AND METHODS

Seven hundred fifty-four incident cases of cancers of the oral cavity and pharynx and 1775 controls, admitted to hospital for acute, non-neoplastic diseases, in Italy and Switzerland. Questionnaire included height, lifetime history of weight and of physical activity, waist and hip measurements, and a validated food-frequency section.

RESULTS

Leanness at diagnosis was associated with elevated risk in men (adjusted odds ratio, OR for 5-unit decrease in body-mass index, BMI = 1.9; 95% confidence interval (CI): 1.6-2.2 in men). Male cases were significantly leaner than control subjects at the age of 30 and of 50. Thinner women also had an increased risk, but the inverse association with BMI was non linear. In both sexes, the association with leanness was restricted to smokers and moderate/heavy drinkers, but was not accounted for by drinking and smoking habits, nor by differences in physical activity or dietary habits.

CONCLUSIONS

Leanness appears to be an early marker of some unknown biological effect of smoking and/or of alcohol abuse, which may contribute to the prediction of cancers of the oral cavity and pharynx. Cessation of smoking and substantial reduction of alcohol intake may improve nutritional status, besides stopping carcinogen exposure.

Promotion of hepatocarcinogenesis by hexachlorobenzene in energy-restricted rats

The interaction between dietary energy restriction and low dose of the fungicide hexachlorobenzene (HCB) was evaluated in a rat liver medium-term bioassay for carcinogenesis. Male Wistar rats were fed a control or a 50% energy-restricted diet, both added or not with 50 ppm HCB, for 6 weeks. HCB exposure or energy restriction separately did not exert any influence on the development of glutathione S-transferase placental form (GST-P(+)) foci of hepatocytes. Simultaneous HCB exposure and energy restriction induced a significant increase in liver centrilobular hypertrophy and GST-P(+) foci development. Our findings suggest that energy restriction increases liver response to low dose of HCB, unmasking the promoting potential of this fungicide.

Diet restriction increases ubiquinone contents and inhibits progression of hepatocellular carcinoma in the rat

BACKGROUND

The aim of the present study was to evaluate the effect of a moderate diet restriction on the progression of preneoplastic foci into hepatocellular carcinomas (HCCs) and whether such an effect was related to altered cell proliferation, apoptosis, and/or tumour contents of lipid-soluble antioxidants.

METHODS

Male Wistar rats were exposed to diethylnitrosamine as initiator and 2-acetylaminofluorene plus partial hepatectomy as promoter. Six weeks after initiation the animals were given a diet restricted to 75%-80% of that given to controls until being killed 45 weeks later. Macroscopic liver tumours were histologically classified. In hepatocellular carcinomas the numbers of S-phase (labelling index) and DNA-fragmented (apoptotic index) nuclei were calculated immunohistochemically, and the tumour contents of alpha-tocopherol and ubiquinone were determined.

RESULTS

The number of animals with HCC and the number of HCCs per animal were significantly reduced in restricted-diet animals compared with controls. In HCCs the contents of ubiquinone-9 and -10 were significantly increased, labelling indices were enhanced 3-fold, and apoptotic indices 12-fold as a response to food restriction. Neither the size nor the differentiation of HCCs was altered by food restriction. The numbers and areas of preneoplastic foci were similar in restricted-diet animals compared with those of controls.

CONCLUSION

Moderate, long-term food restriction inhibits the progression of preneoplastic liver foci into HCC. Possible mechanisms of this inhibition are a shift in the balance between apoptosis and cell division towards cell death and an adaptive response to oxidative stress by increased tumour contents of ubiquinones.

Dietary energy restriction abolishes development of prolactin-producing pituitary tumors in Fischer 344 rats treated with 17beta-estradiol

Reduction in energy consumption is known to inhibit development of a variety of spontaneous, carcinogen-induced, and hormone-dependent cancers, but the mechanism or mechanisms by which this occurs remain unknown. We hypothesize that energy consumption may modulate development of estrogen-dependent neoplasms by altering the manner in which target cells respond to estrogens. To test this hypothesis, ovariectomized female Fischer 344 rats were fed diets that allowed consumption of different amounts of energy, and the ability of 17beta-estradiol (E2), administered for 10 wk from subcutaneous Silastic implants, to promote development of prolactin-producing pituitary tumors was examined. A 40% restriction of energy consumption virtually abolished the ability of E2 to promote development of pituitary tumors and associated hyperprolactinemia. A 25% restriction of energy consumption appeared to slightly inhibit E2-induced pituitary growth and hyperprolactinemia, but the observed degree of inhibition was not statistically significant. Interestingly, dietary energy restriction did not inhibit induction by E2 of pituitary cell proliferation and lactotroph hyperplasia. Furthermore, E2 treatment inhibited expression of testosterone-repressed prostate message-2 mRNA, a cellular marker of apoptosis, and this inhibitory effect of E2 was blocked by 40% energy restriction. These data suggest that dietary energy restriction virtually abolished E2-induced development of prolactin-producing pituitary tumors, not by blocking the ability of E2 to induce cell proliferation but rather by blocking the ability of E2 to enhance cell survival. This study and the accompanying paper provide the first indication that dietary energy consumption may modulate estrogen action at the level of the target cell.

Stimulatory effects of high-fat diets on colon cell proliferation depend on the type of dietary fat and site of the colon

To compare the effects of various types of dietary fat on colon cell proliferation used as an intermediate biomarker for colon carcinogenesis, groups of 10 male Sprague-Dawley rats were fed one of four high-fat diets (45% of total calories from corn oil, butter, beef tallow, and fish oil) for three weeks. As a control, a low-fat diet (15% of total calories from corn oil) was fed to a separate group. Cell proliferation was measured by in vivo incorporation of bromodeoxyuridine into DNA in the proximal and distal colon. Total lipids in feces were measured by a gravimetric method. There were significant differences in colon cell proliferation among the diet groups, where the high corn oil diet stimulated cell proliferation in proximal and distal colon compared with the high fish oil diet (p < 0.05). The protective effect of the high fish oil diet on cell proliferation was similar to that of the low corn oil diet. The effects of high beef tallow and butter diets on colon cell proliferation were highly dependent on sites of the colon, because the hyperproliferative effects by these diets were found only in the distal colon (p < 0.05). Fecal total lipids and fecal lipid concentrations were significantly affected by the dietary fat sources, in that the groups fed the saturated fats, such as butter and beef tallow, excreted more lipids into feces than did the groups fed the unsaturated fats, such as corn oil and fish oil. Fecal lipids were significantly correlated to colon cell proliferation in the way that distal colon cell proliferation increases as fecal lipids increase. Therefore, these data suggest that high levels of dietary fats may not always promote colon carcinogenesis, and the effects may be dependent on the types of dietary fat and sites of the colon.

Childhood leg length and adult mortality: follow up of the Carnegie (Boyd Orr) Survey of Diet and Health in Pre-war Britain

OBJECTIVE

To investigate the relation between childhood height, its components--leg length and trunk length--and mortality in adulthood.

DESIGN

Cohort study based on the Carnegie (Boyd Orr) Survey of diet and health in pre-war Britain, 1937-9.

SETTING

The 14 centres in England and Scotland that participated in the Carnegie Survey and where children were examined. Scottish centres: Aberdeen, Dundee, West Wemyss, Coaltown of Wemyss, Hopeman, Methlick, Tarves, Barthol Chapel. English Centres: Liverpool, York-shire, Barrow in Furness, Wisbech, Fulham, and Bethnal Green.

SUBJECTS

2990 boys and girls aged between 2 years and 14 years 9 months when they were examined in 1937-9. These children were drawn from 1134 families who underwent a one week assessment of family diet and home circumstances. Of these, 2547 (85%) have been traced and flagged using the NHS Central Register.

MAIN OUTCOME MEASURES

Age adjusted overall, coronary heart disease, and cancer mortality in men and women in relation to age and sex specific z scores for height, leg length, and trunk length. All analyses were adjusted for the possible confounding effects of childhood and adult socioeconomic circumstances and childhood diet.

RESULTS

Leg length was the component of childhood height most strongly associated with socioeconomic and dietary exposures. There was no significant relation between childhood height and overall mortality. Height-mortality relations were observed in relation to both coronary heart disease (CHD) and cancer. Leg length was the component of height most strongly related to cause specific mortality. In men and women CHD mortality increased with decreasing childhood leg length. Men in the lowest leg length quintile had a relative risk (RR) of 2.5 (95% CI 1.0 to 6.2) compared to those with the longest legs (linear trend p = 0.14). Similarly, women in the lowest leg length quintile had a RR of 3.9 (95% CI 0.8 to 19.0; linear trend p < 0.01). Adjustment for childhood and adult socioeconomic circumstances had little effect on these trends. In men, but not women, those who as children had long legs experienced increased cancer mortality. The significant relations between anthropometry and both CHD and cancer mortality were restricted to those aged < 8 years when measured.

CONCLUSIONS

These findings suggest that adverse diet and living conditions in childhood, for which leg length seems to be a particularly sensitive indicator, are associated with increased risk of CHD in adulthood and possibly reduced cancer risk. It is likely that these influences operate after birth, during the first few years of life.

Effect of dietary optimization on growth, survival, tumor incidences and clinical pathology parameters in CD Sprague-Dawley and Fischer-344 rats: a 104-week study

Controversy regarding the use of ad libitum feeding in chronic rodent toxicity studies will soon result in issue of a FDA Points to Consider document. Caloric intakes are now recognized to be important uncontrolled variables in bioassays because rodents chronically fed ad libitum become obese, reproductively senile and have increased incidences of age-related diseases, higher tumor burdens and decreased survival. The available literature suggests that ad libitum feeding neither optimizes the health and well-being of rodents nor provides the best model for use in evaluation of pharmacological and toxicological profiles. Use of an optimized diet, restricted in terms of caloric intakes, has been proposed for chronic toxicity and carcinogenicity studies in rodents. It is suggested that limiting caloric intakes to 50-80% of ad libitum consumption would result in lower body weights, decreased tumor incidences and prolonged survival in the controls. To evaluate the influence of diet on chronic toxicity and carcinogenicity studies in rats, two 104-week studies were conducted. These studies consisted of 280 CD Sprague-Dawley and 280 Fischer-344 rats fed ad libitum, and 140 CD Sprague-Dawley and 140 Fischer-344 rats fed a diet that was optimized by limiting caloric intakes by 15-35%. Both diets consisted of certified commercial diet in meal form. The optimized diet reduced weight gain approximately 50% after 100 weeks. Clinical chemistry and hematology parameters showed negligible effects of reduced diet, with the exception that serum triglycerides were lower in males and females in both strains at weeks 52 and 104. The ad libitum-fed animals had a higher incidence of pseudopregnancy, aggressiveness, foot sores and abscesses than the animals fed an optimized diet. These effects were more pronounced in the CD Sprague-Dawley rats than in the Fischer-344 rats. At the completion of the 104-week study, survival in the ad libitum fed CD Sprague-Dawley rats was approximately one-half that of the animals fed an optimized diet (39% versus 76%). The difference in survival between Fischer-344 rats fed ad libitum and those fed an optimized diet was less pronounced (78% versus 89%). A reduced incidence of palpable tissue masses in the ad libitum-fed CD Sprague-Dawley rats versus the animals fed an optimized diet reflected inability to detect small masses in the obese ad libitum-fed animals. In contrast, the leaner Fischer-344 ad libitum-fed animals had an increased incidence of palpable tissue masses. After 52 weeks, 40 animals from each strain and feeding regimen were killed and subjected to complete necropsy and histopathological examination; the remainder of the survivors was examined at the completion of the study (104 weeks). Use of an optimized diet substantially reduced the incidences of endocrine-mediated tumors in both rat strains and delayed the onset of leukemia in Fischer-344 rats. These results indicate the need to further investigate the relationship of increased caloric intakes and endocrine-mediated or strain specific tumors and support FDA's and others' positions that use of diet optimization in chronic toxicity and carcinogenicity rodent bioassays has the potential to remarkably improve the scientific quality and relevance of these studies. It also identified that the small increases in cost associated with diet optimization are far exceeded by the advantages of increased survival of animals, reduced intercurrent disease and rumor burdens, and increased ease of histopathological processing and evaluation.

Chronic dietary restriction influences tumor metastasis in the rat: parametric considerations

Chronic dietary restriction is a well-documented means of inhibiting tumor growth. This study examines the effects of chronic dietary restriction on tumor metastasis in the rat. We investigate the effect of 1) the degree of food restriction, 2) the effect of preexposure to food restriction, and 3) the duration of food restriction after tumor inoculation on tumor metastasis. We also compare two methods of dietary restriction: 1) the time that food is available and 2) the amount of food available. Our findings demonstrate that rats restricted to 50% of ad libitum diet for one week before inoculation with MADB106 tumor cells and for three weeks after inoculation exhibit a significant (p < 0.001) reduction in lung colonization compared with animals fed ad libitum. Animals restricted to access to food for 4 hrs/day (60% of ad libitum) for the same period of time exhibit significantly (p < 0.005) greater lung tumor colonization than animals fed ad libitum. Preadaptation to the feeding regimen for one week before tumor inoculation proved to be critical in inhibiting tumor metastasis. The tumor-inhibitory effect was not significantly influenced by the duration of restriction after inoculation or by the manner in which food restriction was implemented. Finally, we demonstrate that inhibition of tumor colonization may be mediated by enhanced natural killer cell activity in the early postinoculation period.

Risk factors, lifetime risk, and age at onset of breast cancer

PURPOSE

We evaluated the relationship between exposure variables and both lifetime risk and mean age at diagnosis of breast cancer in subjects from the Adventist Health Study who developed breast cancer before the age of 91 years.

METHODS

Multiple decrement life-table analysis was used. This study provided data from 20,341 women followed for 6 years.

RESULTS

In the total population, 30-year-old women with a parental history of any cancer or a maternal history of breast cancer had, respectively, 72% (P < 0.002) and 98% (P < 0.03) higher lifetime risks of breast cancer. Thirty-year-old women who had their first delivery after age 24 years or body mass indices above the 50th percentile had, respectively, 53% (P < 0.007) or 57% (P = 0.01) greater lifetime risk of breast cancer. Women who exercised infrequently had a 27% higher life-time risk (P = 0.09) and an age at diagnosis of breast cancer 6.6 years younger (P < 0.005) than other women.

CONCLUSIONS

Standard risk factors account for substantial increases in lifetime risk of breast cancer and may be associated with differences in age at diagnosis.

The effects of diet, overfeeding and moderate dietary restriction on Sprague-Dawley rat survival, disease and toxicology

Overfeeding by ad libitum (AL) food consumption is the most significant, uncontrolled variable affecting the outcome of the current rodent bioassay. The correlation of food consumption, the resultant adult body weight and the 2-y survival in Sprague-Dawley rats is highly significant. Feeding natural ingredient diets that varied in protein, fiber and metabolizable energy content did not improve low 2-y survival if Sprague-Dawley rats were allowed AL food consumption. Moderate dietary restriction (DR) of all diets tested significantly improved survival and delayed the onset of spontaneous degenerative disease (i.e., nephropathy and cardiomyopathy) and diet-related tumors. By 2 y, moderate DR resulted in an incidence of spontaneous tumors similar to that seen with AL consumption; however, the tumors were more likely to be incidental and did not result in early mortality. There was a decreased age-adjusted incidence in pituitary and mammary gland tumors, but tumor volume and growth time were similar in the AL and DR groups, indicating a similar tumor progression with a delay in tumor onset. Moderate DR did not significantly alter drug-metabolizing enzyme activities or the toxicologic response to five pharmaceuticals tested at maximum tolerated doses (MTD). However, moderate DR did require higher doses of compounds to be given before classical MTD were produced with four pharmaceutical drug candidates. Toxicokinetic studies of two of these compounds demonstrated steady-state systemic exposures that were equal or higher in moderate DR-fed rats. These and other data indicate that moderate DR is the most appropriate method of dietary control for rodent bioassays used to assess human safety of candidate pharmaceuticals.

Up-regulation of IGF binding protein-1 as an anticarcinogenic strategy: relevance to caloric restriction, exercise, and insulin sensitivity

The mitotic rate of stem cells is a major determinant of cancer risk. Insulin-like growth factors (IGFs) are virtually obligate stimulants of cell turnover in nearly every tissue. IGF activity is subject to rapid modulation by hepatic release of IGF binding protein-1 (IGFBP-1), a factor whose synthesis is suppressed by insulin and increased by glucagon. Up-regulation of IGFBP-1 production can be expected to decrease IGF activity and thereby diminish cancer risk. Measures that sensitize peripheral tissues to insulin, and thereby down-regulate insulin secretion, can be expected to increase IGFBP-1 synthesis, provided that they do not unduly sensitize hepatocytes as well. Prolonged aerobic exercise and caloric restriction also increase IGFBP-1 production. Since IGF-1 suppresses hepatic synthesis of sex hormone binding globulin (SHBG), down-regulation of IGF activity will increase SHBG levels and thus diminish the availability of free sex hormones--an effect that should further decrease cancer risk in sex hormone-responsive tissues. These considerations rationalize many findings in animal and epidemiologic studies, and suggest that non-diabetic insulin resistance may be a significant cancer risk factor. Increased IGF activity associated with insulin resistance may also promote benign hyperplasias-most notably atherosclerosis. Hyperinsulinemia stimulates intimal hyperplasia indirectly, via IGF.