Association of body size and fat distribution with risk of breast cancer among Chinese women

The relationship between central obesity and risk of breast cancer: a dose-response meta-analysis of 7,989,315 women

Purpose

Central obesity may contribute to breast cancer (BC); however, there is no dose-response relationship. This meta-analysis examined the effects of central obesity on BC and their potential dose-response relationship.

Methods

In the present study, PubMed, Medline, Embase, and Web of Science were searched on 1 August 2022 for published articles. We included the prospective cohort and case-control studies that reported the relationship between central obesity and BC. Summary effect size estimates were expressed as risk ratios (RRs) or odds ratios (ORs) with 95% confidence intervals (95% CI) and were evaluated using random-effect models. The inconsistency index (I2) was used to quantify the heterogeneity magnitude derived from the random-effects Mantel-Haenszel model.

Results

This meta-analysis included 57 studies (26 case-control and 31 prospective cohort) as of August 2022. Case-control studies indicated that waist circumference (WC) (adjusted OR = 1.18; 95% CI: 1.00-1.38; P = 0.051) and waist-to-hip ratio (WHR) (adjusted OR = 1.28; 95% CI: 1.07-1.53; P = 0.008) were significantly positively related to BC. Subgroup analysis showed that central obesity measured by WC increased the premenopausal (adjusted OR = 1.15; 95% CI: 0.99-1.34; P = 0.063) and postmenopausal (adjusted OR = 1.18; 95% CI: 1.03-1.36; P = 0.018) BC risk and the same relationship appeared in WHR between premenopausal (adjusted OR = 1.38; 95% CI: 1.19-1.59; P < 0.001) and postmenopausal (adjusted OR = 1.41; 95% CI: 1.22-1.64; P < 0.001). The same relationship was observed in hormone receptor-positive (HR+) (adjusted ORWC = 1.26; 95% CI: 1.02-1.57; P = 0.035, adjusted ORWHR = 1.41; 95% CI: 1.00-1.98; P = 0.051) and hormone receptor-negative (HR-) (adjusted ORWC = 1.44; 95% CI: 1.13-1.83; P = 0.003, adjusted ORWHR = 1.42; 95% CI: 0.95-2.13; P = 0.087) BCs. Prospective cohort studies indicated that high WC (adjusted RR = 1.12; 95% CI: 1.08-1.16; P < 0.001) and WHR (adjusted RR = 1.05; 95% CI: 1.018-1.09; P = 0.017) may increase BC risk. Subgroup analysis demonstrated a significant correlation during premenopausal (adjusted RR = 1.08; 95% CI: 1.02-1.14; P = 0.007) and postmenopausal (adjusted RR = 1.14; 95% CI: 1.10-1.19; P < 0.001) between BC and central obesity measured by WC, and WHR was significantly positively related to BC both premenopausal (adjusted RRpre = 1.04; 95% CI: 0.98-1.11; P = 0.169) and postmenopausal (adjusted RRpost = 1.04; 95% CI: 1.02-1.07; P = 0.002). Regarding molecular subtype, central obesity was significantly associated with HR+ (adjusted ORWC = 1.13; 95% CI: 1.07-1.19; P < 0.001, adjusted ORWHR = 1.03; 95% CI: 0.98-1.07; P = 0.244) and HR- BCs (adjusted ORWC =1.11; 95% CI: 0.99-1.24; P = 0.086, adjusted ORWHR =1.01; 95% CI: 0.91-1.13; P = 0.808). Our dose-response analysis revealed a J-shaped trend in the relationship between central obesity and BC (measured by WC and WHR) in case-control studies and an inverted J-shaped trend between BMI (during premenopausal) and BC in the prospective cohort.

Conclusion

Central obesity is a risk factor for premenopausal and postmenopausal BC, and WC and WHR may predict it. Regarding the BC subtype, central obesity is proven to be a risk of ER+ and ER- BCs. The dose-response analysis revealed that when BMI (during premenopausal) exceeded 23.40 kg/m2, the risk of BC began to decrease, and WC higher than 83.80 cm or WHR exceeded 0.78 could efficiently increase the BC risk.

Systematic review registration

https://www.crd.york.ac.uk/PROSPERO/, identifier: CRD42022365788.

Predictive models for overall survival in breast cancer patients with a second primary malignancy: a real-world study in Shanghai, China

BACKGROUND

The incidents of second primary malignancy (SPM) is increasing among breast cancer (BC) patients with long-term progression, adversely affecting survival. The purpose of this study was to screen independent overall survival (OS) risk factors and establish nomograms to predict the survival probabilities of BC patients with SPM.

METHOD

A total of 163 BC patients with SPM were recruited during 2002-2015 from a total of 50 hospitals in Shanghai, China. Two nomograms to predict survival from primary BC and SPM diagnosis were constructed based on independent factors screened from multivariable analysis. The calibration and discrimination of nomograms were calculated in the training and validation cohorts.

RESULTS

The overall survival rates of BC patients with SPM were 88.34%, 64.42% and 54.66% at 5, 10 and 15 years, respectively. Factors of late TNM stage of SPM (HR = 4.68, 95% CI 2.14-10.25), surgery for SPM (HR = 0.60, 95% CI 0.36-1.00), SPM in the colon and rectum (HR = 0.49, 95% CI 0.25-0.98) and thyroid (HR = 0.08, 95% CI 0.01-0.61) independently affected the OS of BC patients with SPM (p < 0.05). In addition, a longer latency (≥ 5 years) was associated with better OS from BC diagnosis (p < 0.001). Older age (≥ 56) was associated with poor OS from SPM diagnosis (p = 0.019). Two nomograms established based on the above factors had better calibration and discrimination.

CONCLUSION

The TNM stage of SPM, surgery for SPM, SPM sites, latency and age at BC diagnosis are independent factors for survival and the two nomograms may provide more personalized management for BC patients with SPM.

OUP accepted manuscript

Background

Methods

Results

Conclusion

Knowledge of a cancer diagnosis is a protective factor for the survival of patients with breast cancer: a retrospective cohort study

BACKGROUND

The health burden of breast cancer is rising in China. The effect of informed diagnosis on long-term survival is not fully understood. This retrospective cohort study aims to explore the association between early informed diagnosis and survival time in breast cancer patients.

METHODS

A total of 12,327 breast cancer patients were enrolled between October 2002 and December 2016. Potential factors, including knowing the cancer diagnosis status, sex, age, clinical stage, surgery history, grade of reporting hospital and diagnostic year were, analyzed. We followed up all participants every 6 months until June 2017. Propensity score matching (PSM) was used to balance the clinicopathologic characteristics between patients who knew their diagnosis and those who did not.

RESULTS

By June 2017, 18.04% of the participants died of breast cancer. Before PSM, both the 3-year and 5-year survival rates of patients who knew their cancer diagnosis were longer (P < 0.001). After PSM, the above conclusion was still established. By stratified analysis, except for the subgroups of male patients and stage III patients, patients who knew their diagnosis showed a better prognosis in all the other subgroups (P < 0.05). Cox regression analysis showed that knowing a cancer diagnosis was an independent risk factor for survival in breast cancer patients (P < 0.001).

CONCLUSIONS

Being aware of their cancer diagnosis plays a protective role in extending the survival time of breast cancer patients, which suggests that medical staff and patients' families should disclose the cancer diagnosis to patients in a timely manner. Further prospective studies need to be made to validate our findings.

Women's cancers in China: a spatio-temporal epidemiology analysis

BACKGROUND

Women's cancers, represented by breast and gynecologic cancers, are emerging as a significant threat to women's health, while previous studies paid little attention to the spatial distribution of women's cancers. This study aims to conduct a spatio-temporal epidemiology analysis on breast, cervical and ovarian cancers in China, thus visualizing and comparing their epidemiologic trends and spatio-temporal changing patterns.

METHODS

Data on the incidence and mortality of women's cancers between January 2010 and December 2015 were obtained from the National Cancer Registry Annual Report. Linear tests and bar charts were used to visualize and compare the epidemiologic trends. Two complementary spatial statistics (Moran's I statistics and Kulldorff's space-time scan statistics) were adopted to identify the spatial-temporal clusters.

RESULTS

The results showed that the incidence and mortality of breast cancer displayed slow upward trends, while that of cervical cancer increase dramatically, and the mortality of ovarian cancer also showed a fast increasing trend. Significant differences were detected in incidence and mortality of breast, cervical and ovarian cancer across east, central and west China. The average incidence of breast cancer displayed a high-high cluster feature in part of north and east China, and the opposite traits occurred in southwest China. In the meantime, the average incidence and mortality of cervical cancer in central China revealed a high-high cluster feature, and that of ovarian cancer in northern China displayed a high-high cluster feature. Besides, the anomalous clusters were also detected based on the space-time scan statistics.

CONCLUSION

Regional differences were detected in the distribution of women's cancers in China. An effective response requires a package of coordinated actions that vary across localities regarding the spatio-temporal epidemics and local conditions.

Genetic Profiling of Breast Cancer with and Without Preexisting Metabolic Disease

Breast cancer is the most commonly diagnosed cancer and the leading cause of cancer death among women. Various mechanisms are involved in the initiation and progression of breast cancer. Metabolic dysregulation has been associated with increasing breast cancer incidence and mortality. However, little is known about how metabolic disease regulates the development and progression of breast cancer at the molecular level. Here, using a hybridization capture-based panel including 124 cancer-associated genes, we performed targeted next-generation sequencing of tumor tissues and matched blood samples from 20 postmenopausal patients with primary breast cancer, in which 6 cases suffered from preexisting metabolic disorders including hypertension, type 2 diabetes, and coronary heart disease. We took only the protein-altering variants and identified 170 somatic mutations of 59 genes. Among these, 40 mutated genes were found in the metabolic disease group, and 33 mutated genes were found in the non-metabolic disease group. Importantly, nonsynonymous mutations of 26 genes (MSH3, BRAF, MLH3, MTOR, DDR2, ALK, etc.) were uniquely present in the metabolic disease group. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes enrichment analysis were performed to investigate biological functions and key pathways of somatic mutations. TP53, PIK3CA, and PTEN were the top three commonly mutated genes at a higher frequency compared with the Cancer Genome Atlas (TCGA) data, and several novel but infrequent mutations in other genes were also found. Although further studies are required to validate these variants, our results are the first to suggest a specific molecular profile of breast cancer with preexisting metabolic disease.

Metabolic Syndrome, and Particularly the Hypertriglyceridemic-Waist Phenotype, Increases Breast Cancer Risk, and Adiponectin Is a Potential Mechanism: A Case-Control Study in Chinese Women

Objective: To investigate the association between metabolic syndrome and breast cancer and to elucidate the potential mechanism underlying this association. Patients and Methods: Based on baseline data drawn from 21 hospitals in 11 provinces of China, we performed a case-control study among 1,127 women (595 cases and 532 controls), divided into premenopausal, and postmenopausal subgroups. Student's t test, Pearson's χ² test, and logistic regression analyses were performed to ascertain the association between breast cancer and metabolic syndrome, including all of its components. In addition, we attempted to clarify the potential role of adiponectin in this association. Results: Among the components of metabolic syndrome, abnormal waist circumference was the component that markedly increased breast cancer risk in premenopausal women (OR 1.447, 95% CI 1.043-2.006). Metabolic syndrome with clusters of special risk factors showed an association with breast cancer risk. Among all these components of metabolic syndrome, the hypertriglyceridemic-waist (HW) phenotype significantly increased breast cancer risk (OR 1.56, 95% CI 1.02-2.39), regardless of menopausal status, rendering it a strong predictor of breast cancer. Total adiponectin levels and high-molecular-weight adiponectin were reversely associated with metabolic syndrome. In addition, total adiponectin levels among breast cancer patients were much lower than among controls (6.67 ± 3.05 vs. 8.01 ± 4.18, p = 0.014) only in the HW phenotype subgroup. Furthermore, the HW phenotype was associated with increased risk of estrogen receptor/progesterone receptor-positive (ER+/PR+) and -negative (ER-/PR-) breast cancer, with a 51% (OR 1.51, 95% CI 1.03-2.21) and 69% (OR 1.69, 95% CI 1.05-2.72) increase, respectively. However, there was no significant association between the HW phenotype and the ER+/PR- subtype. These results suggested that low adiponectin levels may be a mechanism that explains the association between the HW phenotype and breast cancer risk. Conclusion: Metabolic syndrome with special cluster factors is related to breast cancer risk; in particular, the HW phenotype can be regarded as a strong predictor of breast cancer. As an important factor involved in fat metabolism, adiponectin may strongly predict metabolic syndrome, especially the HW phenotype and breast cancer. Further research into this mechanism and epidemiological studies are needed. This study provides new evidence for the role of a healthy lifestyle in preventing breast cancer.

Adult weight change and the risk of pre- and postmenopausal breast cancer in the Chinese Wuxi Exposure and Breast Cancer Study

PURPOSE

The accumulating evidence indicates that weight gain in adulthood is more predictive of breast cancer risk than absolute body weight. However, the relative impact of timing of weight gain in adulthood on breast cancer as well as other characteristics of the association between weight and breast cancer has not been well documented.

METHODS

This population-based case-control study of breast cancer included 818 patients with newly diagnosed primary breast cancer and 935 residence and age-matched healthy controls. The body weight values at 18 years old, 1 year before diagnosis, and at menopause were obtained during in-person interviews. Unconditional logistic regression was used to estimate the effects of the weight change over adulthood on breast cancer risk. Linear mixed-effects regression was also applied as a secondary analysis.

RESULTS

We found that the increased risk of breast cancer was associated with the weight gain in adulthood among postmenopausal women (OR 1.23; 95% CI 1.10-1.37 per 5 kg increase) but not in the premenopausal women. The risk associated with weight gain since menopause (OR 1.65; 95% CI 1.28-2.14 a 5-kg increase) was higher than that from age 18 to menopause (OR 1.14; 95% CI 1.02, 1.28 a 5-kg increase). The association tended to be stronger in those with higher waist circumference and who had never used hormone replacement therapy (HRT). Women who had never used HRT, the increased risk of breast cancer associated with weight gain was more consistent in leaner women at age 18 (BMI < 18.5) or at menopause (BMI < 24).

CONCLUSIONS

Our findings indicated that weight gain has significant impact on postmenopausal breast cancer risk. The time periods of weight gain, central body fat, and HRT may affect the observed association, which should be further studied.

Adiposity, Inflammation, and Breast Cancer Pathogenesis in Asian Women

Obesity is associated with white adipose tissue (WAT) inflammation in the breast, elevated levels of the estrogen biosynthetic enzyme, aromatase, and systemic changes that predispose to breast cancer development. We examined whether WAT inflammation and its associated systemic effects correlate with body fat levels in an Asian population where body mass index (BMI) is not an accurate assessment of obesity and cancer risk. We also investigated whether biologic differences could account for the greater proportion of premenopausal estrogen receptor (ER)-positive breast cancer in Asian versus Western countries. Breast WAT and fasting blood were prospectively collected from Taiwanese women undergoing mastectomy for breast cancer treatment. Body composition was measured in a subgroup using bioelectrical impedance analysis. WAT inflammation was defined by the presence of crown-like structures of the breast, which are composed of dead or dying adipocytes surrounded by macrophages. Findings were compared with U.S. Caucasian women. In the Taiwanese cohort (n = 72), breast WAT inflammation was present in 31 (43%) women and was associated with elevated BMI (P < 0.01) and increased levels of body fat (P < 0.01), C-reactive protein (P = 0.02), triglycerides (P < 0.01), insulin resistance scores (P = 0.04), and lower HDL cholesterol (P < 0.01). ER+ tumors were associated with greater body fat versus other subtypes (P = 0.03). Compared with U.S. Caucasians (n = 267), Taiwanese women had larger breast adipocytes despite lower BMI after adjusting for BMI and menopausal status (P = 0.01). A subclinical inflammatory state associated with increased adiposity and metabolic dysfunction could contribute to breast cancer pathogenesis in Asian women. Cancer Prev Res; 11(4); 227-36. ©2017 AACR.

Body fatness at a young age, body fatness gain and risk of breast cancer: systematic review and meta-analysis of cohort studies

Higher body fatness in adulthood has been consistently associated with an increased risk of postmenopausal breast cancer, as well as a tendency towards a lower risk of premenopausal breast cancer. However, the association between body fatness at a young age (≤30 years), body fatness gain and the risk of breast cancer is less defined. PubMed and Web of Science databases were searched to identify relevant publications. Risk estimates with 95% confidence intervals from each study were transformed into a continuous variable for each 5 kg m^-2 increase in body mass index (BMI) and were pooled under a random-effects model. Each 5 kg m^-2 increase in BMI was significantly associated with a 14%, 12% and 17% lower risk of breast cancer later in life among all women, premenopausal women and postmenopausal women, respectively. Significant heterogeneity and publication bias were observed. The results remained unchanged after the trim and fill method was applied to correct the bias. Each 5 kg m^-2 increase in BMI from a young age until cohort entry was significantly associated with a 13% and 14% higher risk of breast cancer in all women and postmenopausal women, respectively. In summary, higher body fatness at a young age may have a protective role in the later development of breast cancer in both premenopausal and postmenopausal women. However, this potential benefit should not be overemphasized, as our findings suggest that increased body fatness gain from a young age is positively associated with postmenopausal breast cancer risk. These findings further justify the need to maintain a steady weight throughout life.

Traditional Breast Cancer Risk Factors in Filipina Americans Compared with Chinese and Japanese Americans in Los Angeles County

BACKGROUND

Filipina Americans have one of the highest breast cancer incidence rates among Asian Americans for poorly understood reasons.

METHODS

Breast cancer risk factors were investigated in a population-based study of Filipina (790 cases, 587 controls), Japanese (543 cases, 510 controls), and Chinese (913 cases, 904 controls) Americans. Cases were identified by the Los Angeles County Cancer Surveillance Program, and controls were matched to cases on age, ethnicity, and neighborhood. Multivariable conditional logistic regression was performed by Asian ethnicity.

RESULTS

In Filipina, Chinese, and Japanese Americans, breast cancer risk decreased significantly with increasing parity (all Ptrend < 0.0001). Breast cancer risk increased with increasing quartiles of cumulative menstrual months in premenopausal (Ptrend = 0.019) and postmenopausal Filipina (Ptrend = 0.008), in premenopausal (Ptrend = 0.0003) but not postmenopausal Chinese (Ptrend = 0.79), and in neither premenopausal (Ptrend = 0.092) nor postmenopausal (Ptrend = 0.75) Japanese Americans. For postmenopausal Filipina and Japanese, greater weight gain since age 18 (Ptrend = 0.019 and 0.053, respectively), high current body mass index (both Ptrend < 0.01), and greater waist circumferences (both Ptrend < 0.04) were statistically significant; these associations were weaker for postmenopausal Chinese women.

CONCLUSIONS

Cumulative menstrual months and body size factors were statistically significant risk factors for Filipina. Total menstrual months were associated with breast cancer among Chinese but not for Japanese, while body size factors were significantly associated with risk among Japanese but not among Chinese.

IMPACT

Characterization of breast cancer risk factors in Filipina will help to generate hypotheses for their high breast cancer incidence. Cancer Epidemiol Biomarkers Prev; 25(12); 1572-86. ©2016 AACR.

Central obesity increases risk of breast cancer irrespective of menopausal and hormonal receptor status in women of South Asian Ethnicity

BACKGROUND

Current evidence suggests that the relationship between obesity and breast cancer (BC) risk may vary between ethnic groups.

METHODS

A total of 1633 BC cases and 1504 controls were enrolled in hospital-based case-control study in Mumbai, India, from 2009 to 2013. Along with detailed questionnaire, we collected anthropometric measurements on all participants. We used unconditional logistic regression models to estimate odds ratios (ORs) and 95% confidence interval (CI) for BC risk associated with anthropometry measurements, stratified on tumour subtype and menopausal status.

RESULTS

Waist-to-hip ratio (WHR) of ≥0.95 was strongly associated with risk of BC compared to WHR ≤0.84 in both premenopausal (OR = 4.3; 95% CI: 2.9-6.3) and postmenopausal women (OR = 3.4; 95% CI: 2.4-4.8) after adjustment for body mass index (BMI). Premenopausal women with a BMI ≥30 were at lower risk compared to women with normal BMI (OR = 0.5; 95% CI: 0.4-0.8). A similar protective effect was observed in women who were postmenopausal for <10 years (OR = 0.6; 95% CI: 0.4-0.9) but not in women who were postmenopausal for ≥10 years (OR = 1.8; 95% CI: 1.1-3.3). Overweight and obese women (BMI: 25-29.9 and ≥ 30 kg/m(2), respectively) were at increased BC risk irrespective of menopausal status if their WHR ≥0.95. Central obesity (measured in terms of WC and WHR) increased the risk of both premenopausal and postmenopausal BCs irrespective of hormone receptor (HR) status.

CONCLUSIONS

Central obesity appears to be a key risk factor for BC irrespective of menopausal or HR status in Indian women with no history of hormone replacement therapy.

Temporal Trends in Geographical Variation in Breast Cancer Mortality in China, 1973-2005: An Analysis of Nationwide Surveys on Cause of Death

To describe geographical variation in breast cancer mortality over time, we analysed breast cancer mortality data from three retrospective national surveys on causes of death in recent decades in China. We first calculated the age-standardized mortality rate (ASMR) for each of the 31 provinces in mainland China stratified by survey period (1973-1975, 1990-1992 and 2004-2005). To test whether the geographical variation in breast cancer mortality changed over time, we then estimated the rate ratio (RR) for the aggregated data for seven regions and three economic zones using generalized linear models. Finally, we examined the correlation between mortality rate and several macro-economic measures at the provincial level. We found that the overall ASMR increased from 2.98 per 100,000 in 1973-1975 to 3.08 per 100,000 in 1990-1992, and to 3.85 per 100,000 in 2004-2005. Geographical variation in breast cancer mortality also increased significantly over time at the regional level (p = 0.002) but not at the economic zone (p = 0.089) level, with RR being generally lower for Western China (Northwest and Southwest) and higher in Northeast China over the three survey periods. These temporal and spatial trends in breast cancer mortality were found to be correlated with per capita gross domestic product, number of hospitals and health centres' beds per 10,000 population and number of practicing doctors per 10,000 population, and average number of live births for women aged 15-64. It may be necessary to target public health policies in China to address the widening geographic variation in breast cancer mortality, and to take steps to ensure that the ease of access and the quality of cancer care across the country is improved for all residents.

Descriptive epidemiology of breast cancer in China: incidence, mortality, survival and prevalence

Breast cancer is the most common neoplasm diagnosed amongst women worldwide and is the leading cause of female cancer death. However, breast cancer in China is not comprehensively understood compared with Westernised countries, although the 5-year prevalence statistics indicate that approximately 11 % of worldwide breast cancer occurs in China and that the incidence has increased rapidly in recent decades. This paper reviews the descriptive epidemiology of Chinese breast cancer in terms of incidence, mortality, survival and prevalence, and explores relevant factors such as age of manifestation and geographic locations. The statistics are compared with data from the Westernised world with particular emphasis on the United States and Australia. Potential causal agents responsible for differences in breast cancer epidemiology between Chinese and other populations are also explored. The need to minimise variability and discrepancies in methods of data acquisition, analysis and presentation is highlighted.

Body fatness throughout the life course and the incidence of premenopausal breast cancer

BACKGROUND

The role of body fatness in the aetiology of breast cancer is complex. We evaluated the independent and synergistic effects of body fatness, at different stages throughout a woman's life course, on premenopausal breast cancer risk.

METHODS

Premenopausal participants of the Nurses' Health Study II (NHSII) were followed from 1991 up to 2009. Body fatness factors including birthweight, somatotype (a 9-level pictogram with level 1 being the leanest) at ages 5 and 10 years and body mass index (BMI) at age 18 were collected at baseline. Current BMI was updated biennially. Multivariate Cox regression models were used to evaluate the association between each body fatness factor as well as cross-classification of all factors and the incidence of breast cancer.

RESULTS

Based on 1574 incident premenopausal breast cancer cases and 1 133 893 person-years of follow-up, a lower incidence was associated with lower birthweight: hazard ratio (HR) [95% confidence interval (CI)] = 0.74 (0.58-0.95) for <2.5kg vs 3.9+kg, P for trend < 0.001; higher somatotype at age 5: HR=0.57 (95% CI 0.44-0.73) for 5-9 vs 1, P fortrend < 0.0001]; and at age 10: HR=0.61 (95% CI 0.49-0.75) for 5-9 vs 1, P for trend < 0.0001]; and BMI at age 18: HR=0.67 (95% 0.47-0.95) for ≥ 27.5 kg/m² vs < 18.5 kg/m², P for trend = 0.009], after adjusting for age and body fatness measures earlier in life and other risk factors, respectively. No significant interaction between body fatness measures was found. Women with the lowest birthweight, the highest somatotype at ages 5 and 10 and the highest BMI at age 18 and currently had a 72% (95% CI 54%-83%) lower incidence of invasive premenopausal breast cancer than women with the opposite extreme of each body fatness indicator.

CONCLUSION

The lowest incidence of premenopausal breast cancer was associated with the lowest birthweight and the highest childhood, adolescent and early adult body fatness.

Understanding rural-urban differences in risk factors for breast cancer in an Indian population

PURPOSE

Although cancer registry data indicate that there are large differences in breast cancer (BC) rates between rural and urban regions of India, the reasons for these differences are not well understood.

METHODS

We conducted a hospital based case-control study (1,637 breast cancer cases; 1,515 visitor controls) in Mumbai, India, during the years 2009-2013. Extensive questionnaire data, anthropometry measurement and blood samples were collected on all participants. Using logistic regression models, we estimated risk based on odds ratio (OR) and 95 % confidence intervals (CI) for various reproductive and anthropometric measures, stratified by rural-urban status depending upon residence in first 20 years of life.

RESULTS

Waist-to-hip ratio of ≥0.95 compared to ratio ≤0.84 was strongly associated with risk of BC in both rural and urban populations (ORurban = 4.10, 95 % CI 3.03-5.56; ORrural = 3.01, 95 % CI 1.85-4.90). First full-term pregnancy after the age of 25 compared to first full-term pregnancy below 20 years of age was associated with risk of BC in both urban and rural women (ORurban = 1.78, 95 % CI 1.32-2.41; ORrural = 2.24, 95 % CI 1.13-4.43). The prevalence of age at first full-term pregnancy was significantly lower in rural (mean age at first full-term pregnancy = 19.39 years) versus urban women (mean age at first full-term pregnancy = 22.62 years), whereas mean waist circumference was much higher in urban women (82.13 cm) compared to rural women (79.26 cm). We did not observe any association between breast feeding and risk of BC.

CONCLUSIONS

Differences in the prevalence of central adiposity and age at first full-term pregnancy between rural and urban women from India may explain some differences in breast cancer rates between these two populations.

Racial and ethnic disparities in the impact of obesity on breast cancer risk and survival: a global perspective

Obesity is a global concern, affecting both developed and developing countries. Although there are large variations in obesity and breast cancer rates worldwide and across racial/ethnic groups, most studies evaluating the impact of obesity on breast cancer risk and survival have been conducted in non-Hispanic white women in the United States or Europe. Given the known racial/ethnic differences in tumor hormone receptor subtype distribution, obesity prevalence, and risk factor profiles, we reviewed published data for women of African, Hispanic, and Asian ancestry in the United States and their countries of origin. Although the data are limited, current evidence suggests a stronger adverse effect of obesity on breast cancer risk and survival in women of Asian ancestry. For African Americans and Hispanics, the strength of the associations appears to be more comparable to that of non-Hispanic whites, particularly when accounting for subtype and menopausal status. Central obesity seems to have a stronger impact in African-American women than general adiposity as measured by body mass index. International data from countries undergoing economic transition offer a unique opportunity to evaluate the impact of rapid weight gain on breast cancer. Such studies should take into account genetic ancestry, which may help elucidate differences in associations between ethnically admixed populations. Overall, additional large studies that use a variety of adiposity measures are needed, because the current evidence is based on few studies, most with limited statistical power. Future investigations of obesity biomarkers will be useful to understand possible racial/ethnic biological differences underlying the complex association between obesity and breast cancer development and progression.

Body mass index and breast cancer: analysis of a nation-wide population-based prospective cohort study on 1 393 985 Taiwanese women

BACKGROUND

Asian women have a younger age at onset of breast cancer and a lower body mass index (BMI) than Western women. The link between obesity and risk of breast cancer in Asian women is still elusive. We aimed to investigate the effect of BMI on the risk of incident breast cancer in Taiwanese women.

METHODS

A total of 1,393,985 women who had been cancer-free before recruitment and attended a nation-wide Taiwanese breast cancer-screening program between 1999 and 2009 were enrolled using a prospective cohort study. Obesity and other relevant variables (such as menopause status and other biochemical markers) were collected through in-person interviews, anthropometric measurements and blood samples at first screen. Incident breast cancers during follow-up were ascertained through the linkage of the cohort with the National Cancer Registry and the National Death Certification System.

RESULTS

A total of 6969 and 7039 incident breast cancer cases were identified among women enrolled before and after menopause, respectively. Compared with a BMI range of 18.5-23.9 kg m(-)(2), the incremental level of BMI in the enrolled women before menopause revealed a lack of statistically significant association with the risk of incident breast cancer (adjusted hazard ratio=0.94, 0.98, 1.02, 1.01 and 0.82 for BMI <18.5, 24-26.9, 27-29.9, 30-34.9 and ⩾35, respectively), but the incremental level of BMI in the enrolled women after menopause led to a statistically significant incremental increase in the risk of breast cancer (adjusted hazard ratio=0.78, 1.19, 1.31, 1.53 and 1.65 for BMI <18.5, 24-26.9, 27-29.9, 30-34.9 and ⩾35, respectively) after adjusting for other explanatory risk factors.

CONCLUSION

Obesity acts mainly as an influential promoter of the development of late-onset breast cancer after menopause in Taiwanese women.

Relationships between cancer pattern, country income and geographical region in Asia

BACKGROUND

Cancer incidence and mortality varies across region, sex and country's economic status. While most studies focused on global trends, this study aimed to describe and analyse cancer incidence and mortality in Asia, focusing on cancer site, sex, region and income status.

METHODS

Age-standardised incidence and mortality rates of cancer were extracted from the GLOBOCAN 2012 database. Cancer mortality to incidence ratios (MIRs) were calculated to represent cancer survival. The data were analysed based on the four regions in Asia and income.

RESULTS

Cancer incidence rate is lower in Asia compared to the West but for MIR, it is the reverse. In Asia, the most common cancers in men are lung, stomach, liver, colorectal and oesophageal cancers while the most common cancers in women are breast, lung, cervical, colorectal and stomach cancers. The MIRs are the highest in lung, liver and stomach cancers and the lowest in colorectal, breast and prostate cancers. Eastern and Western Asia have a higher incidence of cancer compared to South-Eastern and South-Central Asia but this pattern is the reverse for MIR. Cancer incidence rate increases with country income particularly in colorectal and breast cancers but the pattern is the opposite for MIR.

CONCLUSION

This study confirms that there is a wide variation in cancer incidence and mortality across Asia. This study is the first step towards documenting and explaining the changing cancer pattern in Asia in comparison to the rest of the world.

Breast cancer in China

The health burden of cancer is increasing in China, with more than 1·6 million people being diagnosed and 1·2 million people dying of the disease each year. As in most other countries, breast cancer is now the most common cancer in Chinese women; cases in China account for 12·2% of all newly diagnosed breast cancers and 9·6% of all deaths from breast cancer worldwide. China's proportional contribution to global rates is increasing rapidly because of the population's rising socioeconomic status and unique reproductive patterns. In this Review we present an overview of present control measures for breast cancer across China, and emphasise epidemiological and socioeconomic diversities and disparities in access to care for various subpopulations. We describe demographic differences between China and high-income countries, and also within geographical and socioeconomic regions of China. These disparities between China and high-income countries include younger age at onset of breast cancer; the unique one-child policy; lower rates of provision and uptake for screening for breast cancer; delays in diagnosis that result in more advanced stage of disease at presentation; inadequate resources; and a lack of awareness about breast cancer in the Chinese population. Finally, we recommend key measures that could contribute to improved health outcomes for patients with breast cancer in China.

Anthropometry, silhouette trajectory, and risk of breast cancer in Mexican women

BACKGROUND

Obesity has been associated with breast cancer risk in the Caucasian population but the association remains unclear in the Hispanics. Previous studies conducted among Hispanics in the U.S. have shown inconsistent results.

PURPOSE

The association between anthropometry, body shape evolution across lifetime, and the risk of breast cancer was assessed using a multi-center population-based case-control study conducted in Mexico.

METHODS

One thousand incident cases and 1074 matched control women aged 35-69 years were recruited between 2004 and 2007, and analyzed in 2011-2012. Conditional logistic regression models were used.

RESULTS

Height was related to an increased risk of breast cancer in both premenopausal (p trend=0.03) and postmenopausal women (p trend=0.002). In premenopausal women, increase in BMI; waist circumference (WC); hip circumference (HC); and waist-hip ratio (WHR) were inversely associated with breast cancer risk (p trends<0.001 for BMI and WC, 0.003 for HC, and 0.016 for WHR). In postmenopausal women, decreased risks were observed for increased WC (p trend=0.004) and HC (p trend=0.009) among women with time since menopause <10 years. Further analysis of body shape evolution throughout life showed strong and significant increase in risk of breast cancer among women with increasing silhouettes size over time compared to women with no or limited increase.

CONCLUSIONS

These findings suggest that anthropometric factors may have different associations with breast cancer risk in Hispanic women than in Caucasian women. This study also shows the importance of considering the evolution of body shape throughout life.

Cancer incidence in Jordan from 1996 to 2009--a comprehensive study

BACKGROUND

Cancer is a major health problem facing the entire world, and Jordan is no exception. However, patterns of cancer incidence and cancer burden in Jordan have never been explored thoroughly, and the aim of this study was to close this knowledge gap.

MATERIALS AND METHODS

The study was based on data obtained from the Jordan cancer registry from 1996 to 2009. All cancer cases that were diagnosed during the study period were registered and included in this study.

RESULTS

A total of 51,626 cases were registered in Jordan during the 14- year period. The incidence rate showed no significant increase in males (percent change PC 6.8%), while in females a marked increase was observed (PC 14.8%). The major cancer sites for males were bronchus and lung, colorectal, bladder, leukemia and prostate. In females, the leading cancer sites were breast, colorectal, leukemia, thyroid and NHL.

CONCLUSIONS

Compared to other countries in the region, Jordan has comparable rates. On the other hand the rates of cancer are markedly lower in Jordan compared to more industrialized countries such as the US and Europe. There was an overall increase in the incidence of cancer in Jordan, especially among females, which stresses the need for programs to raise awareness on the importance of early diagnosis and preventive life style measures.

Insulin and IGFs in obesity-related breast cancer

Obesity and the Metabolic Syndrome are associated with multiple factors that may cause an increased risk for cancer and cancer-related mortality. Factors involved include hyperinsulinemia, hyperglycemia, hyperlipidemia and IGFs. Insulin resistance is also associated with alterations in the levels of proinflammatory cytokines, chemokines, adipokines (leptin, adiponectin) that may also be contributing factors. The insulin family of proteins is ubiquitously expressed and has pleiotropic effects on metabolism and growth. However insulin, IGF-1 and particularly IGF-2 have been identified as tumor promoters in multiple studies. Mouse models have focused on insulin and IGF-1 and their receptors as being involved in tumor progression and metastases. The role of the insulin receptor as either mediating the effects on tumors or as compensating for the insulin-like growth factor receptor has arisen. Its role has been supported by preclinical studies and the importance of insulin resistance and hyperinsulinemia in obesity and early diabetes. Since the focus of this review is the insulin-family we will focus on insulin, IGF-1 and IGF-2.

Risk factors for breast cancer among Chinese women: a 10-year nationwide multicenter cross-sectional study

Background

The characteristics of established risk factors for breast cancer may vary among countries. A better understanding of local characteristics of risk factors may help in devising effective prevention strategies for breast cancer.

Methods

Information on exposures to risk factors was collected from the medical charts of 4211 women with breast cancer diagnosed during 1999–2008. The distributions of these exposures among regions, and by menopausal status and birth period, were compared with the χ² test. Crude associations between the selected factors and breast cancer were estimated using the cases in the present study and a representative control population, which was selected from qualified published studies.

Results

As compared with cases from less developed regions, those from more developed regions were significantly more likely to be nulliparous, had fewer childbirths (P < 0.05), and were less likely to have breastfed (P = 0.08). As compared with premenopausal cases, postmenopausal cases were more likely to be overweight and to have breastfed and had more childbirths (P < 0.05). The number of live births and rate of breastfeeding decreased in relation to birth period (P for trends <0.001). Overweight, late menopause, and family history of breast cancer were significantly associated with breast cancer among Chinese women.

Conclusions

Breast cancer incidence was associated with nulliparity and history of breastfeeding. Population attributable risks should be assessed, especially for more developed areas and young women. The effects of body mass index, age at menopause, and family history of breast cancer should be given priority during assessment of breast cancer risk among Chinese women.

Overweight, obesity and risk of premenopausal breast cancer according to ethnicity: a systematic review and dose-response meta-analysis

The association of overweight and obesity with premenopausal breast cancer remained unclear, ethnicity could play a role. A MEDLINE and PUBMED search of all studies on obesity and premenopausal breast cancer published from 2000 to 2010 was conducted. Dose-response meta-analysis was used to determine the risk of premenopausal breast cancer associated with different anthropometric measurements in different ethnic groups. For body mass index (BMI), each 5 kg m(-2) increase was inversely associated with the risk of premenopausal breast cancer (RR = 0.95, 95% confidence interval [CI]: 0.94, 0.97). After stratification by ethnicity, the inverse association remained significant only among Africans (RR = 0.95, 95% CI: 0.91, 0.98) and Caucasians (RR = 0.93, 95% CI: 0.91, 0.95). In contrast, among Asian women, a significant positive association was observed. For waist-to-hip ratio (WHR), each 0.1 unit increase was positively associated with premenopausal breast cancer (RR = 1.08, 95% CI: 1.01, 1.16); the largest effect was detected in Asian women (RR = 1.19, 95% CI: 1.15, 1.24), while small effects of 5% and 6% were observed in African and Caucasian women, respectively. Our results suggest the importance of considering both fat distribution and ethnicity when studying premenopausal breast cancer.

Risk factors for premenopausal breast cancer: a case-control study in Uruguay

In order to thoroughly analyze risk factors of breast cancer (BC) in premenopausal Uruguayan women, a case-control study was carried out at the Pereira Rossell Women's Hospital, Montevideo, where 253 incident BC cases and 497 frequency-matched healthy controls were interviewed on menstrual and reproductive story, were administered a short food frequency questionnaire and undertook a series of body measurements necessary to calculate body composition and somatotype. Odds ratio (OR) coefficients were taken as estimates of relative risk derived from unconditional logistic regression. Among the classical risk factors, only the family history of BC in first degree relatives was significantly associated with risk of premenopausal BC (OR=2.20, 95% CI 1.33-3.62). Interestingly, this risk factor was found to be stronger in women of ages >40 (OR=4.05, 95% CI 2.10-7.81), late menarche (OR= 2.39, 95% CI 1.18-4.85), early age for their first delivery (OR=3.02, 95% CI 1.26-7.22), short time between menarche and first delivery (OR=3.22, 95% CI 1.29-8.07), and with high parity (OR=4.10, 95% CI 1.79-9.36), although heterogeneity was detected only for age and parity. High consumption of red meat was positively associated with the disease risk (OR=2.20, 95% CI 1.35-3.60), in the same way as fried foods (OR=1.79, 95% CI 1.12-2.84). Conversely, a high intake of plant foods displayed a protective effect (OR=0.41, 95% CI 0.26-0.65). Except for hypertension (OR=1.55, 95% CI 1.03-2.35), none of the analyzed components of metabolic syndrome were associated to BC risk. Particular increases of risk for premenopausal BC were found for family history in first degree relatives in certain subsets derived from the menstrual-reproductive history. Preventive strategies could broaden their scope if new studies confirm the present results, in view of the limited prevention measures that premenopausal BC currently has.

Effect of body mass index on breast cancer during premenopausal and postmenopausal periods: a meta-analysis

OBJECTIVE

There is no universal consensus on the relationship between body mass index (BMI) and breast cancer. This meta-analysis was conducted to estimate the overall effect of overweight and obesity on breast cancer risk during pre- and post-menopausal period.

DATA SOURCES

All major electronic databases were searched until April 2012 including Web of Knowledge, Medline, Scopus, and ScienceDirect. Furthermore, the reference lists and related scientific conference databases were searched.

REVIEW METHODS

All prospective cohort and case-control studies investigating the association between BMI and breast cancer were retrieved irrespective of publication date and language. Women were assessed irrespective of age, race and marital status. The exposure of interest was BMI. The primary outcome of interest was all kinds of breast cancers confirmed pathologically. Study quality was assessed using the checklist of STROBE. Study selection and data extraction were performed by two authors separately. The effect measure of choice was risk ratio (RR(i)) and rate ratio (RR(a)) for cohort studies and odds ratio (OR) in case-control studies.

RESULTS

Of 9163 retrieved studies, 50 studies were included in meta-analysis including 15 cohort studies involving 2,104,203 subjects and 3,414,806 person-years and 35 case-control studies involving 71,216 subjects. There was an inverse but non-significant correlation between BMI and breast cancer risk during premenopausal period: OR = 0.93 (95% CI 0.86, 1.02); RR(i) = 0.97 (95% CI 0.82, 1.16); and RR(a) = 0.99 (95% CI 0.94, 1.05), but a direct and significant correlation during postmenopausal period: OR = 1.15 (95% CI 1.07, 1.24); RR(i) = 1.16 (95% CI 1.08, 1.25); and RR(a) = 0.98 (95% CI 0.88, 1.09).

CONCLUSION

The results of this meta-analysis showed that body mass index has no significant effect on the incidence of breast cancer during premenopausal period. On the other hand, overweight and obesity may have a minimal effect on breast cancer, although significant, but really small and not clinically so important.

Body fat distribution and breast cancer risk: findings from the Nigerian breast cancer study

PURPOSE

The relationship between overall obesity and breast cancer risk has been well recognized, but the role of central obesity in breast cancer development is uncertain.

METHODS

Between 1998 and 2009, 1,233 invasive breast cancer cases and 1,101 community controls were recruited into the Nigerian Breast Cancer Study at Ibadan, Nigeria. Logistic regressions were used to calculate multivariate odds ratio (OR) and 95% confidence intervals (CI), adjusting for age, body mass index (BMI), and other known risk factors for breast cancer.

RESULTS

The OR for the highest quartile group of waist circumference relative to the lowest was 2.39 (95% CI, 1.59-3.60; P-trend < 0.001). Comparing women with waist/hip ratio (WHR) in the lowest quartile group, the OR for women in the highest quartile category was 2.15 (95% CI, 1.61-2.85; P-trend < 0.001). An inverse association was observed between hip circumference and breast cancer, with an OR of 0.36 for the highest quartile (95% CI, 0.24-0.55; P-trend < 0.001). The effects of these three measures existed in both pre- and postmenopausal women. Of note, we found a significant interaction between WHR and BMI (P-interaction = 0.016): the OR comparing the highest to the lowest WHR quartile was 2.81 (95% CI, 1.90-4.16) for women with BMI < 25 kg/m2 and 1.70 (95% CI, 1.11-2.61) for women with BMI ≥ 25 kg/m2.

CONCLUSIONS

These results suggest that central adiposity, measured by waist circumference and waist/hip ratio, was an important risk factor for breast cancer in Nigerian women, and the effect of central adiposity was strong in normal-weight women.

Association between body mass index and risk of breast cancer in Tunisian women

BACKGROUND AND OBJECTIVES

The number of breast cancer in women has increased dramatically in Tunisia. The cause is perceived to stem from adaptation to a westernized life style which increases body mass index (BMI). This study aimed to investigate the association between BMI and breast cancer among Tunisian women.

DESIGN AND SETTING

Hospital-based case control study of breast cancer patients seen between November 2006 and April 2009 at the University College Hospital Farhat Hached in Sousse, Tunisia.

PATIENTS AND METHODS

Standardized questionnaires concerning BMI and other anthropometric data were completed on 400 breast cancer cases and 400 controls. The controls were frequency-matched to the cases by age.

RESULTS

BMI at diagnosis was positively correlated with the risk of breast cancer among postmenopausal women (P<.001 for trend). When compared with women with a low BMI (<19), women with a BMI of 23-27 and 27-31 had a 1.7-fold (95% CI, 1.1-2.9) and 2.1-fold (95% CI, 1.1-3.9) increased risk of breast cancer, respectively, after adjustment for non-anthropometric risk factors. BMI at diagnosis was not related to the risk of breast cancer among premenopausal women. The odds ratios for premenopausal women with a BMI of 23-27 and 27-31 were 1.5 (95% CI, 0.8-2.8) and 1.3 (95% CI, 0.4-4.5), respectively. Furthermore, present BMI was not associated with breast cancer risk in either pre- and postmenopausal women.

CONCLUSIONS

Weight control in obese women may be an effective measure of breast cancer prevention in postmenopausal women.

Distribuição da gordura corporal e câncer de mama: um estudo de caso-controle no Sul do Brasil

O presente estudo tem como objetivo verificar a associação entre a distribuição da gordura corporal e o câncer de mama em mulheres do Rio Grande do Sul. Para este estudo, utilizou-se um delineamento de caso-controle, no qual foram avaliadas cem mulheres com diagnóstico histopatológico de câncer de mama em comparação com o grupo controle ambulatorial (400 mulheres) durante os meses de janeiro a outubro de 2005. As variáveis antropométricas coletadas foram: massa corporal (kg), estatura, circunferência da cintura (CC) e perímetro do quadril. Não foi encontrada associação entre o índice de massa corporal (IMC) e a razão cintura/quadril (RCQ) com ocorrência de câncer de mama. Já para CC, observou-se que mulheres com essa medida elevada (> 88 cm) apresentam 2,08 vezes mais chance de desenvolver a doença do que aquelas com as medidas normais ou moderadas (< 80 cm-87 cm). Quando essas mulheres foram agrupadas por estado menopausal (pré e pós) e variáveis antropométricas, somente a CC apresentou associação OR ajustado=3,15. Conclusão: acúmulo de gordura na parte superior do corpo (CC > 88 cm) é um preditor de câncer de mama especialmente em mulheres pré-menopausa.

Relation of FGFR2 genetic polymorphisms to the association between oral contraceptive use and the risk of breast cancer in Chinese women

The fibroblast growth factor receptor 2 gene (FGFR2) has been associated with the risk of breast cancer in multiple ethnic populations, and its effect has been suggested to be hormone-dependent. A large, 2-stage, population-based case-control study was conducted in urban Shanghai, China, during the periods of 1996-1998 and 2002-2005. Exposure and genotyping information from 2,073 patients with breast cancer and 2,084 age-matched population controls was available for evaluation of the interactions between FGFR2 polymorphisms and exogenous estrogen exposure in the development of breast cancer. A logistic regression model was used to compute adjusted odds ratios and 95% confidence intervals. Of 20 genotyped and 25 imputed single nucleotide polymorphisms (SNPs), 22 were significantly associated with breast cancer. Three genotyped SNPs in close linkage disequilibrium, rs2303568, rs3135730, and rs1078806, and an imputed SNP of rs755793 in complete linkage disequilibrium with other 8 SNPs were observed to interact significantly with oral contraceptive (OC) use. The SNP-cancer association was evident only among OC users, and the OC use was only associated with the risk of breast cancer among carriers of these minor alleles at these loci. These findings suggest that genetic variants in FGFR2 may modify the role of OC use in causing breast cancer in Chinese women.

Trends in the incidence of cancer in the Sousse region, Tunisia, 1993-2006

In this article, we analyzed trends in incidence rates of the major cancer sites for a 14-year period, 1993-2006, in the Sousse region localized in the centre of Tunisia. Five-year age-specific rates, crude incidence rates (CR), world age-standardized rates (ASR), percent change (PC) and annual percent change (APC) were calculated using annual data on population size and its estimated age structure. A total of 6,975 incident cases of cancer were registered, with a male to-female sex ratio of 1.4:1. ASRs showed stable trends (-0.1% in males, and +1.0% in females). The leading cancer sites in rank were lung, breast, lymphoma, colon-rectum, bladder, prostate, leukemia, stomach and cervix uteri. For males, the incidence rates of lung, bladder and prostate cancers remained stable over time. While, cancers of colon-rectum showed a marked increase in incidence (APC: +4.8%; 95% CI: 1.2%, 8.4%) and non-Hodgkin's lymphoma (NHL) showed a notable decline (APC: -4.4%; 95% CI: -8.2, -0.6). For females, cancers of the breast (APC: +2.2%; 95% CI: 0.4%, 4.0%) and corpus uteri (APC: +7.4%; 95% CI: 2.8%, 12.0%) showed a marked increase in incidence during the study period, while the cervix uteri cancer decreased significantly (APC: -6.1%; 95% CI: -9.2%, -3.0%). The results underline the increasing importance of cancer as a cause of mortality and morbidity in Tunisia. Our findings justify the need to develop effective program aiming at the control and prevention of the spread of cancer amongst Tunisian population.

Case-control study of body size and breast cancer risk in Nigerian women

Previous studies have shown that weight is inversely associated with premenopausal breast cancer and positively associated with postmenopausal disease. Height has been shown to be positively correlated with breast cancer risk, but the association was not conclusive for premenopausal women. These previous studies were conducted primarily in Western countries, where height is not limited by nutritional status during childhood. The authors assessed the association between breast cancer and anthropometric measures in the Nigerian Breast Cancer Study (Ibadan, Nigeria). Between 1998 and 2009, 1,233 invasive breast cancer cases and 1,101 controls were recruited. The multivariate-adjusted odds ratio for the highest quartile group of height relative to the lowest was 2.03 (95% confidence interval (CI): 1.51, 2.72; P-trend < 0.001), with an odds ratio of 1.22 (95% CI: 1.14, 1.32) for each 5-cm increase, with no difference by menopausal status. Comparing women with a body mass index in the lowest quartile group, the adjusted odds ratio for women in the highest quartile category was 0.72 (95% CI: 0.54, 0.94; P-trend = 0.009) for premenopausal and postmenopausal women. Influence of height on breast cancer risk was quite strong in this cohort of indigenous Africans, which suggests that energy intake during childhood may be important in breast cancer development.

Body mass index and waist circumference are predictor biomarkers of breast cancer risk in Iranian women

Both obesity and breast cancer incidence increased dramatically during two recent decades in a rapidly changing society in northern Iran. In this study, we examined the ability of body mass index (BMI) and waist circumference (WC) as predictor biomarkers of breast cancer risk in Iranian women. In a case-control study of 100 new cases of histological confirmed breast cancer and 200 age-matched controls, in Babol, we measured weight, height, waist and hip circumference at time of diagnosis with standard methods. The data of demographic, characteristics, reproductive and lifestyle factors were collected by interview. We used both regression and receiver operator characteristics (ROC) analysis to estimate the predictive ability of BMI and WC for breast cancer as estimated by area under the curve (AUC). The results showed a significant difference in the mean of weight, BMI and WC between patients and controls in pre- and postmenopausal women (P<0.001). While after adjusting for BMI, no longer an association between WC and breast cancer was found. The overall accuracy of observed BMI and WC were 0.79 (95% CI: 0.74-0.84) and 0.68 (95% CI: 0.61-0.74), respectively. The accuracy of BMI and WC were 0.82 (95% CI: 0.76-0.89), 0.75(0.67-0.83) for premenopausal and 0.77(0.68-0.85), 0.60 (0.50-0.71) for postmenopausal women, respectively. BMI and WC are predictor biomarkers of breast cancer risk in both pre- and postmenopausal Iranian women while after adjusting for BMI, no longer an association between WC and breast cancer was observed. These findings imply to perform breast cancer screening program in women with a higher BMI and WC.

Hormonal and metabolic modulation through nutrition: towards a primary prevention of breast cancer

Breast cancer (BC) is a polygenic and multifactorial disease for which estrogens have been recognized as the main risk factor, and for which lifestyle plays a key role. Previous epidemiologic cancer research performed in Uruguayan population delimited its dietary and anthropometric profiles. Recognizing the difficulty for universalizing a nutritional basis for prevention due to different eating patterns among regions and countries, we summarize the existent knowledge linking nutrition, estrogens, metabolism and BC. As an attempt towards primary prevention of BC, we present recommendations mainly based on country-specific research findings and modifiable putative risk and protective factors, proposing to modify the intake of meats and other fatty foods--especially sources of Ω-6 and Ω-3 fatty acids--adding olive oil, selected vegetables, citrus fruits and working towards adequate body fat/muscle proportions. From a medical and ethical viewpoint, it is justified to recommend certain nutritional changes to women, because no adverse side effects are expected to occur.

A case-control study of body mass index and breast cancer risk in white and African-American women

OBJECTIVE

Large body size has been associated with decreased risk of breast cancer in premenopausal women but with increased risk in postmenopausal women. Limited information is available about African-American women and differences by estrogen and progesterone receptor status.

METHODS

We analyzed data from the Women's Contraceptive and Reproductive Experiences Study among 3,997 white and African-American breast cancer case patients diagnosed in 1994 to 1998 and 4,041 control participants ages 35 to 64 years. We calculated multivariate odds ratios (OR) as measures of relative risk of breast cancer associated with self-reported body mass index (BMI) at age 18 and 5 years before diagnosis (recent BMI).

RESULTS

Risk tended to decrease with increasing BMI at age 18 years in all women [OR(BMI > or = 25 kg/m(2) versus < 20 kg/m(2)) = 0.76; 95% confidence interval (CI), 0.63-0.90; P(trend) = 0.005] and with recent BMI in premenopausal women (OR(BMI > or = 35 kg/m(2) versus < 25 kg/m(2)) = 0.81; 95% CI, 0.61-1.06; P(trend) = 0.05), unmodified by race. Among postmenopausal white but not African-American women, there was an inverse relation between recent BMI and risk. High recent BMI was associated with increased risk of estrogen receptor- and progesterone receptor-positive tumors among postmenopausal African-American women (OR(BMI > or = 35 kg/m(2) versus < 25 kg/m(2)) = 1.83; 95% CI, 1.08-3.09; P(trend) = 0.03).

CONCLUSION

Among women at age 35 to 64 years, BMI at age 18 years is inversely associated with risk of breast cancer, but association with recent BMI varies by menopause status, race, and hormone receptor status.

IMPACT

Our findings indicate that studies of BMI and breast cancer should consider breast cancer subtypes.

Adiposity, adult weight gain and mammographic breast density in US Chinese women

The association of adiposity with dense tissue area in the breast is unclear, but suggests a mechanism by which adiposity might increase breast cancer risk. We examined associations of body mass index (BMI), usual BMI from age 20 to 29, waist circumference and adult weight gain with breast density in a sample of premenopausal United States Chinese immigrant women. Analyses included 415 participants in a longitudinal breast density study in Philadelphia. In addition to detailed questionnaire information, data collection included measures of anthropometry, and assessment of mammographic breast density using a computer-assisted method. We used multivariate linear regression to quantify cross-sectional associations with dense and nondense tissue area and percent breast density assessed at baseline. In adjusted models, BMI and waist circumference were significantly positively associated with nondense tissue area and inversely associated with percent density. BMI was also significantly positively associated with dense tissue area. Adult weight gain was associated with dense tissue area after adjusting for weight from age 20 to 29. In stratified analyses, BMI and adult weight gain were significantly associated with dense tissue area among women with BMI < 23 kg/m², and BMI was associated with nondense tissue area among women with BMI ≥ 23 kg/m². In this sample, adiposity and weight gain were associated with dense breast tissue area, although associations differed by level of adiposity. Given the potential implications of these findings for breast cancer prevention in premenopausal women, comparable studies in other population groups and with longitudinal data are needed. Reasons for the noted differences in associations by level of adiposity also warrant further investigation.

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.

Breast cancer in the Thai Cohort Study: an exploratory case-control analysis

Breast cancer incidence may be increasing in Thailand but very little research has assessed core breast cancer risk factors in this country.

We used baseline questionnaire data from a national cohort study of Thai Open University students in an exploratory case-control study of breast cancer. The study included 43 female cases and 860 age-matched controls selected from the remaining 47,271 female cohort participants. Odds ratios and 95% confidence intervals were calculated using conditional logistic regression.

The women were predominantly premenopausal. Taller women had an increased risk of breast cancer (OR = 2.3, 95% CI 1.1–4.8, for height ≥160 cm vs ≤154 cm) as did women with non-insulin dependent diabetes mellitus (OR = 8.4, 95% CI 1.7–41). Women with older siblings had a reduced risk of breast cancer compared to those firstborn (OR = 0.3, 95% CI0.2–0.7).

Although limited by small case numbers, our findings suggest substantial increases in breast cancer rates in Thailand could be expected in the future.

Risk factors according to estrogen receptor status of breast cancer patients in Trivandrum, South India

Estrogen receptor (ER) status is an important biomarker in defining subtypes of breast cancer differing in antihormonal therapy response, risk factors and prognosis. However, little is known about association of ER status with various risk factors in the developing world. Our case-control study done in Kerala, India looked at the associations of ER status and risk factors of breast cancer. From 2002 to 2005, 1,208 cases and controls were selected at the Regional Cancer Center (RCC), Trivandrum, Kerala, India. Information was collected using a standardized questionnaire, and 3-way analyses compared ER+/ER- cases, ER+ cases/controls and ER- cases/controls using unconditional logistic regression to calculate odds ratios and 95% confidence intervals. The proportion of ER- cases was higher (64.1%) than ER+ cases. Muslim women were more likely to have ER- breast cancer compared to Hindus (OR = 1.48, 95% CI = 1.09, 2.02), an effect limited to premenopausal group (OR = 1.87, 95% CI = 1.26, 2.77). Women with higher socioeconomic status were more likely to have ER+ breast cancer (OR = 1.48, 95% CI = 1.11, 1.98). Increasing BMI increased likelihood of ER- breast cancer in premenopausal women (p for trend < 0.001). Increasing age of marriage was positively associated with both ER+ and ER- breast cancer. Increased breastfeeding and physical activity were in general protective for both ER+ and ER- breast cancer. The findings of our study are significant in further understanding the relationship of ER status and risk factors of breast cancer in the context of the Indian subcontinent.

Mutations in the mitochondrial DNA D-loop region and breast cancer risk

Mitochondrial genome alterations have been suggested to play an important role in carcinogenesis. The D-loop region of mitochondrial DNA (mtDNA) contains essential transcription and replication elements, and mutations in this region may serve as a potential sensor for cellular DNA damage and a marker for cancer development. Using data and samples from the Shanghai Breast Cancer Study, we investigated MnlI restriction sites located between nucleotides 16,106 and 16,437 of the mtDNA D-loop region to evaluate restriction fragment length polymorphism (RFLP) patterns in tumor tissue from 501 primary breast cancer patients when compared with tumor tissue from 203 women with benign breast disease (BBD). RFLP patterns in correspondingly paired, adjacent, non-tumor tissues taken from 120 primary breast cancer patients and 59 BBD controls were also evaluated. Five common RFLP patterns were observed, and no significant differences were observed in the distribution of these patterns between tumor and adjacent non-tumor tissue samples from breast cancer patients and tissue samples from BBD controls. On the other hand, somatic MnlI site mutations, defined as a difference in MnlI RFLP pattern between tumor tissue and the corresponding, adjacent, non-tumor tissue, occurred more frequently in breast cancer patients (28.3%) than in BBD patients (15.3%) (P = 0.05) and more frequently in proliferative BBD (13.0%) than in non-proliferative BBD (7.1%). Our data suggest that somatic MnlI site mutations may play a role in the pathogenesis of breast cancer.

Energy balance, physical activity, and cancer risk

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

Association of mitochondrial DNA displacement loop (CA)n dinucleotide repeat polymorphism with breast cancer risk and survival among Chinese women

Mitochondrial genome alternations may be involved in carcinogenesis. The noncoding region of the mitochondrial DNA (mtDNA) displacement loop (D-loop) has emerged as a mutational hotspot. Using data from a population-based case-control study conducted among Chinese women in Shanghai, we evaluated associations of breast cancer risk and survival with the mtDNA D-loop (CA)(n) dinucleotide repeat polymorphism. Included in the study were 1,058 cases and 1,129 age frequency-matched community controls that participated in the Shanghai Breast Cancer Study between 1996 and 1998. Breast cancer patients were followed to determine intervals of overall survival and disease-free survival. Overall, there was no association between the mtDNA D-loop (CA)(n) repeat polymorphism and breast cancer risk. Patients with multiple alleles of the mtDNA D-loop (CA)(n) polymorphism (heteroplasmy) had significantly poorer disease-free survival than those with one allele of the mtDNA D-loop (CA)(n) polymorphism (hazard ratio 1.62; 95% confidence interval, 1.16-2.26). These results suggest that the mtDNA D-loop (CA)(n) repeat polymorphism may be associated with breast cancer survival. Additional studies with a larger sample size are warranted.

Effects of reproductive and demographic changes on breast cancer incidence in China: a modeling analysis

BACKGROUND

Breast cancer incidence is currently low in China. However, the distribution of reproductive and lifestyle risk factors for breast cancer among Chinese women is changing rapidly. We quantified the expected effect of changes in breast cancer risk factors on future rates of breast cancer in China.

METHODS

We first validated and calibrated the Rosner-Colditz log-incidence breast cancer model in Chinese women who participated in the Shanghai Women's Health Study cohort (N = 74,942). We then applied the calibrated model to a representative sample of Chinese women who were aged 35-49 years in 2001 using data from the Chinese National Family Planning and Reproductive Health Survey (NFPRHS, N = 17,078) to predict the age-specific and cumulative breast cancer incidence among all Chinese women of this age group. We evaluated the relative impact of changes in modifiable risk factors, including alcohol intake, parity, postmenopausal hormone use, and adult weight gain, on cumulative incidence of breast cancer.

RESULTS

Breast cancer incidence in China is expected to increase substantially from current rates, estimated at 10-60 cases per 100,000 women, to more than 100 new cases per 100,000 women aged 55-69 years by 2021. We predicted 2.5 million cases of breast cancer by 2021 among Chinese women who were 35-49 years old in 2001. Modest reductions in hormone and alcohol use, and weight maintenance could prevent 270,000 of these cases.

CONCLUSIONS

China is on the cusp of a breast cancer epidemic. Although some risk factors associated with economic development are largely unavoidable, the substantial predicted increase in new cases of breast cancer calls for urgent incorporation of this disease in future health care infrastructure planning.

Somatotype and risk of breast cancer: a case-control study in Uruguay

According to the evidence, there is a need for more thorough assessment and quantification of body size and shape and the risk of breast cancer. Using the somatotype methodology, we carried out an original research in order to explore possible associations between body shape and the risk of breast cancer in Uruguayan women. With this objective, 254 recent breast cancer cases and 1,000 frequency-matched healthy controls were interviewed on menstrual and reproductive story, and a series of skinfolds, circumferences and diameters were measured specifically to calculate somatotype. A positive association with breast cancer was found for high endomorphy (Odds Ratio [OR] = 2.82, p < 0.001), mainly among pre-menopausal women (OR = 4.98, p <0.001) and normoweight women (OR = 5.12, p = 0.002), whereas almost no differences were observed for mesomorphic and ectomorphic women. Analysis showed a high meso-endomorphic pattern in the study population. Further studies are needed to confirm the present results obtained in a country with high incidence of the disease.

Insulin resistance, obesity and breast cancer risk

Breast cancer (BC) is one of the most important problems of public health. Among the avoidable risk factors during a woman's life, overweight and obesity are very important ones. Furthermore they are increasing worldwide. The risk of breast cancer is traditionally linked to obesity in postmenopausal women; conversely, it is neutral or even protective in premenopausal women. Since the initiator and promoter factors for BC act over a long time, it seems unlikely that the menopausal transition may have too big an impact on the role of obesity in the magnitude of the risk. We reviewed the literature in an attempt to understand this paradox, with particular attention to the body fat distribution and its impact on insulin resistance. The association of insulin resistance and obesity with BC risk are biologically plausible and consistent. Estradiol (E2) and IGFs act as mitogens in breast cancer cells. They act together and reciprocally. However the clinical and biological methods to assess the impact of insulin resistance are not always accurate. Furthermore insulin resistance is far from being a constant feature in obesity, particularly in premenopausal women; this complicates the analysis and explains the discrepancies in large prospective trials. The most consistent clinical feature to assess risk across epidemiological studies seems to be weight gain during lifetime. Loss of weight is associated with a lower risk for postmenopausal BC compared with weight maintenance. This observation should be an encouragement for women since loss of weight may be an effective strategy for breast cancer risk reduction.