Overweight, obesity, and cancer risk

Varying recurrence rates and risk factors associated with different definitions of local recurrence in patients with surgically resected, stage I nonsmall cell lung cancer

BACKGROUND

The objective of this study was to examine the effects of different definitions of local recurrence on the reported patterns of failure and associated risk factors in patients who undergo potentially curative resection for stage I nonsmall cell lung cancer (NSCLC).

METHODS

The study included 306 consecutive patients who were treated from 2000 to 2005 without radiotherapy. Local recurrence was defined either as 'radiation' (r-LR) (according to previously defined postoperative radiotherapy fields), including the bronchial stump, staple line, ipsilateral hilum, and ipsilateral mediastinum; or as 'comprehensive' (c-LR), including the same sites plus the ipsilateral lung and contralateral mediastinal and hilar lymph nodes. All recurrences that were not classified as "local" were considered to be distal.

RESULTS

The median follow-up was 33 months. The proportions of c-LR and r-LR at 2 years, 3 years, and 5 years were 14%, 21%, and 29%, respectively, and 7%, 12%, and 16%, respectively. Significant risk factors for c-LR on multivariate analysis were diabetes, lymphatic vascular invasion, and tumor size; and significant factors for r-LR were resection of less than a lobe and lymphatic vascular invasion. The proportions of distant (non-local) recurrence using these definitions at 2 years, 3 years, and 5 years were 10%, 12%, and 18%, respectively, and 14%, 19%, and 29%, respectively. Significant risk factors for distant failure were histology when using the c-LR definition and tumor size when using the r-LR definition.

CONCLUSIONS

Local recurrence increased nearly 2-fold when a broad definition was used instead of a narrow definition. The definition also affected which factors were associated significantly with both local and distant failure on multivariate analysis. Comparable definitions must be used when analyzing different series.

Adipocytokine resistin and breast cancer risk

Adipocytokine resistin is a member of the newly discovered family of cysteine-rich protein. Recent data suggest that macrophages are a major source of human resistin. Given the obesity-breast cancer link and convergence of adipocyte and macrophage function, resistin may provide unique insight into links between obesity, inflammation, and breast cancer risk in humans. We conducted a hospital-based case-control study to evaluate whether plasma resistin levels were associated with breast cancer risk in women. We also examined the modification effect of estrogen exposures on the resistin-breast cancer link. Questionnaire information, anthropometric measures, and blood samples were taken before treatment from 380 incident cases with breast cancer and 760 controls admitted for health examination at the Tri-Service General Hospital, Taipei between 2004 and 2008. Plasma levels of resistin were measured by enzyme immunoassay. Cumulative exposure to estrogens were estimated according to the age at menarche and age at enrollment for premenopausal women and age at menarche and age at menopause for postmenopausal women. Cases with breast cancer had significantly elevated resistin concentrations as compared with control subjects. Compared with those in the lowest quartile, the adjusted odds ratios of breast cancer for women in the second, third, and highest quartiles were 1.48 [95% confidence interval (CI) = 0.65-3.38], 1.76 (95% CI = 1.00-4.73), and 2.08 (95% CI = 1.04-3.85), respectively. Furthermore, the biological gradient of breast cancer risk by plasma resistin levels remained after adjustment for measures of adiposity. The dose-dependent relationship of resistin levels with breast cancer risk was notably pronounced among women with excess exposure to estrogens. Adipocytokine resistin may have an adiposity-independent role in breast carcinogenesis. Mechanistic studies to fully elucidate the mechanisms underlying resistin's effects should be pursued in future investigations.

Past recreational physical activity, body size, and all-cause mortality following breast cancer diagnosis: results from the Breast Cancer Family Registry

Few studies have considered the joint association of body mass index (BMI) and physical activity, two modifiable factors, with all-cause mortality after breast cancer diagnosis. Women diagnosed with invasive breast cancer (n = 4,153) between 1991 and 2000 were enrolled in the Breast Cancer Family Registry through population-based sampling in Northern California, USA; Ontario, Canada; and Melbourne and Sydney, Australia. During a median follow-up of 7.8 years, 725 deaths occurred. Baseline questionnaires assessed moderate and vigorous recreational physical activity and BMI prior to diagnosis. Associations with all-cause mortality were assessed using Cox proportional hazards regression, adjusting for established prognostic factors. Compared with no physical activity, any recreational activity during the 3 years prior to diagnosis was associated with a 34% lower risk of death [hazard ratio (HR) = 0.66, 95% confidence interval (CI): 0.51-0.85] for women with estrogen receptor (ER)-positive tumors, but not those with ER-negative tumors; this association did not appear to differ by race/ethnicity or BMI. Lifetime physical activity was not associated with all-cause mortality. BMI was positively associated with all-cause mortality for women diagnosed at age > or =50 years with ER-positive tumors (compared with normal-weight women, HR for overweight = 1.39, 95% CI: 0.90-2.15; HR for obese = 1.77, 95% CI: 1.11-2.82). BMI associations did not appear to differ by race/ethnicity. Our findings suggest that physical activity and BMI exert independent effects on overall mortality after breast cancer.

Dietary and genetic obesity promote liver inflammation and tumorigenesis by enhancing IL-6 and TNF expression

Epidemiological studies indicate that overweight and obesity are associated with increased cancer risk. To study how obesity augments cancer risk and development, we focused on hepatocellular carcinoma (HCC), the common form of liver cancer whose occurrence and progression are the most strongly affected by obesity among all cancers. We now demonstrate that either dietary or genetic obesity is a potent bona fide liver tumor promoter in mice. Obesity-promoted HCC development was dependent on enhanced production of the tumor-promoting cytokines IL-6 and TNF, which cause hepatic inflammation and activation of the oncogenic transcription factor STAT3. The chronic inflammatory response caused by obesity and enhanced production of IL-6 and TNF may also increase the risk of other cancers.

Dietary and genetic obesity promote liver inflammation and tumorigenesis by enhancing IL-6 and TNF expression

Epidemiological studies indicate that overweight and obesity are associated with increased cancer risk. To study how obesity augments cancer risk and development, we focused on hepatocellular carcinoma (HCC), the common form of liver cancer whose occurrence and progression are the most strongly affected by obesity among all cancers. We now demonstrate that either dietary or genetic obesity is a potent bona fide liver tumor promoter in mice. Obesity-promoted HCC development was dependent on enhanced production of the tumor-promoting cytokines IL-6 and TNF, which cause hepatic inflammation and activation of the oncogenic transcription factor STAT3. The chronic inflammatory response caused by obesity and enhanced production of IL-6 and TNF may also increase the risk of other cancers.

Insulin-mediated acceleration of breast cancer development and progression in a nonobese model of type 2 diabetes

Epidemiologic studies suggest that type 2 diabetes (T2D) increases breast cancer risk and mortality, but there is limited experimental evidence supporting this association. Moreover, there has not been any definition of a pathophysiological pathway that diabetes may use to promote tumorigenesis. In the present study, we used the MKR mouse model of T2D to investigate molecular mechanisms that link T2D to breast cancer development and progression. MKR mice harbor a transgene encoding a dominant-negative, kinase-dead human insulin-like growth factor-I receptor (IGF-IR) that is expressed exclusively in skeletal muscle, where it acts to inactivate endogenous insulin receptor (IR) and IGF-IR. Although lean female MKR mice are insulin resistant and glucose intolerant, displaying accelerated mammary gland development and enhanced phosphorylation of IR/IGF-IR and Akt in mammary tissue, in the context of three different mouse models of breast cancer, these metabolic abnormalities were found to accelerate the development of hyperplastic precancerous lesions. Normal or malignant mammary tissue isolated from these mice exhibited increased phosphorylation of IR/IGF-IR and Akt, whereas extracellular signal-regulated kinase 1/2 phosphorylation was largely unaffected. Tumor-promoting effects of T2D in the models were reversed by pharmacological blockade of IR/IGF-IR signaling by the small-molecule tyrosine kinase inhibitor BMS-536924. Our findings offer compelling experimental evidence that T2D accelerates mammary gland development and carcinogenesis,and that the IR and/or the IGF-IR are major mediators of these effects.

An updating meta-analysis of the glutathione S-transferase T1 polymorphisms and colorectal cancer risk: a HuGE review

INTRODUCTION

GSTT1 status has been extensively studied as a colorectal cancer risk factor. However, the results are inconsistent. To examine this controversy, we performed a meta-analysis to evaluate the relationship between GSTT1 polymorphism and colorectal cancer.

MATERIALS AND METHODS

We performed a literature search using PUBMED, EMBASE, Cochrane Library, and HuGNet database to February 2009, with no restrictions. All articles were independent and contained the minimum information necessary to estimate the colorectal cancer risk associated with GSTT1 null. Summary odds ratio (ORs) and 95% confidence intervals (CIs) were calculated using random-effect or fixed-effect models based on the heterogeneity of included studies.

RESULTS

A total of 23 case-control studies, including a total of 11,057 subjects (5,058 cases and 5,999 controls), that related to GSTT1 polymorphism and risk of colorectal cancer were identified and included for analysis. The random-effect meta-analyses of all the 23 studies suggested that there was a small increased risk of colorectal cancer for individuals with GSTT1 null (OR was 1.23; 95% CI 1.02-1.49; I (2) = 76.9%, P for heterogeneity <0.001). The fixed-effect meta-analyses reached a similar results in Caucasians populations of ten studies (OR = 1.39; 95% CI 1.21-1.59; I (2) = 29.8%, P for heterogeneity = 0.171) and Asians populations of five studies (OR = 1.23; 95% CI 1.04-1.45; I (2) = 0.0%, P for heterogeneity = 0.428), with as inversely association in the other ethnic populations from four studies (OR = 0.69; 95% CI 0.54-0.877; I (2) = 0.0%, P for heterogeneity = 0.58).

CONCLUSION

There was a small increased risk of colorectal cancer for individuals with GSTT1 null, especially for Caucasians populations and Asian populations.

Obesity: focus on all-cause mortality and cancer

Excess body weight is a strong determinant as well as modifiable risk factor for all-cause and cancer mortality, and as such carries the potential for primary prevention. Recently published studies greatly enhance our knowledge about the impact of body fat distribution on relative risks specific to cancer type, and among women, there is further evidence for the role of menopausal status in modifying relative risks. However, the magnitude of all-cause as well as cancer mortality related to excess body weight varies between prospective cohort studies and the strength of the association, in particular in the overweight range, is still a matter of debate. The distribution of total body fat, how we measure it, and the ratio of body fat to fat-free mass explains to some degree the inconsistencies in associated disease risks in the literature. Physical activity, a potential confounder, has been shown to lower the risk of many chronic diseases, independently of the degree of adiposity. A review of the literature provides much support for public health messages that advocate the benefit of change to a more active lifestyle regardless of age and level of excess body fat.

Metabolic syndrome and hepatocellular carcinoma: two growing epidemics with a potential link

Hepatocellular carcinoma (HCC) is the most rapidly increasing cause of cancer death in the United States. Although many risk factors for HCC are well defined, including hepatitis B virus (HBV), hepatitis C virus (HCV), and alcohol, most series have indicated that 5% to 30% of patients with HCC lack a readily identifiable risk factor for their cancer. The majority of "cryptogenic" HCC in the United States is attributed to nonalcoholic fatty liver disease (NAFLD), a hepatic manifestation of the metabolic syndrome. The metabolic syndrome is a constellation of problems that includes insulin resistance, obesity, hypertension, and hyperlipidemia. Increasingly, components of the metabolic syndrome are being linked to various forms of cancer with respect to both increased risk of disease and worsened outcome. In this review, the authors focused on the relation between metabolic syndrome and HCC. They investigated the increased risks of HCC among individuals with features of metabolic syndrome, potentially worsened cancer outcomes in these patients, possible pathogenic mechanisms to explain these relations, and treatment options for those with NAFLD and its progressive counterpart, nonalcoholic steatohepatitis. It is predicted that metabolic syndrome will lead to large increases in the incidence of HCC over the next decades. A better understanding of the relation between these 2 diseases ultimately should lead to improved screening and treatment options for patients with HCC.

Characterization and comparison of adipose tissue-derived cells from human subcutaneous and omental adipose tissues

Different fat depots contribute differently to disease and function. These differences may be due to the regional variation in cell types and inherent properties of fat cell progenitors. To address the differences of cell types in the adipose tissue from different depots, the phenotypes of freshly isolated adipose tissue-derived cells (ATDCs) from subcutaneous (SC) and omental (OM) adipose tissues were compared using flow cytometry. Our results showed that CD31(-)CD34(+)CD45(-)CD90(-)CD105(-)CD146(+) population, containing vascular smooth muscle cells and pericytes, was specifically defined in the SC adipose tissue while no such population was observed in OM adipose tissue. On the other hand, CD31(-)CD34(+)CD45(-)CD90(-)CD105(-)CD146(-) population, which is an undefined cell population, were found solely in OM adipose tissue. Overall, the SC adipose tissue contained more ATDCs than OM adipose tissue, while OM adipose tissue contained more blood-derived cells. Regarding to the inherent properties of fat cell progenitors from the two depots, adipose-derived stem cells (ADSCs) from SC had higher capacity to differentiate into both adipogenic and osteogenic lineages than those from OM, regardless of that the proliferation rates of ADSCs from both depots were similar. The higher differentiation capacity of ADSCs from SC adipose tissue suggests that SC tissue is more suitable cell source for regenerative medicine than OM adipose tissue.

Obesity, the PI3K/Akt signal pathway and colon cancer

Obesity is currently reaching epidemic levels worldwide and is a major predisposing factor for a variety of life-threatening diseases including diabetes, hypertension and cardiovascular diseases. Recently, it has also been suggested to be linked with cancer. Epidemiological studies have shown that obesity increases the risk of colon cancer by 1.5-2 fold with obesity-associated colon cancer accounting for 14-35% of total incidence. Several factors, altered in obesity, may be important in cancer development including increased levels of blood insulin, insulin-like growth factor I, leptin, TNF-alpha, IL-6 as well as decreased adiponectin. A unifying characteristic of all these factors is that they increase the activity of the PI3K/Akt signal pathway. The PI3K/Akt signal pathway in turn activates signals for cell survival, cell growth and cell cycle leading to carcinogenesis. Here we review the evidence that PI3K/Akt and its downstream targets are important in obesity-associated colon cancer and thus, that targeted inhibition of this pathway could be employed for the prevention of obesity-associated colon cancer and incorporated into the therapy regime for those with irremovable colon cancers.

Diet-induced obesity is associated with hyperleptinemia, hyperinsulinemia, hepatic steatosis, and glomerulopathy in C57Bl/6J mice

Obesity and obesity-related illnesses are global epidemics impacting the health of adults and children. The purpose of the present work is to evaluate a genetically intact obese mouse model that more accurately reflects the impact of aging on diet-induced obesity and type 2 diabetes in humans. Male C57Bl/6J mice consumed either a control diet or one in which 60% kcal were due to lard beginning at 5-6 weeks of age. Body weight and fat measurements were obtained and necropsy performed at 15, 20, 30, and 40 weeks of age. Serum chemistry, histopathology, gene expression of the liver, and renal and hepatic function were also evaluated. In concert with significant increases in percent body fat and weight, mice fed the high-fat versus control diet had significantly increased levels of serum cholesterol. At ages 20 and 30 weeks, serum glucose was significantly higher in obese versus controls, while serum insulin levels were >/=4-fold higher in obese mice at ages 30 and 40 weeks. The effect of age exacerbated the effects of consuming a high-fat diet. In addition to being hyperinsulinemic and leptin resistant, older obese mice exhibited elevated hepatic PAI-1 and downregulation of GLUT4, G6PC, IGFBP-1, and leptin receptor mRNA in the liver, steatosis with subsequent inflammation, glomerular mesangial proliferation, elevated serum ALT, AST, and BUN, and increased numbers of pancreatic islets.

Invariant NKT cells and CD1d(+) cells amass in human omentum and are depleted in patients with cancer and obesity

Invariant NKT (iNKT) cells recognize lipid antigens presented by CD1d and respond rapidly by killing tumor cells and release cytokines that activate and regulate adaptive immune responses. They are essential for tumor rejection in various mouse models, but clinical trials in humans involving iNKT cells have been less successful, partly due to their rarity in humans compared with mice. Here we describe an accumulation of functional iNKT cells in human omentum, a migratory organ with healing properties. Analysis of 39 omental samples revealed that T cells are the predominant lymphoid cell type and of these, 10% expressed the invariant Valpha24Jalpha18 TCR chain, found on iNKT cells, higher than in any other human organ tested to date. About 15% of omental hematopoietic cells expressed CD1d, compared with 1% in blood (p<0.001). Enriched omental iNKT cells killed CD1d(+) targets and released IFN-gamma and IL-4 upon activation. Omental iNKT-cell frequencies were lower in patients with severe obesity (p=0.005), and with colorectal carcinoma (p=0.004) compared with lean healthy subjects. These data suggest a novel role for the omentum in immune regulation and tumor immunity and identify it as a potential source of iNKT cells for therapeutic use.

Expression changes of angiotensin II pathways and bioactive mediators during human preadipocytes-visceral differentiation

Obesity is a worldwide serious health problem; and it may result in a wide range of complications, such as hypertension and diabetes mellitus. As a consequence, molecular identification on the differentiation of preadipocytes and the generation of bioactive mediators is crucial in understanding the formation and development of obesity and obesity-associated health problems. In addition, exhaustive exhibition and purposeful control of adipocytes formation also play critical roles in the plastic and reconstructive surgical procedures. The primary purpose of this study was to exhibit the expression changes of angiotensin II (Ang II) pathways and 2 vital adipokines, leptin and resistin, during human preadipocytes-visceral differentiation by real-time quantitative reverse transcription-polymerase chain reaction. The present result indicated that the generation of Ang II during preadipocytes differentiation was achieved through both renin-angiotensin system pathway and non-renin-angiotensin system pathways, and the latter may be more important in this process. Gene expression of Ang II receptor type 1 and 2 increased in the initial phase of differentiation and then quickly decreased after 9 days. Moreover, the expression of both leptin and resistin increased significantly during preadipocyte-adipocyte conversion. The present work provided a fundamental understanding of human visceral preadipocytes differentiation molecularly. It may promote the understanding of obesity and obesity-associated diseases to some extent. However, there is still a long way to go to treat obesity and its complications effectively; and more efforts should be devoted urgently.

Parity and breastfeeding in relation to obesity among black and white women in the southern community cohort study

OBJECTIVE

This research sought to describe associations among parity, breastfeeding, and adult obesity in black and white women in the southeastern United States.

METHODS

Cross-sectional data from 7,986 white women and 23,198 black women (age 40-79 years) living in the southeastern United States and enrolled in the Southern Community Cohort Study during 2002-2006 were used to examine self-reported body mass index (BMI) and weight change since age 21 in association with parity and breastfeeding. Multiple linear regression and logistic regression with adjustment for demographic and lifestyle factors were used.

RESULTS

At all levels of parity and breastfeeding, black women had higher BMI and weight gain since age 21 than white women. Compared to nulliparity, five or more live births was associated with increased odds of obesity in white women (odds ratio [OR] = 1.37, 95% confidence interval [CI] = 1.08-1.74) and, to a lesser extent, in black women (OR = 1.22, 95% CI = 1.07-1.38). In white women, breastfeeding for more than 12 months compared to none was associated with decreased odds of obesity (OR = 0.68, 95% CI = 0.56-0.82), whereas in black women, no association between obesity and breastfeeding was seen.

CONCLUSIONS

The associations between childbearing factors and measures of adult obesity appear to be larger in white women compared to black women but relatively small overall. However, when considered as part of the constellation of factors that lead to obesity, even these small associations may be important in an overall obesity prevention strategy.

Diet-induced obesity in male mice is associated with reduced fertility and potentiation of acrylamide-induced reproductive toxicity

The prevalence of human obesity and related chronic disorders such as diabetes, cardiovascular diseases, and cancer is rapidly increasing. Human studies have shown a direct relationship between obesity and infertility. The objective of the current work was to examine the effect of diet-induced obesity on male fertility and the effect of obesity on susceptibility to chemical-induced reproductive toxicity. From 5 to 30 wk of age, genetically intact male C57Bl/6J mice were fed a normal diet or one in which 60% of the kilocalories were from lard. Obese mice exhibited significant differences in the mRNA of several genes within the testes in comparison to lean males. Pparg was increased 2.2-fold, whereas Crem, Sh2b1, Dhh, Igf1, and Lepr were decreased 6.7, 1.4, 3.2, 1.6, and 7.2-fold, respectively. The fertility of male mice was compared through mating with control females. Acrylamide (AA)-induced reproductive toxicity was assessed in obese or lean males treated with water or 25 mg AA kg(-1) day(-1) via gavage for 5 days and then mated to control females. Percent body fat and weight were significantly increased in mice fed a high-fat vs. a normal diet. Obesity resulted in significant reduction in plugs and pregnancies of control females partnered with obese vs. lean males. Serum leptin and insulin levels were each approximately 5-fold higher in obese vs. age-matched lean mice. Sperm from obese males exhibited decreased motility and reduced hyperactivated progression vs. lean mice. Treatment with AA exacerbated male infertility of obese and lean mice; however, this effect was more pronounced in obese mice. Further, females partnered with AA-treated obese mice exhibited a further decrease in the percentage of live fetuses, whereas the percentage of resorptions increased. This work demonstrated that diet-induced obesity in mice caused a significant reduction in male fertility and exacerbated AA-induced reproductive toxicity and germ cell mutagenicity.

Serum triglyceride concentrations and cancer risk in a large cohort study in Austria

Background:

Blood lipid levels as part of the metabolic syndrome are thought to be linked to cancer risk. Few epidemiological studies have addressed the association between serum triglyceride (STG) concentrations and cancer risk.

Methods:

Serum triglyceride concentrations were collected in a health investigation (1988–2003). The analyses included 156 153 subjects (71 693 men and 84 460 women), with 5079 incident cancers in men and 4738 cancers in women, and an average of 10.6 years of follow-up. All malignancies were ascertained from the population cancer registry. Multivariate Cox proportional hazard models stratified by age and sex were used to determine adjusted cancer risk estimates and 95% confidence interval (95% CI).

Results:

In men and women combined, higher STG concentrations were associated with increased risk of lung (4th vs 1st quartile: HR, 1.94; 95% CI, 1.47–2.54), rectal (HR, 1.56; 95% CI, 1.00–2.44), and thyroid cancer (HR, 1.96; 95% CI, 1.00–3.84). Serum triglyceride concentrations were inversely associated with non-Hodgkin's lymphoma. In men, STG concentrations were inversely associated with prostate cancer and positively with renal cancer. In women, STG concentrations were positively associated with gynaecological cancers. Stratification by BMI revealed a higher risk of gynaecological cancers in overweight than in normal weight women. No other associations were found.

Conclusions:

Our findings support the hypothesis that STG concentrations are involved in the pathogenesis of lung, rectal, thyroid, prostate, and gynaecological cancers.

Longitudinal evaluation of sleep-disordered breathing and sleep symptoms with change in quality of life: the Sleep Heart Health Study (SHHS)

STUDY OBJECTIVES

Findings from population studies evaluating the progression and incidence of sleep disordered breathing have shown evidence of a longitudinal increase in the severity of sleep disordered breathing. The present study evaluates the association among changes in sleep disordered breathing, sleep symptoms, and quality of life over time.

DESIGN

Prospective cohort study. Data were from the Sleep Heart Health Study.

SETTING

Multicenter study.

PARTICIPANTS

Three thousand seventy-eight subjects aged 40 years and older from the baseline and follow-up examination cycles were included.

MEASUREMENTS

The primary outcomes were changes in the Physical Component Summary and Mental Component Summary scales obtained from the Medical Outcomes Study Short-Form Health Survey. The primary exposure was change in the respiratory disturbance index obtained from unattended overnight polysomnograms performed approximately 5 years apart. Other covariates included measures of excessive daytime sleepiness and difficulty initiating and maintaining sleep.

RESULTS

Mean respiratory disturbance index increased from 8.1 +/- 11 SD at baseline to 10.9 +/- 14 (P < 0.0001) at follow-up. The mean Physical Component Summary and Mental Component Summary scores were 48.5 and 54.1 at baseline and 46.3 and 54.8 at follow-up. No associations between change in respiratory disturbance index and changes in Physical Component Summary or Mental Component Summary scores were seen. However, worsening of difficulty initiating and maintaining sleep and excessive daytime sleepiness were significantly associated with lower quality of life.

CONCLUSIONS

A slight increase in severity of sleep disordered breathing was seen over 5 years; this was not associated with worsening of quality of life. However, subjective symptoms of quality of sleep and daytime sleepiness were associated with declining quality of life.

Body mass index, height, and risk of lymphatic malignancies: a prospective cohort study

The association among body mass index (BMI), height, and the risk of lymphatic malignancies was investigated in the Netherlands Cohort Study. The participants (n = 120,852), Dutch men and women aged 55-69 years, completed a self-administered questionnaire at baseline in 1986. After 13.3 years of follow-up, data on 1,042 lymphatic malignancy cases (including diffuse large-cell lymphoma, chronic lymphocytic leukemia, multiple myeloma, and other subtypes) and 4,588 subcohort members were available. Incidence rate ratios were estimated by using Cox regression models. BMI at baseline and BMI change since the age of 20 years were not associated with lymphatic malignancy risk. However, the rate ratio of lymphatic malignancies per 4-unit increase in BMI at 20 years of age was 1.13 (95% confidence interval (CI): 1.01, 1.25). The rate ratio of lymphatic malignancies per 5-cm increase in height was 1.08 (95% CI: 1.02, 1.15). For diffuse large-cell lymphoma, follicular lymphoma, and chronic lymphocytic leukemia, the relative risks were 1.19 (95% CI: 1.07, 1.33), 1.15 (95% CI: 0.95, 1.40), and 1.09 (95% CI: 0.95, 1.26), respectively, for each 5-cm increase in height. The positive associations among BMI at 20 years of age, height, and the risk of lymphatic malignancies suggest that exposures during early life play a role in the etiology of lymphatic malignancies.

A prospective study of gout and cancer

Gout patients might be at an increased risk of cancer because of obesity and heavy alcohol drinking, but uric acid has antioxidant properties, which may protect against carcinogenesis. We compared the incidence of cancer among 16 857 gout patients admitted to hospitals in Sweden during 1965-1995 with that of the national population. A total of 1425 malignant neoplasms were diagnosed in gout patients (standardized incidence ratio 1.25, 95% confidence limits 1.18, 1.31). The incidence of cancers of the oral cavity and pharynx, colon, liver and biliary tract, pancreas, lung, skin (melanoma and nonmelanoma), endometrium and kidney, as well as of malignant melanoma was increased among gout patients. With the exception of lung cancer, the risk remained elevated during the entire follow-up. This study provides no evidence of a protective effect of uric acid. Hyperuricemia may be an early manifestation of the carcinogenic process.

Hormone therapy and breast cancer risk

Hormone therapy (HT) is the most efficacious intervention for the relief of climacteric symptoms. Controversies surrounding HT have left many women puzzled and afraid. Gynecologists are faced with long-standing beneficial assumptions challenged by an abundance of robust detrimental new data, with little guidance on how to interpret these findings. Prescriptions for HT (and incidence of breast cancers in some areas) have fallen over the last 3 years due to anxiety provoked about breast cancer risk and recurrence. The current 'clinical climate' is against HT. Due to a lack of effective alternatives, women suffering from estrogen-deficiency symptoms are still requesting objective information about HT, particularly those at higher risk of breast cancer or those with a past history of breast cancer. In this situation, discussion of the current clinical uncertainty surrounding the use of HT must be undertaken to ensure that women are adequately informed. The objective of this presentation is to provide a framework for understanding breast cancer risk associated with HT. What are the precise molecular mechanisms of estrogen and progestin in the initiation of breast cancer? Does the risk of estrogen-only therapy on breast cancer vary by dose, constituent, route and duration of administration and cessation of use? Does HT, in addition to increasing risk for breast cancer, affect the type of breast cancer (lobular and ductal) diagnosed? Is HT associated with breast cancers that have better prognostic factors? How relevant are the changes in mammographic breast density associated with HT for the evaluation of breast cancer risk? What is the additional global health risk/benefit ratio associated with the selective use of progesterone or progestin that may confer a significant cardiovascular benefit, such as drospirenone? It is currently assumed and tested that new hormones with particular pharmacological profiles may ultimately achieve their therapeutic goal of relieving climacteric symptoms without an associated moderate increased risk of breast cancer.

Lifestyle factors and colorectal cancer risk (1): systematic review and meta-analysis of associations with body mass index

OBJECTIVE

Excess body weight, defined by body mass index (BMI), may increase the risk of colorectal cancer. As a prerequisite to the determination of lifestyle attributable risks, we undertook a systematic review and meta-analysis of prospective observational studies to quantify colorectal cancer risk associated with increased BMI and explore for differences by gender, sub-site and study characteristics.

METHOD

We searched MEDLINE and EMBASE (to December 2007), and other sources, selecting reports based on strict inclusion criteria. Random-effects meta-analyses and meta-regressions of study-specific incremental estimates were performed to determine the risk ratio (RR) and 95% confidence intervals (CIs) associated with a 5 kg/m(2) increase in BMI.

RESULTS

We analysed 29 datasets from 28 articles, including 67,361 incident cases. Higher BMI was associated with colon (RR 1.24, 95% CIs: 1.20-1.28) and rectal (1.09, 1.05-1.14) cancers in men, and with colon cancer (1.09, 1.04-1.12) in women. Associations were stronger in men than in women for colon (P < 0.001) and rectal (P = 0.005) cancers. Associations were generally consistent across geographic populations. Study characteristics and adjustments accounted for only moderate variations of associations.

CONCLUSION

Increasing BMI is associated with a modest increased risk of developing colon and rectal cancers, but this modest risk may translate to large attributable proportions in high-prevalence obese populations. Inter-gender differences point to potentially important mechanistic differences, which merit further research.

Relation between obesity and adenomatous polyps of the large bowel

BACKGROUND

We compared the prevalence of colorectal adenoma (polyps) in men and women and examined the role of body mass index (BMI) on polyp risk according to patient age and gender.

METHODS

The risk of developing colorectal polyps was studied in 15 380 subjects (7155 men and 8225 women) who underwent colonoscopy for the first time from April 1998 to March 2006 at our 'Human Dry Dock', which is the check-up service provided in Japan. Eligible subjects were 20-86 years old (mean age +/- SD, 47.3 +/- 8.5) and were free of invasive cancer, hyperplastic polyps and familial polyposis. Polyps were found in 1590 subjects (1062 men and 528 women). The odds ratio (OR) of detection of polyps in relation to obesity was determined in all cases by multivariate logistic regression analysis after making an adjustment for gender and age.

RESULTS

The OR of polyp detection in obese subjects (BMI >or= 25) versus non-obese subjects (BMI < 25, OR = 1) was 1.34 (P < 0.001) in men and 1.13 (P = 0.26) in women. As the BMI increased in increments of one, the OR in men increased significantly to 1.01 (P < 0.001), whereas the OR in women was unchanged at 1.00 (P = 0.23), which was without significance.

CONCLUSIONS

We conclude that obesity in men is a risk factor for the development of polyps. These results must be confirmed by additional epidemiological studies.

The impact of dietary and lifestyle risk factors on risk of colorectal cancer: a quantitative overview of the epidemiological evidence

Colorectal cancer is a major cause of cancer mortality and is considered to be largely attributable to inappropriate lifestyle and behavior patterns. The purpose of this review was to undertake a comparison of the strength of the associations between known and putative risk factors for colorectal cancer by conducting 10 independent meta-analyses of prospective cohort studies. Studies published between 1966 and January 2008 were identified through EMBASE and MEDLINE, using a combined text word and MESH heading search strategy. Studies were eligible if they reported estimates of the relative risk for colorectal cancer with any of the following: alcohol, smoking, diabetes, physical activity, meat, fish, poultry, fruits and vegetables. Studies were excluded if the estimates were not adjusted at least for age. Overall, data from 103 cohort studies were included. The risk of colorectal cancer was significantly associated with alcohol: individuals consuming the most alcohol had 60% greater risk of colorectal cancer compared with non- or light drinkers (relative risk 1.56, 95% CI 1.42-1.70). Smoking, diabetes, obesity and high meat intakes were each associated with a significant 20% increased risk of colorectal cancer (compared with individuals in the lowest categories for each) with little evidence of between-study heterogeneity or publication bias. Physical activity was protective against colorectal cancer. Public-health strategies that promote modest alcohol consumption, smoking cessation, weight loss, increased physical activity and moderate consumption of red and processed meat are likely to have significant benefits at the population level for reducing the incidence of colorectal cancer.

Overweight, obesity and gastric cancer risk: results from a meta-analysis of cohort studies

The relationship between excess body weight and gastric cancer risk has not been well studied to date. We therefore carried out a systematic review and meta-analysis of published cohort studies to evaluate the association between excess body weight and gastric cancer risk. An electronic search of the MEDLINE, PubMed, EMBASE and Academic Search Premier (EBSCO) databases, which contain articles published from 1950 onwards, was conducted in order to select studies for this meta-analysis. Ten studies with a total number of 9492 gastric cancer cases and a studied population of 3,097,794 were identified. Overall, excess body weight [body mass index (BMI)25] was associated with an increased risk of gastric cancer [odds ratio (OR)=1.22; 95% confidence intervals (CIs)=1.06-1.41]. Specifically, a stratified analysis showed that excess body weight was associated with an increased risk of cardia gastric cancer [overweight and obese (BMI 25), OR=1.55, 95% CIs=1.31-1.84] and gastric cancer among non-Asians (overweight and obese, OR=1.24, 95% CIs=1.14-1.36); however, the stratified analysis also showed that there was no statistically significant link between excess body weight and gastric cancer in the following subgroups: males (overweight and obese, OR=1.22, 95% CIs=0.96-1.55), females (overweight and obese, OR=1.13, 95% CIs=0.65-1.94), non-cardia gastric cancer (overweight and obese, OR=1.18, 95% CIs=0.96-1.45) and Asians (overweight and obese, OR=1.17, 95% CIs=0.88-1.56). The combined results of this meta-analysis, however, do indicate that overweight and obesity are associated with an increased risk of gastric cancer. The strength of the association also increases with increasing BMI.

Effect of body mass index on shifts in ultrasound-based image-guided intensity-modulated radiation therapy for abdominal malignancies

BACKGROUND AND PURPOSE

We investigated whether corrective shifts determined by daily ultrasound-based image-guidance correlate with body mass index (BMI) of patients treated with image-guided intensity-modulated radiation therapy (IG-IMRT) for abdominal malignancies. The utility of daily image-guidance, particularly for patients with BMI>25.0, is examined.

MATERIALS AND METHODS

Total 3162 ultrasound-directed shifts were performed in 86 patients. Direction and magnitude of shifts were correlated with pretreatment BMI. Bivariate statistical analysis and analysis of set-up correction data were performed using systematic and random error calculations.

RESULTS

Total 2040 daily alignments were performed. Average 3D vector of set-up correction for all patients was 12.1mm/fraction. Directional and absolute shifts and 3D vector length were significantly different between BMI cohorts. 3D displacement averaged 4.9 mm/fraction and 6.8mm/fraction for BMI < or = 25.0 and BMI>25.0, respectively. Systematic error in all axes and 3D vector was significantly greater for BMI>25.0. Differences in random error were not statistically significant.

CONCLUSIONS

Set-up corrections derived from daily ultrasound-based IG-IMRT of abdominal tumors correlated with BMI. Daily image-guidance may improve precision of IMRT delivery with benefits assessed for the entire population, particularly patients with increased habitus. Requisite PTV margins suggested in the absence of daily image-guidance are significantly greater in patients with BMI>25.0.

Genetic variation in genes of the fatty acid synthesis pathway and breast cancer risk

Fatty acid synthase (FAS) is the major enzyme of lipogenesis. It catalyzes the NADPH-dependent condensation of acetyl-CoA and malonyl-CoA to produce palmitic acid. Transcription of the FAS gene is controlled synergistically by the transcription factors ChREBP (carbohydrate response element-binding protein), which is induced by glucose, and SREBP-1 (sterol response element-binding protein-1), which is stimulated by insulin through the PI3K/Akt signal transduction pathway. We investigated whether the genetic variability of the genes encoding for ChREBP, SREBP and FAS (respectively, MLXIPL, SREBF1 and FASN) is related to breast cancer risk and body-mass index (BMI) by studying 1,294 breast cancer cases and 2,452 controls from the European Prospective Investigation on Cancer (EPIC). We resequenced the FAS gene and combined information of SNPs found by resequencing and SNPs from public databases. Using a tagging approach and selecting 20 SNPs, we covered all the common genetic variation of these genes. In this study we were not able to find any statistically significant association between the SNPs in the FAS, ChREBP and SREPB-1 genes and an increased risk of breast cancer overall and by subgroups of age, menopausal status, hormone replacement therapy (HRT) use or BMI. On the other hand, we found that two SNPs in FASN were associated with BMI.

Novel mechanism for obesity-induced colon cancer progression

Adipose tissue secretes factors linked to colon cancer risk including leptin. A hallmark of cancer is sustained angiogenesis. While leptin promotes angiogenesis in adipose tissue, it is unknown whether leptin can induce epithelial cells to produce factors that may drive angiogenesis, vascular development and therefore cancer progression. The purpose of this study was to compare the effects of leptin-stimulated colon epithelial cells differing in adenomatous polyposis coli (Apc) genotype (gatekeeper tumor suppressor gene for colon cancer) on angiogenesis. We employed novel colonic epithelial cell lines derived from the Immorto mouse [young adult mouse colon (YAMC)] and the Immorto-Min mouse [Immorto-Min colonic epithelial cell (IMCE)], which carries the Apc Min mutation, to study the effects of leptin-stimulated colon epithelial cells on angiogenesis. We utilized ex vivo rat mesenteric capillary bioassay and human umbilical vein endothelial cell (HUVEC) models to study angiogenesis. IMCE cells stimulated with leptin produced significantly more vascular endothelial growth factor (VEGF) than YAMC (268 +/- 18 versus 124 +/- 8 pg/ml; P < 0.01) cells. Leptin treatment induced dose-dependent increases in VEGF only in IMCE cells. Conditioned media from leptin (50 ng/ml)-treated IMCE cells induced significant capillary formation compared with control, which was blocked by the addition of a neutralizing antibody against VEGF. Conditioned media from leptin-treated IMCE cells also induced HUVEC cell proliferation, chemotaxis, upregulation of adhesion proteins and cell-signaling activation resulting in nuclear factor kappa B nuclear translocation and DNA binding due to VEGF. This is the first study demonstrating that leptin can induce preneoplastic colon epithelial cells to orchestrate VEGF-driven angiogenesis and vascular development, thus providing a specific mechanism and potential target for obesity-associated cancer.

Energy balance, physical activity, and cancer risk

This chapter posits that cancer is a complex and multifactorial process as demonstrated by the expression and production of key endocrine and steroid hormones that intermesh with lifestyle factors (physical activity, body size, and diet) in combination to heighten cancer risk. Excess weight has been associated with increased mortality from all cancers combined and for cancers of several specific sites. The prevalence of obesity has reached epidemic levels in many parts of the world; more than 1 billion adults are overweight with a body mass index (BMI) exceeding 25. Overweight and obesity are clinically defined indicators of a disease process characterized by the accumulation of body fat due to an excess of energy intake (nutritional intake) relative to energy expenditure (physical activity). When energy intake exceeds energy expenditure over a prolonged period of time, the result is a positive energy balance (PEB), which leads to the development of obesity. This physical state is ideal for intervention and can be modulated by changes in energy intake, expenditure, or both. Nutritional intake is a modifiable factor in the energy balance-cancer linkage primarily tested by caloric restriction studies in animals and the effect of energy availability. Restriction of calories by 10 to 40% has been shown to decrease cell proliferation, increasing apoptosis through anti-angiogenic processes. The potent anticancer effect of caloric restriction is clear, but caloric restriction alone is not generally considered to be a feasible strategy for cancer prevention in humans. Identification and development of preventive strategies that "mimic" the anticancer effects of low energy intake are desirable. The independent effect of energy intake on cancer risk has been difficult to estimate because body size and physical activity are strong determinants of total energy expenditure. The mechanisms that account for the inhibitory effects of physical activity on the carcinogenic process are reduction in fat stores, activity related changes in sex-hormone levels, altered immune function, effects in insulin and insulin-like growth factors, reduced free radical generation, and direct effect on the tumor. Epidemiologic evidence posits that the cascade of actions linking overweight and obesity to carcinogenesis are triggered by the endocrine and metabolic system. Perturbations to these systems result in the alterations in the levels of bioavailable growth factors, steroid hormones, and inflammatory markers. Elevated serum concentrations of insulin lead to a state of hyperinsulinemia. This physiological state causes a reduction in insulin-like growth factor-binding proteins and promotes the synthesis and biological activity of insulin-like growth factor (IGF)-I, which regulates cellular growth in response to available energy and nutrients from diet and body reserves. In vitro studies have clearly established that both insulin and IGF-I act as growth factors that promote cell proliferation and inhibit apoptosis. Insulin also affects on the synthesis and biological availability of the male and female sex steroids, including androgens, progesterone, and estrogens. Experimental and clinical evidence also indicates a central role of estrogens and progesterone in regulating cellular differentiation, proliferation, and apoptosis induction. Hyperinsulinemia is also associated with alterations in molecular systems such as endogenous hormones and adipokines that regulate inflammatory responses. Obesity-related dysregulation of adipokines has the ability to contribute to tumorigenesis and tumor invasion via metastatic potential. Given the substantial level of weight gain in industrialized countries in the last two decades, there is great interest in understanding all of the mechanisms by which obesity contributes to the carcinogenic process. Continued focus must be directed to understanding the various relationships between specific nutrients and dietary components and cancer cause and prevention. A reductionist approach is not sufficient for the basic biological mechanisms underlying the effect of diet and physical activity on cancer. The joint association between energy balance and cancer risk are hypothesized to share the same underlying mechanisms, the amplification of chemical mediators that modulate cancer risk depending on the responsiveness to those hormones to the target tissue of interest. Disentangling the connection between obesity, the insulin-IGF axis, endogenous hormones, inflammatory markers, and their molecular interaction is vital.

Identification and characterization of a leptin-responsive neuroblastoma cell line

The adipocyte-derived hormone leptin plays a critical role in a variety of physiological and pathological actions. As such the determination of leptin signal transduction pathways are important both for understanding the molecular mechanisms of leptin action and for identifying sites for possible therapeutic intervention. Since the hypothalamus is the primary site of leptin action, we sought to identify a neuronal-derived human cell line containing the long form of the leptin receptor (OBRb). To this end, we screened several neuroblastoma cell lines and isolated a sub-line of SH-SY5Y cells, which we designated as SH-OBRb, for further studies. We characterized the transduction pathways induced by leptin in SH-OBRb cells and demonstrated that OBRb mediates tyrosine phosphorylation of STAT3, phosphorylation of ERK1/2, but not SAPK/JNK and p38 MAPK, in a dose and time dependent fashion. In addition, Akt appears to be phosphorylated in the basal state and to be insensitive to further activation by leptin. In summary, we have isolated a unique cell line that can be utilized as a model for use in the study of leptin action and molecular mechanisms.

Energy intake, physical activity, energy balance, and cancer: epidemiologic evidence

Energy intake, physical activity, and obesity are modifiable lifestyle factors. This chapter reviews and summarizes the epidemiologic evidence on the relation of energy intake, physical activity, and obesity to cancer. High energy intake may increase the risk of cancers of colon-rectum, prostate (especially advanced prostate cancer), and breast. However, because physical activity, body size, and metabolic efficiency are highly related to total energy intake and expenditure, it is difficult to assess the independent effect of energy intake on cancer risk. There are sufficient evidences to support a role of physical activity in preventing cancers of the colon and breast, whereas the association is stronger in men than in women for colon cancer and in postmenopausal than in premenopausal women for breast cancer. The evidence also suggests that physical activity likely reduces the risk of cancers of endometrium, lung, and prostate (to a lesser extent). On the other hand, there is little or no evidence that the risk of rectal cancer is related to physical activity, whereas the results have been inconsistent regarding the association between physical activity and the risks of cancers of pancreas, ovary and kidney. Epidemiologic studies provide sufficient evidence that obesity is a risk factor for both cancer incidence and mortality. The evidence supports strong links of obesity with the risk of cancers of the colon, rectum, breast (in postmenopausal women), endometrium, kidney (renal cell), and adenocarcinoma of the esophagus. Epidemiologic evidence also indicates that obesity is probably related to cancers of the pancreas, liver, and gallbladder, and aggressive prostate cancer, while it seems that obesity is not associated with lung cancer. The role of obesity in other cancer risks is unclear.

Weight, dietary behavior, and physical activity in childhood and adolescence: implications for adult cancer risk

Lifestyle factors related to energy balance, including weight, dietary behavior and physical activity, are associated with cancer risk. The period of childhood and growth into adolescence and early adulthood may re-present a 'cumulative risk' for later adult-onset cancers. We review a number of epidemiologic studies that have examined associations among childhood and adolescent body size, diet, and physical activity with adult cancer risk. These studies suggest that unhealthy behaviors that develop early in life and persist over time may increase the risk of some cancer types, such as premenopausal breast, ovarian, endometrial, colon and renal cancer, adversely affect cancer-related morbidities, and increase mortality. Continued research is needed to further determine and refine how timing and degree of such exposures in early childhood and adolescence relate to adult cancer risk. Presently, sufficient evidence suggests a continued need for stronger primary prevention in cancer and obesity research via modified lifestyle behaviors earlier in the developmental spectrum, i.e. during childhood and adolescence.

C/EBPbeta regulates body composition, energy balance-related hormones and tumor growth

The prevalence of obesity, an established epidemiologic risk factor for many chronic diseases including cancer, has been steadily increasing in the US over several decades. The mechanisms used to regulate energy balance and adiposity and the relationship of these factors to cancer are not completely understood. Here we have used knockout mice to examine the roles of the transcription factors CCAAT/enhancer-binding protein (C/EBP) beta and C/EBPdelta in regulating body composition and systemic levels of hormones such as insulin-like growth factor-1 (IGF-1), leptin and insulin that mediate energy balance. Dual-energy X-ray absorptiometry showed that C/EBPbeta, either directly or indirectly, modulated body weight, fat content and bone density in both males and females, while the effect of C/EBPdelta was minor and only affected adiposity and body weight in female animals. Levels of IGF-1, leptin and insulin in the serum were decreased in both male and female C/EBPbeta(-/-) mice, and C/EBPbeta was associated with their promoters in vivo. Moreover, colon adenocarcinoma cells displayed reduced tumorigenic potential when transplanted into C/EBPbeta-deficient animals, especially males. Thus, C/EBPbeta contributes to endocrine expression of IGF-1, leptin and insulin, which modulate energy balance and can contribute to cancer progression by creating a favorable environment for tumor cell proliferation and survival.

Is increased body mass index associated with the incidence of testicular germ cell cancer?

PURPOSE

Epidemiological and ecological evidences suggest a positive association of overweight and obesity with the risk of testicular germ cell cancer (GCC). Previous controlled trials reported conflicting results. The present study aimed to analyse the putative association of overweight with GCC risk in a large patient sample and to summarize previous data.

METHODS

A total of 8,498 GCC patients were enrolled in a nationwide multicentric case control study. Self-reported body dimensions were recorded for calculation of the body mass index (BMI; kg/m(2)). For comparison, 2,070 age-matched male probands of the latest German National Health Survey (NHS) were employed. Patients and controls were categorized according to age as follows: 18-29, 30-39, and 40-49 years, respectively, and according to BMI, as follows: <18.5; 18.5 to <25; 25 to <30; >30 kg/m(2), respectively. Frequencies of BMI-categories in the three age groups were tabulated and compared statistically. The literature was searched for previous controlled trials regarding BMI and GCC risk.

RESULTS

The median BMI of all GCC patients is 24.69 kg/m(2). Overall comparison of frequencies of BMI categories of cases and controls did not reveal any significant difference. However, in young men (18-29 years) BMI categories 25 to <30 kg/m(2) and >30 kg/m(2) were significantly more frequent in GCC patients than in controls (p < 0.00001). Nineteen previous studies were identified in the literature, one of which being clearly in accordance with the present hypothesis, one being antithetical while the remaining studies were inconclusive in various aspects.

CONCLUSION

The results of this population-based study lend support to two hypotheses regarding the pathogenesis of GCC: First, as high-calorie nutrition is the most important reason for increased BMI, it appears conceivable that nutritional factors are involved in the pathogenesis of GCC. Second, as nonseminoma is the most prevalent histological subtype among younger patients, the association of increased BMI with incidence of GCC in this particular subgroup may point to divergent pathogenetic pathways of nonseminoma and seminoma, respectively.

Obesity accelerates mouse mammary tumor growth in the absence of ovarian hormones

Obesity increases incidence and mortality of breast cancer in postmenopausal women. Mechanisms underlying this association are poorly understood. Suitable animal models are needed to elucidate potential mechanisms for this association. To determine the effects of obesity on mammary tumor growth, nonovariectomized and ovariectomized C57BL/6 mice of various body weights (lean, overweight, and obese) were implanted subcutaneously with mammary tumor cells from syngeneic Wnt-1 transgenic mice. In mice, the lean phenotype was associated with reduced Wnt-1 tumor growth regardless of ovarian hormone status. Ovariectomy delayed Wnt-1 tumor growth consistent with the known hormone responsiveness of these tumors. However, obesity accelerated tumor growth in ovariectomized but not in nonovariectomized animals. Diet-induced obesity in a syngeneic mouse model of breast cancer enhanced tumor growth, specifically in the absence of ovarian hormones. These results support epidemiological evidence that obesity is associated with increased breast cancer incidence and mortality in postmenopausal but not premenopausal women. In contrast, maintaining a lean body weight phenotype was associated with reduced Wnt-1 tumor growth regardless of ovarian hormone status.

Impact of obesity on the surgical outcome following repeat hepatic resection in Japanese patients with recurrent hepatocellular carcinoma

AIM

To evaluate the impact of obesity on the posto-perative outcome after hepatic resection in patients with hepatocellular carcinoma (HCC).

METHODS

Data from 328 consecutive patients with primary HCC and 60 patients with recurrent HCC were studied. We compared the surgical outcomes between the non-obese group (body mass index: BMI < 25 kg/m(2)) and the obese group (BMI > or = 25 kg/m(2)).

RESULTS

Following curative hepatectomy in patients with primary HCC, the incidence of postoperative complications and the long-term prognosis in the non-obese group (n = 240) were comparable to those in the obese group (n = 88). Among patients with recurrent HCC, the incidence of postoperative complications after repeat hepatectomy was not significantly different between the non-obese group (n = 44) and the obese group (n = 16). However, patients in the obese group showed a significantly poorer long-term prognosis than those in the non-obese group (P < 0.05, five-year survival rate; 51.9% and 92.0%, respectively).

CONCLUSION

Obesity alone may not have an adverse effect on the surgical outcomes of patients with primary HCC. However, greater caution seems to be required when planning a repeat hepatectomy for obese patients with recurrent HCC.

Obesity and Risk of Cancer in Postmenopausal Korean Women

Purpose

To evaluate an association between obesity, measured by body mass index (BMI; kg/m2), and risk of cancer at individual and all sites in postmenopausal women.

Methods

A cohort of 170,481 postmenopausal Korean women who were age 40 to 64 years at baseline measurement of BMI was observed prospectively from 1994 to 2003 for cancer incidence. Multivariable adjusted proportional hazard models were used for evaluating the association.

Results

Women with a BMI of 30 kg/m2 or higher had a 23% higher risk of cancer than women with a BMI between 21.0 and 22.9 kg/m2 (hazard ratio = 1.23; 95% CI, 1.08 to 1.41). According to the increase in BMI level, significant positive trends existed in cancers of colon, breast, corpus uteri, and kidney with hazard ratios of 1.05 (95% CI, 1.02 to 1.08), 1.07 (95% CI, 1.05 to 1.10), 1.13 (95% CI, 1.07 to 1.20), and 1.08 (95% CI, 1.02 to 1.15), respectively, for the increase of BMI by 1 kg/m2. When the analysis was limited to never-smokers, women with a BMI of 25 kg/m2 or higher showed a significantly increased risk of cancers of the colon, breast, corpus uteri, and kidney and leukemia compared with the normal BMI (18.5 to 22.9 kg/m2) group.

Conclusion

Although variations exist between the individual cancer sites, obesity was associated with an overall increased risk of cancer in postmenopausal Korean women. To reduce the risk of cancer, active strategies to prevent obesity should be implemented in postmenopausal women.

Resistance of Janus kinase-2 dependent leptin signaling in natural killer (NK) cells: a novel mechanism of NK cell dysfunction in diet-induced obesity

Leptin acts not only as an anorexigenic hormone but also regulates cell-mediated immunity via leptin receptors (Ob-R) expressed on T and B lymphocytes. However, the impact of leptin on natural killer (NK) cells is currently elusive. We evaluated leptin effects on NK cells in relation to the body weight in rats using in vivo and in vitro approaches. Leptin was injected iv in male lean and diet-induced obese Lewis and F344 rats. NK cell numbers were analyzed in blood and spleen by fluorescence activated cell sorting and immunohistochemistry, and the activity of NK cells was measured by chromium release assay. Ob-R expression was investigated by confocal laser scanning and quantitative RT-PCR. To compare leptin-dependent intracellular signaling under basal and leptin- and tumor cell (MADB106)-stimulated conditions, intracellular target proteins of NK cells were evaluated by Western blotting. Number and distribution pattern of splenic NK cells were significantly different in lean and obese animals. Leptin administration resulted in a 4-fold higher stimulation of the NK activity in lean than obese animals. This was not due to a decreased expression of Ob-R because quantitative RT-PCR revealed significantly higher Ob-Rb mRNA levels in NK cells from obese rats. In contrast, postreceptor signaling is differentially abrogated in obese animals with significantly lower activation of postreceptor signaling components (Janus kinase-2p, protein kinase B pT308, AMPalphapT172) after an in vivo leptin challenge. In conclusion, the results for the first time assign leptin a central role as a modulator of NK cell number and activity only in lean but not obese subjects. The differential role of leptin has important implications for the influence of body weight in the response to systemic inflammations and in the immunological defense of cancer.

Prostate cancer

In developed countries, prostate cancer is the second most frequently diagnosed cancer, and the third most common cause of death from cancer in men. Apart from age and ethnic origin, a positive family history is probably the strongest known risk factor. Clinically, prostate cancer is diagnosed as local or advanced, and treatments range from surveillance to radical local treatment or androgen-deprivation treatment. Androgen deprivation reduces symptoms in about 70-80% of patients with advanced prostate cancer, but most tumours relapse within 2 years to an incurable androgen-independent state. The recorded incidence of prostate cancer has substantially increased in the past two decades, probably because of the introduction of screening with prostate-specific antigen, the use of improved biopsy techniques for diagnosis, and increased public awareness. Trends in mortality from the disease are less clearcut. Mortality changes are not of the same magnitude as the changes in incidence, and in some countries mortality has been stable or even decreased. The disparity between reported incidence and mortality rates leads to the probable conclusion that only a small proportion of diagnosed low-risk prostate cancers will progress to life-threatening disease during the lifetime of the patient.

The role of testosterone in the pathogenesis of prostate cancer

Relationships between androgenic hormones and prostatic tissue growth are complex. It is certainly true that the prostate will not develop without androgens and the gland will atrophy if androgen support is withdrawn. The hormonal hypothesis remains one of the most important hypotheses in the etiology of prostate cancer (PCa), and efforts are continuing to improve the understanding of androgen actions in PCa. Although evidence from epidemiological studies of associations between circulating levels of androgens and PCa risk has been inconsistent, the traditional view that higher testosterone (T) levels represent a risk factor for PCa appears to have little evidentiary support. Reinvestigation of the relationship between T and PCa seems important and necessary if a new, clinically and scientifically rewarding concept is to be constructed. The present review considers the metabolism and intraprostatic action of T, epidemiological evidence, and the association between T and PCa risk.

Weight gain in overweight and obese community dwelling old-old

OBJECTIVES

The purpose of this study was to 1) investigate lifetime weight changes in community dwelling old-old, those age 80 or older; 2) explore reasons for weight changes from their personal perspective and 3) examine ways the old-old feel they can successfully lose weight. A cross sectional design was used for this qualitative study.

SETTING

One county of a southeastern U.S. state.

PARTICIPANTS

Nine community dwelling old-old.

MEASUREMENT

Content analysis of transcripts was used to examine the interviews.

RESULTS

All of the old-old interviewed had reached their maximum weight after the age of 65. Average lifetime weight gain was 73 pounds. All wanted to lose weight and found ways to incorporate small changes in their everyday lives.

CONCLUSION

With increasing life expectancy among older adults, health promotion targeting weight control needs to include the old-old.

Plasma vitamin B12 concentrations and the risk of colorectal cancer: a nested case-referent study

In this nested case-referent study, we related plasma concentrations of vitamin B12 to the risk of colorectal cancer, taking into consideration prediagnostic plasma folate and total homocysteine concentrations. Subjects were 226 cases and double matched referents from the population-based Northern Sweden Health and Disease Study. Follow-up times from recruitment to diagnosis ranged from 0.1 to 12.7 years, with a median of 4.2 years. Plasma vitamin B12 concentrations were inversely associated with the risk of rectal cancer: univariate odds ratio for the highest versus lowest quintile 0.34 (95% confidence interval (95% CI) 0.13-0.83), p(trend) = 0.004. Risk estimates were attenuated slightly but remained statistically significant after adjustment for body mass index, current smoking, recreational and occupational physical activity, alcohol intake and prediagnostic plasma folate and total homocysteine concentrations: OR 0.30 (95% CI 0.08-0.99), p(trend) = 0.025. The corresponding univariate and fully adjusted odds ratios for colon cancer were 1.25 (CI 0.66-2.36), p(trend) = 0.185 and 1.42 (CI 0.67-3.05), p(trend) = 0.113, respectively. The observed over-risk was attributable to left-sided colon cancer. Interaction analyses including vitamin B12, folate and homocysteine were in line with the results for vitamin B12 alone. In conclusion, these results suggest that increasing levels of plasma vitamin B12, alone or together with other factors involved in one-carbon metabolism, may reduce the risk of rectal cancer, whereas for colon cancer, the association appears to be less clear.