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Are There Environmental Causes Of Breast Cancer

What Causes Her2 Positive Breast Cancer

Exposure: Environmental Links to Breast Cancer

The exact cause of HER2 positive breast cancer is not yet known, though researchers believe that environment, lifestyle and genetics may all play a role in the development of this malignancy. That said, HER2 positive breast cancer is not hereditary you cant inherit a bad HER2 gene from a parent or pass one on to a child.

Studies Assessing The Potential Modification Of Known Breast Cancer Risk Variants By Environmental Factors

Several studies have investigated whether breast cancer risk associated with the common susceptibility variants might be modified by environmental factors. Here the investigators formally tested for geneenvironment interaction on the multiplicative scale. Details on the studies can be found in . Prior to the large studies, a number of smaller studies investigated possible interactions between the known susceptibility variants in FGFR2 and menopausal hormone therapy and yielded inconclusive results . In the beginning, studies included a limited set of single-nucleotide polymorphism , which were identified by the first genome-wide association studies to be associated with breast cancer risk.

Table 1 Overview of studies investigating geneenvironment interaction for breast cancer risk in the general population

For the interaction between 1p11.2-rs11249433 and ever being parous, the OR for interaction in BPC3 was in the same direction as in BCAC OR for interaction BPC3=1.07 OR for interaction META=1.13 ). Here the lack of replication could be attributed to the smaller sample size of the study by in BPC3 compared with the study by in BCAC.

Figure 2

Environmental Exposures And Breast Cancer Risk

With your help we have continued to put pressure on the leading cancer agency, the National Cancer Institute to revise and clarify the connection between environmental exposures and breast cancer.

Our work to calling for transparency from the NCI started out as a Think Before You Pink® campaign. Thanks to your continued engagement, this work has not let up, and we have another response from the NCI.

Here are the latest updates on the campaign, an overview of how the NCIs recent updates undermine the very scientific principles that guide many of our national-level regulatory and research standards, and the NCIs most recent response:

  • On the NCIs breast cancer prevention webpage, the agencys recent revisions are misleading and suggest there isnt enough evidence to connect chemicals in the environment to breast cancer risk.
  • The revisions also state that a chemical that causes cancer in laboratory animals may not cause cancer in people, but it ignores the fact that many chemicals that cause cancer in laboratory animals do cause cancer in people. Laboratory tests on animals often yield important and widely accepted red flags that are the basis for chemical regulations, for example to ensure safety of drinking water. Currently these laboratory studies remain the best method for identifying potential human carcinogens in order to make rational decisions about exposure safety.

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What Causes Breast Cancer

Many different things can affect your chances of getting breast cancer.

Theres no single cause. It results from a combination of the way we live our lives, our genes and our environment.

We cant predict who will get breast cancer. And we cant confidently say what might have caused someones breast cancer.

There are, however, some things you can do to lower your chances of getting it.

Which Environmental Factors Increase The Risk For Breast Cancer

Breast cancer

A number of environmental exposures have been investigated in relation to breast cancer risk in humans, including the following :

  • Tobacco smoke

  • Dietary

  • Alcohol consumption

  • Environmental carcinogens

Of these environmental exposures, only high doses of ionizing radiation to the chest area, particularly during puberty, have been unequivocally linked with an increased risk of breast cancer in adulthood. Because of the strong association between ionizing radiation exposure and breast cancer risk, medical diagnostic procedures are performed in such a way as to minimize exposure to the chest area, particularly during adolescence.

Women with a history of radiation exposure to the chest area should be examined and counseled regarding their risk of breast cancer on the basis of the timing and dose of the previous exposure. A patient treated for Hodgkin lymphoma with Mantel radiation that includes the breasts in the radiation field has a 5-fold higher risk of developing breast cancer. This risk increases markedly for women treated during adolescence evidence suggests that cumulative risk increases with age as a function of age of exposure and type of therapy.

A meta-analysis by Yuan et al found an increased risk of breast cancer in women who do long-term night shift work. In North America and Europe, working the night shift was associated with a 32% increased risk for breast cancer overall . Risk increased in a dose-response fashion, rising 3.3% Risk was even higher for nurses .

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Breast Cancer Is An Environmental Health Issue

Dr. Devra Davis, EHT Co-Founder, and President has long championed the issue of environmental factors contributing to breast cancer.

A substantial body of scientific evidence indicates that exposures to common chemicals and radiation, alone and in combination, are an important cause of breast cancer. The challenge in understanding breast cancer is considerable as the disease can arise decades after critical exposures take place. The disease may well arise from either hormonally active materials or those that directly damage DNA.

Pre-menopausal breast cancer and postmenopausal breast cancer are likely to have different causes. Several classes of environmental factors have been implicated as an increased risk for breast cancer, including hormones and endocrine-disrupting compounds, organic chemicals and by-products of industrial and vehicular combustion, and both ionizing and non-ionizing radiation.

In its review of The State of the Evidence, the Breast Cancer Fund recently concluded that there are major opportunities to reduce breast cancer risk through lowering chemical exposures in many different workplaces.

We cannot wait for sufficient numbers of illnesses or deaths to amass when we already know that certain compounds and professions increase the risk of breast cancer in women. Acting to control or restrict such exposures is critical in order to control disease.

-Devra Davis PhD, MPH

What is Body Burden?

Prevention or Cure?

What can I do to reduce my risk?

Environmental Risk Factors And Female Breast Cancer

Annual Review of Public Health

Vol. 19:101-123

Francine Laden1, 2 and David J. Hunter1, 2, 3

1Department of Epidemiology, Harvard School of Public Health, 2Channing Laboratory, Department of Medicine, Harvard Medical School and Brigham and Women’s Hospital, 3Harvard Center for Cancer Prevention, Boston, Massachusetts 02115 e-mail:

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A Family History Of Breast Cancer

Having someone in your family with breast cancer doesnt automatically mean your own risk is increased. For most people, having a relative with breast cancer does not increase their risk.

However, a small number of women and men have an increased risk of developing breast cancer because they have a significant family history.

How Does Her2 Positive Breast Cancer Develop

What do we Know About Environmental Causes of Breast Cancer? Answers From Epidemiology and the Lab

While we are still learning about the causes of HER2 positive breast cancer, researchers have identified how HER2 positive breast cancer develops. In about 25 percent of breast cancers, the cancer cells have an excess of the HER2 protein. This is caused by a mutation in the HER2 gene. When the HER2 gene mutates, it causes cells in the breast to grow and divide at an uncontrolled rate, leading to tumor growth.

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Who Decides Which Environmental Exposures Cause Cancer In Humans

Two organizationsthe National Toxicology Program , an interagency program of the U.S. Department of Health and Human Services , and the International Agency for Research on Cancer , the cancer agency of the World Health Organizationhave developed lists of substances that, based on the available scientific evidence, are known or are reasonably anticipated to be human carcinogens.

Specifically, the NTP publishes the Report on Carcinogens every few years. This congressionally mandated publication identifies agents, substances, mixtures, or exposures in the environment that may cause cancer in humans. The 2016 edition lists 62 known human carcinogens and includes descriptions of the process for preparing the science-based report and the criteria used to list a substance as a carcinogen.

IARC also produces science-based reports on substances that can increase the risk of cancer in humans. Since 1971, the agency has evaluated more than 1,000 agents, including chemicals, complex mixtures, occupational exposures, physical agents, biological agents, and lifestyle factors. Of these, more than 500 have been identified as carcinogenic, probably carcinogenic, or possibly carcinogenic to humans.

What Do Scientists Actually Know About The Cause Of Breast Cancer

Cancer grows when a cells DNA is damaged, but why or how that DNA becomes damaged is still unknown. It could be genetic or environmental, or in most cases, a combination of the two. But most patients will never know exactly what caused their cancer. However, there are certain established risk factors that are associated with breast cancer.

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What Are Environmental Risk Factors And How Can I Avoid Them

Tobacco smoke at a concert. Pollution from the factory around the corner. Radiation from a routine X-ray. When it comes to environmental factors that raise the risk of cancer, it may seem like avoiding exposure is as impossible as avoiding the air you breathe. In reality, though, you have more control than you think. Experts say you can lower your cancer risk simply by making strategic lifestyle changes or taking conscious measures to reduce your exposure. Environmental risk factors account for at least two-thirds of all cancer cases in the United States, so knowing more about what to look out for, and what to avoid, may go a long way in protecting your health.

Cancer develops when changes, or mutations, in a cells DNA cause the cell to grow out of control. Sometimes, the mutations are caused by chemicals and other toxic substances in the environmentclassified as carcinogens because of their cancer-causing potential. While such chemicals are toxic, they dont always cause cancer. Your risk for developing the disease depends on several factorsincluding how long and how often youre exposed, your genetic makeup, your diet and lifestyle, your overall health, and your age and gender.

What Is Niehs Doing

Risk Factors

NIEHS plays a leadership role in funding and conducting studies on the ways in which environmental exposures increase breast cancer risk. This research seeks to understand the role of environmental agents, such as toxic chemicals, in the initiation and progression of cancer, as well as genetic susceptibility. Identifying and reducing contact with environmental factors linked to breast cancer presents tremendous opportunity to prevent this disease.

Sister Study The NIEHS Sister Study has recruited more than 50,000 sisters of women with breast cancer from the U.S. and Puerto Rico. This landmark observational study is looking at lifestyle and environmental exposures, as well as genetic and biological factors that may increase breast cancer risk. Important findings from this study follow.

Two Sister Study An offshoot of the Sister Study, this study focuses on breast cancer in women younger than 50, who may have different breast cancer risk factors than older women. Approximately 1,300 women with young-onset breast cancer are participating, along with their sisters from the Sister Study and their biological parents. Some results from the study include the following.

In-house NIEHS researchers have also studied how environmental exposures can interact with genetic factors to affect breast cancer risk.

Some hallmark findings from BCERP follow.

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The Role Of Environmental Chemicals

In the aftermath of World War II, industry began producing large quantities of synthetic chemicals including pesticides, plastics, solvents, and other substances. These chemicals made their way into our everyday products and into our environment, with little regard for safety. Since then, tens of thousands of chemicals have been produced and sold on the market, the vast majority of which have not been tested for their effects on human health.

Over the last couple of decades, studies show exposure to certain chemicals can contribute to the development of breast cancer. In a landmark study published in 2007 in the journal Cancer, researchers at Silent Spring identified 216 chemicals that cause mammary tumors in animals. About half of these are chemicals women are routinely exposed to in their everyday lives.

Meanwhile, laboratory studies have uncovered several biological mechanisms by which chemicals can lead to breast cancer: Chemicals can damage DNA causing uncontrolled cell growth they can act as tumor promoters that make cells grow and they can change the way the breast develops, leaving it more vulnerable to carcinogens.

In a study in 2003, we detected dozens of EDCs in air and dust inside the home, demonstrating for the first time that consumer products are major source of indoor air pollutants.

How Does The Ntp Decide Whether To Include A Substance On Its List Of Known Human Carcinogens

As new potential carcinogens are identified, they are evaluated scientifically by the NTPs Board of Scientific Counselors and the NTP Director. Next, a draft Report on Carcinogens monograph is prepared, which is reviewed by other scientific experts as needed, the public, and other federal agencies. The draft monograph is then revised as necessary and released for additional public comment and peer review by a dedicated panel of experts. Lastly, a finalized monograph and recommendation for listing is sent to the HHS Secretary for approval.

  • Reviewed:

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Caroline Myss: The 4th Chakra Connection

A leading authority in holistic health, and author of many books about the human energy field, Dr Caroline Myss makes a correlation between the bodys energy chakras and the stresses that can disturb the flow of life energy, leading to illness.

  • There are 7 chakras, starting from the base of the spine and ending at the top of the head. Each chakra supplies life energy to its surrounding organs.
  • The chest/breast area is served by the 4th or heart chakra. The heart chakra is associated with love, forgiveness and compassion qualities of the heart.
  • Breast cancer is caused by a disturbance in the energy flow in this chakra.

General Concept Of Geneenvironment Interaction Studies

Deliberation on evidence for environmental causes of breast cancer

Knowledge of geneenvironment interaction is important for risk prediction and the identification of certain high-risk populations to inform public health strategies for targeted prevention. Geneenvironment interaction studies may also help to discover novel genetic risk factors for example, variants in NAT2 and GSTM1 may not have been identified as relevant genetic risk factors, if their association with bladder cancer risk would have been evaluated in a population of non-smokers. In the same way, novel environmental risk factors might be identified when the environmental exposure is a mixture of several composites . For example, when investigating whole-body fat distribution, with new techniques such as MRI, as a breast cancer risk factor, investigating geneenvironment interactions may help to determine probable risk increasing or protective relationships between breast cancer risk and different adipose tissue compartments, such as subcutaneous or visceral fat. Geneenvironment interactions studies may also be used to gain insight into the biological mechanisms underlying an association between a risk factor and the disease of interest. In the bladder cancer example, geneenvironment interaction studies pointed to aromatic amines as the most important bladder carcinogen in tobacco smoke.

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Understanding Your Risk Of Breast Cancer

Several breast cancer risk assessment tools have been developed to help a woman estimate her chance of developing breast cancer. The best studied is the Gail model, which is available on the National Cancer Institutes website at After you enter some personal and family information, including race/ethnicity, the tool provides you with a 5-year and lifetime estimate of the risk of developing invasive breast cancer. Because it only asks for information about breast cancer in first-degree family members and does not include their ages at diagnosis, the tool works best at estimating risk in women without a strong inherited breast cancer risk. For some women, other ways of determining the risk of breast cancer may work better. For example, women with a strong family history of breast cancer risk should consider talking to a genetic counselor.

It is important to talk with your doctor about how to estimate your personal risk of breast cancer and to discuss risk-reducing or prevention options .

Websites Of Breast Cancer Organizations Have Limited Discussions Of Environmental Factors With More Frequent Mentions Of Lifestyle And Genetic Risk Factors

We analyzed terms on 14,087 URLs belonging to 81 breast cancer organizations . We found 31% of the organizations made a general mention of the environment , 40% mentioned a specific class of chemicals that may act as breast carcinogens or endocrine disrupting compounds, and 82% mentioned a risk factor not related to environmental exposures. While the majority of organizations mentioned either an environmental, lifestyle, or genetic risk factor on their websites, it was rare that website content discussed risk factors at length based on our term scraping analysis most organizations mention these topics less than once per page on average, with references to environmental factors in particular clustering at or close to zero for many websites .

Fig. 1

Average mentions per page of environmental topics versus other risk factors, such as lifestyle or genetic, on organizations websites. Organizations that are primarily national in scope are represented in blue circles and local or regional organizations are represented in purple squares. Dashed line indicates equal average usage of both environmental and non-environmental terms. N =81

Both websites have lifestyle-related tips, such as exercising and reducing risk factors such as drinking alcohol, as key recommendations for reducing overall cancer risk.

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