Childhood body mass index and later cancer risk: A 50-year follow-up of the Boyd Orr study

Professional, educational and psychosocial impacts of the COVID-19 pandemic on pediatricians

OBJECTIVES

COVID-19 infection is not limited to medical aspects, but may have significant negative impacts on education, tourism, the economy as well as sociocultural, ethical, and legal aspects. We aimed to assess the multidimensional impact of the COVID-19 pandemic on pediatricians by examining their COVID-19 infection, domestic life and quarantine, as well as work patterns, educational activities, and psychosocial impact.

METHODS

An online survey consisted of seven sections and 68 questions was prepared through 'Google Forms.' The survey was sent via e-mail to physicians who are members of the National Pediatric Association of Turkey.

RESULTS

The pandemic has affected pediatricians working in our country in a multifaceted aspect. They experienced significant anxiety/depression/stress, 8% of them felt it at a pathological level and were receiving treatment, and women and young pediatricians were more vulnerable to the pandemic. The more adequately informed about the disease, the more prepared for COVID-19 and lower levels of psychological distress, which emphasizes the importance of education and institutional continuing support. Our study showed that academic education was seriously disrupted and the satisfaction rate with virtual education was low.

CONCLUSION

Although COVID-19 has less impact today, it has taught us that it is necessary to be ready for new pandemics in the future. The required measures should be taken urgently and effectively healthcare professionals should follow a rational and applicable disaster plan.

Historical Obesity and Early-Onset Cancers: A Propensity-Weighted Analysis of the National Health and Nutrition Examination Survey

BACKGROUND

The incidence of early-onset obesity-related cancers (diagnosed < 50 years) is increasing in the U.S. We examined the reported historical body mass index (BMI) of adults with early and later-onset cancers to explore relation to obesity.

METHODS

We queried the 1999-2018 NHANES database for adults diagnosed with obesity-related cancers (colorectal, non-colorectal gastrointestinal, uterine, breast). We classified early and late-onset cancer based on a diagnosis age of < 50 and ≥ 50 years, respectively. Propensity-weighted analysis was used to compare prior historical BMIs between the matched groups.

RESULTS

After weighing, we included 2,966,528 patients with obesity-related cancers, 846,211 (28%) of which were < 50 years. In the matched analysis, 69.1% of early-onset CRC cases were diagnosed as obese (BMI ≥ 30 kg/m2) before cancer diagnosis, compared to 47.2% of late-onset cases (p < 0.03). Similarly, a higher percentage of adults with other early-onset gastrointestinal cancers had prior obesity as compared to the late-onset cohort (70.3% vs. 40.5%, p = 0.0002). BMI showed a trend toward higher values at ages 20-24 for early-onset CRC and 30-34 for other gastrointestinal cancers. In contrast, later-onset CRC and other gastrointestinal cancers exhibited higher BMI values at later ages (30-34 and 35-39, respectively). Early-onset uterine cancer was linked to a higher BMI compared to later-onset cancer (34.0 vs. 31.1 kg/m2, p < 0.0001), with a trend towards a higher BMI before 19 years old.

CONCLUSIONS

Our nationally representative data reveal that higher and earlier body fatness in adulthood associates with early-onset gastrointestinal and uterine cancers. These findings underscore the importance of intensifying efforts to combat early-life obesity.

Association of High Body Mass Index in Early Life With the Development of Colorectal Cancer

SIGNIFICANCE

This study on the relationship between early life high BMI and the development of CRC reveals the role of high BMI during childhood and adolescence in the occurrence and progression of CRC. It suggests the importance of restoring normal weight or reducing weight in individuals with high BMI early in life for the prevention of colorectal cancer.

Association of Maternal TSH, FT4 With Children's BMI Trajectories, and Obesity: A Birth Cohort Study

OBJECTIVE

To investigate the association between maternal TSH, free thyroxine (FT4), and children's body mass index (BMI) trajectories and obesity.

METHOD

Based on the Ma'anshan Birth Cohort in China, we repeatedly assayed maternal thyroid functions in 3 trimesters of pregnancy. Children's height and weight were measured 15 times before they were age 6 years. Body fat was assessed when children were aged 6 years. Mplus software was used to fit maternal thyroid hormone trajectories and BMI trajectories. Multivariate logistic regression models and generalized linear models were used in data analysis.

RESULTS

Low maternal FT4 trajectory was observed to be related to an increased risk of a high children's BMI trajectory and overweight, with an odds ratio and 95% CI of 1.580 (1.169-2.135) and 1.505 (1.064-2.129), respectively. Increased maternal FT4 concentrations in the first, second, and third trimesters were associated with a decreased risk of high children's BMI trajectories and obesity. There was a positive association between low maternal FT4 trajectory and 6-year-old children's body fat ratio with β and 95% CI of 0.983 (0.138-1.829). Furthermore, negative correlations between maternal FT4 concentration in the first, second, and third trimesters of pregnancy and body fat ratio were observed.

CONCLUSIONS

Low maternal FT4 trajectory during pregnancy may predict a high BMI trajectory in children and relate to overweight and high body fat ratio in 6-year-old children. High maternal FT4 concentrations throughout pregnancy may be associated with the decreasing risk of obesity and low body fat ratio in 6-year-old children.

Genetically predicted childhood body mass index and lung cancer susceptibility: A two-sample Mendelian randomization study

BACKGROUND

The association between adult body mass index (BMI) and lung cancer (LC) susceptibility have been reported, but the causal relationship with childhood BMI remains largely unclear. To evaluate the causal effect of childhood BMI on LC susceptibility, a two-sample Mendelian randomization (MR) study was performed.

METHODS

The two-sample MR analysis utilized 25 single nucleotide polymorphisms (SNPs) as instrumental variables for childhood BMI. Genetic summary data from the International Lung Cancer Consortium and FinnGen databases were analyzed to estimate the causal effect of these SNPs on LC susceptibility. The IVW method was employed as the primary analysis, supplemented by the Weighted Median, MR-Egger, and MR pleiotropy residual sum and outlier test.

RESULTS

Our findings indicated that there was no causal association between childhood BMI and the susceptibility of LC (odds ratio [OR]: 1.03, 95% confidence interval [CI]: 0.90-1.17, p = 0.705), lung adenocarcinoma (OR: 0.99, 95% CI: 0.86-1.13, p = 0.832), lung squamous cell carcinoma (OR: 0.97, 95% CI: 0.84-1.13, p = 0.726), and small cell LC (OR: 1.09, 95% CI: 0.82-1.45, p = 0.554) based on the IVW as well as other methods employed. Furthermore, these findings indicated no causal effect of childhood BMI on the LC susceptibility in both ever smokers and never smokers.

CONCLUSION

This study did not conclude a causal effect between childhood BMI and LC susceptibility. However, given the complex nature of cancer development, further studies are needed to verify these findings.

Association of childhood and adolescence obesity with incidence and mortality of adulthood cancers. A systematic review and meta-analysis

BACKGROUND

Prevalence and subsequent conditions of childhood and adolescent obesity are increasing. It has been seen that obesity in youth is associated with adulthood cancer. This systematic review and meta-analysis aimed to determine the pooled association of childhood obesity with cancers in adulthood.

METHODS

In this systematic review, international electronic databases such as Scopus, PubMed, Web of Science, and EMBASE were searched using relevant keywords until February 2022. All Cohort studies assessing the association of childhood and adolescent obesity (under 18 years old) with the incidence and mortality of all types of cancers were included. Two independent reviewers screened and carried out the quality assessment of included studies. Between-studies heterogeneity was assessed using the I squared and Cochran's Q tests. Random/fixed-effect meta-analyses were used to pool the appropriate effect sizes (Hazard ratios (HR)).

RESULTS

Overall, 46 studies were found to be relevant and were included in this study. Based on the random-effects model meta-analysis, childhood obesity increased the hazard of cancer incidence and mortality in adulthood by 33% (HR: 1.33, 95%CI (1.25, 1.41)) and by 28% (HR: 1.28, 95%CI (1.13, 1.42)), respectively. In the subgroups meta-analysis, the HR of childhood obesity and adulthood cancer incidence mortality in women was higher than in men (HR=1.39, 95%CI (1.25, 1.53) vs HR= 1.20, 95%CI (1.07, 1.32)) and (HR= 1.40, 95%CI (1.10, 1.69) vs HR=1.20, 95%CI (1.04, 1.36)) respectively.

CONCLUSION

This study found that obesity in childhood and adolescence is associated with a significant increase in the incidence and mortality of cancers in adulthood. Prevention of childhood obesity, in addition to its short-term beneficial effects, can reduce the burden of cancer in adulthood. The data sets of this study are present in the Tables of the current manuscript. Moreover this study was registered online in PROSPERO (registration code: CRD42022331958).

SYSTEMIC REVIEW REGISTRATION

https://www.crd.york.ac.uk/Prospero/, identifier CRD42022331958.

Guidelines for treating child and adolescent obesity: A systematic review

Obesity is a chronic disease that compromises the physical and mental health of an increasing proportion of children globally. In high-income countries, prevalence of paediatric obesity is increasing faster in those from marginalised populations such as low-income households, suggesting the disease as one that is largely systemic. Appropriate treatment should be prioritised in these settings to prevent the development of complications and co-morbidities and manage those that already exist. An array of clinical practice guidelines are available for managing overweight and obesity in children and adolescents, but no systematic review has yet compared their quality or synthesised their recommendations. We aimed to narratively review clinical practice guidelines published in English for treating child and adolescent obesity, to identify the highest quality guidelines, and assess similarities, conflicts, and gaps in recommendations. We systematically searched academic databases and grey literature for guidelines published. We used the AGREE II tool to assess the quality, and identified nine high quality guidelines for inclusion in a narrative review of recommendations. Guidelines predominantly recommended the delivery of multi-component behaviour-change interventions aimed at improving nutrition and physical activity. Treatment outcomes were generally focussed on weight, with less emphasis on managing complications or improving quality-of-life. There was no evidence-based consensus on the best mode of delivery, setting, or treatment format. The guidelines rarely included recommendations for addressing the practical or social barriers to behaviour change, such as cooking skills or supervised physical activity. There is insufficient evidence to evaluate pharmaceutical and surgical interventions in children, and these were generally not recommended. It should be noted that this review addressed documents published in English only, and therefore the included guidelines were applicable predominantly to high-resource settings.

The socialisation of the adolescent who carries out team sports: a transversal study of centrality with a social network analysis

OBJECTIVES

To analyse the physical activity carried out by the adolescents in the study, its relationship to being overweight (overweight+obese) and to analyse the structure of the social network of friendship established in adolescents doing group sports, using different parameters indicative of centrality.

SETTING

It was carried out in an educational environment, in 11 classrooms belonging to 5 Schools in Ponferrada (Spain).

PARTICIPANTS

235 adolescents were included in the study (49.4% female), who were classified as normal weight or overweight.

PRIMARY AND SECONDARY OUTCOME MEASURES

Physical Activity Questionnaire for Adolescents (PAQ-A) was used to study the level of physical activity. A social network analysis was carried out to analyse structural variables of centrality in different degrees of contact.

RESULTS

30.2% of the participants in our study were overweight. Relative to female participants in this study, males obtained significantly higher scores in the PAQ-A (OR: 2.11; 95% CI: 1.04 to 4.25; p value: 0.036) and were more likely to participate in group sport (OR: 4.59; 95% CI: 2.28 to 9.22; p value: 0.000). We found no significant relationship between physical activity and the weight status in the total sample, but among female participants, those with overweight status had higher odds of reporting high levels of physical exercise (OR: 4.50; 95% CI: 1.21 to 16.74; p value: 0.025). In terms of centrality, differentiating by gender, women who participated in group sports were more likely to be classified as having low values of centrality, while the opposite effect occurred for men, more likely to be classified as having high values of centrality.

CONCLUSIONS

Our findings, with limitations, underline the importance of two fundamental aspects to be taken into account in the design of future strategies: gender and the centrality within the social network depending on the intensity of contact they have with their peers.

The Impact of the Coronavirus Disease-2019 Pandemic on Childhood Obesity and Vitamin D Status

BACKGROUND

The risk of weight gain as a consequence of school closure in children during the coronavirus disease-2019 (COVID-19) pandemic has been recognized. This study was performed to investigate changes in anthropometric and metabolic parameters in children following a 6-month period of social distancing and school closure due to the pandemic.

METHODS

This retrospective cohort study was conducted in school-aged children that were on routine follow-up at the Growth Clinic of Seoul St. Mary's Hospital. Changes in body mass index (BMI) standard deviation scores (z-scores), lipid profiles, and vitamin D levels were investigated. The 1-year period prior to school closure was defined as "pre-COVID-19 period," and the subsequent 6-month period as "COVID-19 period."

RESULTS

Overall, 226 children between 4 to 14 years old without comorbidities were assessed. On average, their BMI z-scores increased by 0.219 (95% confidence interval [CI], 0.167-0.271; P < 0.001) in the COVID-19 period compared to the pre-COVID-19 period, and the proportion of overweight or obesity increased from 23.9% in the pre-COVID-19 period to 31.4% in the COVID-19 period. The number of days after school closure (P = 0.004) and being in the normoweight category in the pre-COVID-19 period (P = 0.017) were factors associated with an increased BMI in the COVID-19 period. The mean triglyceride (105.8 mg/dL vs. 88.6 mg/dL, P < 0.001) and low-density lipoprotein-cholesterol (100.2 mg/dL vs. 94.0 mg/dL, P = 0.002) levels were higher, whereas the calcidiol level (18.9 mg/dL vs. 23.8 mg/dL, P < 0.001) was lower in the COVID-19 period compared to the pre-COVID-19 period.

CONCLUSION

Within 6 months, increased childhood obesity and vitamin D deficiencies were observed. The duration of school closure was significantly associated with an increased BMI and being normoweight does not exclude the risks for gaining weight.

Obesity, oxidative DNA damage and vitamin D as predictors of genomic instability in children and adolescents

BACKGROUND/OBJECTIVES

Epidemiological evidence indicates obesity in childhood and adolescence to be an independent risk factor for cancer and premature mortality in adulthood. Pathological implications from excess adiposity may begin early in life. Obesity is concurrent with a state of chronic inflammation, a well-known aetiological factor for DNA damage. In addition, obesity has been associated with micro-nutritional deficiencies. Vitamin D has attracted attention for its anti-inflammatory properties and role in genomic integrity and stability. The aim of this study was to determine a novel approach for predicting genomic instability via the combined assessment of adiposity, DNA damage, systemic inflammation, and vitamin D status.

SUBJECTS/METHODS

We carried out a cross-sectional study with 132 participants, aged 10-18, recruited from schools and paediatric obesity clinics in London. Anthropometric assessments included BMI Z-score, waist and hip circumference, and body fat percentage via bioelectrical impedance. Inflammation and vitamin D levels in saliva were assessed by enzyme-linked immunosorbent assay. Oxidative DNA damage was determined via quantification of 8-hydroxy-2'-deoxyguanosine in urine. Exfoliated cells from the oral cavity were scored for genomic instability via the buccal cytome assay.

RESULTS

As expected, comparisons between participants with obesity and normal range BMI showed significant differences in anthropometric measures (p < 0.001). Significant differences were also observed in some measures of genomic instability (p < 0.001). When examining relationships between variables for all participants, markers of adiposity positively correlated with acquired oxidative DNA damage (p < 0.01) and genomic instability (p < 0.001), and negatively correlated with vitamin D (p < 0.01). Multiple regression analyses identified obesity (p < 0.001), vitamin D (p < 0.001), and oxidative DNA damage (p < 0.05) as the three significant predictors of genomic instability.

CONCLUSIONS

Obesity, oxidative DNA damage, and vitamin D deficiency are significant predictors of genomic instability. Non-invasive biomonitoring and predictive modelling of genomic instability in young patients with obesity may contribute to the prioritisation and severity of clinical intervention measures.

Childhood Obesity and Cancer Risk in Adulthood

PURPOSE OF REVIEW

The purpose of this review is to summarize our current understanding of the association between childhood obesity and cancer risk later in life.

RECENT FINDINGS

Adipose tissue secrets a variety of adipocytokines, and expression and/or secretion rate of most of them seems to be increased or dysregulated in obesity. In addition, obesity leads to increased secretion of proinflammatory cytokines such as interferon-γ (IFN-γ), interleukin 6 (IL-6), and tumor necrosis factor-α (TNF-α), which promotes an infiltration of inflammatory immune cells into adipose tissue. This process may facilitate a state of "subclinical inflammation" (metaflammation) and may lead to the development of the metabolic syndrome (MetS), starting as early as during childhood. In addition, several oncogenes have been linked to inflammation and cancer development via different pathways, and several types of tumors need an inflammatory environment before a malignant change occurs. An inflammatory environment seems to promote the proliferation and survival of malignant cells as well as angiogenesis. Natural killer (NK) cells play an important role in this process, as they are able to kill transformed cells without prior sensitization and coordinate subsequent immune responses by producing distinct cytokines, thus providing antitumor immunity. First studies in children have suggested that NK cells from obese children are activated, metabolically stressed, and functionally deficient. This may lead to a suppression of antitumor immunity as early as during childhood, probably many years before the development of cancer. Epidemiological studies have shown a strong association between higher body mass index (BMI) during childhood and adolescence and increased risk for several malignancies in adulthood, including leukemia, Hodgkin's disease, colorectal cancer, and breast cancer. Underlying mechanisms are not completely understood, but several adipocytokines and inflammatory markers including NK cells seem to be "key players" in this process.

Excessive Body Fat at a Young Age Increases the Risk of Colorectal Cancer: A Systematic Review and Meta-Analysis

Overweight and obesity was considered as a risk factor for colorectal cancer (CRC), and CRC development may be due to exposure during one's youth. Metabolic syndrome and insulin resistance seem to play an important role in the underlying mechanisms. Even though several studies indicated the association between BMI at young age and CRC risks, an identified founding is still lacked. Therefore, we conducted a meta-analysis and a dose-response analysis to quantify the association between BMI at young age and CRC risks with relative accuracy. We searched the PubMed, Embase, Medline and Cochrane Library databases for articles published before Sep. 15, 2019. Fifteen articles with 2 520 091 participants were included. Risk for CRC was estimated using relative risks (RR) and 95% confidence intervals (CIs). Compared with individuals with normal weight, overweight and obese young adults had a significantly higher risk of CRC (relative risks (RR):18%, 95% CI:1.08, 1.28； RR:32%, 95% CI: 1.11, 1.56, respectively). However, this correlation may not exist for obese women (RR: 1.22, 95% CI: 0.99, 1.51); Overweight may not a risk factor for rectal cancer (RC) (RR: 1.12, 95% CI: 0.97, 1.29). In the dose-response analysis, we observed a linear relationship between BMI at a young age and CRC risk, with each 1 kg/m² increment associated with a 2% increased risk. Higher BMI at a young age was positively associated with CRC risk, which indicates that weight control since a young age was needed.

The Effects of Interrupting Sitting Time on Affect and State Anxiety in Children of Healthy Weight and Overweight: A Randomized Crossover Trial

PURPOSE

Sedentary time relates to higher anxiety and more negative affect in children. This study assessed whether interrupting sitting over 3 hours is sufficient to influence state anxiety, positive affect, or negative affect, and tested weight status as a moderator.

METHODS

Analyses were the second (preplanned) purpose of a larger study. Children (N = 61; age: mean [SD] = 9.5 [1.3]; 43% healthy weight) completed 2 experimental conditions: continuous sitting for 3 hours and sitting for 3 hours interrupted with walking for 3 minutes in every 30 minutes. State anxiety, positive affect, and negative affect were reported at pretest and posttest. Multilevel models for repeated measures assessed whether experimental condition predicted posttest scores.

RESULTS

Experimental condition was unrelated to posttest state anxiety or positive affect. Weight status moderated how experimental condition influenced posttest negative affect (P = .003). Negative affect was lower in the children of healthy weight after interrupted sitting (vs continuous sitting; β = -0.8; 95% confidence interval, -1.5 to 0.0, P = .05), but it was higher in the children with overweight/obesity after interrupted sitting (vs continuous sitting; β = 0.6; 95% confidence interval, 0.0 to 1.2, P = .06).

CONCLUSIONS

Interrupting sitting acutely reduced negative affect in children of healthy weight, but not in children with overweight. Further research is needed to better understand the potential emotional benefits of sitting interruptions in youth.

Intervention Fidelity Within Trials of Infant Feeding Behavioral Interventions to Prevent Childhood Obesity: A Systematic Review

Background

Intervention fidelity refers to whether an intervention has been implemented as intended. Trials of infant feeding behavioral interventions to prevent childhood obesity show inconsistent evidence of effectiveness. However, intervention fidelity has not been previously explored within these trials, limiting interpretation of findings.

Purpose

To review the use and/or reporting of strategies to enhance and assess intervention fidelity within trials of infant feeding interventions to prevent childhood obesity, and their association with study quality, effectiveness, and publication year.

Methods

Seven electronic databases were searched, with articles screened for inclusion by two reviewers. The National Institutes of Health Behaviour Change Consortium fidelity checklist was used to assess use and/or reporting of fidelity strategies across five domains (design, provider training, delivery, receipt, and enactment).

Results

Ten trials (16 papers) were identified. Average use/reporting of fidelity strategies was moderate (54%), ranging from 28.9% to 76.7%. Levels of use/reporting ranged from 15.9% in the domain of provider training to 95% for enactment. No association was found between these levels and study quality, effectiveness, or publication year.

Conclusions

The moderate use/reporting of fidelity strategies within trials of infant feeding interventions suggests that previous findings of inconsistent effectiveness may not fully reflect the intended interventions. The review highlights key considerations for improving future research, both in the area of behavioral infant feeding and wider behavior change literature. This includes improving reporting across all fidelity domains and ensuring an enhanced focus on provider training and control group content to optimize the translation of research into practice.

PROSPERO Registration number

CRD42016033492.

Adolescent obesity and midlife cancer risk: a population-based cohort study of 2·3 million adolescents in Israel

BACKGROUND

Obesity has been established as a causal factor for several types of cancer, and adolescent obesity is increasing worldwide. We examined associations between measured body-mass index (BMI) at age 17 years and cancer incidence, and with mortality among those who developed cancer.

METHODS

In a nationwide, population-based cohort of adolescents, height and weight were measured at pre-recruitment mandatory medical examination during 1967-2010. BMI was classified according to US Center for Disease Control and Prevention percentiles. We applied Cox proportional hazard models to estimate the hazard ratios (HRs) and 95% CIs for incident cases of cancer using the 5th-49th BMI percentile group as a reference. The primary outcome was any cancer diagnosis between Jan 1, 1967, and Dec 31, 2012, as recorded in the Israeli National Cancer Registry. Participants with a diagnosis of cancer at baseline (before military recruitment assessment) were excluded from this analysis. The secondary outcome of this study was all-cause mortality among cohort members who had cancer, between Jan 1, 1967, and Dec 31, 2017.

FINDINGS

Of the 2 458 170 participants examined between Jan 1, 1967, and Dec 31, 2010, 160 040 were excluded. 2 298 130 participants of which 928 110 were women and 1 370 020 were men. During 29 542 735 person-years of follow-up in men, 26 353 incident cases of cancer were recorded and in 18 044 863 person-years of follow-up in women, 29 488 incident cases of cancer were recorded. Cancer incidence increased gradually across BMI percentiles. The adjusted HR was 1·26 (95% CI 1·18-1·35) among men with adolescent obesity. Among women, we found no association between obesity and overall cancer, driven by inverse associations of obesity with cervical and breast cancers. When these cancers were excluded, the adjusted HR for cancer was 1·27 (1·13-1·44) among women with adolescent obesity. In both sexes, high BMI (≥85th percentile) was associated with an increased cancer risk after 10 years. This association was accentuated in the late period of the cohort versus the early period of the cohort. BMI was positively associated with a higher risk of mortality. The projected population attributable risk for high BMI was 5·1% (4·2-6·1) for men and 5·7% (4·2-7·3) for women.

INTERPRETATION

The increasing prevalence of adolescent obesity and the possible association between adolescent BMI and cancer incidence might increase the future burden of obesity-related cancers. BMI among adolescents could constitute an important intervention target for cancer prevention.

FUNDING

None.

Childhood Body Mass Index Is Associated with Risk of Adult Colon Cancer in Men: An Association Modulated by Pubertal Change in Body Mass Index

BACKGROUND

The relative contribution of childhood and pubertal body mass index (BMI) for the risk of adult colorectal cancer is not known. The aim of this study was to evaluate the independent associations for childhood BMI and pubertal BMI change with risk of colorectal cancer in men.

METHODS

We included 37,663 men born in 1946 to 1961 who had weight and height measured at 8 (childhood) and 20 (young adult age) years of age available from the BMI Epidemiology Study. Information on colorectal cancer was retrieved from the Swedish National Patient Register (257 cases of colon cancer and 159 cases of rectal cancer).

RESULTS

Childhood BMI at 8 years of age [HR, 1.19 per SD increase; 95% confidence interval (CI), 1.06-1.33], but not pubertal BMI change (HR, 1.02; 95% CI, 0.90-1.15), was associated with increased risk of colon cancer. Due to a significant interaction between childhood BMI and pubertal BMI change (P < 0.001), we stratified the analyses according to the median of pubertal BMI change. Childhood BMI was associated with risk of colon cancer in individuals with a pubertal BMI change above, but not below, the median (above: HR = 1.48, 95% CI, 1.26-1.74; below: HR = 0.95, 95% CI, 0.80-1.12). Neither childhood BMI nor pubertal BMI change was associated with rectal cancer.

CONCLUSIONS

High childhood BMI was associated with increased risk of colon cancer only if it was followed by a pubertal BMI increase above the median.

IMPACT

Further studies should evaluate prepubertal childhood BMI in relation to pubertal BMI change and BMI in middle age for the risk of colon cancer.

Childhood obesity: increased risk for cardiometabolic disease and cancer in adulthood

Prevalence of childhood obesity has worldwide more than doubled since 1980. Underlying factors are complex and are far from completely understood. Strategies to prevent childhood obesity have mainly focused on behavioral intervention; and obesity therapy was mainly based on lifestyle modification to date. However, effects for both have been quite limited so far and no country has succeeded in fighting the obesity epidemy we are facing. Normalization of body weight before onset of puberty is crucial for several reasons: First, obese children and adolescents frequently stay obese until adulthood. Second, obesity during adolescence is significantly associated with increased risk for cardiovascular and metabolic disease such as type 2 diabetes in adulthood. And third, recent data have shown a strong association between higher body mass index (BMI) during adolescence and increased risk for several malignancies such as leukemia, Hodgkin's disease, colorectal cancer, breast cancer and others in adulthood. This review summarizes our current understanding of epidemiology, underlying factors, concomitant disease, as well as available intervention strategies and gives an overview of what has been reached so far and what measures should be undertaken to counteract the obesogenic environment.

Early-life obesity and adulthood colorectal cancer risk: a meta-analysis

Objective

This meta-analysis examines the relationship between early-life obesity and risk of colorectal cancer (CRC) in adulthood.

Methods

A systematic search of Google Scholar, PubMed, and reference data was conducted. Fifteen relevant studies were identified and meta-analyzed, for men and women separately. A random-effects model was used to compare the multivariable-adjusted relative risks (RR) of overall and subsite-specific CRC to the highest versus lowest categories of body mass index (BMI) in early life. Meta-regression was performed on factors that may have contributed to between-study heterogeneity.

Results

High early-life BMI was associated with a 39% increased risk of CRC in adult men (RR = 1.39, 95%CI = 1.20 – 1.62, P < 0.0001) and a 19% increased risk of CRC in adult women (RR = 1.19, 95%CI = 1.06 – 1.35, P = 0.004). No statistically significant heterogeneity was identified in meta-regression according to tumor subsite (RR = 1.06, 95%CI = 0.97 – 1.17, RR = 1.08, 95%CI = 0.99 – 1.18 for male and female proximal colon cancer; RR = 1.51, 95%CI = 1.22 – 1.87, RR = 1.08, 95%CI = 0.98 – 1.19 for male and female distal colon cancer; and RR = 1.39, 95%CI = 1.1 – 1.77, RR = 1.51, 95%CI = 0.94 – 2.03 for male and female rectal cancer) or other factors, including age of BMI assessment, self-reported or measured BMI, and adjustment for smoking.

Conclusions

The results suggest that high early-life BMI is associated with increased risk of CRC in adulthood. Further studies should investigate adult CRC risk in early-life obese individuals from non-Western countries and the underlying mechanisms by which early-life adiposity may influence CRC pathogenesis.

Complications of obesity

Global obesity rates have increased exponentially in recent decades. People are becoming obese younger, morbid obesity is increasing and the full health implications are only beginning to be seen. This article discusses the latest epidemiological data on obesity in adults and children, and systemically reviews the complications associated with the condition.

Early breast cancer: why does obesity affect prognosis?

High BMI is associated with an increased risk of breast cancer in post-menopausal women but poorer outcomes in all age groups. The underlying mechanism is likely to be multi-factorial. Patients with a high BMI may present later due to body habitus. Some studies have also indicated an increased incidence of biologically adverse features, including a higher frequency of oestrogen receptor (ER negative) tumours, in obese patients. Obese patients have a higher frequency of surgical complications, potentially delaying systemic therapies, and reports suggest that chemotherapy and endocrine therapy are less effective in patients with BMI ≥30 kg/m2.High BMI is generally interpreted as excess adiposity and a World Cancer Research Fund report judged that the associations between BMI and incidence of breast cancer were due to body fatness. However, BMI cannot distinguish lean mass from fat mass, or characterise body fat distribution. Most chemotherapy drugs are dosed according to calculated body surface area (BSA). Patients with a similar BSA or BMI may have wide variations in their distribution of adipose tissue and skeletal muscle (body composition); however, few studies have looked at the effect of this on chemotherapy tolerance or effectiveness. Finally, adjuvant treatments for breast cancer can themselves result in body composition changes.Research is required to fully understand the biological mechanisms by which obesity influences cancer behaviour and the impact of obesity on treatment effectiveness and tolerance so that specific management strategies can be developed to improve the prognosis of this patient group.

Is Timing Important? The Role of Diet and Lifestyle during Early Life on Colorectal Neoplasia

PURPOSE OF THE REVIEW

To summarize the current evidence on the most important dietary and lifestyle factors in colorectal carcinogenesis during different stages of a lifetime with special emphasis on studies investigating exposure during childhood, adolescence and young adulthood.

RECENT FINDINGS

A number of studies showed that independent of adult obesity, higher body fatness during childhood, adolescence and young adulthood is associated with risk of colorectal cancer later in life. In one large cohort study, the Nurses' Health Study II, adherence to a western pattern diet during adolescence was associated with higher risk of advanced adenoma. The current evidence relating consumption of individual foods and nutrients as well as physical activity during early life to colorectal cancer is sparse and less consistent, at least in part due to limitations in study design, such as sample size, limited data on potential confounders or lack of a validated dietary assessment instrument.

SUMMARY

As colorectal carcinogenesis is a long process and can take up to several decades to develop, early life risk factors may also be etiologically relevant. The recent rise in early-onset colorectal cancer incidence and mortality in the US, i.e., in individuals younger than 55 years at diagnosis, strongly supports that early life risk factors may influence colorectal carcinogenesis. Considering that the majority of colorectal cancers are preventable, there is an urgent need for well-designed investigations on the role of diet and lifestyle factors throughout the life course and risk of colorectal cancers.

Obesity, Diabetes and Gastrointestinal Malignancy: The role of Metformin and other Anti-diabetic Therapy

The association between Diabetes and cancer has been known for decades with obesity and insulin resistance being postulated as the main underlying risk factors for both disorders. With rise of the epidemic of obesity in the USA and around the globe, there has been a rise in diabetes that is currently reaching epidemic proportions. Diabetes is known to be associated with increased risk of several types of malignancy including breast, cervical, pancreatic and colon cancer. In this review, we discuss the epidemic of obesity and its consequential epidemic of diabetes highlighting the pathophysiologic mechanisms of increased cancer in the diabetic population. We will then discuss the role of insulin therapy as well as, other antidiabetic medications, particularly metformin that has been to be associated with lower risk as well as better survival with GI malignancies based on several studies including a study that was recently published by our group.

Associations between childhood body size and seventeen adverse outcomes: analysis of 65,057 European women

Large childhood body size has been consistently shown to be associated with decreased breast cancer risk. However, it is important to consider the effects of a large childhood body size on other adult diseases. It is not clear if the associations between childhood body size and adult diseases will persist if they later attain healthy weight. The associations between body size at age 7 and 17 adverse outcomes in adulthood were examined using Cox models in a Swedish study of 65,057 women. Large body size at age 7, when compared to small body size, was associated with decreased risk for breast cancer (HR [95% CI]: 0.81 [0.70–0.93]) and increased risks for anorexia (2.13 [1.63–2.77]) and bulimia (1.91 [1.35–2.70]). Neither adjusting for adult BMI nor restricting the dataset to lean adults (BMI < 25 kg/m²) attenuated the associations. While large body size at age 7 by itself was positively associated with increased risks of diabetes (1.34 [1.16–1.55]), PCOS (1.69 [1.13–2.51]) and hypertension (before age 60), the associations were no longer significant after controlling for adult BMI. No clear associations were found with the remaining adverse outcomes (cervical, uterine, melanoma, colon cancer, depression, ovarian cyst, stroke, hyperlipidemia, heart failure, myocardial infarction, and angina pectoris).

Body fatness at an early age and risk of colorectal cancer

While there is convincing evidence that excess body fatness in adulthood is positively associated with colorectal cancer risk, the association between body fatness at an early age (≤30 years) and the risk of colorectal cancer has been equivocal. The present meta-analysis was performed to clarify this association. PubMed and Web of Science databases were searched for relevant studies that investigated this association. The risk estimates from each study were transformed into a continuous variable for each 5 kg/m² increase in body mass index (BMI). A random effects model was used to calculate the summary relative risks (RRs) with 95% confidence intervals (CIs). A total of 15 observational studies (13 cohort studies and two case-control studies) were included in this meta-analysis. Each 5 kg/m² increase in BMI was significantly associated with a 13% (RR 1.13, 95% CI 1.08, 1.19), 17% (RR 1.17, 95% CI 1.09, 1.25) and 8% (RR 1.08, 95% CI 1.04, 1.11) higher risk of colorectal cancer overall, in men, and in women, respectively. Substantial heterogeneity was observed across studies. Based on the anatomic subsite, each 5 kg/m² increase in BMI was significantly associated with a 14% (RR 1.14, 95% CI 1.07, 1.22) higher risk of colon cancer, whereas no association (RR 1.03, 95% CI 0.95, 1.13) was observed with rectal cancer. In summary, body fatness at an early age may affect colon cancer risk later in life. Prevention of overweight and obesity in young individuals should be emphasized to prevent early-onset colon cancer attributed to excess body fatness.

Childhood body mass index and height in relation to site-specific risks of colorectal cancers in adult life

As colorectal cancers have a long latency period, their origins may lie early in life. Therefore childhood body mass index (BMI; kg/m²) and height may be associated with adult colorectal cancer. Using a cohort design, 257,623 children from The Copenhagen School Health Records Register born from 1930 to 1972 with measured heights and weights at ages 7 to 13 years were followed for adult colon and rectal adenocarcinomas by linkage to the Danish Cancer Registry. Hazard ratios (HRs) with 95% confidence intervals (CI) were estimated by Cox proportional hazard regressions. During follow-up, 2676 colon and 1681 rectal adenocarcinomas were diagnosed. No sex differences were observed in the associations between child BMI or height and adult colon or rectal cancers. Childhood BMI and height were positively associated with colon cancer; at age 13 years the HRs were 1.09 (95% CI 1.04-1.14) and 1.14 (95% CI 1.09-1.19) per z-score, respectively. Children who were persistently taller or heavier than average, had increased risk of colon cancer. Similarly, growing taller or gaining more weight than average was positively associated with colon cancer. No associations were observed between BMI or height and rectal cancer. Childhood BMI and height, along with above average change during childhood are significantly and positively associated with adult colon cancers, but not with rectal cancer, suggesting different etiologies.

Adolescent body mass index and erythrocyte sedimentation rate in relation to colorectal cancer risk

OBJECTIVE

Adult obesity and inflammation have been associated with risk of colorectal cancer (CRC); however, less is known about how adolescent body mass index (BMI) and inflammation, as measured by erythrocyte sedimentation rate (ESR), relate to CRC risk. We sought to evaluate these associations in a cohort of 239 658 Swedish men who underwent compulsory military enlistment examinations in late adolescence (ages 16-20 years).

DESIGN

At the time of the conscription assessment (1969-1976), height and weight were measured and ESR was assayed. By linkage to the national cancer registry, these conscripts were followed for CRC through 1 January 2010. Over an average of 35 years of follow-up, 885 cases of CRC occurred, including 501 colon cancers and 384 rectal cancers. Cox regression was used to estimate adjusted HRs and corresponding 95% CIs.

RESULTS

Compared with normal weight (BMI 18.5 to <25 kg/m(2)) in late adolescence, upper overweight (BMI 27.5 to <30 kg/m(2)) was associated with a 2.08-fold higher risk of CRC (95% CI 1.40 to 3.07) and obesity (BMI 30+ kg/m(2)) was associated with a 2.38-fold higher risk of CRC (95% CI 1.51 to 3.76) (p-trend: <0.001). Male adolescents with ESR (15+ mm/h) had a 63% higher risk of CRC (HR 1.63; 95% CI 1.08 to 2.45) than those with low ESR (<10 mm/h) (p-trend: 0.006). Associations did not significantly differ by anatomic site.

CONCLUSIONS

Late-adolescent BMI and inflammation, as measured by ESR, may be independently associated with future CRC risk. Further research is needed to better understand how early-life exposures relate to CRC.

The use of measures of obesity in childhood for predicting obesity and the development of obesity-related diseases in adulthood: a systematic review and meta-analysis

BACKGROUND

It is uncertain which simple measures of childhood obesity are best for predicting future obesity-related health problems and the persistence of obesity into adolescence and adulthood.

OBJECTIVES

To investigate the ability of simple measures, such as body mass index (BMI), to predict the persistence of obesity from childhood into adulthood and to predict obesity-related adult morbidities. To investigate how accurately simple measures diagnose obesity in children, and how acceptable these measures are to children, carers and health professionals.

DATA SOURCES

Multiple sources including MEDLINE, EMBASE and The Cochrane Library were searched from 2008 to 2013.

METHODS

Systematic reviews and a meta-analysis were carried out of large cohort studies on the association between childhood obesity and adult obesity; the association between childhood obesity and obesity-related morbidities in adulthood; and the diagnostic accuracy of simple childhood obesity measures. Study quality was assessed using Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) and a modified version of the Quality in Prognosis Studies (QUIPS) tool. A systematic review and an elicitation exercise were conducted on the acceptability of the simple measures.

RESULTS

Thirty-seven studies (22 cohorts) were included in the review of prediction of adult morbidities. Twenty-three studies (16 cohorts) were included in the tracking review. All studies included BMI. There were very few studies of other measures. There was a strong positive association between high childhood BMI and adult obesity [odds ratio 5.21, 95% confidence interval (CI) 4.50 to 6.02]. A positive association was found between high childhood BMI and adult coronary heart disease, diabetes and a range of cancers, but not stroke or breast cancer. The predictive accuracy of childhood BMI to predict any adult morbidity was very low, with most morbidities occurring in adults who were of healthy weight in childhood. Predictive accuracy of childhood obesity was moderate for predicting adult obesity, with a sensitivity of 30% and a specificity of 98%. Persistence of obesity from adolescence to adulthood was high. Thirty-four studies were included in the diagnostic accuracy review. Most of the studies used the least reliable reference standard (dual-energy X-ray absorptiometry); only 24% of studies were of high quality. The sensitivity of BMI for diagnosing obesity and overweight varied considerably; specificity was less variable. Pooled sensitivity of BMI was 74% (95% CI 64.2% to 81.8%) and pooled specificity was 95% (95% CI 92.2% to 96.4%). The acceptability to children and their carers of BMI or other common simple measures was generally good.

LIMITATIONS

Little evidence was available regarding childhood measures other than BMI. No individual-level analysis could be performed.

CONCLUSIONS

Childhood BMI is not a good predictor of adult obesity or adult disease; the majority of obese adults were not obese as children and most obesity-related adult morbidity occurs in adults who had a healthy childhood weight. However, obesity (as measured using BMI) was found to persist from childhood to adulthood, with most obese adolescents also being obese in adulthood. BMI was found to be reasonably good for diagnosing obesity during childhood. There is no convincing evidence suggesting that any simple measure is better than BMI for diagnosing obesity in childhood or predicting adult obesity and morbidity. Further research on obesity measures other than BMI is needed to determine which is the best tool for diagnosing childhood obesity, and new cohort studies are needed to investigate the impact of contemporary childhood obesity on adult obesity and obesity-related morbidities.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42013005711.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Childhood obesity as a predictor of morbidity in adulthood: a systematic review and meta-analysis

Obese children are at higher risk of being obese as adults, and adult obesity is associated with an increased risk of morbidity. This systematic review and meta-analysis investigates the ability of childhood body mass index (BMI) to predict obesity-related morbidities in adulthood. Thirty-seven studies were included. High childhood BMI was associated with an increased incidence of adult diabetes (OR 1.70; 95% CI 1.30-2.22), coronary heart disease (CHD) (OR 1.20; 95% CI 1.10-1.31) and a range of cancers, but not stroke or breast cancer. The accuracy of childhood BMI when predicting any adult morbidity was low. Only 31% of future diabetes and 22% of future hypertension and CHD occurred in children aged 12 or over classified as being overweight or obese. Only 20% of all adult cancers occurred in children classified as being overweight or obese. Childhood obesity is associated with moderately increased risks of adult obesity-related morbidity, but the increase in risk is not large enough for childhood BMI to be a good predictor of the incidence of adult morbidities. This is because the majority of adult obesity-related morbidity occurs in adults who were of healthy weight in childhood. Therefore, targeting obesity reduction solely at obese or overweight children may not substantially reduce the overall burden of obesity-related disease in adulthood.

European Code against Cancer 4th Edition: Obesity, body fatness and cancer

It is estimated that over half the population of the European Union (EU) is overweight or obese due to an imbalance between energy expenditure and energy intake; this is related to an obesogenic environment of sociocultural, economic and marketing challenges to the control of body weight. Excess body fat is associated with nine cancer sites - oesophagus, colorectum, gall bladder, pancreas, postmenopausal breast, endometrium, ovary, kidney and prostate (advanced) - and 4-38% of these cancers (depending on site and gender) can be attributed to overweight/obesity status. Metabolic alterations which accompany excess body weight are accompanied by increased levels of inflammation, insulin, oestrogens and other hormonal factors. There are some indications that intentional weight loss is associated with reduced cancer incidence (notably in postmenopausal breast and endometrial cancers). Excess body weight is also a risk factor for several other diseases, including diabetes and heart disease, and is related to higher risk of premature death. In reviewing the current evidence related to excess body fat and cancer, the European Code against Cancer Nutrition Working Group has developed the following recommendation: 'Take action to be a healthy body weight'.

Childhood body weight in relation to morbidity from cardiovascular disease and cancer in older adulthood: 67-year follow-up of participants in the 1947 Scottish Mental Survey

Although it has been well documented that elevated body weight in middle- and older-aged populations is associated with multiple morbidities, the influence of childhood body weight on health endpoints other than coronary heart disease is not well understood. Accordingly, using a subsample of 4,620 participants (2,288 women) from the Scottish Mental Survey of 1947, we examined the association between body mass index measured at 11 years of age and future risk of 9 independent health endpoints as ascertained from national hospital admissions and cancer registers until 2014 (up to age 77 years). Although there was some evidence of a relationship between elevated childhood body mass index and higher rates of peripheral vascular disease (per each 1-standard deviation increase in body mass index, hazard ratio = 1.21, 95% confidence interval: 1.07, 1.37) and smoking-related cancers (per each 1-standard deviation increase in body mass index, hazard ratio = 1.09, 95% confidence interval: 1.01, 1.17), there was no apparent association with coronary heart disease, stroke (including ischemic stroke), heart failure, or carcinomas of the colorectum, stomach, lung, prostate, or breast. In conclusion, a relationship between childhood body weight and later morbidity was largely lacking in the present study.

Early life body fatness and risk of colorectal cancer in u.s. Women and men-results from two large cohort studies

BACKGROUND

The association between body fatness before adulthood and later risk of colorectal cancer remains unclear. We hypothesized that, independent of adult body fatness, early life body fatness would be associated with a higher risk of developing colorectal cancer.

METHODS

We assessed body fatness during childhood and adolescence using a validated 9-level somatotype and inquired body weight in young adulthood in the Nurses' Health Study and Health Professionals Follow-up Study. We used the Cox proportional hazard regression modeling to estimate relative risks [RR, 95% confidence intervals (CI)] adjusting for adult body mass index (BMI) and other known colorectal cancer risk factors.

RESULTS

We identified 2,100 incident colorectal cancer cases (1,292 in women and 808 in men) during 22 years of follow-up. Among women, the RR (95% CI) for childhood body fatness of level 5 or higher versus level 1 was 1.28 (1.04-1.58; Ptrend = 0.08) and for adolescent body fatness, it was 1.27 (1.01-1.60; Ptrend = 0.23). The corresponding RRs for men were 1.04 (0.82-1.31; Ptrend = 0.48) and 0.98 (0.75-1.27; Ptrend = 0.20), respectively. Results were generally similar across anatomic subsites within the colorectum. In addition, the RRs comparing BMI categories ≥27.5 to <19 kg/m(2) were 1.44 (1.06-1.95, at age 18; Ptrend = 0.009) for women and 1.18 (0.84-1.65, at age 21; Ptrend = 0.57) for men.

CONCLUSION

Increased body fatness in early life, independent of adult obesity, might be a risk factor for colorectal cancer in women, but we observed a weaker association in men.

IMPACT

Our findings support the growing evidence that early life body fatness affects the risk of colorectal cancer many decades later.

Adipose tissue dysregulation and metabolic consequences in childhood and adolescent obesity: potential impact of dietary fat quality

Evidence suggests that at a population level, childhood and adolescent obesity increase the long-term risk of chronic diseases such as type 2 diabetes and CVD. At an individual level, however, the metabolic consequences of obesity in youth vary immensely. Despite comparable BMI, some adolescents develop impaired glucose tolerance while others maintain normal glucose homeostasis. It has been proposed that the variation in the capacity to store lipid in the subcutaneous adipose tissue (SAT) may partially discriminate metabolically healthy from unhealthy obesity. In positive energy balance, a decreased capacity to expand SAT may drive lipid accumulation to visceral adipose tissue, liver and skeletal muscle. This state of lipotoxicity is associated with chronic low-grade inflammation, insulin resistance and dyslipidaemia. The present review examines the differential adipose tissue development and function in children and adolescents who exhibit metabolic dysregulation compared with those who are protected. Additionally, the role of manipulating dietary fat quality to potentially prevent and treat metabolic dysfunction in obesity will be discussed. The findings of the present review highlight the need for further randomised controlled trials to establish the effect of dietary n-3 PUFA on the metabolic phenotype of obese children and adolescents. Furthermore, using a personalised nutrition approach to target interventions to those at risk of, or those with established metabolic dysregulation may optimise the efficacy of modifying dietary fat quality.

Obesity at adolescence and gastric cancer risk

BACKGROUND AND OBJECTIVE

During the last few decades, prevalence of obesity has risen rapidly worldwide, markedly in children and adolescents. Epidemiologic studies have associated obesity to several cancer types, yet little is known for the effect of early life exposure to obesity on cancer risk in later life, especially in gastric cancer. Thus, the present study aimed to investigate the association of body mass index (BMI) of adolescence and the risk of gastric cancer.

METHODS

A multicenter case-control study was conducted between 2010 and 2014 in Korea with 1,492 incident gastric cancer cases and 1,492 controls matched by age and sex. The BMI at age 18 was calculated by using weight and height from questionnaire. The association with the risk of gastric cancer was evaluated using odds ratios by logistic regression model adjusted for potential confounding factors.

RESULTS

Compared with BMI 21.75 kg/m(2), higher BMI at age 18 was associated with higher risk of gastric cancer showing a nonlinear, threshold effect. Statistically significant odds ratio was observed in men with BMI higher than 25.3 kg/m(2) (OR 1.13, 95 % CI 1.01-1.27) and in women with BMI 25.3 kg/m(2) and above (OR 1.25, 95 % CI 1.01-1.55).

CONCLUSION

Similar to some other cancer types, overweight or obese in adolescence was found to be associated with the increased risk of gastric cancer. The results imply for stratified approach of tactics in prevention of gastric cancer in different population.

Childhood body mass index and the risk of prostate cancer in adult men

BACKGROUND

Prostate cancer aetiology is poorly understood. It may have origins early in life; previously we found a positive association with childhood height. The effects of early life body mass index (BMI; kg m(-2)) on prostate cancer remain equivocal. We investigated if childhood BMI, independently and adjusted for height, is positively associated with adult prostate cancer.

METHODS

Subjects were a cohort of 125208 boys formed from the Copenhagen School Health Records Register, born 1930-1969 with height and weight measurements at 7-13 years. Cases were identified through linkage to the Danish Cancer Registry. Cox proportional hazards regressions were performed.

RESULTS

Overall, 3355 men were diagnosed with prostate cancer. Body mass index during childhood was positively associated with adult prostate cancer. The hazard ratio of prostate cancer was 1.06 (95% confidence interval (CI): 1.01-1.10) per BMI z-score at age 7, and 1.05 (95% CI: 1.01-1.10) per BMI z-score at age 13. Estimates were similar and significant at all other ages. However, adjustment for childhood height attenuated the associations at all but the youngest ages as most estimates became nonsignificant.

CONCLUSIONS

These results suggest that at most childhood ages, BMI does not confer an additional risk for prostate cancer beyond that of height.

Impact of body size and physical activity during adolescence and adult life on overall and cause-specific mortality in a large cohort study from Iran

We conducted this study to examine life-course body size and physical activity in relation to total and cause-specific mortality, which has not previously been studied in the low and middle-income countries in Asia. The Golestan Cohort Study is a population-based cohort in northeastern Iran in which 50,045 people above the age of 40 have been followed since 2004. Participants were shown a validated pictogram to assess body size at ages 15, 30, and the time of recruitment. Information on occupational physical activity at these ages was also collected. Subjects were followed up annually, and cause of death was determined. Cox regression models were adjusted for age at cohort start, smoking, socioeconomic status, ethnicity, place of residence, education, and opium use. Models for body size were also adjusted for physical activity at the same age, and vice versa. During a total of 252,740 person-years of follow-up (mean follow-up duration 5.1 ± 1.3 years) through December 2011, 2,529 of the cohort participants died. Larger body sizes at ages 15 or 30 in both sexes were associated with increased overall mortality. Cancer mortality was more strongly associated with adolescent obesity, and cardiovascular mortality with early adulthood body size. Weight gain between these ages was associated with cardiovascular mortality. Obese adolescents who lost weight still had increased mortality from all medical causes in both sexes. Physical activity during adolescence and early adulthood had no association with mortality, but at cohort baseline higher levels of activity were associated with reduced mortality. Mortality in this Middle-Eastern population was associated with obesity both during adolescence and early adult life.

Prostate cancer: is it time to expand the research focus to early-life exposures?

Although the contribution of lifestyle and environment (non-genetic factors) to prostate carcinogenesis is indicated by international variation in prostate cancer occurrence and migration studies, no conclusive modifiable risk factors have yet been identified. One possible reason for this may be the dearth of epidemiological research on exposures experienced early in life, when the immature prostate may be more susceptible to carcinogenic exposures. In this Opinion article, we summarize the rationale for studying early-life exposures, describe the small body of early-life research and its associated challenges, and point to solutions for future research.

Obesity as a major risk factor for cancer

The number of cancer cases caused by being obese is estimated to be 20% with the increased risk of malignancies being influenced by diet, weight change, and body fat distribution together with physical activity. Reports from the International Agency for Research into Cancer and the World Cancer Research Fund (WCRF) have shown that the strongest evidence exists for an association of obesity with the following cancer types: endometrial, esophageal adenocarcinoma, colorectal, postmenopausal breast, prostate, and renal, whereas the less common malignancies are leukemia, non-Hodgkin's lymphoma, multiple myeloma, malignant melanoma, and thyroid tumours. To be able to develop novel methods in prevention and treatment, we first must understand the underlying processes which link cancer to obesity. Four main systems have been identified as potential producers of cancer in obesity: insulin, insulin-like growth factor-I, sex steroids, and adipokines. Various novel candidate mechanisms have been proposed: chronic inflammation, oxidative stress, crosstalk between tumour cells and surrounding adipocytes, migrating adipose stromal cells, obesity-induced hypoxia, shared genetic susceptibility, and the functional defeat of immune function. Herein, we review the major pathogenic links between obesity and susceptibility to cancer.

The impact of childhood obesity on morbidity and mortality in adulthood: a systematic review

The objective of this study was to evaluate the evidence on whether childhood obesity is a risk factor for adult disease, independent of adult body mass index (BMI). Ovid MEDLINE (1948-May 2011), EMBASE (1980-2011 week 18) and the Cochrane Library (1990-2011) were searched for published studies of BMI from directly measured weight and height in childhood (2-19 years) and disease outcomes in adulthood. Data were synthesized in a narrative fashion. Thirty-nine studies (n 181-1.1 million) were included in the review. There was evidence for associations between childhood BMI and type 2 diabetes, hypertension and coronary heart disease. Few studies examined associations independent of adult BMI; these showed that effect sizes were attenuated after adjustment for adult BMI in standard regression analyses. Although there is a consistent body of evidence for associations between childhood BMI and cardiovascular outcomes, there is a lack of evidence for effects independent of adult BMI. Studies have attempted to examine independent effects using standard adjustment for adult BMI, which is subject to over-adjustment and problems with interpretation. Studies that use more robust designs and analytical techniques are needed to establish whether childhood obesity is an independent risk factor for adult disease.

Molecular mechanisms of cancer development in obesity

The increasing incidence of obesity and its co-morbid conditions poses a great challenge to global health. In addition to cardiovascular disease and diabetes, epidemiological data demonstrate a link between obesity and multiple types of cancer. The molecular mechanisms underlying how obesity causes an increased risk of cancer are poorly understood. Obesity disrupts the dynamic role of the adipocyte in energy homeostasis, resulting in inflammation and alteration of adipokine (for example, leptin and adiponectin) signalling. Additionally, obesity causes secondary changes that are related to insulin signalling and lipid deregulation that may also foster cancer development. Understanding these molecular links may provide an avenue for preventive and therapeutic strategies to reduce cancer risk and mortality in an increasingly obese population.

Body fatness during childhood and adolescence, adult height, and risk of colorectal adenoma in women

The latest report by the World Cancer Research Fund/American Institute of Cancer Research concluded that there is convincing evidence that adult height and obesity are risk factors for colorectal cancer. However, studies relating body fatness during early life to the risk of colorectal cancer or adenoma are scarce. In the Nurses' Health Study II, participants recalled adult attained height and body shape at ages 5, 10, and 20 years (using a 9-level pictogram: 1 = most lean body shape, 9 = most overweight body shape) at baseline. Among 32,707 women who had at least one lower bowel endoscopy between 1991 and 2005, 2,327 colorectal adenomas were documented. Adult height was positively associated with risk of colorectal adenoma (multivariate OR per 2 inch increment 1.05, 95% CI: 1.01-1.09). Comparing women who were overweight (body shape level 6 or higher) to women who were most lean (body shape level 1), ORs (95% CI, P(trend)) of colorectal adenoma for body shapes at ages 5, 10, and 20 years were 1.44 (1.04-1.99, 0.01), 1.21 (0.93-1.56, 0.05), and 1.03 (0.74-1.42, 0.58), respectively. Adjustment for adult body mass index did not change results substantially. The positive associations for body fatness at ages 5 and 10 years as well as adult height were restricted to distal adenoma, while not seen for proximal or rectal adenoma. Higher height and body fatness during childhood was associated with increased risk of distal adenoma later in life, independent of adult body weight.

Long-term impact of overweight and obesity in childhood and adolescence on morbidity and premature mortality in adulthood: systematic review

BACKGROUND AND OBJECTIVE

The last systematic review on the health consequences of child and adolescent obesity found little evidence on consequences for adult health. The present study aimed to summarize evidence on the long-term impact of child and adolescent obesity for premature mortality and physical morbidity in adulthood.

METHODS

Systematic review with evidence searched from January 2002 to June 2010. Studies were included if they contained a measure of overweight and/or obesity between birth and 18 years (exposure measure) and premature mortality and physical morbidity (outcome) in adulthood.

RESULTS

Five eligible studies examined associations between overweight and/or obesity, and premature mortality: 4/5 found significantly increased risk of premature mortality with child and adolescent overweight or obesity. All 11 studies with cardiometabolic morbidity as outcomes reported that overweight and obesity were associated with significantly increased risk of later cardiometabolic morbidity (diabetes, hypertension, ischaemic heart disease, and stroke) in adult life, with hazard ratios ranging from 1.1-5.1. Nine studies examined associations of child or adolescent overweight and obesity with other adult morbidity: studies of cancer morbidity were inconsistent; child and adolescent overweight and obesity were associated with significantly increased risk of later disability pension, asthma, and polycystic ovary syndrome symptoms.

CONCLUSIONS

A relatively large and fairly consistent body of evidence now demonstrates that overweight and obesity in childhood and adolescence have adverse consequences on premature mortality and physical morbidity in adulthood.

Childhood economic conditions and length of life: evidence from the UK Boyd Orr cohort, 1937-2005

We study the importance of childhood socioeconomic conditions in predicting differences in life expectancy using data from a large sample of children collected in 16 locations in England and Scotland in 1937-39, who have been traced through official death records up to 2005. We estimate a number of duration of life models that control for unobserved family heterogeneity. Our results confirm that childhood conditions such as household income and the quality of the home environment are significant predictors of longevity. Importantly, however, the role of socioeconomic status appears to differ across cause of death, with household income being a significant predictor of death from smoking-related cancer. Moreover, we find that (1) poor housing conditions in childhood is associated with reduced longevity, that (2) early doctor-assessed childhood health conditions significantly predict a reduced length of life, that (3) children born in a location with relatively high infant mortality rates live significantly fewer years, and that (4) there is a high correlation in longevity across children from the same family across all causes of death. We estimate that the difference in life expectancy between those with the 'best' and 'worst' observable characteristics is about 9 years, which increases to 20 years when we take into account the 'best' and 'worst' observable and unobservable household characteristics.

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.