Timing of weight gain in relation to breast cancer risk

Role of body mass index and weight change in the risk of cancer: A systematic review and meta-analysis of 66 cohort studies

Background

This study was designed to evaluate the effects of body mass index (BMI) and weight change on the risk of developing cancer overall and cancer at different sites.

Methods

We searched PubMed and other databases up to July 2023 using the keywords related to 'risk', 'cancer', 'weight', 'overweight', and 'obesity'. We identified eligible studies, and the inclusion criteria encompassed cohort studies in English that focused on cancer diagnosis and included BMI or weight change as an exposure factor. Multiple authors performed data extraction and quality assessment, and statistical analyses were carried out using RevMan and R software. We used random- or fixed-effects models to calculate the pooled relative risk (RR) or hazard ratio along with 95% confidence intervals (CIs). We used the Newcastle-Ottawa Scale to assess study quality.

Results

Analysis included 66 cohort studies. Compared to underweight or normal weight, overweight or obesity was associated with an increased risk of endometrial cancer, kidney cancer, and liver cancer but a decreased risk of prostate cancer and lung cancer. Being underweight was associated with an increased risk of gastric cancer and lung cancer but not that of postmenopausal breast cancer or female reproductive cancer. In addition, weight loss of more than five kg was protective against overall cancer risk.

Conclusions

Overweight and obesity increase the risk of most cancers, and weight loss of >5 kg reduces overall cancer risk. These findings provide insights for cancer prevention and help to elucidate the mechanisms underlying cancer development.

Registration

Reviewregistry1786.

Metabolic Syndrome and Breast Cancer: Prevalence, Treatment Response, and Prognosis

Metabolic syndrome is a type of multifactorial metabolic disease with the presence of at least three factors: obesity, diabetes mellitus, low high-density lipoprotein, hypertriglyceridemia, and hypertension. Recent studies have shown that metabolic syndrome and its related components exert a significant impact on the initiation, progression, treatment response, and prognosis of breast cancer. Metabolic abnormalities not only increase the disease risk and aggravate tumor progression but also lead to unfavorable treatment responses and more treatment side effects. Moreover, biochemical reactions caused by the imbalance of these metabolic components affect both the host general state and organ-specific tumor microenvironment, resulting in increased rates of recurrence and mortality. Therefore, this review discusses the recent advances in the association of metabolic syndrome and breast cancer, providing potential novel therapeutic targets and intervention strategies to improve breast cancer outcome.

Body size in early life and risk of breast cancer

Background

Body size in early life is inversely associated with adult breast cancer (BC) risk, but it is unclear whether the associations differ by tumor characteristics.

Methods

In a pooled analysis of two Swedish population-based studies consisting of 6731 invasive BC cases and 28,705 age-matched cancer-free controls, we examined the associations between body size in early life and BC risk. Self-reported body sizes at ages 7 and 18 years were collected by a validated nine-level pictogram (aggregated into three categories: small, medium and large). Odds ratios (OR) and corresponding 95% confidence intervals (CI) were estimated from multivariable logistic regression models in case-control analyses, adjusting for study, age at diagnosis, age at menarche, number of children, hormone replacement therapy, and family history of BC. Body size change between ages 7 and 18 were also examined in relation to BC risk. Case-only analyses were performed to test whether the associations differed by tumor characteristics.

Results

Medium or large body size at age 7 and 18 was associated with a statistically significant decreased BC risk compared to small body size (pooled OR (95% CI): comparing large to small, 0.78 (0.70–0.86), P_trend <0.001 and 0.72 (0.64–0.80), P_trend <0.001, respectively). The majority of the women (~85%) did not change body size categories between age 7 and 18 . Women who remained medium or large between ages 7 and 18 had significantly decreased BC risk compared to those who remained small. A reduction in body size between ages 7 and 18 was also found to be inversely associated with BC risk (0.90 (0.81–1.00)). No significant association was found between body size at age 7 and tumor characteristics. Body size at age 18 was found to be inversely associated with tumor size (P_trend = 0.006), but not estrogen receptor status and lymph node involvement. For all analyses, the overall inferences did not change appreciably after further adjustment for adult body mass index.

Conclusions

Our data provide further support for a strong and independent inverse relationship between early life body size and BC risk. The association between body size at age 18 and tumor size could be mediated by mammographic density.

Electronic supplementary material

The online version of this article (doi:10.1186/s13058-017-0875-9) contains supplementary material, which is available to authorized users.

Metabolic syndrome is associated with increased breast cancer risk: a systematic review with meta-analysis

Background. Although individual metabolic risk factors are reported to be associated with breast cancer risk, controversy surrounds risk of breast cancer from metabolic syndrome (MS). We report the first systematic review and meta-analysis of the association between MS and breast cancer risk in all adult females. Methods. Studies were retrieved by searching four electronic reference databases [PubMed, Cumulative Index to Nursing and Allied Health Literature (CINAHL), Web of Science, and ProQuest through June 30, 2012] and cross-referencing retrieved articles. Eligible for inclusion were longitudinal studies reporting associations between MS and breast cancer risk among females aged 18 years and older. Relative risks and 95% confidence intervals were calculated for each study and pooled using random-effects models. Publication bias was assessed quantitatively (Trim and Fill) and qualitatively (funnel plots). Heterogeneity was examined using Q and I² statistics. Results. Representing nine independent cohorts and 97,277 adult females, eight studies met the inclusion criteria. A modest, positive association was observed between MS and breast cancer risk (RR: 1.47, 95% CI, 1.15–1.87; z = 3.13; p = 0.002; Q = 26.28, p = 0.001; I² = 69.55%). No publication bias was observed. Conclusions. MS is associated with increased breast cancer risk in adult women.

Weight change in adulthood and risk of postmenopausal breast cancer: the HUNT study of Norway

BACKGROUND

Adult weight gain is associated with increased risk of postmenopausal breast cancer. Most previous studies are limited by using recalled or self-reported data, and it is not known if age-specific weight changes are important for breast cancer risk.

METHODS

In a Norwegian cohort of 28,153 women (and 900 incident breast cancers) with longitudinal anthropometric measurements over up to 30 years, we studied both overall and age-related weight changes in adulthood and risk of postmenopausal breast cancer.

RESULTS

Overall, weight gain in adulthood was associated with increased breast cancer risk (hazard ratio (HR) per kg per year 1.31, 95% confidence interval (CI) 1.11-1.54). Weight gain before (HR per kg per year 1.38, 95% CI 1.09-1.75) or around menopause (1.69, 95% CI 1.32-2.16) was associated with increased risk, but there was no clear risk increase associated with later weight gain (HR per kg per year 0.92, 95% CI 0.73-1.18).

CONCLUSION

Weight gain in adulthood was associated with increased risk of breast cancer. Our results suggest that weight gain before and around menopausal age may be particularly important for breast cancer risk among postmenopausal women.

Adult weight gain in relation to breast cancer risk by estrogen and progesterone receptor status: a meta-analysis

Adult weight gain is positively associated with postmenopausal breast cancer and inversely associated with premenopausal breast cancer risk. To date, no meta-analysis has been conducted to assess this association by estrogen receptor (ER) and progesterone receptor (PR) status. We searched PubMed for relevant studies published through March 2010. Summarized risk estimates (REs) with 95% confidence intervals (CIs) were calculated using random effects or fixed effects models. We retrieved nine articles on weight gain from adulthood to reference age and ER- and/or PR-defined breast cancer risk, reporting on three prospective cohort studies and eight case-control studies. Comparing the highest versus the lowest categories of adult weight gain, risk was increased for ER(+)PR(+) and ER(+) tumors combined (11 studies; RE = 2.03; 95% CI 1.62, 2.45). Statistically significant heterogeneity (p (heterogeneity) = 0.002) was shown between REs for a mixed population of pre- and postmenopausal women combined (4 studies; RE = 1.54; 95% CI 0.86, 2.22) and for postmenopausal women only (7 studies; RE = 2.33; 95% CI 2.05, 2.60). Risk for ER(-)PR(-) tumors among postmenopausal women was also slightly increased (7 studies; RE = 1.34; 95% CI 1.06, 1.63), but statistically significantly different from risk for ER(+)PR(+) tumors (p (heterogeneity) < 0.0001). No associations were observed for ER(+)PR(-) tumors whereas risk for ER(-)PR(+) tumors could not be assessed. In conclusion, the association between adult weight gain and postmenopausal breast cancer risk is heterogeneous according to ER/PR status and stronger for ER(+)PR(+) than for ER(-)PR(-) tumors.

Obesity, body fat distribution and breast cancer

Abstract Strong epidemiological data exists implicating anthropometric risk factors in breast cancer aetiology. In premenopausal women the risk of breast cancer increases with increased height, yet decreases with increasing weight and BMI. Although the evidence is not strong, a counter-intuitive positive relationship between central adiposity and premenopausal breast cancer risk is emerging. In post-menopausal women an increased risk in breast cancer has been found for all anthropometric measures: height, weight, BMI, measures of central adiposity (waist:hip ratio and waist circumference) and weight gain, with breast size being a possible additional risk factor. Weight loss as a strategy for reducing breast cancer risk seems to offer a viable prophylaxis in obese post-menopausal women, although data are limited. The evidence for anthropometric measures in relation to breast cancer risk is consistently stronger for post-menopausal women compared with premenopausal women and seems to be dependent on age. A number of possible biological mechanisms have been offered to explain the link between breast cancer risk and anthropometric measures. It has been hypothesised that obesity, especially central fat deposits, linked to insulin resistance, increases circulating hormones such as oestrogens, androgens, insulin, insulin-like growth factor-1 (IGF-1), and decreased levels of hormone-binding proteins such as steroid hormone-binding globulin and IGF-1 binding protein-1. Thus there are resulting increased concentrations of bioavailable sex hormones, which have been linked to increased breast cancer risk. As obesity is an important modifiable risk factor, which has been linked to increased post-menopausal breast cancer, public health recommendations to maintain ideal weight throughout life are warranted.

Role of exercise and nutrition in menopause

Menopause and the aging process itself cause many physiologic changes, which explain the increased prevalence of chronic diseases observed in postmenopausal women. Exercise and nutrition play important roles in the prevention and treatment of cardiovascular disease, cancer, obesity, diabetes, osteoporosis, and depression.

Pregnancy weight gain is not associated with maternal or mixed umbilical cord estrogen and androgen concentrations

The association of maternal weight gain with serum hormone concentrations was explored in 75 women who had healthy, singleton pregnancies. Estradiol, estriol, estrone, androstenedione, testosterone, dehydroepiandrosterone (DHEA), and DHEA sulfate concentrations were measured both in maternal and mixed umbilical cord serum to assess hormone levels in both the maternal and fetal circulation at delivery. Our data show no association of maternal or cord steroid hormone concentrations with pregnancy weight gain. Increased exposure to steroid hormones, especially estrogens, during pregnancy has been hypothesized to play a role in subsequent breast cancer risk for both mother and female offspring. Our results are not consistent with an effect of pregnancy weight gain being mediated by this pathway as reflected by hormone concentrations at the end of pregnancy.

Weight, height, body mass index and risk of breast cancer in postmenopausal women: a case-control study

Background

Many women in Iran have a relatively high body mass index. To investigate whether the condition contributes to excess breast cancer cases, a case-control study was conducted to assess the relationships between anthropometric variables and breast cancer risk in Tehran, Iran.

Methods

All incident cases of breast cancer in the Iranian Centre for Breast Cancer (ICBC) were identified through the case records. Eligible cases were all postmenopausal women with histological confirmed diagnosis of breast cancer during 1996 to year 2000. Controls were randomly selected postmenopausal women attending the ICBC for clinical breast examination during the same period. The body mass index (BMI) was calculated based on weights and heights as measured by the ICBC nursing staff. Both tests for trend and logistic regression analysis were performed to calculate odds ratios and 95% confidence intervals as measures of relative risk.

Results

In all, 116 breast cancer cases and 116 controls were studied. There were no significant differences between cases and control with regard to most independent variables studied. However, a significant difference was observed between cases and controls indicating that the mean BMI was higher in cases as compared to controls (P = 0.004). Performing logistic regression analysis while controlling for age, age at menopause, family history of breast cancer and parity, the results showed that women with a BMI in the obese range had a three fold increased risk of breast cancer [odds ratio (OR) = 3.21, 95% confidence interval (CI): 1.15–8.47].

Conclusion

The results suggest that obesity in postmenopausal women could increase risk of breast cancer and it merits further investigation in populations such as Iran where it seems that many women are short in height, and have a relatively high body mass index.

Modifying effects of IL-6 polymorphisms on body size-associated breast cancer risk

OBJECTIVE

The association between obesity and breast cancer risk is complex. We examined whether the association between body size and breast cancer risk is modified by interleukin-6 (IL6) genotype.

METHODS AND PROCEDURES

Five polymorphisms in the IL-6 gene (rs1800797/-596A>G, rs1800796/-572G>C, rs1800795/-174G>C, rs2069832/IVS2G>A, and rs2069849 exon 5 C>T) were studied. We investigated IL6 genotypes and haplotypes with indicators of body size among non-Hispanic white (NHW) and Hispanic/American Indian (AI) breast cancer cases and controls living in the Southwestern United States.

RESULTS

We observed lower mean levels of BMI among NHW women who carried one or two copies of the GGCAC haplotype (in order: rs1800797, rs1800796, rs1800795, rs2069832, and rs2069849; P trend 0.02). This haplotype, with an estimated frequency of 43% in NHW study controls, was considerably less common in Hispanic/AI controls (19%). We did not detect significant interactions between IL6 genotypes or haplotypes and BMI categorized as low/normal (<25), overweight (25 to <30), or obese (> or =30) and breast cancer risk in either NHW or Hispanic/AI women. However, we detected consistent and significant interactions between waist-to-hip ratio (WHR) and IL6 rs1800795/-174 G>C genotype for breast cancer risk. These associations were restricted to postmenopausal NHW women. Among women without recent hormone exposure, those with a WHR >0.9 and the rs1800795 GG genotype had a greater than threefold increased risk of breast cancer (odds ratios (ORs) 3.22, 95% confidence intervals (CIs) 1.27, 817) when compared with women with a WHR <0.8 and the rs1800795 GG genotype (P interaction 0.01).

DISCUSSION

These data suggest that IL-6 genotypes may influence breast cancer risk in conjunction with central adiposity.

Body size, weight change, fat distribution and breast cancer risk in Hispanic and non-Hispanic white women

INTRODUCTION

The incidence of breast cancer varies among women living in the Southwestern part of the US. We evaluate how body size influences breast cancer risk among these women.

METHODS

Cases (n = 2,325) diagnosed with breast cancer between October 1, 1999 and May 2004 residing in Arizona, Colorado, New Mexico, or Utah were matched to controls (n = 2,525). Participants were interviewed; height, weight, waist, and hip circumference were measured at the time of interview; blood was drawn.

RESULTS

A large body mass index (BMI) at age 15 was inversely associated with pre-menopausal breast cancer risk in both non-Hispanic white (NHW) and Hispanic women (Odds ratio, ORs 0.68 95% CI 0.44, 1.04, and 0.65 95% CI 0.39, 1.08, respectively); BMI at age 15 also had an impact on subsequent breast cancer associated with obesity after menopause. Among post-menopausal women, recent exposure to hormones was an important modifier of risk associated with body size. Among women not recently exposed to hormones risk associated with obesity was 1.61 (95% CI 1.05, 2.45) for NHW women; gaining > or = 25 kg between 15 and age 50 was inversely associated with breast cancer among Hispanic women (OR 0.51, 95% CI 0.23, 1.14). A large weight gain and a large waist-to-hip ratio (WHR) was associated with an increased odds of having an estrogen receptor negative tumor among NHW only (OR 1.81, 95% CI 1.07, 3.08, and 2.04 95% CI 1.20,3.50).

CONCLUSIONS

These findings suggest that the metabolic consequences of obesity on breast cancer risk differ between NHW and Hispanic women living in the Southwest.

Lifetime adult weight gain, central adiposity, and the risk of pre- and postmenopausal breast cancer in the Western New York exposures and breast cancer study

While there are quite consistent data regarding associations of body weight and postmenopausal breast cancer, there are now accumulating data that would indicate that weight gain in adult life is more predictive of risk than absolute body weight. There is, however, little known about the relative impact of timing of weight gain in adult life as well as other characteristics of the weight and breast cancer association that might provide insight into the mechanism of the observation. We conducted a population-based case control study of breast cancer (1996-2001), the Western New York Exposures and Breast Cancer Study. Included were 1,166 women with primary, histologically confirmed, incident breast cancer and 2,105 controls frequency-matched on age, race and county of residence. Unconditional logistic regression was used to estimate odds ratios and 95% confidence intervals. We found increased risk of breast cancer associated with lifetime adult weight gain among post- but not premenopausal women, and there was a 4% increase in risk for each 5 kg increase in adult weight. Further there was a tendency toward a stronger association for those with higher waist circumference and those with positive estrogen or progesterone status, and who had never used HRT. We also found an association with risk for weight gain since first pregnancy and for weight gain between the time of the first pregnancy and menopause, independent of body mass index and lifetime adult weight gain. Our results suggest that there are time periods of weight gain that have greater impact on risk, and that central body fat, receptor status and hormone replacement therapy may all affect the observed association.

Ethnic differences in cause specific mortality among hospitalised patients with diabetes: a linkage study in New Zealand

STUDY OBJECTIVE

To describe patterns of excess mortality among patients with diabetes in three ethnic groups.

DESIGN

A linkage study of national hospital discharge records to death records.

SETTING

New Zealand.

PARTICIPANTS

The study included 74 847 patients (11,268 Māori, 5730 Pacific, and 57,849 non-Māori/non-Pacific) aged over 25 years with a hospital discharge diagnosis of diabetes between 1988 and 2001. By the end of 2001, 29,295 (39%) of the cohort had died. Based on the underlying cause of death, standardised mortality ratios (SMRs) (95% confidence intervals) were calculated for each ethnic group and sex.

MAIN RESULTS

Comparing the mortality patterns of patients with diabetes to the general population of the same ethnic group, adjusting for age and calendar period, all cause SMRs were higher for Māori women and men: 3.80 (95% CI: 3.64 to 3.97) and 3.44 (95%CI: 3.30 to 3.58) than for Pacific (men: 2.41 (95%CI: 2.21 to 2.61); women: 2.23 (95%CI: 2.06 to 2.41)) and non-Māori/non-Pacific (men: 2.98 (95%CI: 2.93 to 3.04); women: 2.99 (95%CI: 2.93 to 3.04)) people. SMRs were significantly raised for several causes of death, including cardiovascular disease and many site specific cancers.

CONCLUSIONS

The pattern of excess mortality among Māori with diabetes may relate to severity of disease. This needs further investigation, as the excess mortality may be amenable to intervention.

A case-control study evaluating the association of purposeful physical activity, body fat distribution, and steroid hormones on premenopausal breast cancer risk

The objective of this case-control study was to investigate the relationship between purposeful physical activity, body fat distribution, body mass index, and steroid hormones. These factors are known to be implicated in modulating breast cancer risk in premenopausal women. A total of 112 newly diagnosed, premenopausal breast cancer patients and 106 age-matched premenopausal disease-free controls were admitted to the study. Information regarding personal, medical, hormonal, and reproductive history, smoking and alcohol use, physical activity history, and anthropometric measurements was obtained. Serum samples for steroid hormone assays were collected and analyzed. Disease-free premenopausal controls had a significantly higher physical activity index (PAI) (p</=0.05), however, significantly higher weight (p</=0.05), body mass index (BMI) (p=0.01), waist (p</=0.005) and hip (p</=0.05) circumferences, waist:hip ratios (p</=0.05), and serum total estradiol levels (p<0.0005) were observed in cancer cases. The final model using stepwise logistic regression analysis indicates that the variables that significantly predicted breast cancer risk were waist:hip ratio (odds ratio [OR]=1.11, p</=0.005) and serum total estradiol levels (OR=1.03, p</=0.0001). Our study provides some evidence that purposeful physical activity may reduce upper body fat distribution associated with adult weight gain. This may be a result of alterations in the steroid hormone pathway, such as reduced estradiol levels. This demonstrates the potential mechanism through which increased physical activity can reduce the risk for breast cancer in premenopausal women.

Changes in body weight and the risk of breast cancer in BRCA1 and BRCA2 mutation carriers

BACKGROUND

Several anthropometric measures have been found to be associated with the risk of breast cancer. Current weight, body mass index, and adult weight gain appear to be predictors of postmenopausal breast cancer. These factors have been associated with a reduced risk of premenopausal breast cancer. We asked whether there is an association between changes in body weight and the risk of breast cancer in women who carry a mutation in either breast cancer susceptibility gene, BRCA1 or BRCA2.

METHODS

A matched case-control study was conducted in 1,073 pairs of women carrying a deleterious mutation in either BRCA1 (n = 797 pairs) or BRCA2 (n = 276 pairs). Women diagnosed with breast cancer were matched to control subjects by year of birth, mutation, country of residence, and history of ovarian cancer. Information about weight was derived from a questionnaire routinely administered to women who were carriers of a mutation in either gene. Conditional logistic regression was used to estimate the association between weight gain or loss and the risk of breast cancer, stratified by age at diagnosis or menopausal status.

RESULTS

A loss of at least 10 pounds in the period from age 18 to 30 years was associated with a decreased risk of breast cancer between age 30 and 49 (odds ratio (OR) = 0.47; 95% confidence interval (CI) 0.28-0.79); weight gain during the same interval did not influence the overall risk. Among the subgroup of BRCA1 mutation carriers who had at least two children, weight gain of more than 10 pounds between age 18 and 30 was associated with an increased risk of breast cancer diagnosed between age 30 and 40 (OR = 1.44, 95% CI 1.01-2.04). Change in body weight later in life (at age 30 to 40) did not influence the risk of either premenopausal or postmenopausal breast cancer.

CONCLUSION

The results from this study suggest that weight loss in early adult life (age 18 to 30) protects against early-onset BRCA-associated breast cancers. Weight gain should also be avoided, particularly among BRCA1 mutation carriers who elect to have at least two pregnancies.

Number of children and the risk of obesity in older women

BACKGROUND

The purpose of this study is to examine number of live births, other reproductive factors, and health behaviors in relation to obesity risk among older women.

METHODS

Data were collected during in-person and telephone-based interviews from a population-based cohort in Utah.

RESULTS

A total of 2,035 women aged 66-102 are included in this report. Overall, 403 (20%) older women were determined to be obese. The rates of obesity were significantly higher with increasing numbers of children, demonstrating a dose-response relationship (P < 0.05). After adjustment for age, education, marital status, BMI at age 18, use of oral contraceptives, hysterectomy status, physical activity, current use of hormone therapy, and age at menarche, the risk of obesity increased 11% with each additional live birth. In additional analyses that excluded nulliparous women, after adjusting for cumulative months of breast-feeding, the risk of obesity increased 7% with each live birth. In this cohort of older women, we found higher rates of obesity with increasing number of children that was independent of socioeconomic status and other confounding factors.

CONCLUSIONS

In a cohort of older women, higher rates of obesity were associated with increasing number of children that was independent of socioeconomic status and other confounding factors.

Weight Change and the Risk of Late-Onset Breast Cancer in the Original Framingham Cohort

OBJECTIVE

Adult weight gain has been associated with a twofold risk of postmenopausal breast cancer. Data are limited regarding whether weight gain at specific periods of marked changes in estrogen- and insulin-related hormones have different risk associations. This study assesses the relation of adult weight change overall and at specific, hormonally relevant times with diagnosis of a first breast cancer after age 55 (late onset).

METHODS

Framingham study data were used to assess premenopausal (25-44 yr), perimenopausal (45-55 yr), postmenopausal (after 55 yr), and adult lifetime (from 25 yr) weight change in relation to late-onset breast cancer in 2,873 women followed for up to 48 yr, with 206 late-onset breast cancers.

RESULTS

Adult lifetime weight gain was associated with an increased risk of late-onset breast cancer (P trend = 0.046). Weight gain during specific time periods was not associated with breast cancer. Data suggested a possible decreased risk of breast cancer with weight loss from ages 25 to 44 and 45 to 55 yr (relative risk = 0.4 [0.2-1.2] and 0.5 [0.3-0.9], respectively).

CONCLUSION

These data confirm prior reports of an association between adult lifetime weight gain and increased risk of late-onset breast cancer and support current recommendations to avoid adult weight gain.

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

Associations between childhood BMI and adult cancer risk were investigated in a historical cohort study based on the Carnegie ("Boyd Orr") Survey of Diet and Health in Pre-War Britain (1937-9). In 14 centres in England and Scotland, children had their height and weight measured. We included 2,347 individuals aged between 2 and 14 years 9 months at the time of measurement, who were traced through the National Health Service Central Register. Relative cancer risk (registration or death) was estimated in relation to age- and sex-specific BMI SD scores. We studied associations with (i) all cancers, (ii) cancer groups stratified according to their relationship to smoking and (iii) certain site-specific cancers. In the 50 years of follow-up, 188 men and 192 women developed cancer. There was a 9% increase (95% CI -3 to 22%) in risk of cancer in adulthood per SD increase in BMI measured in childhood. There was no evidence of confounding by childhood or adulthood socioeconomic position, other anthropometric variables, childhood energy intake or birth order. There was a 30% increase (95% CI 10-54%) in risk of smoking-related cancers per SD increase in childhood BMI. There was no relationship between BMI and cancers not related to smoking. Associations for all cancers and non-smoking-related cancers tended to be stronger in children who were measured at an older (>8 years) rather than a younger (< or =8 years) age. We conclude that childhood BMI is related to increased risk of cancer in later life, particularly smoking-related cancers.

Number of Children Associated with Obesity in Middle-Aged Women and Men: Results from the Health and Retirement Study

OBJECTIVE

To study associations between number of children and obesity in middle-aged women and men.

METHODS

In the Health and Retirement Study, a national survey of households, we tested the association between increasing number of children and obesity (body mass index [BMI] >or= 30) in 9046 middle-aged women and men (4523 couples).

RESULTS

Women (n = 4523) who were obese were more frequently nonwhite, reported lower household income, were more frequently employed outside the home, were less frequently covered by health insurance, and were more frequently less educated compared with nonobese women. Men (n = 4523) who were obese were younger, were more frequently African American, and were more frequently less educated and poorer compared with nonobese men. Among women, a 7% increase in risk of obesity was noted for each additional child, adjusting for age, race, household income, work status, physical activity, tobacco use, and alcohol use. Among men, a 4% increase in risk of obesity was noted for each additional child, adjusting for the same covariates. These sex differences were not significantly different.

CONCLUSIONS

Previous research has demonstrated an association between number of children and obesity among women. These results suggest a similar association among men. Public health interventions focused on obesity prevention should target both parents, especially those parents with several children.

Breast cancer and obesity: an update

Obesity has a complicated relationship to both breast cancer risk and the clinical behavior of the established disease. In postmenopausal women, particularly the elderly, various measures of obesity have been positively associated with risk. However, before menopause increased body weight is inversely related to breast cancer risk. In both premenopausal and postmenopausal breast cancer, the mechanisms by which body weight and obesity affect risk have been related to estrogenic activity. Obesity has also been related to advanced disease at diagnosis and with a poor prognosis in both premenopausal and postmenopausal breast cancer. Breast cancer in African-American women, considering its relationship to obesity, exhibits some important differences from those described in white women, although the high prevalence of obesity in African-American women may contribute to the relatively poor prognosis compared with white American women. Despite the emphasis on estrogens to explain the effects of obesity on breast cancer, other factors may prove to be equally or more important, particularly as they relate to expression of an aggressive tumor phenotype. Among these, this review serves to stress insulin, insulin-like growth factor-I, and leptin, and their relationship to angiogenesis, and transcriptional factors.

Body mass index in early and mid-adulthood, and subsequent mortality: a historical cohort study

BACKGROUND

The aim of this study was to investigate the associations between body mass index (BMI) in early and mid-adulthood, and BMI change between these ages, and mortality.

METHODS

Historical cohort study of 629 men, who had height and weight measured at the Student Health Service of the University of Glasgow in 1948-1949 (median age 22 y) and who reported their weight in a postal questionnaire in 1963-1966 (median age 38 y). The participants were followed up until April 2002 (mean follow-up: 35 y). During this time, 124 men died, 68 of cardiovascular disease (CVD) and 33 of cancer.

FINDINGS

Mean BMI increased from 21.4 kg/m(2) (standard deviation (s.d.): 2.2 kg/m(2)) in early adulthood to 24.2 kg/m(2) (s.d.: 3.0 kg/m(2)) in mid-adulthood. All-cause mortality was associated with being overweight (BMI> or =25 kg/m(2)) at age 22 but not at age 38, adjusted hazard ratio (HR): 1.85 (95% confidence interval (CI) 1.09-3.13) and 1.05 (95% CI: 0.73-1.52), respectively. BMI at age 22 y was more strongly associated with CVD mortality than was BMI at age 38 y, adjusted HR(22 y): 2.41 (95% CI: 1.26-4.60) and HR(38 y): 1.33 (95% CI: 0.82-2.16). There was no clear relationship between cancer mortality and BMI at either age: HR(22 y): 0.68 (95% CI: 0.16-2.91), HR(38 y): 0.90 (95% CI: 0.44-1.84), although relatively few men died of cancer in the follow-up period. Similar patterns were seen for obesity (BMI> or =30 kg/m(2)) as for being overweight. Analyses of weight patterns indicated particularly detrimental effects of overweight persisting from early to mid-adulthood.

CONCLUSIONS

BMI in early adulthood is positively related to CVD mortality in later life in men. The risk associated with early adulthood adiposity appeared to be greater than that in mid-adulthood. We did not demonstrate an association between weight gain and later mortality. These results reinforce the need to stem the obesity epidemic in children and young adults.

BRCA1 interacts with acetyl-CoA carboxylase through its tandem of BRCT domains

Germ-line alterations in BRCA1 are associated with an increased susceptibility to breast and ovarian cancer. BRCA1 is a 220-kDa protein that contains a tandem of two BRCA1 C-Terminal (BRCT) domains. Among missense and nonsense BRCA1 mutations responsible for family breast cancer, some are located into the BRCT tandem of BRCA1 coding sequence. In an attempt to understand how BRCT is critical for BRCA1 function, we search for partners of this BRCT tandem of BRCA1. Using a glutathione-S-transferase (GST) pull-down assay with murine cells, we isolated only one major BRCA1-interacting protein, further identified as Acetyl Coenzyme A (CoA) Carboxylase alpha (ACCA). We showed that this interaction is conserved through murine and human species. We also delineated the minimum interacting region as being the whole tandem of BRCT domains. We demonstrated that BRCA1 interacts in vitro and in vivo with ACCA. This interaction is completely abolished by five distinct germline BRCA1 deleterious mutations affecting the BRCT tandem of BRCA1. Interestingly, ACCA originally known as a rate-limiting enzyme for fatty acids biosynthesis, has been recently shown to be over-expressed in breast cancers and considered as a potential target for anti-neoplastic therapy. Furthermore, our observation is making a bridge between the genetic factors involved in susceptibility to breast and ovarian cancers, and environmental factors such as nutrition considered as key elements in the etiology of those cancers.

Review of anthropometric factors and breast cancer risk

Epidemiological evidence implicating anthropometric risk factors in breast cancer aetiology is accumulating. For premenopausal women, breast cancer risk increases with increasing height, but decreases with higher weight or body mass index, and no association with increased central adiposity exists. For postmenopausal women, an increased risk of breast cancer is found with increasing levels of all the anthropometric variables including height, weight, body mass index, waist-hip ratio, waist circumference and weight gain. Weight loss appears to decrease risk, particularly if it occurs later in life. Breast size may be a risk factor for breast cancer, however, the current evidence is inconclusive. Several hypothesized biologic mechanisms exist to explain how anthropometric factors influence breast cancer risk. Obesity may increase levels of circulating endogenous sex hormones, insulin and insulin-like growth factors that all, in turn, increase breast cancer risk. Genetic predisposition to obesity and to specific body fat distributions are also implicated. With obesity, there are increased levels of fat tissue that can store toxins and can serve as a continuous source of carcinogens. Recommendations for future research on anthropometric factors and breast cancer are provided. Sufficient evidence exists to support strategies to avoid weight gain throughout life as a means of reducing postmenopausal breast cancer risk.

Android obesity at diagnosis and breast carcinoma survival: Evaluation of the effects of anthropometric variables at diagnosis, including body composition and body fat distribution and weight gain during life span,and survival from breast carcinoma

BACKGROUND

Although a large body of research exists concerning pathologic prognostic indicators of the rate of incidence and survival from breast carcinoma, to the authors' knowledge very few studies have examined the effects of anthropometric variables such as height, obesity, weight gain in adulthood, timing of weight gain, and body composition to survival, although these variables are related to the incidence rate.

METHODS

The survival status of 166 patients diagnosed with primary breast carcinoma and followed for at least 10 years was obtained from the Cancer Center's registry, and significant anthropometric and other known prognostic indicators regarding survival after diagnosis were determined by Cox proportional hazards analysis.

RESULTS

Eighty-three of 166 breast carcinoma patients (50%) with up to 10 years of follow-up died of disease. Android body fat distribution, as indicated by a higher suprailiac:thigh ratio, was a statistically significant (P < 0.0001) prognostic indicator for survival after controlling for stage of disease, with a hazards ratio of 2.6 (95% confidence interval [95% CI], 1.63-4.17). Adult weight gain, as indicated specifically by weight at age 30 years, was a statistically significant (P < 0.05) prognostic indicator for survival with a hazards ratio of 1.15 (95% CI, 1.0-1.28). In addition, the authors observed the Quatelet Index, a negatively significant (P < 0.01) prognostic indicator for survival with a hazards ratio of 0.92 (95% CI, 0.87-0.98). Other markers of general obesity such as weight at diagnosis, percent body fat, and body surface area were not significant markers influencing survival. Similarly, height; triceps, biceps; subscapular, suprailiac, abdominal, and thigh skinfolds; waist and hip circumferences; family history; and reproductive and hormonal variables at the time of diagnosis showed no apparent significant relation to survival.

CONCLUSIONS

The results of the current study provide some evidence that android body fat distribution at diagnosis and increased weight at age 30 years increases a woman's risk of dying of breast carcinoma.

Obesidade: atualização sobre sua etiologia, morbidade e tratamento

As tendências de transição nutricional ocorridas neste século direcionam para uma dieta mais ocidentalizada, a qual, aliada à diminuição progressiva da atividade física, converge para o aumento no número de casos de obesidade em todo o mundo. Isso representa aumento na morbidade e na mortalidade associadas à obesidade, já que esta é fator de risco para várias doenças como diabetes tipo II, hipertensão, doenças cardiovasculares e cálculo na vesícula biliar. A obesidade se apresenta não apenas como problema científico e de saúde pública, porém como grande indústria que envolve o desenvolvimento de fármacos, de alimentos modificados e estratégias governamentais estimulando a prática regular de atividade física e a orientação alimentar a fim de promover melhores hábitos. Assim, o conhecimento das causas e estratégias preventivas da obesidade é o objeto de estudo de pesquisadores de diferentes centros. Esse artigo tem como objetivo rever esses estudos, abordando o aumento na prevalência e incidência da obesidade, doenças relacionadas ao excesso de peso e os tratamentos para redução da gordura corporal.

Melancholic depression and abdominal fat distribution: a mini-review

Fat is stored around the abdomen in both subcutaneous and intra abdominal (visceral) sites. Visceral fat is associated in its own right with a set of metabolic abnormalities, including non insulin dependent diabetes, hypertension and dyslipidaemias. States of marked hypercortisolaemia, for example Cushing's syndrome, lead to the preferential accumulation of visceral fat. Since melancholic depression is known to be associated with elevated plasma Cortisol levels, this review explores whether depressed patients are prone to excess visceral fat storage, with the subsequent risk of developing the associated metabolic disturbances. Though the literature is limited, there is evidence that intra abdominal fat is increased in major depression. There is also evidence that depression is associated with increased risk of death from cardiovascular disease. Is visceral fat and its association with metabolic abnormalities the link between depression and physical illness?

Obesity: evaluation and treatment

Obesity as a chronic condition among large numbers of people is a disease of recent origin, often but by no means always associated with dietary habits and sedentary lifestyle. Many obese people want to lose weight, and may have tried to do so numerous times with self-help or proprietary weight-loss programs. When they seek a physician for help in losing weight-or when a physician advises an obese patient to lose weight as part of a clinical strategy-care must be taken to "match" the patient to an appropriate therapeutic program with appropriate therapeutic goals. History and physical examination and psychologic evaluation are essential elements of patient screening. Complications of obesity must be taken into account in any treatment plan. The multidisciplinary management strategy is most likely to succeed in helping the patient lose weight. It also avoids untoward events associated with complications or concomitant disease. The multidisciplinary approach is especially important when the patient does not lose weight, and alternative strategies must be considered, such as surgical approaches.

Can supplementary dietary fibre suppress breast cancer growth?

Case-control studies in diverse populations around the world have reported a lower risk of breast cancer in association with higher intake of dietary fibre and complex carbohydrates. Although this has not been confirmed in prospective studies in the USA, the observations have prompted the hypothesis that prolonged use of dietary fibre supplements might reduce breast cancer risk in high-incidence populations. Several possible mechanisms of action have been suggested, all involving a reduction of bioactive oestrogen levels in the blood. The various mechanisms are not necessarily mutually exclusive. First, a high-fibre diet might reduce circulating oestrogen levels by reducing the enterohepatic recirculation of oestrogen. Second, many plants and vegetables contain isoflavones and lignans capable of conversion in the bowel into weak oestrogens that may compete with oestradiol for target binding-sites. Third, a high-fibre diet is less often associated with obesity, which tends to increase availability of the biologically active 16-alpha metabolites of oestrone. Fourth, a high-fibre diet usually has a lower content of fat and a higher content of antioxidant vitamins, which may protect against breast cancer risk. Finally, diets rich in fibre and complex carbohydrates have been shown to improve insulin sensitivity, with an associated reduction in circulating oestrogen levels. Synergism between these effects offers a possible mechanism by which a high fibre intake might suppress breast cancer growth in women.