Research Results
Beta Version
Use the search bar below to find studies, or apply one or more filters to narrow your results. See our list of keywords to guide your search.
Search by keyword
Select
Select
- All Risk Factors
- Air Pollution
- Alcohol
- Antimicrobials
- Artificial sweeteners
- Bisphenols
- Body Weight
- Breast Density
- Chemical Mixtures
- Chemicals in products
- Cleaning Products
- Diet
- Exercise
- Family History
- Furniture & Electronics
- Genetics
- Gut Health
- Hair Dye
- Hormones
- Inflammation
- Job
- Light at night
- Metals
- Neighborhood
- Night Shift Work
- Noise
- Non-stick Pans & Waterproof Gear
- Oral Contraceptives
- PAHs
- Parabens
- PCBs
- Personal Care Products
- Pesticides
- PFAS
- Pharmaceuticals
- Place-based
- Plastic
- Pregnancy & Breastfeeding
- Processed Food
- Puberty Age
- Race/Ethnicity
- Radiation
- Red meat
- Scented Products & Soft Plastic
- Sleeping Patterns
- Soda
- Stress
- Sugar
- Sunscreen
- Tobacco
- Vitamin D
Select
Select
Select
Select
Select the Chemical Agents
- All Chemical Agents
- 1,1,2,2-TCA
- 1,3-Butadiene
- Acrolein
- Aldrin
- Alkylphenols
- Antimicrobials
- Antimicrobials: QACs, Triclosan, Triclocarban
- Aromatic Amines
- Arsenic
- Artificial Sweeteners
- Atrazine
- Benzene
- Bisphenols
- Cadmium
- Chlordane
- Chlorpyrifos
- DDT
- Dibutyl Phthalate
- Dichlorvos
- Dieldrin
- Dioxins
- ell/
- Ethanol (alcohol)
- Ethyl Benzene
- Ethylene Oxide
- Flame Retardants
- Food
- Formaldehyde
- Glyphosate
- Heptachlor
- Hormones
- Insulin
- Lead
- Light at Night
- Mercury
- Metals
- Methoxyclor
- Naphthalene
- Night Shift Work
- Nitrogen Dioxide
- Noise
- Oral Contraceptives
- Organochlorine Pesticides
- Organophosphate Pesticides
- Ozone
- PAHs
- Parabens
- Particulate Matter
- PCBs
- Pesticides
- PFAS
- Phenols
- Phthalates
- Processed Food
- PVC
- Radiation: Ionizing
- Radiation: Non-Ionizing
- Soda
- Stress
- Sugar
- Tobacco
- Toluene
- Trichloroethylene
- Triclosan
- Ultraviolet Radiation
- UV Filters
- Vinyl Chloride
Select the Study Tags
Sort By
- Relevance
- Title (A to Z)
- Title (Z to A)
- Publication Year (Ascending)
- Publication Year (Descending)
- Authors (A to Z)
- Authors (Z to A)
2025
JAMA Netw Open
In a cross-sectional study involving Black and White women participating in the NCI Maryland Breast Cancer Study, the investigators examined associations between neighborhood-level deprivation, air pollution (PM₂.₅) and presence of breast tissue crown-like structures (CLS-B) plus DNA methylation patterns. Higher PM₂.₅ exposure and greater neighborhood deprivation were associated with increased odds of having CLS-B (OR for PM₂.₅ 2.32, 95% CI: 1.12–4.78). The findings point to how socio-environmental disadvantage and pollution may influence breast adipose inflammation and epigenetic changes linked to cancer risk.
2022
BMC Med
A large European study measuring inflammatory markers in the blood of over 3,000 women found that inflammation’s relationship with breast cancer risk differs dramatically by menopausal status, with higher levels of leptin and C-reactive protein (CRP) appearing protective in premenopausal women but associated with increased risk in postmenopausal women. The opposing effects were particularly evident for leptin and CRP, which showed 11-17% lower breast cancer risk in premenopausal women but 10-16% higher risk in postmenopausal women, and these associations were influenced by body weight. These findings suggest that inflammation and obesity may affect breast cancer development through different biological mechanisms before and after menopause, highlighting the importance of considering menopausal status when assessing breast cancer risk factors.
2018
Environ Health
This longitudinal study examined how exposure to endocrine disrupting chemicals (EDCs) affects the timing of menarche in Chilean girls by measuring 26 phenol and phthalate compounds in urine samples collected before breast development and during adolescence. The researchers found that different chemicals had varying effects depending on when exposure was measured: higher early exposure to DEHP was associated with later menarche, while early exposure to certain phenols and later exposure to some phthalates were linked to earlier menarche. The study also revealed that body weight influenced these effects, with overweight or obese girls showing earlier menarche when exposed to higher levels of certain chemicals like triclosan, while normal-weight girls did not show this association. These findings demonstrate that specific EDCs can disrupt normal sexual development in girls, with timing of exposure and body weight being important factors.
2025
Breast Cancer
A meta-analysis of 10 studies involving 1,730 women found that breast cancer patients had significantly lower gut bacterial diversity compared to healthy controls, with particularly pronounced differences in premenopausal women and women with normal body weight. The reduction in gut microbiome diversity—a marker of gut health—was not seen in overweight or obese women, suggesting body weight may influence the relationship between gut bacteria and breast cancer. These findings support the hypothesis that gut bacteria may play a role in breast cancer development, possibly through their influence on estrogen levels, though more research is needed to understand the underlying mechanisms and whether improving gut health could help prevent breast cancer.
2025
Clin Transl Oncol
A review of 29 studies found that breast cancer patients have distinct imbalances in their gut and breast tissue bacteria that vary based on cancer type, stage, menopause status, body weight, and physical activity, though no single bacterial profile has yet emerged as a reliable biomarker. The research suggests that gut microbiome composition may influence how well breast cancer treatments work, with some beneficial bacteria and their metabolites potentially improving therapy effectiveness or slowing tumor growth. These findings highlight the microbiome as a promising new area for developing personalized breast cancer treatments and improving outcomes, though more research is needed to identify specific bacterial targets and understand the underlying mechanisms.
2025
Nutr J
A prospective cohort study of 13,567 Chinese women followed for nearly 15 years found that consuming one or more servings of sugar-sweetened beverages (SSBs) per week was associated with a 58% increased breast cancer risk compared to consuming less than one serving weekly. The association was partly mediated by body mass index (4.2%) and uric acid (18.8%), with genetic analyses identifying additional metabolic mediators including cholesterol and fatty acid ratios accounting for small portions of the effect. Interestingly, higher soy milk consumption (3-6 portions weekly) was associated with a 69% reduced breast cancer risk, while dairy milk showed a non-significant trend toward increased risk, and no associations were found for juice, coffee, tea, or alcohol, suggesting that reducing SSB consumption and addressing the associated metabolic disruptions could be effective breast cancer prevention strategies.
2024
Breast Cancer Res Treat
A large prospective study of 187,278 nurses followed for up to 31 years found that high levels of recreational physical activity (≥27 vs <3 MET-hours/week, roughly equivalent to ≥9 hours/week of brisk walking) were associated with 17% reduced breast cancer risk in both premenopausal and postmenopausal women. The protective effect was strongest for hormone receptor-positive (ER+/PR+) tumors in both groups, with no significant associations observed for hormone receptor-negative cancers, and while the benefit in postmenopausal women was partly explained by lower body weight, the association in premenopausal women remained independent of BMI. These findings provide strong evidence that regular recreational physical activity is a modifiable risk factor that reduces breast cancer risk across the lifespan, regardless of menopausal status, supporting public health recommendations for regular exercise as an accessible breast cancer prevention strategy for all women.
2024
Br J Cancer
A large prospective study of 1,275,783 women aged 45+ years followed for a median 12.7 years from 2004 examined associations between menopausal hormone therapy (HT) types and breast cancer risk, finding that oral estrogen combined with daily progestin carried the highest risk (HR=2.42; 95% CI: 2.31-2.54), with drug-specific hazard ratios ranging from Cliovelle® (HR=1.63) to Kliogest® (HR=2.67), while vaginal estradiol showed no association with breast cancer. The associations varied substantially by molecular subtype (stronger for luminal A: HR=1.97 vs. other subtypes), detection mode (stronger for interval-detected: HR=2.00 vs. screen-detected cancers: HR=1.33 in women 50-71), and BMI (decreasing hazard ratios with increasing BMI). These contemporary findings confirm that oral and transdermal HT use increases breast cancer risk with important variation by specific formulations, administration routes, tumor characteristics, and patient factors, providing critical updated evidence for clinical decision-making about menopausal hormone therapy use and emphasizing the need for individualized risk-benefit assessment accounting for HT type, body weight, and cancer screening participation.
2024
Cancer Epidemiol
A large collaborative study of 609,880 women from 16 prospective studies, including 9,956 breast cancer cases before age 55, examined when the relationship between body mass index (BMI) and breast cancer risk transitions from protective (before menopause) to harmful (after menopause). During the critical age window of 45-55 years, the study found that a five-unit BMI increment remained associated with reduced or neutral breast cancer risk across all menopausal status groups: HR=0.87 for premenopausal women, HR=1.00 for women after natural menopause, HR=0.99 after interventional loss of ovarian function, and HR=0.88 after hysterectomy without bilateral oophorectomy. The findings indicate that the well-documented reversal from BMI being protective to being a risk factor for breast cancer occurs after age 55, later than previously thought, suggesting that the transition to increased risk with higher BMI is not directly tied to the menopausal transition itself but occurs in the years following menopause. This timing provides important insight into how adiposity influences breast cancer risk across the lifespan and suggests that the hormonal and metabolic changes associated with higher BMI have different effects on breast tissue depending on age and years since menopause.
2023
Ann Agric Environ Med
A case-control study of 111 postmenopausal women with breast cancer and 111 controls found that shift work was associated with a 165% increased breast cancer risk, but this risk was dramatically amplified by body weight status. Overweight shift workers showed a staggering 884% increased breast cancer risk compared to normal-weight women who had never worked shifts, indicating a powerful synergistic effect between shift work and excess body weight. With 72% of breast cancer cases having a history of shift work compared to 49% of controls, these findings suggest that the combination of circadian disruption from shift work and metabolic dysfunction from excess weight creates a particularly high-risk scenario, highlighting the urgent need for targeted prevention strategies—including weight management and lifestyle interventions—specifically for women working non-standard hours.
2023
Adv Nutr
A systematic review and meta-analysis of 31 studies (29 included in quantitative analysis) following Cochrane methodology examined associations between healthy lifestyle indices (incorporating factors like healthy body weight, diet, physical activity) and breast cancer risk. Comparing the highest versus lowest adherence categories, the analysis found a 20% breast cancer risk reduction in prospective studies (HR=0.80; 95% CI: 0.78-0.83) and 26% reduction in retrospective studies (OR=0.74; 95% CI: 0.63-0.86), with inverse associations remaining significant when stratified by menopausal status (except for premenopausal BC in prospective studies) and across molecular subtypes: ER+/PR+ (HR=0.68; 95% CI: 0.63-0.73), ER+/PR- (HR=0.78; 95% CI: 0.67-0.90), and ER-/PR- (HR=0.77; 95% CI: 0.64-0.92). These findings—with most studies scoring low risk of bias and moderate certainty of evidence—demonstrate that adherence to healthy lifestyles reduces breast cancer risk by approximately 20-30% regardless of molecular subtype or menopausal status, supporting the prioritization of lifestyle-based recommendations for population-level breast cancer prevention as a key modifiable approach to reducing the substantial disease burden.
2023
Nutrients
A case-control study of 42 newly diagnosed, treatment-naïve breast cancer patients and 44 age-matched cancer-free controls at Oregon Health & Science University (2020-2021) found reduced gut microbial diversity in breast cancer patients and enrichment of three specific bacterial genera—Acidaminococcus, Tyzzerella, and Hungatella—in fecal samples from cases, with these genera associated with distinct dietary patterns including vegetables and dairy (Hungatella) and whole fruits (Acidaminococcus). Breast cancer patients also had significantly higher BMI and lower physical activity levels, and microbiome analysis revealed significant differences in composition between cases and controls using 16S rRNA sequencing. These findings highlight complex interactions between the gut microbiome, dietary habits (assessed via National Cancer Institute Diet History Questionnaire), lifestyle factors like weight management and physical activity, and breast cancer risk, suggesting the gut microbiome may serve as a source of biomarkers for breast cancer risk assessment, though larger studies are needed to establish causal relationships and validate these microbial signatures.
2022
Int J Obesity
A large retrospective cohort study using South Korea’s National Health Insurance Service database followed 691,253 premenopausal and 1,519,211 postmenopausal women aged ≥40 who underwent three consecutive biennial breast cancer screenings between 2009-2014 and were followed until 2020, identifying 9,485 and 12,553 breast cancer cases respectively over a median 6.9 years. In postmenopausal women, consecutive weight gains increased breast cancer risk by 11% while consecutive weight losses decreased risk by 16%; similarly, continuous increases in waist circumference raised risk by 13% while continuous decreases lowered risk by 16%, demonstrating a dose-response relationship. In premenopausal women, a single weight gain was associated with 7% increased breast cancer risk. These findings indicate that longitudinal changes in weight and waist circumference—not just baseline measurements—are important predictors of breast cancer risk in a dose-response manner, with the direction and consistency of changes over time being particularly significant for postmenopausal women, suggesting that sustained weight loss and waist reduction may be effective breast cancer prevention strategies even in midlife and beyond.
2022
Int J Epidemiol
A large European prospective study of 150,257 women followed for 14 years found that weight gain of more than 10 kg from age 20 to middle adulthood was associated with a 42% increased postmenopausal breast cancer risk among women who were lean at age 20, with the association present in both HRT users (23% increased risk) and non-users (40% increased risk) and particularly strong for ER+/PR+ breast cancers (46% increased risk). The findings indicate that maintaining stable weight from young adulthood is especially important for women who start out lean, as weight gain appears to negate the protective effect of lower early-life body weight. These results highlight a critical window for breast cancer prevention: while being lean in early adulthood is protective, this benefit is substantially diminished by subsequent weight gain, suggesting that weight management efforts should focus not just on current weight but on preventing long-term weight accumulation from young adulthood through menopause.
2022
Cancer Epidemiol Biomark Prev
A study of 102,572 women aged 40-69 years with normal BMI (18.5-<25 kg/m²) from the UK Biobank examined whether a healthy lifestyle index (HLI)—a composite score based on diet quality, low alcohol consumption, no smoking, moderate-to-high physical activity, and waist circumference <80 cm—was associated with breast cancer risk. Postmenopausal women with the highest HLI scores (3rd tertile) had a 24% reduced risk of breast cancer compared to those with the lowest scores (HR = 0.76; 95% CI: 0.64-0.91), while premenopausal women showed similar but non-significant trends, except when smoking was excluded from the score (HR = 0.71; 95% CI: 0.56-0.90). These findings demonstrate that even among women with normal BMI—a group traditionally considered at lower risk—adhering to multiple healthy lifestyle behaviors is associated with reduced breast cancer risk in postmenopausal women. The results suggest that maintaining a healthy lifestyle through diet, physical activity, limited alcohol, healthy waist circumference, and not smoking may provide breast cancer protection beyond weight management alone, particularly for postmenopausal women.
2022
Int J Environ Res Public Health
A recent study highlights the risk of Bisphenol A (BPA) exposure from bottled water, emphasizing how temperature can influence BPA leaching into the water. While BPA isn’t used in PET bottle manufacturing, contamination can occur due to recycled materials. Findings indicate that BPA levels in bottled water increase with temperature, even when not at the highest temperatures. BPA, a known endocrine-disrupting chemical (EDC), is linked to reproductive health issues, developmental disorders, and even cancer.
2020
Eur J Clinic Nutr
A prospective cohort study in the Multiethnic Cohort found no direct associations between four widely-used diet quality indexes—including the Healthy Eating Index 2015, Alternate Healthy Eating Index 2010, alternate Mediterranean diet score, and DASH diet—and breast cancer risk when comparing highest versus lowest quintiles of adherence. However, overweight and obesity were significantly associated with breast cancer incidence, suggesting that diet quality may influence breast cancer risk indirectly through its effects on body weight rather than through direct mechanisms. These findings indicate that the breast cancer prevention benefits of healthy dietary patterns may operate primarily through weight management pathways, highlighting that maintaining healthy body weight through diet—rather than specific dietary patterns per se—may be the critical factor for breast cancer prevention, and underscoring the importance of comprehensive lifestyle interventions that address both diet quality and weight control rather than focusing on dietary patterns alone.
2020
Breast Cancer Res Treat
A pilot study of 37 breast cancer patients found that women with HER2-positive breast cancer (an aggressive subtype) had 12-23% lower gut bacterial diversity and different bacterial compositions compared to HER2-negative patients, with less Firmicutes and more Bacteroidetes bacteria. The research also revealed that women who started menstruating early (age 11 or younger) and those with higher body fat had lower gut bacterial diversity, suggesting links between gut microbiome composition and known breast cancer risk factors. While the study was small, these findings indicate that gut bacteria composition may be connected to both breast cancer characteristics and established risk factors, warranting larger studies to better understand these relationships and their potential implications for prevention and treatment.
2020
Nutrients
A prospective cohort study of 10,930 Spanish female university graduates in the SUN (“Seguimiento Universidad de Navarra”) project examined whether adherence to the 2018 World Cancer Research Fund/American Institute for Cancer Research (WCRF/AICR) cancer prevention recommendations was associated with breast cancer risk. The study used an 8-item score measuring compliance with recommendations including body fat, physical activity, consumption of wholegrains/vegetables/fruit/beans, avoidance of fast foods and processed meats, limited sugar-sweetened drinks and alcohol, and breastfeeding. While no significant association was found for overall breast cancer risk, women who scored highest on adherence (>5 points vs. ≤3 points) had a 73% reduced risk of postmenopausal breast cancer after adjusting for other variables. The findings suggest that following multiple WCRF/AICR lifestyle and nutritional recommendations together may significantly reduce postmenopausal breast cancer risk through their combined protective effects.
2020
J Natl Cancer Inst
A prospective study of 146,326 women in the UK Biobank found that maintaining a healthy lifestyle—combining favorable diet, physical activity, healthy weight, limited alcohol, and no smoking—was associated with 22% and 31% reduced breast cancer risk in premenopausal and postmenopausal women respectively, even among women with high genetic risk (top third of polygenic risk score). Importantly, women with high genetic risk who maintained favorable lifestyles still achieved 27-32% risk reductions across menopausal groups, and while high genetic risk doubled breast cancer risk overall, lifestyle factors provided consistent protective benefits regardless of genetic predisposition. These findings demonstrate that genetic risk is not destiny: even women with the highest genetic susceptibility to breast cancer can substantially reduce their risk through modifiable lifestyle factors, supporting the critical importance of population-wide lifestyle interventions for breast cancer prevention and providing hope that women at elevated genetic risk can take meaningful action to lower their cancer risk through behavioral changes.
2020
Nutr J
A case-control study of 350 breast cancer patients and 700 controls in Iran found that women with the healthiest combined lifestyle scores—encompassing diet quality, physical activity, and non-smoking—had a 38% reduced breast cancer risk compared to those with the least healthy scores, with effects particularly pronounced in postmenopausal women who showed a 44% risk reduction. Notably, when examining individual lifestyle components, diet quality (measured by the Healthy Eating Index-2010) emerged as the strongest protective factor with a 46% risk reduction in the highest versus lowest category, while physical activity and smoking individually showed no significant associations. These findings suggest that comprehensive healthy lifestyle patterns—particularly high-quality diet—may substantially reduce breast cancer risk in postmenopausal women, though the lack of association in premenopausal women and the dominance of diet over other factors highlights the need for prospective studies to clarify whether combined lifestyle interventions offer synergistic benefits or whether specific components (like diet) drive most of the protective effect.
2019
Environ Int
A case-control study within the California Teachers Study examined 902 women with invasive breast cancer and 936 controls to assess whether serum levels of polybrominated diphenyl ethers (PBDEs)—common environmental contaminants with endocrine-disrupting properties—are associated with breast cancer risk. Blood samples were analyzed for three prevalent PBDE congeners (BDE-47, BDE-100, and BDE-153), with measurements taken an average of 35 months after cancer diagnosis. The study found no significant association between serum levels of any of the three PBDE congeners and breast cancer risk, even when stratified by menopausal status, tumor characteristics, or body weight. However, the authors note important limitations, including that post-diagnosis blood measurements may not reflect pre-diagnostic or lifetime exposures, and the study lacked information on genetic factors that could influence individual susceptibility.
2019
J Expo Sci Environ Epidemiol
This study from a longitudinal cohort of 133 women diagnosed with breast cancer before age 50 and 133 age-matched controls without breast cancer. DDT is stored in adipose tissue, and the authors found that serum DDE (the main metabolite of DDT) was inversely associated with BMI amont women who were cancer-free, but that this association did not hold among women diagnosed with breast cancer before age 50. The authors suggest that early exposure to breast cancer among women exposed to DDT may be due to an uncoupling of the relationship between BMI and serum DDT, and that this may reveal biomarkers of risk through further research.
2019
Sci Rep
A Spanish case-control study of 973 breast cancer patients matched with controls found that the relationship between caloric intake and breast cancer risk varied dramatically by menopausal status: premenopausal women consuming 20% or more below their predicted caloric needs had a 64% reduced risk, while postmenopausal women consuming 40% or more above predicted needs had a 181% increased risk. For every 20% increase in relative caloric intake (observed versus predicted based on individual metabolism and activity), hormone receptor-positive and HER2-positive breast cancer risk increased by 13%, with triple-negative tumors showing a 7% increase per 20% caloric excess. These findings suggest that maintaining appropriate caloric intake matched to individual energy needs—and potentially moderate caloric restriction combined with regular physical activity—could be an effective breast cancer prevention strategy, particularly important given the different effects observed in pre- versus postmenopausal women.
2018
Breast Cancer Res Treat
A study of 27,153 postmenopausal women in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial created an estrogen-related lifestyle score (ERLS) combining four factors: estrogenic diet, alcohol intake, body mass index (BMI), and physical activity, with scores ranging from 0-6 and higher scores representing lower estrogenic lifestyle patterns. Women with ERLS scores of 4 or ≥5 had 23% and 34% lower breast cancer risk, respectively, compared to those with scores ≤2, with similar protective effects observed for invasive cases and estrogen receptor-positive subtypes. The findings indicate that adopting multiple low-estrogen lifestyle behaviors together—including a low estrogenic diet, minimal alcohol consumption, healthy body weight, and high physical activity—has a combined protective effect against postmenopausal breast cancer that is stronger than any single factor alone. The researchers suggest this combined effect likely works by influencing estrogen metabolism, highlighting the importance of addressing multiple lifestyle factors simultaneously for breast cancer prevention in postmenopausal women.
2018
Biomed Res Int
A case-control study of 116 women with newly diagnosed breast cancer and 226 controls used dual-energy X-ray absorptiometry to examine the relationship between body composition, physical activity, and breast cancer risk, analyzing results separately by menopausal status. In premenopausal women, higher total body fat percentage, android (abdominal) fat, and waist circumference were associated with increased breast cancer risk, while higher lean body mass and greater physical activity were protective; among postmenopausal women, physical activity reduced breast cancer risk by 49%. The study concludes that low lean body mass and high abdominal fat increase breast cancer risk in premenopausal women, while regular physical activity is protective against breast cancer in both pre- and postmenopausal women. These findings suggest that maintaining healthy body composition through physical activity may be an important breast cancer prevention strategy across all life stages.
2018
Breast Cancer Res
A pooled analysis of three population-based case-control studies including 6,320 women (3,934 cases, 2,386 controls) aged 35-64 years examined whether the associations between body mass index (BMI) and breast cancer risk differ by tumor subtype defined by estrogen receptor (ER), progesterone receptor (PR), and HER2 status. Higher BMI at age 18 was inversely associated with premenopausal breast cancer risk across all ER/PR/HER2 subtypes (≥25 vs. <20 kg/m²: OR=0.72), with the strongest protection seen in premenopausal women who had high BMI both at age 18 and currently (46% reduced risk; OR=0.54; 95% CI: 0.38-0.78), while no significant associations were found for postmenopausal breast cancer. The findings indicate that high BMI during late adolescence provides similar protective effects against all molecular subtypes of premenopausal breast cancer regardless of hormone receptor or HER2 status, and this protection appears to be maximized when women maintain higher BMI consistently throughout their premenopausal years. These results suggest that the mechanisms by which adiposity protects against premenopausal breast cancer operate broadly across different tumor subtypes rather than being specific to hormone receptor-positive disease.
2018
Curr Oncol Rep
Obesity is now recognized as a leading preventable cause of cancer, particularly postmenopausal estrogen receptor-positive breast cancer, and is associated with worse outcomes across all breast cancer subtypes. Multiple interconnected mechanisms link obesity to breast cancer, including elevated estrogen levels, altered hormone-like molecules from fat tissue (leptin and adiponectin), disrupted insulin signaling, changes in gut bacteria, and chronic inflammation throughout the body. Understanding these complex pathways could lead to new prevention and treatment strategies to reduce the growing burden of obesity-related breast cancers worldwide.
2018
BMC Pub Health
A mixed ecological and case-control study in Australia found that obesity occurring between ages 31-40 was independently associated with a 250% increased breast cancer risk in middle-aged women, though no direct association was found between alcohol consumption and breast cancer in the case-control analysis despite ecological correlations. The study revealed that stress was ecologically linked to both alcohol consumption and obesity but not directly to breast cancer incidence, suggesting that stress may influence breast cancer risk indirectly through health behaviors rather than representing a “missing link” as hypothesized. These findings highlight a critical window for breast cancer prevention: obesity in the decade before age 40 appears particularly risky, supporting targeted weight management interventions for women in their 30s, while the complex interrelationships between stress, alcohol, obesity, and breast cancer warrant further investigation using longitudinal designs that can capture temporal sequences and cumulative exposures across women’s reproductive years.
2022
BMC Med
A large UK study of 472,377 people followed for over 11 years found that vegetarians had 14% lower overall cancer risk compared to regular meat-eaters, with similar reductions seen in low meat-eaters (2% lower) and fish-eaters (10% lower). Vegetarian postmenopausal women had 18% lower breast cancer risk, though this benefit appeared to be largely explained by vegetarians having lower body weight, while men who ate fish or followed vegetarian diets had 20-31% lower prostate cancer risk. Low meat consumption was associated with 9% lower colorectal cancer risk, particularly in men, supporting previous evidence that meat intake increases cancer risk, though the study couldn’t definitively determine whether the observed benefits reflect direct dietary effects or other lifestyle factors associated with these eating patterns.
2022
PLOS Med
A large French study following nearly 103,000 adults for nearly 8 years found that people who consumed higher amounts of artificial sweeteners—particularly aspartame and acesulfame-K found in diet sodas and many processed foods—had a 13-15% increased risk of cancer overall, with specific increases in breast cancer and obesity-related cancers. The research, which carefully tracked detailed dietary records and controlled for multiple lifestyle factors, showed aspartame was associated with a 22% higher breast cancer risk among higher consumers compared to non-consumers. While the study has some limitations including potential confounding factors, these findings add to growing concerns about artificial sweetener safety and support the need for regulatory agencies to re-evaluate the safety of these widely used food additives found in thousands of products worldwide.
2018
Environ Health Perspect
This study examined the relationship between 11 urinary phthalate metabolites and both breast cancer incidence and survival in 710 women with breast cancer and 598 controls from Long Island, New York, followed for a median of 17.6 years. Contrary to expectations, the researchers found that higher levels of several phthalate metabolites (including MCPP, MBzP, MCNP, and MCOP) were associated with reduced breast cancer risk, and higher levels of MEHP and MCOP were linked to better breast cancer survival. The study also revealed that body mass index modified the relationship between certain phthalate metabolites and breast cancer mortality, with positive associations in normal-weight women and inverse associations in overweight/obese women. However, the authors caution that these unexpected protective associations should be interpreted carefully since urine samples were collected after breast cancer diagnosis, which may have influenced the results.