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
Environ Pollut
A study of 574 breast cancer cases and 2,295 controls from rural Arkansas found that moderate exposure to polycyclic aromatic hydrocarbons (PAHs) and high chromium exposure were associated with statistically significant 32% increased breast cancer risk, with the strongest effects observed among women with a family history of breast cancer. When examining 12 hazardous air pollutants as a mixture, there was a suggested but non-statistically significant 21% increased breast cancer risk, with chromium, propylene dichloride, and PCBs contributing most to the elevated risk. This study is important because it demonstrates that hazardous air pollutants pose breast cancer risks even in rural areas, which are often overlooked in environmental health research despite experiencing different pollution sources and healthcare disparities compared to urban populations.
2025
J Clin Oncol
A large California study of over 58,000 racially and ethnically diverse women found that long-term exposure to fine particulate matter (PM2.5) air pollution was associated with a statistically significant 28% increased risk of breast cancer for each 10 μg/m³ increase in PM2.5 concentration, with the association consistent across African American, Latino, and other ethnic groups. When combined with data from 10 other studies in a meta-analysis, PM2.5 exposure showed a borderline significant 5% increased breast cancer risk, providing strong evidence that air pollution is an important breast cancer risk factor. These findings emphasize that breast cancer prevention strategies should extend beyond individual lifestyle changes to include population-level policies aimed at reducing air pollution, particularly as traditional risk factors explain only half of breast cancer cases and incidence continues to rise globally.
2023
Breast Cancer Res
This large study of over 181,000 women from the UK Biobank examined whether allostatic load (AL)—a measure of cumulative physiological stress on the body over time—is associated with breast cancer risk. Women with higher AL scores had a significantly increased risk of developing breast cancer, with each one-unit increase in AL associated with a 5% higher risk, and women in the high AL group showing a 17% increased risk compared to those in the low AL group, even after accounting for known risk factors like family history, lifestyle, and genetic factors. The association was found across multiple subgroups and appeared independent of traditional breast cancer risk factors, suggesting that chronic physiological stress may contribute to breast cancer development. These findings indicate that AL could serve as a valuable biomarker for predicting and stratifying breast cancer risk in women.
2023
Environ Res
A nationwide U.S. study of nearly 45,000 women found clear geographic patterns in breast cancer rates, with lower risk in the South and Southeast and higher risk in the Northwest and parts of the Midwest and Northeast, even after accounting for personal risk factors like family history and reproductive factors. Environmental exposures—including air pollution (nitrogen dioxide and fine particles), light at night, greenspace, and neighborhood socioeconomic disadvantage—explained 21% of the geographic variation in overall breast cancer and 63% of the variation specifically for estrogen receptor-positive (ER+) breast cancer. These findings provide strong evidence that where you live matters for breast cancer risk, with environmental factors playing a substantial role, particularly for ER+ breast cancer, the most common subtype, suggesting that reducing environmental exposures like air pollution and light at night could be effective prevention strategies at the community level.
Association between Urinary Lead and Female Breast Cancer: A Population-Based Cross-Sectional Study.
2023
Discov Med
This study analyzed data from nearly 2,800 women in the National Health and Nutrition Examination Survey (NHANES) to investigate whether urinary lead levels are associated with breast cancer risk. Researchers found that higher urinary lead levels were positively associated with breast cancer, with women having the highest lead levels showing 2.16 times the odds of breast cancer compared to those with the lowest levels, and this association persisted after adjusting for numerous factors including age, BMI, smoking, and socioeconomic status. The positive trend was consistent across different subgroups of women regardless of age, race, pregnancy history, or other health conditions. These findings suggest that lead exposure, as measured in urine, may be a risk factor for breast cancer in US women.
2021
Int J Clin Pract
A case-control study of 250 breast cancer patients and 250 controls found that women consuming diets that trigger higher insulin responses after meals—measured by dietary insulin index (DII) and dietary insulin load (DIL)—had 46-87% increased odds of breast cancer compared to those with lower scores. These high insulin-stimulating diets were more common among overweight women and those with family histories of cancer, suggesting that dietary patterns affecting blood insulin levels may be a modifiable risk factor for breast cancer. The findings support reducing consumption of foods that spike insulin levels—typically refined carbohydrates and high-glycemic foods—as a potential dietary strategy for breast cancer prevention, particularly for women at higher risk.
2020
Br Med J
A large UK study of 98,611 women with breast cancer and 457,498 controls found that long-term hormone replacement therapy (HRT) use (≥5 years) was associated with significantly increased breast cancer risk, with combined estrogen-progestogen therapy showing a 79% increased risk and estrogen-only therapy showing a 15% increased risk. Among combined therapies, norethisterone carried the highest risk (88% increase) while dydrogesterone showed the lowest (24% increase), and importantly, the increased risk from past long-term combined therapy use persisted even after stopping treatment (16% increased risk). In practical terms, recent combined HRT users could expect 9-36 extra breast cancer cases per 10,000 women per year depending on age, while estrogen-only users would see 3-8 extra cases per 10,000 women per year, providing critical information for women and clinicians weighing the benefits and risks of different HRT regimens.
2019
Am J Clin Nutr
A large French cohort study of 76,442 women over age 50 followed for 11 years found that current soy supplement use was associated with a 22% reduced risk of estrogen receptor-positive (ER+) breast cancer but a 101% increased risk of ER-negative breast cancer compared to never users. The risk profile varied significantly by personal characteristics: women with a family history of breast cancer showed a 36% increased risk with soy supplement use, while those without family history showed an 18% reduced risk; premenopausal or recently postmenopausal women showed a 50% risk reduction, while women more than 5 years past menopause showed a 6% increased risk. These findings suggest that soy supplements—often marketed as natural alternatives to hormone therapy—may have complex and opposing effects on breast cancer risk depending on tumor biology and individual characteristics, cautioning against their use particularly in women with breast cancer family history.
2019
Occ Environ Med
This Canadian study of over 2,200 women found that occupational exposure to polycyclic aromatic hydrocarbons (PAHs)—chemicals released from burning materials like coal, oil, and gasoline—increased breast cancer risk by 32%, with higher risks seen in women exposed to high levels for more than 7 years. The association was particularly strong among women with a family history of breast cancer, where prolonged high exposure nearly tripled the risk. These findings suggest that workplace PAH exposure may be an important and preventable breast cancer risk factor, especially for women with genetic susceptibility to the disease.
2018
Int J Psychiatry Med
A hospital-based study of 250 breast cancer patients and 250 controls in Turkey found that recent major stressors—particularly those occurring within the last five years—were associated with a 372% increased risk of breast cancer (the strongest factor identified). Other significant risk factors included inadequate social support (83% increased risk), loss of a father during childhood (168% increased risk), family history of cancer (55% increased risk), and history of psychiatric disorders (95% increased risk), suggesting that psychological trauma and social factors may play substantial roles in breast cancer development alongside genetic predisposition.
2025
Sci Rep
A study of 50 breast cancer patients and 50 healthy women found that 60% of breast cancer patients had metabolic syndrome (a cluster of conditions including high blood pressure, blood sugar, and cholesterol) compared to 40% of healthy controls, and breast cancer patients had significantly lower levels of beneficial gut bacteria—specifically Lactobacillus and Bifidobacterium. These beneficial bacteria normally help protect against disease and regulate the immune system, suggesting their depletion may play a role in breast cancer development. The findings support a connection between metabolic health, gut bacteria composition, and breast cancer risk, pointing to potential new avenues for cancer prevention through dietary or probiotic interventions, though more research is needed.
2024
Front Glob Women’s Health
A systematic review of 51 studies (2 RCTs and 49 observational studies) examined the association between modern contraceptive use and the risk of breast and reproductive cancers in women of reproductive age. The review found that hormonal contraceptive use significantly reduced the risk of ovarian cancer by 36% and endometrial cancer, while cervical cancer rates were lower among contraceptive users compared to non-users; notably, no increased breast cancer risk was found among healthy women (RR 1.00), but BRCA1/2 mutation carriers using oral contraceptives showed a 39% increased risk of breast cancer. These findings highlight the complex cancer-related effects of hormonal contraceptives: while they offer protective benefits against ovarian and endometrial cancers for most women, BRCA mutation carriers face elevated breast cancer risk, emphasizing the need for personalized contraceptive counseling that accounts for individual genetic risk factors. The study underscores the importance of healthcare providers considering family history and genetic profiles when discussing contraceptive options with women, particularly those with hereditary cancer susceptibility.
2023
Frontiers
This meta-analysis aimed to evaluate the association between exposure to endocrine-disrupting chemicals (EDCs), including phthalates and other common environmental pollutants, and breast cancer risk. The study found that certain EDCs—such as p,p′-DDT, chlordane, HCH, and specific PCBs—were positively associated with increased breast cancer risk, while a few compounds like BBP and PFDoDA showed a negative association.
2023
Endocrine
A case-control study in North India found that breast cancer patients had significantly lower serum Vitamin D levels than healthy controls, with women in the highest Vitamin D quartile having 59% lower breast cancer risk than those in the lowest quartile (OR = 2.44; 95% CI: 1.09-5.45); additionally, women with the polymorphic T allele for VDR FokI genotype (CT/TT) had over 4-fold increased breast cancer risk compared to those homozygous for the wild C allele (OR = 4.30; 95% CI: 2.21-8.35). Vitamin D levels were significantly higher in ER+ patients and significantly lower in advanced-stage cancers, suggesting Vitamin D may serve as both a risk factor and prognostic marker. The study concludes that FokI polymorphism of the VDR gene and low circulating Vitamin D levels independently increase breast cancer risk in North Indian women.
2022
Front Endocrinol
A meta-analysis of 8 studies (5 cohort and 3 case-control studies) examined whether fertility treatments increase breast cancer risk in genetically susceptible women, including those with a family history of breast cancer or BRCA mutations. The analysis found no significant increase in breast cancer risk associated with fertility treatments in genetically susceptible women overall (OR 1.18), women with a family history of breast cancer (OR 1.35), or BRCA mutation carriers (OR 1.02), with similarly reassuring results across subgroups including BRCA1 carriers, BRCA2 carriers, and women treated with specific fertility medications like in vitro fertilization, clomiphene citrate, or gonadotropins. This first meta-analysis on this topic provides reassuring evidence that fertility treatments do not significantly increase breast cancer risk even in women with hereditary susceptibility, though the authors note that larger prospective studies with more detailed information are needed to fully understand potential risks. Future research should examine whether risks vary by breast cancer subtype, explore the genetic mechanisms underlying hormone-related breast cancer, and investigate the relationship between BRCA mutations and hormone receptor-positive breast cancer specifically.
2022
Asian Pac J Cancer Prev
A matched case-control study of 187 breast cancer patients and 187 controls in Asia found that irregular sleep patterns and severe stress were the strongest modifiable risk factors, with irregular sleep associated with a staggering 3,311% increased breast cancer risk and severe stress showing a 574% increased risk. Poor sleep quality showed an even more dramatic 1,029% increased risk, while regular multivitamin use was associated with a 238% increased risk—a surprising finding requiring further investigation—and having a first child before age 30 was protective with a 56% risk reduction. Notably, none of the traditional non-modifiable risk factors (such as family history) showed significant associations in this study, suggesting that modifiable lifestyle factors—particularly sleep quality and stress management—may be critically important targets for breast cancer prevention in Asian populations experiencing rapidly rising breast cancer rates.
2021
BMC Women's Health
A meta-analysis of 26 studies including over 1.3 million participants found that short-term night-shift work (<10 years) was associated with a 13% increased breast cancer risk, but surprisingly, long-term night-shift work (≥10 years) showed no statistically significant increased risk (8% increase, not significant). Flight attendants with long overnight flights showed elevated breast cancer risk, though unmeasured confounders may have influenced these results, and the increased risk in short-term workers was most robust in case-control studies that adjusted for reproductive factors and family history. The paradoxical finding that short-term but not long-term night-shift work showed significant associations contradicts the expected dose-response relationship and may reflect healthy worker bias (where women susceptible to night-shift effects leave such work before reaching 10 years), methodological limitations in measuring long-term exposures, or unmeasured confounding factors that accumulate differently over time.
2021
Cancers
A meta-analysis of 42 case-control studies published 2009-2020 including 110,580 women (30,778 breast cancer cases, 79,802 controls) from PubMed, Embase, and Cochrane Library databases examined the association between oral contraceptive (OC) use and breast cancer risk. OC use was associated with a significantly increased breast cancer risk (OR=1.15; 95% CI: 1.01-1.31; p=0.0358), with additional significant risk factors including early menarche, nulliparity, non-breastfeeding, older age at first birth, postmenopause, obesity, smoking, and family history of breast cancer. Despite this meta-analysis and extensive previous studies supporting the conclusion that oral contraceptive pills modestly increase breast cancer risk by approximately 15%, the relatively small effect size, heterogeneity across studies, and authors’ call for further confirmation indicate that the relationship between contemporary OC formulations and breast cancer requires continued investigation, particularly regarding dose-response relationships, specific formulation types, and timing of exposure relative to reproductive events.
2021
Nutr Cancer
A case-control study of 317 breast cancer patients and 526 controls in Córdoba, Argentina found that women consuming the most pro-inflammatory diets (highest Dietary Inflammatory Index scores) had a 34% increased breast cancer risk compared to those with the least inflammatory diets. The association was markedly stronger among overweight and obese women, who showed a 98% increased risk with pro-inflammatory diets, and the effect was amplified in more urbanized areas compared to rural settings. These findings suggest that dietary patterns promoting systemic inflammation contribute to breast cancer risk, particularly in combination with obesity and urban lifestyle factors, highlighting the potential for dietary interventions focused on anti-inflammatory foods as a prevention strategy, especially in overweight women living in urban environments.
2020
Environ Res
A systematic review of 100 publications across 56 epidemiologic studies found that research enriched with women at higher baseline breast cancer risk—through family history, early-onset disease, or genetic susceptibility—consistently showed stronger and more frequent associations between environmental chemical exposures and breast cancer compared to average-risk populations. Specifically, 80% of studies enriched with family history or early-onset cases showed significant associations with exposures including PAHs, air pollution, DDT, PCBs, PFAS, metals, personal care products, and occupational chemicals, while 74% of studies examining genetic susceptibility found significant gene-environment interactions for various pollutants in women with variants affecting carcinogen metabolism, DNA repair, and oxidative stress. These findings suggest that the inconsistent evidence for environmental chemicals and breast cancer in the literature may partly stem from studying predominantly average-risk populations who may be less susceptible to environmental carcinogens, highlighting the critical need for future research to focus on high-risk populations and measure exposures during key windows of susceptibility (puberty, pregnancy, menopause) to more accurately capture the role of environmental chemicals in breast cancer development.
2020
Breast Cancer Res Treat
A prospective cohort study of 57,654 Swedish women aged 40-74 years found that increased alcohol consumption was associated with a 26% higher breast cancer risk, but importantly, this relationship—and the protective effect of physical activity—was consistent across women regardless of their baseline breast cancer risk level. The study used the Tyrer-Cuzick model to categorize women as below average, average, or above average risk and found that additional risk factors (such as family history, reproductive factors, or breast density) did not modify how alcohol and physical activity affected breast cancer risk. These findings support recommending reduced alcohol consumption and increased physical activity for breast cancer prevention in all women, regardless of their individual risk profile, since the lifestyle benefits apply equally whether a woman is at low, average, or high baseline risk of developing the disease.
2020
PLOS One
A matched case-control study in Karachi, Pakistan examined 411 women with newly diagnosed breast cancer and 784 cancer-free controls to investigate the relationship between Vitamin D levels, supplementation, sun exposure, and breast cancer risk in a population where both Vitamin D deficiency and breast cancer are prevalent. The study found that women with Vitamin D deficiency (serum levels <20 ng/ml) had a 65% increased risk of breast cancer compared to those with sufficient levels (>30 ng/ml), while women who took Vitamin D supplements in the year prior had a 68% reduced risk of breast cancer. The researchers conclude that Vitamin D deficiency is associated with increased breast cancer risk in Pakistani women, and suggest that maintaining adequate Vitamin D levels through supplementation could be a safe, affordable prevention strategy. This approach may be particularly beneficial for reducing breast cancer incidence and mortality among economically disadvantaged women in Pakistan who face barriers to early detection and treatment, though further research is needed to confirm these findings.
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.
2019
BMC Women's Health
A case-control study of 450 Jordanian women (225 cases, 225 controls) aged 18-65 examined associations between oral contraceptive (OC) use and breast cancer risk in a Middle Eastern population. Regular OC use was associated with more than double the breast cancer risk (OR=2.25; 95% CI: 1.34-2.79; p=0.002), though duration of use showed no significant association (p>0.05), with additional significant risk factors including age at puberty, age at menopause, pregnancy history, menopausal status, and family history of cancer. These findings suggest that regular oral contraceptive use may be associated with increased breast cancer risk in Jordanian women, though the lack of duration-response relationship is inconsistent with some other studies and the authors note that larger multi-center studies are needed to confirm these findings in the Middle Eastern female population where limited research on OC use and breast cancer has been conducted.
2019
Breast Cancer Res Treat
A case-control study within the MCC-Spain cohort examined 1,389 invasive breast cancer cases and 1,712 controls aged 20-85 years to investigate domain-specific associations between physical activity and breast cancer risk by menopausal status and molecular subtype. The study found unexpected results: occupational physical activity (OPA) intensity was associated with higher breast cancer risk, particularly for premenopausal women (OR = 1.89 for active/very active vs. sedentary jobs) and ER+/PR+, HER2- tumors (OR = 1.80), while sedentary time ≥6 hours/day increased postmenopausal breast cancer risk by 69%; conversely, moderate-to-high intensity household and recreational physical activity above 1,000 MET·min/week reduced breast cancer risk by 14-33% in both pre- and postmenopausal women. These findings reveal important distinctions between types of physical activity: while leisure-time and household physical activity provide protective benefits against breast cancer, occupational physical activity paradoxically showed positive associations with breast cancer risk—particularly for hormone receptor-positive tumors—which may reflect different biological mechanisms, exposure patterns, or confounding factors associated with Occupation. The study highlights that sitting time is an independent breast cancer risk factor regardless of other physical activity, and the surprising positive association between occupational physical activity and ER+/PR+ breast cancer warrants further investigation to understand underlying mechanisms.
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.