Estimating the Influence of Obesity on Cancer Risk: Stratification by Smoking Is Critical

A Validated Estimate of Visceral Adipose Tissue Volume in Relation to Cancer Risk

BACKGROUND

Despite the recognized role of visceral adipose tissue (VAT) in carcinogenesis, its independent association with cancer risk beyond traditional obesity measures remains unknown due to limited availability of imaging data.

METHODS

We developed an estimation equation for VAT volume (L) using Elastic Net Regression based on demographic and anthropometric data in a subcohort of participants in the UK Biobank (UKB; N = 23,148) with abdominal MRI scans. This equation was externally validated in 2,713 participants from the 2017-2018 National Health and Nutrition Examination Survey (NHANES) according to sex, age, and race groups. We then applied the equation to the overall UKB cohort of 461,665 participants to evaluate the prospective association between estimated VAT (eVAT) and cancer risk using Cox proportional hazards models. We also calculated the population attributable risk (PAR) of cancer associated with eVAT and BMI.

RESULTS

eVAT showed a high correlation with measured VAT in internal and external validations (r = 0.81-0.86). During a median 12-year follow-up in the UKB, we documented 37,397 incident cancer cases; eVAT was significantly associated with elevated risk of obesity-related and individual cancers, independent of BMI and waist circumference. PAR for total cancer associated with high (quartiles 2-4 vs 1) eVAT (9.0-11.6%) was higher than high BMI (Q2-4 vs 1; 5.0-8.2%).

CONCLUSIONS

eVAT showed robust performance in both UKB and NHANES and was associated with cancer risk independent of BMI and waist circumference. This study provides a potential clinical tool for VAT estimation and underscores that VAT can be an important target for cancer prevention.

Global burden of esophageal cancer attributable to high BMI in 204 countries and territories: 1990-2019

BACKGROUND

Esophageal cancer (EC), a common and fatal disease, includes two histological subtypes; esophageal squamous cell carcinoma (ESCC) and esophageal adenocarcinoma (ECA). To aid policymakers in the allocation of resources for the prevention and treatment of EC, updated data on EC deaths and disability-adjusted life years (DALYs) attributable to high body mass index (BMI) are necessary. The objective of this study was to identify trends in EC associated with high BMI between 1990 and 2019 using 2019 Global Burden of Disease data.

METHODS

In this observational population-based study, epidemiological data on the association between high BMI and EC were obtained from GBD 2019. The age-standardized mortality rate (ASMRs) and disability-adjusted life year rate (ASDRs) attributable to high BMI-related EC were stratified by year, age, country, and sociodemographic index (SDI). The estimated annual percentage change (EAPC) was calculated to evaluate the temporal trends of the ASMRs and ASDRs between 1990 and 2019.

RESULTS

In 2019, the proportion of EC deaths and DALYs attributed to high BMI was 18.1% and 18.9%, respectively, resulting in 89 904 (95% confidence interval [CI]: 27 879-171 255) deaths and 2 202 314 (95% CI: 681 901-4 173 080) DALYs. High BMI-related deaths and DALYs showed a strong upward trend, increasing by more than two-fold since 1990. East Asia and Western Europe showed the highest risk of EC mortality and DALYs attributable to high BMI; China and the USA bear the greatest burden. The ASMR and ASDR increased in five SDI regions.

CONCLUSIONS

The incidence of EC is increasing, particularly in developing nations, which may be attributed to the prevalence of high BMI. To mitigate the impact of high BMI on the incidence of EC, it is important to increase awareness of its deleterious effects, which may alleviate the burden of this disease.

Are associations between obesity and prostate cancer outcomes following radical prostatectomy the same in smokers and non-smokers? Results from the SEARCH Cohort

PURPOSE

Obesity and smoking have been associated with poor prostate cancer (PC) outcomes. We investigated associations between obesity and biochemical recurrence (BCR), metastasis, castrate resistant-PC (CRPC), PC-specific mortality (PCSM), and all-cause mortality (ACM) and examined if smoking modified these associations.

METHODS

We analyzed SEARCH Cohort data from men undergoing RP between 1990 and 2020. Cox regression models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for associations between body mass index (BMI) as a continuous variable and weight status classifications (normal: 18.5 ≤ 25 kg/m2; overweight: 25-29.9 kg/m2; obese: ≥ 30 kg/m2) and PC outcomes.

RESULTS

Among 6,241 men, 1,326 (21%) were normal weight, 2,756 (44%) overweight and 2159 (35%) obese; 1,841 (30%) were never-smokers, 2,768 (44%) former and 1,632 (26%) current-smokers. Among all men, obesity was associated with non-significant increased risk of PCSM, adj-HR = 1.71; 0.98-2.98, P = 0.057, while overweight and obesity were inversely associated with ACM, adj-HR = 0.75; 0.66-0.84, P < 0.001 and adj-HR = 0.86; 0.75-0.99, P = 0.033, respectively. Other associations were null. BCR and ACM were stratified for smoking status given evidence for interactions (P = 0.048 and P = 0.054, respectively). Among current-smokers, overweight was associated with an increase in BCR (adj-HR = 1.30; 1.07-1.60, P = 0.011) and a decrease in ACM (adj-HR = 0.70; 0.58-0.84, P < 0.001). Among never-smokers, BMI (continuous) was associated with an increase in ACM (adj-HR = 1.03; 1.00-1.06, P = 0.033).

CONCLUSIONS

While our results are consistent with obesity as a risk factor for PCSM, we present evidence of effect modification by smoking for BCR and ACM highlighting the importance of stratifying by smoking status to better understand associations with body weight.

Association between metabolically healthy obesity and metastasis in lung cancer patients - a systematic review and meta-analysis

Background

Many clinical trials have looked at the relationship between obesity and lung cancer (LC), however, there is scarcity of literature specifically addressing the association between metabolically healthy obesity and metastasis in LC patients. To address this gap in the body of evidence, the study was conducted to observe the association between metabolically healthy obesity and metastasis in LC patients.

Methods

We conducted a pre-registered systematic review by searching six major online databases to identify studies relevant related to our investigation, in adherence with the PRISMA guidelines. A proper data extraction protocol was further established to synthesize the findings from the selected papers through a meta-analysis.

Results

Eleven (11) studies met the requisite selection criterion and were included in the study. A random-effect model was used. Obesity was found to have a significant impact on readmission in LC patients. The combined analysis showed a significant effect size of 0.08 (95% CI 0.07 to 0.08), indicating a noticeable impact of obesity. It was also assessed that obese individuals had a 34% reduced risk of LC compared to normal weight individuals. Obesity was associated with a lower risk of surgical complications with a pooled risk ratio of 0.13 (95% CI 0.12 to 0.14). A statistically significant decreased risk of LC (pooled RR = 0.72, 95% CI: 0.68 to 0.77) was also observed in the obese individuals.

Conclusion

The analysis reveals that obesity is associated with a noticeable increase in readmissions, although the impact on LC risk itself is negligible. Moreover, obesity appears to have a beneficial effect by reducing the risk of surgical complications. These results highlight the complex relationship between the two aforementioned factors, emphasizing the importance of considering obesity as a significant factor in patient management and healthcare decision-making.

Systematic review registration

https://www.crd.york.ac.uk/prospero/, identifier CRD42023427612.

Change in Neighborhood Socioeconomic Status and Adherence to the Cancer Prevention Lifestyle Guidelines in Hispanic/Latino Adults: Results from the HCHS/SOL Study

Neighborhood conditions are dynamic; the association of changing neighborhood socioeconomic factors with cancer preventive behaviors remains unclear. We examined associations of neighborhood socioeconomic deprivation, gentrification, and change in income inequality with adherence to the American Cancer Society Guidelines on Nutrition and Physical Activity for Cancer Prevention in The Hispanic Community Health Study/Study of Latinos (HCHS/SOL). The HCHS/SOL enrolled 16,415 adults, ages 18–74 years, at baseline (2008–2011), from communities in the Bronx, NY, Chicago, IL, Miami, FL, and San Diego, CA. Geocoded baseline addresses were linked to the 2000 decennial Census and 5-year American Community Survey (2005–2009 and 2012–2016) tracts to operationalize neighborhood deprivation index (NDI), gentrification, and income inequality. Complex survey multinominal logistic regression models estimated the relative risk ratio (RRR) with overall guideline adherence level (low, moderate, high) and by components—diet, physical activity, body mass index (BMI), and alcohol intake. Overall, 14%, 60%, and 26% of the population had low, moderate, and high ACS guideline adherence, respectively. NDI was negatively associated with risk of high (vs. low) guideline adherence [RRR = 0.87, 95% confidence interval (CI) = 0.78–0.98], although attenuated after controlling for individual socioeconomic status (SES; RRR = 0.89, 95% CI = 0.80–1.00), and associated with lower adherence to BMI recommendations (low vs. moderate RRR = 0.90, 95% CI = 0.84–0.97; high RRR = 0.86, 95% CI = 0.77–0.97). Gentrification was associated with higher likelihood of meeting the dietary recommendations (low vs. moderate RRR = 1.04, 95% CI = 1.01–1.07), but not with overall adherence or individual components. Change in income inequality was not associated with outcomes. Neighborhood deprivation may be negatively associated with ACS guideline adherence among Hispanic/Latino adults.

SIGNIFICANCE

This study provides new evidence on the link between neighborhood gentrification, changing income inequality and adoption and maintenance of cancer preventive behaviors in an understudied population in cancer research. We observed that while neighborhood deprivation may deter from healthy lifestyle behaviors, positive changes in neighborhood SES via the process of gentrification, may not influence lifestyle guideline adherence among Hispanic/Latino adults.

Longitudinal body mass index and cancer risk: a cohort study of 2.6 million Catalan adults

Single body mass index (BMI) measurements have been associated with increased risk of 13 cancers. Whether life course adiposity-related exposures are more relevant cancer risk factors than baseline BMI (ie, at start of follow-up for disease outcome) remains unclear. We conducted a cohort study from 2009 until 2018 with population-based electronic health records in Catalonia, Spain. We included 2,645,885 individuals aged ≥40 years and free of cancer in 2009. After 9 years of follow-up, 225,396 participants were diagnosed with cancer. This study shows that longer duration, greater degree, and younger age of onset of overweight and obesity during early adulthood are positively associated with risk of 18 cancers, including leukemia, non-Hodgkin lymphoma, and among never-smokers, head and neck, and bladder cancers which are not yet considered as obesity-related cancers in the literature. Our findings support public health strategies for cancer prevention focussing on preventing and reducing early overweight and obesity.

Association of smoking, alcohol, and coffee consumption with the risk of ovarian cancer and prognosis: a mendelian randomization study

OBJECTIVE

Currently, the association between smoking, alcohol, and coffee intake and the risk of ovarian cancer (OC) remains conflicting. In this study, we used a two-sample mendelian randomization (MR) method to evaluate the association of smoking, drinking and coffee consumption with the risk of OC and prognosis.

METHODS

Five risk factors related to lifestyles (cigarettes per day, smoking initiation, smoking cessation, alcohol consumption and coffee consumption) were chosen from the Genome-Wide Association Study, and 28, 105, 10, 36 and 36 single-nucleotide polymorphisms (SNPs) were obtained as instrumental variables (IVs). Outcome variables were achieved from the Ovarian Cancer Association Consortium. Inverse-variance-weighted method was mainly used to compute odds ratios (OR) and 95% confidence intervals (Cl).

RESULTS

The two-sample MR analysis supported the causal association of genetically predicted smoking initiation (OR: 1.15 per SD, 95%CI: 1.02-1.29, P = 0.027) and coffee consumption (OR: 1.40 per 50% increase, 95%CI: 1.02-1.93, P = 0.040) with the risk of OC, but not cigarettes per day, smoking cessation, and alcohol consumption. Subgroup analysis based on histological subtypes revealed a positive genetical predictive association between coffee consumption and endometrioid OC (OR: 3.01, 95%CI: 1.50-6.04, P = 0.002). Several smoking initiation-related SNPs (rs7585579, rs7929518, rs2378662, rs10001365, rs11078713, rs7929518, and rs62098013), and coffee consumption-related SNPs (rs4410790, and rs1057868) were all associated with overall survival and cancer-specific survival in OC.

CONCLUSION

Our findings provide the evidence for a favorable causal association of genetically predicted smoking initiation and coffee consumption with OC risk, and coffee consumption is linked to a greater risk of endometrioid OC.

Obesity Paradox: Fact or Fiction?

PURPOSE OF REVIEW

Obesity is related to several comorbidities such as type 2 diabetes mellitus, cardiovascular disease, heart failure, and various types of cancers. While the detrimental effect of obesity in both mortality and morbidity has been well established, the concept of the obesity paradox in specific chronic diseases remains a topic of continuous interest. In the present review, we examine the controversial issues around the obesity paradox in certain conditions such as cardiovascular disease, several types of cancer and chronic obstructive pulmonary disease, and the factors that may confound the relation between obesity and mortality.

RECENT FINDINGS

We refer to the obesity paradox when particular chronic diseases exhibit an interesting "paradoxical" protective association between the body mass index (BMI) and clinical outcomes. This association, however, may be driven by multiple factors among which the limitations of the BMI itself; the unintended weight loss precipitated by chronic illness; the various phenotypes of obesity, i.e., sarcopenic obesity or the athlete's obesity phenotype; and the cardiorespiratory fitness levels of the included patients. Recent evidence highlighted that previous cardioprotective medications, obesity duration, and smoking status seem to play a role in the obesity paradox. The obesity paradox has been described in a plethora of chronic diseases. It cannot be emphasized enough that the incomplete information received from a single BMI measurement may interfere with outcomes of studies arguing in favor of the obesity paradox. Thus, the development of carefully designed studies, unhampered by confounding factors, is of great importance.

Adherence to the American Cancer Society Guidelines on nutrition and physical activity for cancer prevention and obesity-related cancer risk and mortality in Black and Latina Women's Health Initiative participants

BACKGROUND

Although adherence to the American Cancer Society (ACS) Guidelines on Nutrition and Physical Activity for Cancer Prevention associates with lower risk of obesity-related cancer (ORC) incidence and mortality, evidence in Black and Latina women is limited. This association was examined in Black and Latina participants in the Women's Health Initiative (WHI).

METHODS

Semi-Markov multistate model examined the association between ACS guideline adherence and ORC incidence and mortality in the presence of competing events, combined and separately, for 9301 Black and 4221 Latina postmenopausal women. Additionally, ACS guideline adherence was examined in a subset of less common ORCs and potential effect modification by neighborhood socioeconomic status and smoking.

RESULTS

Over a median of 11.1, 12.5, and 3.7 years of follow-up for incidence, nonconditional mortality, and conditional mortality, respectively, 1191 ORCs (Black/Latina women: 841/269), 1970 all-cause deaths (Black/Latina women: 1576/394), and 341 ORC-related deaths (Black/Latina women: 259/82) were observed. Higher ACS guideline adherence was associated with lower ORC incidence for both Black (cause-specific hazard ratio [CSHR]_highvs.low : 0.72; 95% CI, 0.55-0.94) and Latina (CSHR_highvs.low : 0.58, 95% CI, 0.36-0.93) women; but not conditional all-cause mortality (Black hazard ratio [HR]_highvs.low : 0.86; 95% CI, 0.53-1.39; Latina HR_highvs.low : 0.81; 95% CI, 0.32-2.06). Higher adherence was associated with lower incidence of less common ORC (P_trend  = .025), but conditional mortality events were limited. Adherence and ORC-specific deaths were not associated and there was no evidence of effect modification.

CONCLUSIONS

Adherence to the ACS guidelines was associated with lower risk of ORCs and less common ORCs but was not for conditional ORC-related mortality.

LAY SUMMARY

Evidence on the association between the American Cancer Society Guidelines on Nutrition and Physical Activity for Cancer Prevention and cancer remains scarce for women of color. Adherence to the guidelines and risk of developing one of 13 obesity-related cancers among Black and Latina women in the Women's Health Initiative was examined. Women who followed the lifestyle guidelines had 28% to 42% lower risk of obesity-related cancer. These findings support public health interventions to reduce growing racial/ethnic disparities in obesity-related cancers.

The Body Mass Index Paradox in Head and Neck Cancer: A Systematic Review and Meta-Analysis

The body mass index (BMI) paradox describes that among patients with certain cancers, higher pretreatment BMI may be associated with improved survival. We examine the impact of BMI on overall survival (OS) in head and neck squamous cell carcinoma (HNSCC) patients. A literature search was performed, and articles using hazard ratios to describe the prognostic impact of BMI on OS in HNSCC were included. Random-effects DerSimonian and Laird methods were employed for meta-analysis. Meta-analysis of OS indicated a lower hazards of death in the overweight (BMI: 25 kg/m2-30 kg/m2) compared to the normal weight (BMI: 18.5 kg/m2-25 kg/m2). This protective relationship loses significance when BMI exceeds 30 kg/m². Underweight patients (BMI < 18.5 kg/m2) demonstrate higher hazards of death compared to normal weight patients. Compared to HNSCC patients with normal weight, being overweight up to a BMI of 30 kg/m² is a positive predictor of OS, while being underweight confers a prognostic disadvantage. Further studies are needed to determine the mechanisms by which increased body mass influences survival outcomes in HNSCC.

Obesity-related gut hormones and cancer: novel insight into the pathophysiology

The number of cancers attributed to obesity is increasing over time. The mechanisms classically implicated in cancer pathogenesis and progression in patients with obesity involve adiposity-related alteration of insulin, sex hormones, and adipokine pathways. However, they do not fully capture the complexity of the association between obesity-related nutritional imbalance and cancer. Gut hormones are secreted by enteroendocrine cells along the gastrointestinal tract in response to nutritional cues, and act as nutrient sensors, regulating eating behavior and energy homeostasis and playing a role in immune-modulation. The dysregulation of gastrointestinal hormone physiology has been implicated in obesity pathogenesis. For their peculiar function, at the cross-road between nutrients intake, energy homeostasis and inflammation, gut hormones might represent an important but still underestimated mechanism underling the obesity-related high incidence of cancer. In addition, cancer research has revealed the widespread expression of gut hormone receptors in neoplastic tissues, underscoring their implication in cell proliferation, migration, and invasion processes that characterize tumor growth and aggressiveness. In this review, we hypothesize that obesity-related alterations in gut hormones might be implicated in cancer pathogenesis, and provide evidence of the pathways potentially involved.

Body size and composition and risk of site-specific cancers in the UK Biobank and large international consortia: A mendelian randomisation study

BACKGROUND

Evidence for the impact of body size and composition on cancer risk is limited. This mendelian randomisation (MR) study investigates evidence supporting causal relationships of body mass index (BMI), fat mass index (FMI), fat-free mass index (FFMI), and height with cancer risk.

METHODS AND FINDINGS

Single nucleotide polymorphisms (SNPs) were used as instrumental variables for BMI (312 SNPs), FMI (577 SNPs), FFMI (577 SNPs), and height (293 SNPs). Associations of the genetic variants with 22 site-specific cancers and overall cancer were estimated in 367,561 individuals from the UK Biobank (UKBB) and with lung, breast, ovarian, uterine, and prostate cancer in large international consortia. In the UKBB, genetically predicted BMI was positively associated with overall cancer (odds ratio [OR] per 1 kg/m2 increase 1.01, 95% confidence interval [CI] 1.00-1.02; p = 0.043); several digestive system cancers: stomach (OR 1.13, 95% CI 1.06-1.21; p < 0.001), esophagus (OR 1.10, 95% CI 1.03, 1.17; p = 0.003), liver (OR 1.13, 95% CI 1.03-1.25; p = 0.012), and pancreas (OR 1.06, 95% CI 1.01-1.12; p = 0.016); and lung cancer (OR 1.08, 95% CI 1.04-1.12; p < 0.001). For sex-specific cancers, genetically predicted elevated BMI was associated with an increased risk of uterine cancer (OR 1.10, 95% CI 1.05-1.15; p < 0.001) and with a lower risk of prostate cancer (OR 0.97, 95% CI 0.94-0.99; p = 0.009). When dividing cancers into digestive system versus non-digestive system, genetically predicted BMI was positively associated with digestive system cancers (OR 1.04, 95% CI 1.02-1.06; p < 0.001) but not with non-digestive system cancers (OR 1.01, 95% CI 0.99-1.02; p = 0.369). Genetically predicted FMI was positively associated with liver, pancreatic, and lung cancer and inversely associated with melanoma and prostate cancer. Genetically predicted FFMI was positively associated with non-Hodgkin lymphoma and melanoma. Genetically predicted height was associated with increased risk of overall cancer (OR per 1 standard deviation increase 1.09; 95% CI 1.05-1.12; p < 0.001) and multiple site-specific cancers. Similar results were observed in analyses using the weighted median and MR-Egger methods. Results based on consortium data confirmed the positive associations between BMI and lung and uterine cancer risk as well as the inverse association between BMI and prostate cancer, and, additionally, showed an inverse association between genetically predicted BMI and breast cancer. The main limitations are the assumption that genetic associations with cancer outcomes are mediated via the proposed risk factors and that estimates for some lower frequency cancer types are subject to low precision.

CONCLUSIONS

Our results show that the evidence for BMI as a causal risk factor for cancer is mixed. We find that BMI has a consistent causal role in increasing risk of digestive system cancers and a role for sex-specific cancers with inconsistent directions of effect. In contrast, increased height appears to have a consistent risk-increasing effect on overall and site-specific cancers.

DNA methylome analysis identifies BMI-related epigenetic changes associated with non-small cell lung cancer susceptibility

Background

Body mass index (BMI) has been reported to be inversely associated with incident risk of non‐small cell lung cancer (NSCLC). However, the underlying mechanism is still unclear. This study aimed to investigate the role of DNA methylation in the relationship between BMI and NSCLC.

Methods

We carried out a genome‐wide DNA methylation study of BMI in peripheral blood among 2266 Chinese participants by using Illumina Methylation arrays. For the BMI‐related DNA methylation changes, their associations with NSCLC risk were further analyzed and their mediation effects on BMI‐NSCLC association were also evaluated.

Results

The methylation levels of four CpGs (cg12593793, cg17061862, cg11024682, and cg06500161, annotated to LMNA, ZNF143, SREBF1, and ABCG1, respectively) were found to be significantly associated with BMI. Methylation levels of cg12593793, cg11024682, and cg06500161 were observed to be inversely associated with NSCLC risk [OR (95%CI) =0.22 (0.16, 0.31), 0.39 (0.30, 0.50), and 0.66 (0.53, 0.82), respectively]. Additionally, cg11024682 in SREBF1 and cg06500161 in ABCG1 mediated 45.3% and 19.5% of the association between BMI and decreased NSCLC risk, respectively.

Conclusions

In this study, we identified four DNA methylation sites associated with BMI in the Chinese populations at the genome‐wide significant level. We also found that the BMI‐related methylations of SREBF1 and ABCG1 could mediate about a quintile‐to‐half of the effect of BMI on reduced NSCLC risk, which adds a potential mechanism underlying this association.

Association Between Midlife Obesity and Kidney Function Trajectories: The Atherosclerosis Risk in Communities (ARIC) Study

RATIONALE & OBJECTIVE

Obesity has been related to risk for chronic kidney disease. However, the associations of different measures of midlife obesity with long-term kidney function trajectories and whether they differ by sex and race are unknown.

STUDY DESIGN

Observational study.

SETTING & PARTICIPANTS

13,496 participants from the Atherosclerosis Risk in Communities (ARIC) Study.

PREDICTORS

Midlife obesity status as measured by body mass index (BMI), waist-to-hip ratio, and predicted percent fat at baseline.

OUTCOMES

Estimated glomerular filtration rate (eGFR) calculated using serum creatinine level measured at 5 study visits, and incident kidney failure with replacement therapy (KFRT).

ANALYTICAL APPROACH

Mixed models with random intercepts and random slopes for eGFR. Cox proportional hazards models for KFRT.

RESULTS

Baseline mean age was 54 years, median eGFR was 103mL/min/1.73m2, and median BMI was 27kg/m2. Over 30 years of follow-up, midlife obesity measures were associated with eGFR decline in White and Black women but not consistently in men. Adjusted for age, center, smoking, and coronary heart disease, the differences in eGFR slope per 1-SD higher BMI, waist-to-hip ratio, and predicted percent fat were 0.09 (95% CI, -0.18 to 0.36), -0.25 (95% CI, -0.50 to 0.01), and-0.14 (95% CI, -0.41 to 0.13) mL/min/1.73m2 per decade for White men; -0.91 (95% CI, -1.15 to-0.67), -0.82 (95% CI, -1.06 to-0.58), and-1.02 (95% CI, -1.26 to-0.78) mL/min/1.73m2 per decade for White women; -0.70 (95% CI, -1.54 to 0.14), -1.60 (95% CI, -2.42 to-0.78), and-1.24 (95% CI, -2.08 to-0.40) mL/min/1.73m2 per decade for Black men; and-1.24 (95% CI, -2.08 to-0.40), -1.50 (95% CI, -2.05 to-0.95), and-1.43 (95% CI, -2.00 to-0.86) mL/min/1.73m2 per decade for Black women. Obesity indicators were independently associated with risk for KFRT for all sex-race groups except White men.

LIMITATIONS

Loss to follow-up during 3 decades of follow-up with 5 eGFR assessments.

CONCLUSIONS

Obesity status is a risk factor for future decline in kidney function and development of KFRT in Black and White women, with less consistent associations among men.

Body mass index and waist circumference in relation to the risk of 26 types of cancer: a prospective cohort study of 3.5 million adults in Spain

BACKGROUND

A high body mass index (BMI) has been associated with increased risk of several cancers; however, whether BMI is related to a larger number of cancers than currently recognized is unclear. Moreover, whether waist circumference (WC) is more strongly associated with specific cancers than BMI is not well established. We aimed to investigate the associations between BMI and 26 cancers accounting for non-linearity and residual confounding by smoking status as well as to compare cancer risk estimates between BMI and WC.

METHODS

Prospective cohort study with population-based electronic health records from Catalonia, Spain. We included 3,658,417 adults aged ≥ 18 years and free of cancer at baseline between 2006 and 2017. Our main outcome measures were cause-specific hazard ratios (HRs) with 99% confidence intervals (CIs) for incident cancer at 26 anatomical sites.

RESULTS

After a median follow-up time of 8.3 years, 202,837 participants were diagnosed with cancer. A higher BMI was positively associated with risk of nine cancers (corpus uteri, kidney, gallbladder, thyroid, colorectal, breast post-menopausal, multiple myeloma, leukemia, non-Hodgkin lymphoma) and was positively associated with three additional cancers among never smokers (head and neck, brain and central nervous system, Hodgkin lymphoma). The respective HRs (per 5 kg/m2 increment) ranged from 1.04 (99%CI 1.01 to 1.08) for non-Hodgkin lymphoma to 1.49 (1.45 to 1.53) for corpus uteri cancer. While BMI was negatively associated to five cancer types in the linear analyses of the overall population, accounting for non-linearity revealed that BMI was associated to prostate cancer in a U-shaped manner and to head and neck, esophagus, larynx, and trachea, bronchus and lung cancers in an L-shaped fashion, suggesting that low BMIs are an approximation of heavy smoking. Of the 291,305 participants with a WC measurement, 27,837 were diagnosed with cancer. The 99%CIs of the BMI and WC point estimates (per 1 standard deviation increment) overlapped for all cancers.

CONCLUSIONS

In this large Southern European study, a higher BMI was associated with increased risk of twelve cancers, including four hematological and head and neck (only among never smokers) cancers. Furthermore, BMI and WC showed comparable estimates of cancer risk associated with adiposity.

Overall and abdominal obesity and prostate cancer risk in a West African population: An analysis of the Ghana Prostate Study

Obesity has been associated with an increased risk of advanced prostate cancer. However, most studies have been conducted among North American and European populations. Prostate cancer mortality appears elevated in West Africa, yet risk factors for prostate cancer in this region are unknown. We thus examined the relationship between obesity and prostate cancer using a case-control study conducted in Accra, Ghana in 2004 to 2012. Cases and controls were drawn from a population-based sample of 1037 men screened for prostate cancer, yielding 73 cases and 964 controls. An additional 493 incident cases were recruited from the Korle-Bu Teaching Hospital. Anthropometric measurements were taken at enrollment. We used logistic regression to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for associations between body mass index (BMI), waist circumference (WC), waist-hip ratio (WHR) and prostate cancer, adjusting for potential confounders. The mean BMI was 25.1 kg/m2 for cases and 24.3 kg/m2 for controls. After adjustment, men with BMI ≥ 30 kg/m2 had an increased risk of prostate cancer relative to men with BMI < 25 kg/m2 (OR 1.86, 95% CI 1.11-3.13). Elevated WC (OR 1.76, 95% CI 1.24-2.51) and WHR (OR 1.46, 95% CI 0.99-2.16) were also associated with prostate cancer. Associations were not modified by smoking status and were evident for low- and high-grade disease. These findings indicate that overall and abdominal obesity are positively associated with prostate cancer among men in Ghana, implicating obesity as a potentially modifiable risk factor for prostate cancer in this region.

A Large Cohort Study of Body Mass Index and Pancreatic Cancer by Smoking Status

BACKGROUND

Some evidence suggests the association between body mass index (BMI) and pancreatic cancer risk is weaker among current smokers than among never smokers.

METHODS

We examined the association between BMI and pancreatic cancer mortality among adults who reported smoking status at enrollment into Cancer Prevention Study-II in 1982, including 420,543 never smokers, 282,244 former cigarette smokers, and 219,885 current cigarette smokers. After excluding the first 3 years of follow-up to reduce reverse causation, we calculated multivariable-adjusted hazard ratios (HR).

RESULTS

During the full follow-up period from 1985 to 2014, 7,904 participants died of pancreatic cancer. The HR per 5 BMI units was lower among current smokers [HR = 1.14; 95% confidence interval (CI), 1.07-1.20] than never smokers (HR = 1.22; 95% CI, 1.17-1.27), although this difference was not statistically significant (P = 0.06). BMI was significantly less strongly associated with pancreatic cancer mortality among current smokers reporting ≥20 cigarettes/day (HR = 1.10; 95% CI, 1.03-1.18) than among never smokers. During follow-up within 10 years of enrollment, when current smokers at enrollment were the most likely to have still been smoking, BMI was not associated with pancreatic cancer mortality among current smokers (HR = 1.02; 95% CI, 0.90-1.16, P = 0.03 for difference between current and never smokers). BMI HRs were similar among former and never smokers.

CONCLUSIONS

These results support a weaker association between BMI and pancreatic cancer among current smokers than among never smokers.

IMPACT

In populations with low smoking prevalence, the pancreatic cancer burden due to BMI is likely to be higher than that predicted by risk estimates from studies including substantial numbers of smokers.

Physical Activity Does Not Lower the Risk of Lung Cancer

Observational studies have suggested that physical activity might lower the risk of lung cancer in former and current smokers, but not in never-smokers. Using genetic instruments for self-reported and accelerometer-measured physical activity traits implemented through two-sample Mendelian randomization (MR), we sought to strengthen the evidence for causality. We used 18 genome-wide significant (P < 5 × 10-8) single-nucleotide polymorphisms (SNP) for self-reported moderate-to-vigorous physical activity and seven SNP for accelerometer-measured ("average acceleration") physical activity from up to 377,234 UK Biobank participants and evaluated these in relation to risk using 29,266 lung cancer cases (including 11,273 adenocarcinomas, 7,426 squamous cell carcinoma, and 2,664 small-cell carcinoma cases) and 56,450 controls. MR analysis suggested no effect of self-reported physical activity [OR (95% confidence interval (CI)) = 0.67 (0.42-1.05); P = 0.081; Q-value = 0.243] and accelerometer-measured activity [OR (95% CI) = 0.98 (0.93-1.03); P = 0.372; Q-value = 0.562] on lung cancer. There was no evidence for associations of physical activity with histologic types and lung cancer in ever and never smokers. Replication analysis using genetic instruments from a different genome-wide study and sensitivity analysis to address potential pleiotropic effects led to no substantive change in estimates. Collectively, these findings do not support a protective relationship between physical activity and the risk of lung cancer. SIGNIFICANCE: A new genetic study provides little evidence that recommending physical activity would help prevent lung cancer.

Body mass index trajectories and prostate cancer risk: Results from the EPICAP study

Elevated body mass index (BMI) has been inconsistently associated with prostate cancer occurrence but it has been suggested that life course adulthood obesity may be associated with an increased risk of prostate cancer. However, few studies have investigated lifetime BMI and prostate cancer risk. We analyzed life course BMI trajectories on prostate cancer risk based on data from the Epidemiological study of Prostate Cancer (EPICAP). We included in our analyses 781 incident prostate cancer cases and 829 controls frequency matched by age. Participants were asked about their weight every decade from age 20 to two years before reference date. BMI trajectories were determined using group-based trajectory modeling to identify groups of men with similar patterns of BMI changes. We identified five BMI trajectories groups. Men with a normal BMI at age 20 developing overweight or obesity during adulthood were at increased risk of aggressive prostate cancer compared to men who maintained a normal BMI. Our results suggest that BMI trajectories resulting in overweight or obesity during adulthood are associated with an increased risk of aggressive prostate cancer, particularly in never smokers, emphasizing the importance of maintaining a healthy BMI throughout adulthood.

The Obesity Paradox in Cancer: Epidemiologic Insights and Perspectives

PURPOSE OF REVIEW

Controversy exists whether excess body fatness (measured by body mass index (BMI)) is associated with better cancer survival ("obesity paradox"). Here, we review the obesity paradox in cancer research and discuss potential explanations and future research directions.

RECENT FINDINGS

Overweight and obese cancer patients have better survival for diverse cancers. This apparent obesity paradox may be largely explained by methodological limitations including reverse causation, selection bias, confounding, and reliance of BMI as a measure of adiposity in cancer patients. A growing number of studies show promising evidence that precisely quantified body composition can provide important prognostic information in cancer care, such that low muscle and high adiposity are associated with worse clinical outcomes in cancer patients. The term obesity paradox in cancer, implying a causally beneficial role of adiposity, is misleading. Understanding the role of muscle and adiposity may reduce the confusion and inform precision oncology care.

The Effect of Smoking and Sex on the Association Between Long-term Alcohol Consumption and Metabolic Syndrome in a Middle-aged and Older Population

Background

The effect of smoking and sex on the relationship between alcohol consumption and risk of developing metabolic syndrome (MetS) and its components has not been investigated.

Methods

A total of 5,629 Korean adults aged 40–69 years without MetS were recruited at baseline. Alcohol consumption was assessed biennially, and participants were classified as never, light, moderate, or heavy drinkers. Smoking status was examined at baseline and categorized into non-smokers and current smokers. Risk of incident MetS and its components according to alcohol consumption was examined by smoking status and sex using a multivariate Cox proportional hazards model.

Results

During a follow-up of 12 years, 2,336 participants (41.5%) developed MetS. In non-smokers, light or moderate alcohol drinkers had a lower risk of developing MetS, abdominal obesity, hyperglycemia, hypertriglyceridemia, and low HDL-C compared with never drinkers. Heavy alcohol consumption was associated with a higher risk of incident elevated blood pressure (hazard ratio [HR] 1.48; 95% confidence interval [CI], 1.07–2.06; P = 0.020) in men and abdominal obesity (HR 1.86; 95% CI, 1.06–3.27; P = 0.030) in women. However, in smokers, the inverse association of light or moderate alcohol consumption with hypertriglyceridemia and abdominal obesity was not present, whereas a positive association between heavy alcohol consumption and hyperglycemia (HR 1.39; 95% CI, 1.07–1.80; P = 0.014) was observed.

Conclusions

Smoking status and sex strongly affects the association between long-term alcohol consumption and MetS and its components by the amount of alcohol consumed.

Preventable incidence of carcinoma associated with adiposity, alcohol and physical inactivity according to smoking status in the United States

The changing profile of lifestyles and their intricate relationships with smoking indicate the importance of accounting for smoking status when assessing cancer preventability. We assessed the association of body mass index, weight change, alcohol intake and physical activity with risk of total carcinoma among 53,195 smokers and 62,842 nonsmokers in two prospective cohorts. Then, leveraging the national prevalence estimates, we calculated the population attributable risk (PAR) for healthy lifestyle defined as body mass index ≥18.5 and <27.5 kg/m² , mid-life weight change of ≤20 pounds, no or moderate alcohol drinking (≤1 and 2 drinks/day for women and men, respectively) and weekly moderate or vigorous physical activity of at least 150 min. The PAR (95% CI) for healthy lifestyle was 18% (14-22%) in nonsmokers and 14% (10-19%) in smokers among women, and 20% (12-27%) in nonsmokers and 11% (5-17%) in smokers among men. While adiposity accounted for a substantially higher proportion of carcinoma cases in nonsmokers than smokers (16% vs. 2% in women, 15% vs. 2% in men), alcohol contributed more in smokers than nonsmokers (7% vs. 3% in women, 8% vs. 1% in men). When more strict criteria were used to define healthy lifestyle, the PAR estimates further increased (for women: 37% in smokers and 32% in nonsmokers; for men: 15% and 24%, respectively). In conclusion, lifestyle modification has great potential to reduce cancer risk in both smokers and nonsmokers. Weight control and reducing alcohol consumption should be prioritized for cancer prevention in nonsmokers and smokers, respectively.

Bacterial Translocation and Risk of Liver Cancer in a Finnish Cohort

BACKGROUND

Elevated systemic exposure to gut-derived bacterial products has been associated with hepatic inflammation and chronic liver diseases, potentially increasing the risk of liver cancer. However, only one prior study prospectively examined exposure to bacterial products in the circulation and risk of liver cancer, with a relatively limited coverage of biomarkers.

METHODS

We conducted a nested case-control study (224 liver cancer cases and 224 matched controls) in a large cohort of Finnish male smokers followed from baseline (1985-1988) to 2014. The associations between a panel of biomarkers for bacterial translocation and the risk of liver cancer were assessed using multivariable-adjusted conditional logistic regression. The biomarkers included immunoglobulin (Ig) A, IgG, and IgM against lipopolysaccharide (LPS) and flagellin, soluble CD14 (an LPS coreceptor), and the LPS-binding protein.

RESULTS

Anti-flagellin IgA [odds ratios (OR), 2.79; 95% confidence intervals (CI), 1.34-5.78; P trend = 0.01] and anti-LPS IgA (2.44; 95% CI, 1.33-4.48; P trend < 0.01) were significantly associated with risk of liver cancer. When restricting the analysis to histologically classified hepatocellular carcinoma, the ORs were 4.18 (95% CI, 1.60-10.92; P trend < 0.01) and 2.48 (95% CI, 1.16-5.29; P trend < 0.01), respectively. The results were not substantially changed after excluding cases diagnosed within the first 5 years of follow-up and those with hepatitis C virus infection.

CONCLUSIONS

Antibodies to flagellin and LPS were associated with increased risk of liver cancer.

IMPACT

Gut-derived bacterial translocation into the circulation may play a role in the development of primary liver cancer. Our findings could contribute to the understanding of primary liver cancer etiology and further prevention efforts.

Body mass index trajectories across adulthood and smoking in relation to prostate cancer risks: the NIH-AARP Diet and Health Study

BACKGROUND

Previously we showed that adulthood body mass index (BMI) trajectories that result in obesity were associated with elevated risks of fatal prostate cancer (PCA). To further explore this relationship, we conducted a study within the NIH-AARP Diet and Health Study.

METHODS

Among 153 730 eligible men enrolled in the NIH-AARP cohort from 1995 to 1996 (median follow-up = 15.1 years), we identified 630 fatal PCA cases and 16 896 incident cases. BMI was assessed for ages 18, 35 and 50 and at study entry, enabling examination of latent class-identified BMI trajectories. Hazard ratios (HRs) and 95% confidence intervals (CI) were estimated using Cox proportional hazards regression.

RESULTS

BMI at study entry (mean age = 63, HR = 1.12; 95% CI = 1.01, 1.24, per 5-unit increase) and maximum BMI during adulthood (HR = 1.12; 95% CI = 1.02, 1.24, per 5-unit increase) shared modest associations with increased risk of fatal PCA. Smoking status likely modified the relationship between BMI trajectories and fatal PCA (Pinteraction = 0.035 via change-in-estimate variable section, P = 0.065 via full a priori model). Among never-smokers, BMI trajectory of normal weight to obesity was associated with increased risk of fatal disease (HR = 2.37; 95% CI = 1.38, 4.09), compared with the maintained normal weight trajectory, whereas there was no association among former or current-smokers. Total and non-aggressive PCA exhibited modest inverse associations with BMI at all ages, whereas no association was observed for aggressive PCA.

CONCLUSIONS

Increased BMI was positively associated with fatal PCA, especially among never-smokers. Future studies that examine PCA survival will provide additional insight as to whether these associations are the result of biology or confounding.

Cancer risk in relation to body fat distribution, evaluated by DXA-scans, in postmenopausal women - the Prospective Epidemiological Risk Factor (PERF) study

Studies with direct measures of body fat distribution are required to explore the association between central and general obesity to cancer risk in postmenopausal women. This study investigates the association between central obesity and general obesity to overall/site-specific cancer risk in postmenopausal women. The analysis included 4,679 Danish postmenopausal women. Body fat distribution was evaluated by whole-body dual-energy X-ray absorptiometry scanners. Cancer diagnoses were extracted from the Danish Cancer Registry and multivariable Cox regression models explored the association between cancer risk and central obesity after adjusting for BMI. Our results showed that high central obese women had a 50% increased risk of overall cancer relative to low central obese women (Q1vs.Q4: [HR:1.50, CI:1.20-1.88]). For site-specific cancers, central obesity was significantly associated with Respiratory (Q1vs.Q4: [HR:2.01, CI:1.17-3.47]), Gastrointestinal (Q1vs.Q4: [HR:1.55, CI:0.99-2.41]) and Female genital organs (Q1vs.Q4: [HR:1.95, CI:1.00-3.78]) cancer diagnoses. Sub-analyses stratified by smoking-habits found a significant association between central obesity and a cancer diagnosis for current (Q1vs.Q4: [HR:1.93, CI:1.25-2.99]) and former smokers (Q1vs.Q4: [HR:1.90, CI:1.23-2.94]). These analyses suggest that central obesity is associated with some cancers in postmenopausal women independent of BMI.

Global patterns in excess body weight and the associated cancer burden

The prevalence of excess body weight and the associated cancer burden have been rising over the past several decades globally. Between 1975 and 2016, the prevalence of excess body weight in adults-defined as a body mass index (BMI) ≥ 25 kg/m² -increased from nearly 21% in men and 24% in women to approximately 40% in both sexes. Notably, the prevalence of obesity (BMI ≥ 30 kg/m² ) quadrupled in men, from 3% to 12%, and more than doubled in women, from 7% to 16%. This change, combined with population growth, resulted in a more than 6-fold increase in the number of obese adults, from 100 to 671 million. The largest absolute increase in obesity occurred among men and boys in high-income Western countries and among women and girls in Central Asia, the Middle East, and North Africa. The simultaneous rise in excess body weight in almost all countries is thought to be driven largely by changes in the global food system, which promotes energy-dense, nutrient-poor foods, alongside reduced opportunities for physical activity. In 2012, excess body weight accounted for approximately 3.9% of all cancers (544,300 cases) with proportion varying from less than 1% in low-income countries to 7% or 8% in some high-income Western countries and in Middle Eastern and Northern African countries. The attributable burden by sex was higher for women (368,500 cases) than for men (175,800 cases). Given the pandemic proportion of excess body weight in high-income countries and the increasing prevalence in low- and middle-income countries, the global cancer burden attributable to this condition is likely to increase in the future. There is emerging consensus on opportunities for obesity control through the multisectoral coordinated implementation of core policy actions to promote an environment conducive to a healthy diet and active living. The rapid increase in both the prevalence of excess body weight and the associated cancer burden highlights the need for a rejuvenated focus on identifying, implementing, and evaluating interventions to prevent and control excess body weight.

Proportion of cancer cases and deaths attributable to lifestyle risk factors in Brazil

BACKGROUND

Lifestyle risk factors (tobacco smoking, alcohol consumption, overweight and obesity, unhealthy diet, and lack of physical activity) have been associated with increased risk of at least 20 types of cancer. We estimated the proportion of cancer cases and deaths that could be potentially avoided by eliminating or reducing lifestyle risk factors in Brazil.

METHODS

We obtained the distribution of lifestyle risk factors by sex and age groups from recent representative health surveys in Brazil; relative risks from pooled analyses of prospective studies and meta-analyses; and cancer cases and deaths in 2012 from GLOBOCAN.

RESULTS

We found that 26.5% (114,497 cases) of all cancer cases and 33.6% (63,371 deaths) of all cancer deaths could be potentially avoided by eliminating lifestyle risk factors in Brazil. Plausible reductions in these exposures based on policy targets and cancer prevention recommendations could have potentially avoided 4.5% (19,731 cases) and 6.1% (11,480 deaths) of all cancer cases and deaths, respectively. Tobacco smoking accounted for most of the preventable cancer cases and deaths, followed by high body mass index and alcohol consumption. Larynx, lung, oropharynx, esophagus and colorectum cancer cases and deaths could be at least halved by eliminating these lifestyle risk factors.

CONCLUSION

Findings from this study may be useful to inform strategies for cancer prevention and control across Brazil.

Effect of increased body mass index on risk of diagnosis or death from cancer

Background

Whether body mass index (BMI) is causally associated with the risk of being diagnosed with or dying from any cancer remains unclear. Weight reduction has clinical importance for cancer control only if weight gain causes cancer development or death. We aimed to answer the question 'does genetically predicted BMI influence my risk of being diagnosed with or dying from any cancer'.

Methods

We used a Mendelian randomisation (MR) approach to estimate causal effect of BMI in 46,155 white-British participants aged between 40 and 69 years at recruitment (median age at follow-up 61 years) from the UK Biobank, who developed any type of cancer, among whom 6998 died from cancer. To derive MR instruments for BMI, we selected up to 390,628 cancer-free participants.

Results

For each standard deviation (4.78 units) increase in genetically predicted BMI, we estimated a causal odds ratio (COR) of 1.07 (1.02–1.12) and 1.28 (1.16–1.41) for overall cancer risk and mortality, respectively. The corresponding estimates were similar for males and females, and smokers and non-smokers.

Conclusions

Higher genetically predicted BMI increases the risk of being diagnosed with or dying from any cancer. These data suggest that increased overall weight may causally increase overall cancer incidence and mortality among Europeans.

Overall and Central Obesity and Risk of Lung Cancer: A Pooled Analysis

Background

The obesity-lung cancer association remains controversial. Concerns over confounding by smoking and reverse causation persist. The influence of obesity type and effect modifications by race/ethnicity and tumor histology are largely unexplored.

Methods

We examined associations of body mass index (BMI), waist circumference (WC), and waist-hip ratio (WHR) with lung cancer risk among 1.6 million Americans, Europeans, and Asians. Cox proportional hazard regression was used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) with adjustment for potential confounders. Analyses for WC/WHR were further adjusted for BMI. The joint effect of BMI and WC/WHR was also evaluated.

Results

During an average 12-year follow-up, 23 732 incident lung cancer cases were identified. While BMI was generally associated with a decreased risk, WC and WHR were associated with increased risk after controlling for BMI. These associations were seen 10 years before diagnosis in smokers and never smokers, were strongest among blacks, and varied by histological type. After excluding the first five years of follow-up, hazard ratios per 5 kg/m2 increase in BMI were 0.95 (95% CI = 0.90 to 1.00), 0.92 (95% CI = 0.89 to 0.95), and 0.89 (95% CI = 0.86 to 0.91) in never, former, and current smokers, and 0.86 (95% CI = 0.84 to 0.89), 0.94 (95% CI = 0.90 to 0.99), and 1.09 (95% CI = 1.03 to 1.15) for adenocarcinoma, squamous cell, and small cell carcinoma, respectively. Hazard ratios per 10 cm increase in WC were 1.09 (95% CI = 1.00 to 1.18), 1.12 (95% CI = 1.07 to 1.17), and 1.11 (95% CI = 1.07 to 1.16) in never, former, and current smokers, and 1.06 (95% CI = 1.01 to 1.12), 1.20 (95% CI = 1.12 to 1.29), and 1.13 (95% CI = 1.04 to 1.23) for adenocarcinoma, squamous cell, and small cell carcinoma, respectively. Participants with BMIs of less than 25 kg/m2 but high WC had a 40% higher risk (HR = 1.40, 95% CI = 1.26 to 1.56) than those with BMIs of 25 kg/m2 or greater but normal/moderate WC.

Conclusions

The inverse BMI-lung cancer association is not entirely due to smoking and reverse causation. Central obesity, particularly concurrent with low BMI, may help identify high-risk populations for lung cancer.

The Future Colorectal Cancer Burden Attributable to Modifiable Behaviors: A Pooled Cohort Study

BACKGROUND

Previous estimates of the colorectal cancer (CRC) burden attributed to behaviors have not considered joint effects, competing risk, or population subgroup differences.

METHODS

We pooled data from seven prospective Australian cohort studies (n = 367 058) and linked them to national registries to identify CRCs and deaths. We estimated the strength of the associations between behaviors and CRC risk using a parametric piecewise constant hazards model, adjusting for age, sex, study, and other behaviors. Exposure prevalence was estimated from contemporary National Health Surveys. We calculated population attributable fractions for CRC preventable by changes to current behaviors, accounting for competing risk of death and risk factor interdependence. Statistical tests were two-sided.

RESULTS

During the first 10 years of follow-up, there were 3471 incident CRCs. Overweight or obesity explained 11.1%, ever smoking explained 10.7% (current smoking 3.9%), and drinking more than two compared with two or fewer alcoholic drinks per day explained 5.8% of the CRC burden. Jointly, these factors were responsible for 24.9% (95% confidence interval [CI] = 19.7% to 29.9%) of the burden, higher for men (36.7%) than women (13.2%, P difference < .001). The burden attributed to these factors was also higher for those born in Australia (28.7%) than elsewhere (16.8%, P difference = .047). We observed modification of the smoking-attributable burden by alcohol consumption and educational attainment, and modification of the obesity-attributable burden by age group and birthplace.

CONCLUSIONS

We produced up-to-date estimates of the future CRC burden attributed to modifiable behaviors. We revealed novel differences between men and women, and other high-CRC burden subgroups that could potentially benefit most from programs that support behavioral change and early detection.

The increasing burden of cancer attributable to high body mass index in Brazil

BACKGROUND

Body mass index (BMI) has been constantly increasing over the last decades in most parts of the world, most notably in transitioning nations such as Brazil. High BMI (>22 kg/m2) is associated with an increased risk of 14 types of cancer. We estimated the extent to which reducing high BMI could lower cancer incidence in Brazil, nationally as well as at regional and state levels.

METHODS

We calculated fractions of cancer incidence in 2012 attributable to high BMI as well as projections for attributable cases in 2025 using BMI data from representative national surveys and relative risks published in meta-analyses. Estimates of cancer incidence were retrieved from GLOBOCAN and the Brazilian National Cancer Institute.

RESULTS

We found that 15,465 (3.8%) of all new cancer cases diagnosed in Brazil in 2012 were attributable to high BMI, with a higher burden in women (5.2%) than in men (2.6%). The cancer sites contributing most to the number of attributable cases were breast (n = 4777), corpus uteri (n = 1729), and colon (n = 681) in women, and colon (n = 1062), prostate (n = 926), and liver (n = 651) in men. The highest population attributable fractions (PAFs) for all cancers were found in the richer states of the country, located in the south (1.5% men/3.4% women) and the southeast (1.5% men/3.3% women).

CONCLUSIONS

Cancer cases attributable to high BMI will reach 29,490, which will be 4.6% of all cancers in Brazil in 2025; the extent will be greater in women (6.2% or 18,837) than in men (3.2% or 10,653). This information is a tool to support policy makers for future cancer prevention strategies in Brazil.

Longitudinal associations of lifetime adiposity with leukocyte telomere length and mitochondrial DNA copy number

Adiposity may cause adverse health outcomes by increasing oxidative stress and systemic inflammation, which can be reflected by altered telomere length (TL) and mitochondrial DNA copy number (mtCN) in peripheral blood leukocytes. However, little is known about the influence of lifetime adiposity on TL and mtCN in later life. This study was performed to investigate the associations of lifetime adiposity with leukocyte TL and mtCN in 9613 participants from the Nurses' Health Study. A group-based trajectory modelling approach was used to create trajectories of body shape from age 5 through 60 years, and a genetic risk score (GRS) was created based on 97 known adiposity susceptibility variants. Associations of body shape trajectories and GRS with dichotomized TL and mtCN were assessed by logistic regression models. After adjustment for lifestyle and dietary factors, compared with the lean-stable group, the lean-marked increase group had higher odds of having below-median TL (OR = 1.18, 95% CI 1.04, 1.35; P = 0.01), and the medium-marked increase group had higher odds of having below-median mtCN (OR = 1.28, 95% CI 1.00, 1.64; P = 0.047). There was a suggestive trend toward lower mtCN across the GRS quartiles (P for trend = 0.07). In conclusion, telomere attrition may be accelerated by marked weight gain in middle life, whereas mtCN is likely to be reduced persistently by adiposity over the life course. The findings indicate the importance of lifetime weight management to preserve functional telomeres and mitochondria.

Estimating the impact of body mass index on bladder cancer risk: Stratification by smoking status

We estimated the impact of obesity on bladder cancer with stratification by smoking status using nationally representative data on the Korean population from the National Health Insurance System (NHIS). Of the 45,850,458 people who underwent at last one health examination from 2009 to 2012, 23,378,895 without bladder cancer were followed from the January 2009 to the December 2015. First, the HR for bladder cancer was lowest in people with a BMI < 18.5 (HR = 0.92) and highest for those with BMI ≥ 30 (HR = 1.17) in multiple Cox regression analyses. The positive association between bladder cancer and BMI showed an increasing trend beyond the reference BMI. Second, an analysis of HR for bladder cancer stratified by obesity across smoking status strata showed a significant trend of increasing HR for bladder cancer across obesity and smoking status in multivariate-adjusted models. Conclusively, this population-based study showed that increasing BMI was a risk factor for bladder cancer independent of confounding variables. When stratified by smoking status, there was still a positive association between bladder cancer and BMI (P for trend < 0.01).

Pleiotropy of genetic variants on obesity and smoking phenotypes: Results from the Oncoarray Project of The International Lung Cancer Consortium

Obesity and cigarette smoking are correlated through complex relationships. Common genetic causes may contribute to these correlations. In this study, we selected 241 loci potentially associated with body mass index (BMI) based on the Genetic Investigation of ANthropometric Traits (GIANT) consortium data and calculated a BMI genetic risk score (BMI-GRS) for 17,037 individuals of European descent from the Oncoarray Project of the International Lung Cancer Consortium (ILCCO). Smokers had a significantly higher BMI-GRS than never-smokers (p = 0.016 and 0.010 before and after adjustment for BMI, respectively). The BMI-GRS was also positively correlated with pack-years of smoking (p<0.001) in smokers. Based on causal network inference analyses, seven and five of 241 SNPs were classified to pleiotropic models for BMI/smoking status and BMI/pack-years, respectively. Among them, three and four SNPs associated with smoking status and pack-years (p<0.05), respectively, were followed up in the ever-smoking data of the Tobacco, Alcohol and Genetics (TAG) consortium. Among these seven candidate SNPs, one SNP (rs11030104, BDNF) achieved statistical significance after Bonferroni correction for multiple testing, and three suggestive SNPs (rs13021737, TMEM18; rs11583200, ELAVL4; and rs6990042, SGCZ) achieved a nominal statistical significance. Our results suggest that there is a common genetic component between BMI and smoking, and pleiotropy analysis can be useful to identify novel genetic loci of complex phenotypes.

Weight change, obesity and risk of prostate cancer progression among men with clinically localized prostate cancer

Obesity is associated with an increased risk of fatal prostate cancer. We aimed to elucidate the importance and relevant timing of obesity and weight change for prostate cancer progression. We identified 5,158 men diagnosed with localized prostate cancer (clinical stage T1/T2) from 1986 to 2012 in the Health Professionals Follow-up Study. Men were followed for biochemical recurrence and lethal prostate cancer (development of distant metastasis or prostate cancer-specific mortality) until 2012. Cox regression estimated hazard ratios (HRs) for body mass index (BMI) at age 21, BMI at diagnosis, "long-term" weight change from age 21 to diagnosis and "short-term" weight change over spans of 4 and 8 years preceding diagnosis. Because weight, weight change and mortality are strongly associated with smoking, we repeated analyses among never smokers only (N = 2,559). Among all patients, neither weight change nor BMI (at age 21 or at diagnosis) was associated with lethal prostate cancer. Among never smokers, long-term weight gain was associated with an increased risk of lethal disease (HR for gaining >30 pounds vs. stable weight [±10 pounds] 1.59, 95% CI, 1.01-2.50, p-trend = 0.06). Associations between weight change, BMI and lethal prostate cancer were stronger for men with BMI ≥ 25 at age 21 compared to those with BMI < 25. Weight change and obesity were not associated with an increased risk of biochemical recurrence. Our findings among never smoker men diagnosed with localized prostate cancer suggest a positive association between long-term weight gain and risk of lethal prostate cancer. Metabolic changes associated with weight gain may promote prostate cancer progression.

Obesity as an Avoidable Cause of Cancer (Attributable Risks)

Excess body weight, commonly categorised as overweight (body mass index, BMI 25.0-29.9 kg/m2) and obesity (BMI ≥30 kg/m2) is an established risk factor for increased incidence of several adult cancers. As body weight is modifiable, there is a potential for cancer prevention. Calculation of attributable risk (here expressed at population attributable fraction, PAF) offers an estimate of the burden of excess cancers attributable to elevated BMI in populations, and thus an approximation of avoidable cases and the opportunity for prevention. Using counterfactual methods, the estimated PAF worldwide attributed to elevated BMI is 3.6 % or nearly half a million new cancer cases in adults (aged 30 years and older after a 10-year lag period). PAFs are higher in women compared with men (5.4 % vs. 1.9 %). Endometrial, post-menopausal breast, and colon cancers account for nearly two-thirds of cancers attributable to elevated BMI. Globally, excess body weight is the third commonest attributable risk factor for cancer (after smoking and infection); in western populations such as the UK, excess weight ranks as second commonest risk factor.

How to Manage the Obese Patient With Cancer

Purpose

Obesity (body mass index [BMI] ≥ 30 kg/m2) is common among patients with cancer. We reviewed management issues in the obese patient with cancer, focusing on how obesity influences treatment selection (including chemotherapy dosing), affects chemotherapy toxicity and surgical complications, and might be a treatment effect modifier.

Methods

The majority of evidence is drawn from observational studies and secondary analyses of trial data, typically analyzed in N × 3 BMI categories (normal weight, overweight, and obese) matrix structures. We propose a methodological framework for interpretation focusing on sample size and composition, nonlinearity, and unmeasured confounding.

Results

There is a common perception that obesity is associated with increased treatment-related toxicity. Accordingly, cytotoxic chemotherapy dose reduction is common in patients with elevated BMI. Contrary to this, there is some evidence that full dosing in obese patients does not result in increased toxicity. However, these data are from a limited number of regimens, and fail to fully capture cytotoxic drug pharmacodynamics and pharmacokinetic variability in obese patients. Among patients undergoing surgery, there is evidence that elevated BMI is associated with increased perioperative mortality and increased rates of infectious complications. A novel finding is that these relationships hold after surgery for malignancy, but not for benign indications. There are biologic plausibilities that obesity might be an effect modifier of treatment, but supporting evidence from clinical studies is inconsistent.

Conclusion

In line with the ASCO 2012 guidelines, chemotherapy dosing is probably best performed using actual body weight in obese patients. However, specific regimens known to be associated with increased toxicity in this group should be used with caution. There is no guidance on dose for obese patients treated with biologic agents. Currently, there are no specific recommendations for the surgical management of the obese patient with cancer.