Birth weight, weight over the adult life course and risk of breast cancer

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.

Review of mendelian randomization studies on age at natural menopause

Menopause marks the end of the reproductive phase of life. Based on epidemiological studies, abnormal age at natural menopause (ANM) is thought to contribute to a number of adverse outcomes, such as osteoporosis, cardiovascular disease, and cancer. However, the causality of these associations remains unclear. A powerful epidemiological method known as Mendelian randomization (MR) can be used to clarify the causality between ANM and other diseases or traits. The present review describes MR studies that included ANM as an exposure, outcome and mediator. The findings of MR analyses on ANM have revealed that higher body mass index, poor educational level, early age at menarche, early age at first live birth, early age at first sexual intercourse, and autoimmune thyroid disease appear to be involved in early ANM etiology. The etiology of late ANM appears to be influenced by higher free thyroxine 4 and methylene tetrahydrofolate reductase gene mutations. Furthermore, early ANM has been found to be causally associated with an increased risk of osteoporosis, fracture, type 2 diabetes mellitus, glycosylated hemoglobin, and the homeostasis model of insulin resistance level. In addition, late ANM has been found to be causally associated with an increased systolic blood pressure, higher risk of breast cancer, endometrial cancer, endometrioid ovarian carcinoma, lung cancer, longevity, airflow obstruction, and lower risk of Parkinson's disease. ANM is also a mediator for breast cancer caused by birth weight and childhood body size. However, due to the different instrumental variables used, some results of studies are inconsistent. Future studies with more valid genetic variants are needed for traits with discrepancies between MRs or between MR and other types of epidemiological studies.

Birth weight, adult body size, and risk of colorectal cancer

BACKGROUND

Evidence suggests that birth weight may be associated with colorectal cancer (CRC) risk later in life. Whether the association is mediated by adult body size remains unexamined.

METHOD

Cox proportional hazards models (Hazard Ratio (HR) and 95 % Confidence Intervals (CI)) were used to evaluate the association between self-reported birth weight (<6 lbs, 6-<8 lbs, ≥8 lbs) and CRC risk among 70,397 postmenopausal women from the Women's Health Initiative. Further, we assessed whether this association was mediated by adult body size using multiple mediation analyses.

RESULTS

Compared with birth weights of 6-< 8 lbs, birth weight ≥ 8 lbs was associated with higher CRC risk in postmenopausal women (HR = 1.31, 95 % CI 1.16-1.48). This association was significantly mediated by adult height (proportion mediated =11.4 %), weight (11.2 %), waist circumference (10.9 %), and body mass index at baseline (4.0 %). The joint effect of adult height and weight explained 21.6 % of this positive association.

CONCLUSION

Our data support the hypothesis that the intrauterine environment and fetal development may be related to the risk of developing CRC later in life. While adult body size partially explains this association, further investigation is required to identify other factors that mediate the link between birth weight and CRC.

Obesity and Breast Cancer Metastasis across Genomic Subtypes

BACKGROUND

Obese women have higher risk of aggressive breast tumors and distant metastasis. However, obesity has rarely been assessed in association with metastasis in diverse populations.

METHODS

In the Carolina Breast Cancer Study Phase 3 (2008-2013), waist-to-hip ratio (WHR), body mass index (BMI), and molecular subtype [PAM50 risk-of-recurrence (ROR) score] were assessed. Obesity measures were evaluated in association with metastasis within five years of diagnosis, overall and stratified by race and ROR score. Absolute risk of metastasis and risk differences between strata were calculated using the Kaplan-Meier estimator, adjusted for age, grade, stage, race, and ER status. Relative frequency of metastatic site and multiplicity were estimated in association with obesity using generalized linear models.

RESULTS

High-WHR was associated with higher risk of metastasis (5-year risk difference, RD, 4.3%; 95% confidence interval, 2.2-6.5). It was also associated with multiple metastases and metastases at all sites except brain. The 5-year risk of metastasis differed by race (11.2% and 6.9% in Black and non-Black, respectively) and ROR score (19.5% vs. 6.6% in high vs. low-to-intermediate ROR-PT). Non-Black women and those with low-to-intermediate ROR scores had similar risk in high- and low-WHR strata. However, among Black women and those with high ROR, risk of metastasis was elevated among high-WHR (RDBlack/non-Black = 4.6%, RDHigh/Low-Int = 3.1%). Patterns of metastasis were similar by BMI.

CONCLUSIONS

WHR is associated with metastatic risk, particularly among Black women and those with high-risk tumors.

IMPACT

Understanding how risk factors for metastasis interact may help in tailoring care plans and surveillance among patients with breast cancer.

A metabolomic analysis of adiposity measures and pre- and postmenopausal breast cancer risk in the Nurses' Health Studies

BACKGROUND

Adiposity is consistently positively associated with postmenopausal breast cancer and inversely associated with premenopausal breast cancer risk, though the reasons for this difference remain unclear.

METHODS

In this nested case-control study of 1649 breast cancer cases and 1649 matched controls from the Nurses' Health Study (NHS) and the NHSII, we selected lipid and polar metabolites correlated with BMI, waist circumference, weight change since age 18, or derived fat mass, and developed a metabolomic score for each measure using LASSO regression. Logistic regression was used to investigate the association between this score and breast cancer risk, adjusted for risk factors and stratified by menopausal status at blood draw and diagnosis.

RESULTS

Metabolite scores developed among only premenopausal or postmenopausal women were highly correlated with scores developed in all women (r = 0.93-0.96). Higher metabolomic adiposity scores were generally inversely related to breast cancer risk among premenopausal women. Among postmenopausal women, significant positive trends with risk were observed (e.g., metabolomic waist circumference score OR Q4 vs. Q1 = 1.47, 95% CI = 1.03-2.08, P-trend = 0.01).

CONCLUSIONS

Though the same metabolites represented adiposity in pre- and postmenopausal women, breast cancer risk associations differed suggesting that metabolic dysregulation may have a differential association with pre- vs. postmenopausal breast cancer.

Association of birth weight with cancer risk: a dose-response meta-analysis and Mendelian randomization study

BACKGROUND

Several articles have shown that birth weight is associated with the risk of many types of cancers. However, the results are inconsistent, and whether the relationship has a causal effect remains unknown.

METHODS

We searched the PubMed and Embase libraries up to March 2021 and selected observational studies reporting the relationship between birth weight and adult-onset cancer risk. Dose-response meta-analysis and two-sample Mendelian randomization (MR) analysis were used to estimate the effect.

RESULT

In our dose-response meta-analysis, six cancers from 46 studies were found to have significant associations with birth weight. (Ovarian cancer: RR: 1.21, 95% CI 1.01-1.44; breast cancer: RR: 1.12, 95% CI 1.08-1.16; colorectal cancer: RR: 1.20, 95% CI 1.01-1.43; endometrial cancer: RR: 0.85, 95% CI 0.78-0.93; prostate cancer: RR: 1.27, 95% CI 1.01-1.61; testicular cancer: RR: 1.21, 95% CI 1.03-1.43). As birth weight increased, the slope of the dose-response curve of breast cancer increased continuously, and the curve of testicular cancer was U-shaped. In the MR study, seven cancers were included. Only invasive mucinous ovarian cancer was found to have a causal effect on birth weight (OR: 0.62; 95% CI 0.39-0.97), while other cancers did not.

CONCLUSIONS

Our findings suggest that birth weight are unlikely to have a casual effect on risk of cancers via the MR analysis, although the dose-response meta-analysis shows that there is a nonlinear relationship between birth weight and breast cancer and testicular cancer. More relevant researches are needed to further investigate their effect.

Exploring the association between birthweight and breast cancer using summary statistics from a perspective of genetic correlation, mediation, and causality

BACKGROUND

Previous studies demonstrated a positive relationship between birthweight and breast cancer; however, inconsistent, sometimes even controversial, observations also emerged, and the nature of such relationship remains unknown.

METHODS

Using summary statistics of birthweight and breast cancer, we assessed the fetal/maternal-specific genetic correlation between them via LDSC and prioritized fetal/maternal-specific pleiotropic genes through MAIUP. Relying on summary statistics we conducted Mendelian randomization (MR) to evaluate the fetal/maternal-specific origin of causal relationship between birthweight, age of menarche, age at menopause and breast cancer.

RESULTS

With summary statistics we identified a positive genetic correlation between fetal-specific birthweight and breast cancer (r_g = 0.123 and P = 0.013) as well as a negative but insignificant correlation between maternal-specific birthweight and breast cancer (r_g = - 0.068, P = 0.206); and detected 84 pleiotropic genes shared by fetal-specific birthweight and breast cancer, 49 shared by maternal-specific birthweight and breast cancer. We also revealed fetal-specific birthweight indirectly influenced breast cancer risk in adulthood via the path of age of menarche or age at menopause in terms of MR-based mediation analysis.

CONCLUSION

This study reveals that shared genetic foundation and causal mediation commonly drive the connection between the two traits, and that fetal/maternal-specific birthweight plays substantially distinct roles in such relationship. However, our work offers little supportive evidence for the fetal origins hypothesis of breast cancer originating in utero.

Early-life body mass index and risks of breast, endometrial, and ovarian cancers: a dose-response meta-analysis of prospective studies

BACKGROUND

The evidence for the associations between early-life adiposity and female cancer risks is mixed. Little is known about the exact shape of the relationships and whether the associations are independent of adult adiposity.

METHODS

We conducted dose-response meta-analyses of prospective studies to summarise the relationships of early-life body mass index (BMI) with breast, endometrial, and ovarian cancer risks. Pubmed and Embase were searched through June 2020 to identify relevant studies. Using random-effects models, the summary relative risks (RRs) and 95% confidence intervals (CIs) were estimated per 5-kg/m² increase in BMI at ages ≤ 25 years. A nonlinear dose-response meta-analysis was conducted using restricted cubic spline analysis.

RESULTS

After screening 33,948 publications, 37 prospective studies were included in this analysis. The summary RRs associated with every 5-kg/m² increase in early-life BMI were 0.84 (95% CI = 0.81-0.87) for breast, 1.40 (95% CI = 1.25-1.57) for endometrial, and 1.15 (95% CI = 1.07-1.23) for ovarian cancers. For breast cancer, the association remained statistically significant after adjustment for adult BMI (RR = 0.80, 95% CI = 0.73-0.87). For premenopausal breast, endometrial, and ovarian cancers, the dose-response curves suggested evidence of nonlinearity.

CONCLUSIONS

With early-life adiposity, our data support an inverse association with breast cancer and positive associations with ovarian and endometrial cancer risks.

Birth weight and the risk of overall breast cancer, premenopausal and postmenopausal breast cancer in adulthood: a dose-response meta-analysis of observational studies

IMPORTANCE

The effect of birth weight on breast cancer across different menopausal states remains unknown.

OBJECTIVE

The aim of this study was to systematically evaluate the association of birth weight with the risk of overall breast cancer (OBC) and premenopausal and postmenopausal breast cancer during adulthood. In parallel, the dose-response analyses were performed.

EVIDENCE REVIEW

Relevant studies were systematically searched from the PubMed, Embase, and the Cochrane Library databases from the inception to May 25, 2021, without language restrictions. All the results were pooled according to risk ratios (RRs).

FINDINGS

In total, 21 cohort studies comprising 1,139,032 participants were included. An increase in the birth weight was not associated with the risk of OBC and premenopausal and postmenopausal breast cancer. Compared with women having normal weight at birth, those with a high birth weight are likely to have an increased risk of invasive breast cancer (RR: 1.19, 95% confidence intervals: 1.03-1.38; I2: 28.6%). The dose-response analyses showed that the risk of premenopausal breast cancer increased significantly in unknown singleton status with birth weight over 2850 g (RR: 1.14 [1.02-1.30]). Similarly, postmenopausal breast cancer risk was increased in singleton births with birth weight over 3750 g (RR: 1.21 [1.00-1.47]).

CONCLUSIONS AND RELEVANCE

High weight at birth might be not significantly associated with the risk of OBC, premenopausal and postmenopausal breast cancer and ER+ and ER- breast cancer but is positively associated with the risk of invasive breast cancer, regardless of parity. Furthermore, with an increase in birth weight, the risk of postmenopausal breast cancer is likely to increase in the singleton births, whereas the risk of premenopausal breast cancer is likely to increase in unknown singleton status.

Neonatal Birth Weight of the Woman as a Risk Factor for Breast Cancer in her Life: a Case-Control Bicentric Study

Background

It is a global fact that the birth weight is increasing during the years around the world and for this reason it is very important to be examined as a potential risk factor for breast cancer. According to data from World Health Organization, breast cancer is the second most frequent malignancy across the world, after lung cancer, in Europe including Greece in incidence and mortality for women between the ages 0-85 years old.

Objective

The aim of this study was to investigate a possible association between neonatal birth weight of the women and breast cancer risk in Greek women. Although that many studies concluded that birth weight is positively related with breast cancer reinforcing the theory that breast cancer may originate in utero, some studies found no association. Moreover, the results from previous studies are inconsistent maybe due to several factors such as the study design and the number of cases.

Methods

This study was a case-control retrospective bicentric study. The case group included 238 women with breast cancer, while the control group included 153 women without breast cancer who consulted in two breast clinics in Greece. In all women, a clinical examination and breast ultrasound were achieved. Moreover, digital bilateral mammography was performed in patients older than 40 years.

Results

According to Fisher's exact analysis, there is a statistically significant relationship between the higher women's neonatal birth weight and the risk for breast cancer (p<0.001). More specifically in the group of women with breast cancer, 61% of them had more than 3500 grams birth weight, in contrast with 7.8 % in the control group. In our cohort, women who had birth weight more than 3500 grams are more likely to develop breast cancer in their life.

Conclusion

Our study trend to show that the increased neonatal birth weight may influence future risk of breast cancer. However, further studies with larger number of participants are needed in order to clarify the role of birth weight as a complementary risk factor of breast cancer.

Body Habitus Across the Lifespan and Risk of Pituitary Adenoma

CONTEXT

No studies have examined the association between body habitus and incidence of pituitary adenoma.

OBJECTIVE

To determine if body mass index (BMI), waist circumference, body somatotype, or height are associated with risk of pituitary adenoma.

DESIGN

Pooled analysis of 3 prospective cohort studies.

SETTING

Population-based study.

PARTICIPANTS

Participants of the Nurses' Health Study (NHS), Nurses' Health Study II (NHSII), and the Health Professionals Follow-Up Study (HPFS), totaling 284 946 American health professionals.

EXPOSURES

BMI, waist circumference, body somatotype, and height.

OUTCOME MEASURES

Self-reported incident pituitary adenoma. Multivariable (MV)-adjusted hazard ratios (HRs) of pituitary adenoma were estimated using Cox proportional hazards models.

RESULTS

During 7 350 156 person-years of follow-up, 387 incident pituitary adenomas were reported. Comparing BMI of ≥30 to <25 kg/m2, higher adult BMI was associated with higher risk of pituitary adenoma (MV HR = 1.74; 95% CI, 1.33-2.28), as was higher maximum adult BMI (MV HR = 1.76; 95% CI, 1.34-2.30), higher waist circumference (MV HR = 1.06; 95% CI, 1.04-1.09 per inch), and higher BMI during early adulthood (at age 18 to 21, MV HR = 2.65; 95% CI, 1.56-4.49). Taller adult height was associated with pituitary adenoma (MV HR = 1.05; 95% CI, 1.01-1.09 per inch). Overall findings were similar in women and men, although power was limited in men (n = 62 cases). Sensitivity analyses demonstrated that the association between adult BMI and pituitary adenoma extended to at least 14 years prior to diagnosis and that the results were not affected when analyses were restricted to participants with similar healthcare utilization.

CONCLUSION

Higher BMI and waist circumference, from early adulthood to the time of diagnosis, were associated with higher risk of pituitary adenoma.

Birth Weight and Incidence of Breast Cancer: Dose-Response Meta-analysis of Prospective Studies

BACKGROUND

Many studies have shown the association between birth weight and breast cancer (BC), but the evidence remains limited and inconsistent, especially in different menopause status. We sought to clarify the relationship and shape of the dose-response relation between birth weight and BC.

METHODS

The Web of Science, PubMed, and Embase databases were searched for prospective studies involving the relationship between birth weight and risk of BC published to November 2019. Random effects of generalized least squares regression models were used to estimate the quantitative dose-response association, and restricted cubic splines were used to model the association.

RESULTS

We included reports of 16 prospective studies describing 16,000 incident cases among 553,644 participants. We identified a modest-in-magnitude, but significant, association between birth weight and BC risk: risk increased by 2% (risk ratio, 1.02, 95% confidence interval, 1.01-1.03) and 9% (risk ratio, 1.09, 95% confidence interval, 1.04-1.15) with a per-500 g birth weight increment in all ages and premenopausal women, respectively. Our results showed a linear dose-response relationship between birth weight and BC risk (P_nonlinearity = .311) in premenopausal women, with statistical significance when birth weight was above about 3.5 kg. No significant association was found in postmenopausal women.

CONCLUSION

Higher birth weight has a relationship with increased risk of BC in premenopausal women, particularly when birth weight is above 3.5 kg.

Breast Cancer and Nutrition: A Paradigm for Prevention in 3D Across the Life Course

Breast cancer, the most common cancer in women worldwide, has recognized reproductive and anthropometric risk factors including age at menarche and adult height. Yet the age when a woman attains her adult height or experiences menarche for example is simply the timing of the major life event at the end of a long trail of exposures that began in utero. The objective of this article is to investigate through a review of the literature the role of nutrition in breast cancer prevention through three dimensions (D). Each D offers a different lens. The First D identifies windows/ages of exposures or conditions that convey vulnerability or protection from breast cancer. The Second D addresses the intensity and duration of the exposure; and the (Third D) examines the pace, i.e., how rapid or slow the young woman experiences her growth and development. Birthweight illustrative of the First D reveals a strong signal across the life course on BC risk, but the risk group varies from low to high birthweight. Stressful life events like being a pubertal aged girl living in a household with an unemployed father during the Great Depression or high levels of environmental contaminants exposure are representative of the Second D. Height velocity at specific ages and weight loss in postmenopausal years are illustrative of anthropometric trajectories that reveal an adaptive biosystem that provides a contextual state to interact with the other two Ds. This article presents a new paradigm of nutrition and breast cancer prevention through the lens of three very different dimensions. It is the premise of this article that all three dimensions are essential tasks to tease apart the life course and identify windows for preventive strategies.