Optimal cutoffs of obesity measures in relation to cancer risk in postmenopausal women in the Women's Health Initiative Study

Adiposity and cancer: meta-analysis, mechanisms, and future perspectives

Obesity is a recognised risk factor for many cancers and with rising global prevalence, has become a leading cause of cancer. Here we summarise the current evidence from both population-based epidemiologic investigations and experimental studies on the role of obesity in cancer development. This review presents a new meta-analysis using data from 40 million individuals and reports positive associations with 19 cancer types. Utilising major new data from East Asia, the meta-analysis also shows that the strength of obesity and cancer associations varies regionally, with stronger relative risks for several cancers in East Asia. This review also presents current evidence on the mechanisms linking obesity and cancer and identifies promising future research directions. These include the use of new imaging data to circumvent the methodological issues involved with body mass index and the use of omics technologies to resolve biologic mechanisms with greater precision and clarity.

Reassessing the causal role of obesity in breast cancer susceptibility: a comprehensive multivariable Mendelian randomization investigating the distribution and timing of exposure

BACKGROUND

Previous Mendelian randomization (MR) studies on obesity and risk of breast cancer adopted a small number of instrumental variables and focused mainly on the crude total effect. We aim to investigate the independent causal effect of obesity on breast cancer susceptibility, considering the distribution of fat, covering both early and late life.

METHODS

Using an enlarged set of female-specific genetic variants associated with adult general [body mass index (BMI)] and abdominal obesity [waist-to-hip ratio (WHR) with and without adjustment for BMI, WHR and WHRadjBMI] as well as using sex-combined genetic variants of childhood obesity (childhood BMI), we performed a two-sample univariable MR to re-evaluate the total effect of each obesity-related exposure on overall breast cancer (Ncase = 133 384, Ncontrol = 113 789). We further looked into its oestrogen receptor (ER)-defined subtypes (NER+ = 69 501, NER- = 21 468, Ncontrol = 105 974). Multivariable MR was applied to estimate the independent causal effect of each obesity-related exposure on breast cancer taking into account confounders as well as to investigate the independent effect of adult and childhood obesity considering their inter-correlation.

RESULTS

In univariable MR, the protective effects of both adult BMI [odds ratio (OR) = 0.89, 95% CI = 0.83-0.96, P = 2.06 × 10-3] and childhood BMI (OR = 0.78, 95% CI = 0.70-0.87, P = 4.58 × 10-6) were observed for breast cancer overall. Comparable effects were found in ER+ and ER- subtypes. Similarly, genetically predicted adult WHR was also associated with a decreased risk of breast cancer overall (OR = 0.87, 95% CI = 0.80-0.96, P = 3.77 × 10-3), restricting to ER+ subtype (OR = 0.88, 95% CI = 0.80-0.98, P = 1.84 × 10-2). Conditional on childhood BMI, the effect of adult general obesity on breast cancer overall attenuated to null (BMI: OR = 1.00, 95% CI = 0.90-1.10, P = 0.96), whereas the effect of adult abdominal obesity attenuated to some extent (WHR: OR = 0.90, 95% CI = 0.82-0.98, P = 1.49 × 10-2; WHRadjBMI: OR = 0.92, 95% CI = 0.86-0.99, P = 1.98 × 10-2). On the contrary, an independent protective effect of childhood BMI was observed in breast cancer overall, irrespective of adult measures (adjusted for adult BMI: OR = 0.84, 95% CI = 0.77-0.93, P = 3.93 × 10-4; adjusted for adult WHR: OR = 0.84, 95% CI = 0.76-0.91, P = 6.57 × 10-5; adjusted for adult WHRadjBMI: OR = 0.80, 95% CI = 0.74-0.87, P = 1.24 × 10-7).

CONCLUSION

Although successfully replicating the inverse causal relationship between adult obesity-related exposures and risk of breast cancer, our study demonstrated such effects to be largely (adult BMI) or partly (adult WHR or WHRadjBMI) attributed to childhood obesity. Our findings highlighted an independent role of childhood obesity in affecting the risk of breast cancer as well as the importance of taking into account the complex interplay underlying correlated exposures.

Colorectal cancer pain upon diagnosis and after treatment: a cross-sectional comparison with healthy matched controls

BACKGROUND

The current study sought to explore whether cancer pain (CP) already exists in patients at colorectal cancer (CRC) diagnosis before treatment compared with patients with colorectal cancer (CRC) after treatment and a healthy matched control group. The study also sought to examine whether factors related to physical health status could enhance pain processes.

METHODS

An observational cross-sectional study was conducted following the STROBE checklist. Twenty-nine newly diagnosed and forty post-treatment patients with CRC and 40 healthy age/sex-matched controls were included for comparison. Pain, local muscle function, and body composition outcomes were assessed by a physiotherapist with > 3 years of experience. ANCOVA and Kruskal-Wallis tests were performed, with Bonferroni and Dunn-Bonferroni post hoc analyses and Cohen's d and Hedge's effect size, as appropriate.

RESULTS

The analysis detected lower values of pressure pain threshold (PPT) points, the PPT index, and abdominal strength and higher values of self-reported abdominal pain in newly diagnosed patients, with even more marked results observed in the post-treatment patients, where lower lean mass and skeletal muscle index values were also found than those in the healthy matched controls (p < 0.05). In the post-treatment and healthy matched control groups, positive associations were observed between the PPT lumbar dominant side points and abdominal isometric strength and lean mass, and negative associations were observed between the lumbar dominant side points and body fat (p < 0.05).

CONCLUSION

Upon diagnosis, patients with CRC already show signs of hyperalgesia and central sensitization and deteriorated physical conditions and body composition, and this state could be aggravated by subsequent treatments.

Cancer mortality in a population-based cohort of American Indians - The strong heart study

BACKGROUND

Cancer mortality among American Indian (AI) people varies widely, but factors associated with cancer mortality are infrequently assessed.

METHODS

Cancer deaths were identified from death certificate data for 3516 participants of the Strong Heart Study, a population-based cohort study of AI adults ages 45-74 years in Arizona, Oklahoma, and North and South Dakota. Cancer mortality was calculated by age, sex and region. Cox proportional hazards model was used to assess independent associations between baseline factors in 1989 and cancer death by 2010.

RESULTS

After a median follow-up of 15.3 years, the cancer death rate per 1000 person-years was 6.33 (95 % CI 5.67-7.04). Cancer mortality was highest among men in North/South Dakota (8.18; 95 % CI 6.46-10.23) and lowest among women in Arizona (4.57; 95 % CI 2.87-6.92). Factors independently associated with increased cancer mortality included age, current or former smoking, waist circumference, albuminuria, urinary cadmium, and prior cancer history. Factors associated with decreased cancer mortality included Oklahoma compared to Dakota residence, higher body mass index and total cholesterol. Sex was not associated with cancer mortality. Lung cancer was the leading cause of cancer mortality overall (1.56/1000 person-years), but no lung cancer deaths occurred among Arizona participants. Mortality from unspecified cancer was relatively high (0.48/100 person-years; 95 % CI 0.32-0.71).

CONCLUSIONS

Regional variation in AI cancer mortality persisted despite adjustment for individual risk factors. Mortality from unspecified cancer was high. Better understanding of regional differences in cancer mortality, and better classification of cancer deaths, will help healthcare programs address cancer in AI communities.

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.

Methodological considerations for disentangling a risk factor's influence on disease incidence versus postdiagnosis survival: The example of obesity and breast and colorectal cancer mortality in the Women's Health Initiative

Often, studies modeling an exposure's influence on time to disease-specific death from study enrollment are incorrectly interpreted as if based on time to death from disease diagnosis. We studied 151,996 postmenopausal women without breast or colorectal cancer in the Women's Health Initiative with weight and height measured at enrollment (1993-1998). Using Cox regression models, we contrast hazard ratios (HR) from two time-scales and corresponding study subpopulations: time to cancer death after enrollment among all women and time to cancer death after diagnosis among only cancer survivors. Median follow-up from enrollment to diagnosis/censoring was 13 years for both breast (7,633 cases) and colorectal cancer (2,290 cases). Median follow-up from diagnosis to death/censoring was 7 years for breast and 5 years for colorectal cancer. In analyses of time from enrollment to death, body mass index (BMI) ≥ 35 kg/m2 versus 18.5-<25 kg/m2 was associated with higher rates of cancer mortality: HR = 1.99; 95% CI: 1.54, 2.56 for breast cancer (p trend <0.001) and HR = 1.40; 95% CI: 1.04, 1.88 for colorectal cancer (p trend = 0.05). However, in analyses of time from diagnosis to cancer death, trends indicated no significant association (for BMI ≥ 35 kg/m2 , HR = 1.25; 95% CI: 0.94, 1.67 for breast [p trend = 0.33] and HR = 1.18; 95% CI: 0.84, 1.86 for colorectal cancer [p trend = 0.39]). We conclude that a risk factor that increases disease incidence will increase disease-specific mortality. Yet, its influence on postdiagnosis survival can vary, and requires consideration of additional design and analysis issues such as selection bias. Quantitative tools allow joint modeling to compare an exposure's influence on time from enrollment to disease incidence and time from diagnosis to death.

Robotic-assisted hysterectomy: patient selection and perspectives

Minimally invasive hysterectomy via the laparoscopic or vaginal approach is beneficial to patients when compared with laparotomy, but has not been offered in the past to all women because of the technical difficulties and the long learning curve required for laparoscopic hysterectomy. Robotic-assisted hysterectomy for benign indications may allow for a shorter learning curve but does not offer clear advantages over conventional laparoscopic hysterectomy in terms of surgical outcomes. In addition, robotic hysterectomy is invariably associated with increased costs. Nevertheless, this surgical approach has been widely adopted by gynecologic surgeons. The aim of this review is to describe specific indications and patients who may benefit from robotic-assisted hysterectomy. These include hysterectomy for benign conditions in cases with high surgical complexity (such as pelvic adhesive disease and endometriosis), hysterectomy and lymphadenectomy for treatment of endometrial carcinoma, and obese patients. In the future, additional evidence regarding the benefits of single-site robotic hysterectomy may further modify the indications for robotic-assisted hysterectomy.

Can MTHFR C677T and A1298C Polymorphisms Alter the Risk and Severity of Sporadic Breast Cancer in Brazilian Women?

INTRODUCTION

Polymorphisms in the methylenetetrahydrofolate reductase gene (MTHFR) modify the risk and severity of sporadic breast cancer (BC). In this context, the MTHFR C677T and A1298C polymorphisms have been associated with risk and severity of sporadic BC.

PATIENTS AND METHODS

In total, 253 women with BC and 257 controls were enrolled in this study. Polymorphisms were analyzed using restriction fragment length polymorphism - polymerase chain reaction. Epidemiology, tumor characteristics, and reproductive factors were considered in the analysis. Statistical tests included the χ² test, the Fisher exact test, and the Mann-Whitney and Kruskal-Wallis tests, or parametric equivalents.

RESULTS

MTHFR polymorphisms were not a risk factor for BC. The 677CC genotype was associated with distant metastasis (odds ratio [OR] = 5.311; 95% confidence interval [CI] = 1.124-25.09) and lower estrogen receptor expression, whereas the 1298AA genotype was associated with stage 0 (OR = 0.244; 95% CI = 0.077-0.771) and increased estrogen receptor expression. In haplotype analysis, 677CC/1298AA was associated with hypertension (OR = 1.979; 95% CI = 1.036-3.782), and 677CT/1298AC was associated with invasive carcinoma of no special type (OR = 0.472; 95% CI = 0.243-0.918) and stage 0 (OR = 3.476; 95% CI = 1.341-10.47).

CONCLUSION

The MTHFR C677T and A1298C polymorphisms do not alter the risk of BC, but are associated with the clinical severity of BC.

Obesity and breast cancer - what's new?

Obesity rates are increasing in the developed and developing world; this has implications for breast cancer risk and outcome. Areas covered: Recent advances relating to the association of obesity with breast cancer are reviewed. Expert commentary: Obesity has been associated with increased risk of postmenopausal hormone receptor positive and premenopausal triple negative breast cancer and with poor prognosis of most types of breast cancer. Obese individuals may present with breast cancer at a more advanced stage and their breast cancer may differ biologically from cancers diagnosed in nonobese women. A picture of a complex, multifactorial biology underlying the obesity-cancer link is emerging, with the identification of obesity-associated tissue and systemic changes that are cancer promoting, enhancing proliferation, invasion and metastasis. Intervention research to ascertain effects of weight loss and of pharmacologic interventions that reverse the metabolic changes of obesity is needed.

Up to one-third of breast cancer cases in post-menopausal Mediterranean women might be avoided by modifying lifestyle habits: the EPIC Italy study

PURPOSE

Breast cancer (BC) is the most frequent cancer among women in developed countries. Physical activity (PA), body mass index (BMI), and alcohol intake have been identified as relevant lifestyle modifiable risk factors for post-menopausal BC. We aimed to evaluate the role of these factors in modulating post-menopausal BC risk and to estimate the proportion of BC cases attributable to low PA, high BMI, and alcohol taking into account non-modifiable factors.

METHODS

In the Italian section of the EPIC study, 15,010 post-menopausal women were recruited and provided information about dietary and lifestyle habits including PA, smoking, reproductive history, and anthropometric measurements. During 14.8 years of median follow-up, 672 incident BC cases (607 invasive and 65 in situ) were identified.

RESULTS

In multivariate models, inverse associations with BC risk emerged for increasing level of total (p trend 0.02), leisure time (p trend 0.04), and occupational (p trend 0.007) PA. High BMI (HR 1.21; 95% CI 1.02-1.43 and HR 1.33; 95% CI 1.06-1.65 for overweight and obesity, respectively) and alcohol consumption higher than 10 g/day (HR 1.30; 95% CI 1.09-1.54) were associated with BC risk. We estimated that 30% (95% CI 8-50%) of post-menopausal BC cases would be avoided through an increase of leisure time PA, a BMI below 25.0, and consuming no more than one drink/day.

CONCLUSIONS

This large study carried out in Mediterranean women confirms the role of PA, BMI, and alcohol consumption in modulating post-menopausal BC risk and supports the potential benefits obtainable by modifying these lifestyle factors.

Association Between Anthropometric Measures and Long-Term Survival in Frail Older Women: Observations from the Women's Health Initiative Study

OBJECTIVES

To evaluate the association between currently recommended guidelines and commonly used clinical criteria for body mass index (BMI), waist circumference (WC), and waist-to-hip ratio (WHR) and all-cause mortality in frail older women.

DESIGN

Longitudinal prospective cohort study.

SETTING

Women's Health Initiative (WHI)-Observational Study.

PARTICIPANTS

A sample of women aged 65-84 with complete data to characterize frailty in the third year of WHI follow-up (N = 11,070).

MEASUREMENTS

Frailty phenotype was determined using the modified Fried criteria. Information on anthropometric measures (BMI, WC, WHR) was collected in clinical examinations. Cox proportional hazards models were used to estimate the effect of BMI, WC, and WHR on mortality adjusted for demographic characteristics and health behaviors.

RESULTS

Over a mean follow-up of 11.5 years, there were 2,911 (26%) deaths in the sample. Women with a BMI from 25.0 to 29.9 kg/m(2) (hazard rate ratio (HR) = 0.80, 95% confidence interval (CI) = 0.73-0.88) and those with a BMI from 30.0 to 34.9 kg/m(2) (HR = 0.79, 95% CI = 0.71-0.88) had lower mortality than those with a BMI from 18.5 to 24.9 kg/m(2) . Women with a WHR greater than 0.8 had higher mortality (HR = 1.16, 95% CI = 1.07-1.26) than those with a WHR of 0.8 or less. No difference in mortality was observed according to WC. Stratifying according to chronic morbidity or smoking status or excluding women with early death and unintentional weight loss did not substantially change these findings.

CONCLUSION

In frail, older women, having a BMI between 25.0 and 34.9 kg/m(2) or a WHR of 0.8 or less was associated with lower mortality. Currently recommended healthy BMI guidelines should be reevaluated for frail older women.

Randomized trial of a phone- and web-based weight loss program for women at elevated breast cancer risk: the HELP study

Excess weight and physical inactivity are modifiable risk factors for breast cancer. Behavioral intervention is particularly important among women with an elevated risk profile. This trial tested an intervention that trained women to use a self-monitoring website to increase activity and lose weight. Women with BMI ≥27.5 kg/m(2) at elevated breast cancer risk were randomized to the intervention (N = 71) or usual care (N = 34). The intervention group received telephone-based coaching and used web-based self-monitoring tools. At 6 months, significant weight loss was observed in the intervention group (4.7 % loss from starting weight; SD = 4.7 %) relative to usual care (0.4 % gain; SD = 3.0 %) (p < 0.0001). By 12 months, the intervention group had lost 3.7 % of weight (SD = 5.4 %), compared to 1.3 % (SD = 4.2) for usual care (p = 0.003). At 12 months, accelerometer-measured moderate-to-vigorous physical activity increased by 12 min/day (SD = 24) compared to no change in usual care (p = 0.04. In summary, this web- and phone-based approach produced modest but significant improvements in weight and physical activity for women at elevated breast cancer risk.

Why are there race/ethnic differences in adult body mass index-adiposity relationships? A quantitative critical review

Body mass index (BMI) is now the most widely used measure of adiposity on a global scale. Nevertheless, intense discussion centers on the appropriateness of BMI as a phenotypic marker of adiposity across populations differing in race and ethnicity. BMI-adiposity relations appear to vary significantly across race/ethnic groups, but a collective critical analysis of these effects establishing their magnitude and underlying body shape/composition basis is lacking. Accordingly, we systematically review the magnitude of these race-ethnic differences across non-Hispanic (NH) white, NH black and Mexican American adults, their anatomic body composition basis and potential biologically linked mechanisms, using both earlier publications and new analyses from the US National Health and Nutrition Examination Survey. Our collective observations provide a new framework for critically evaluating the quantitative relations between BMI and adiposity across groups differing in race and ethnicity; reveal new insights into BMI as a measure of adiposity across the adult age-span; identify knowledge gaps that can form the basis of future research and create a quantitative foundation for developing BMI-related public health recommendations.