How Does Smoking Lead To Breast Cancer

Smoking And Breast Cancer Risk

Introduction: Women who smoke for many years may have a slightly increased risk of breast cancer. Women who are current smokers and have been smoking for more than 10 years appear to have about a 10 percent higher risk of breast cancer than women whove never smoked .

Women who are current smokers but have smoked for less than 10 years dont appear to have an increased risk of breast cancer.

Whether the risk of breast cancer is increased in past smokers is under study.

Smoking increases the risk of many other types of cancer .

*Please note, the information provided within Komen Perspectives articles is only current as of the date of posting. Therefore, some information may be out of date.

Study selection criteria: Prospective cohort studies with at least 1,000 breast cancer cases, pooled analyses and meta-analyses.

Table note: Relative risk above 1 indicates increased risk. Relative risk below 1 indicates decreased risk.

NS = No statistically significant increase or decrease in risk

Most participants were premenopausal.

The Field Cancerization Effect

Beginning with the groundbreaking investigations of Auerbach and colleagues , an extensive literature documents that tobacco smokers’ respiratory epithelium often contains multifocal premalignant lesions that can occur throughout the bronchial tree. These findings have been referred to as the field cancerization effect, and implicate the capacity of tobacco carcinogens to mutagenize the respiratory epithelium extensively . In analyzing premalignant and malignant epithelium from patients with squamous cell carcinoma, Wistuba and coworkers found multiple, sequentially occurring allele-specific chromosomal deletions in widely dispersed, apparently clonally independent foci, early in the multistage pathogenesis of lung squamous cell carcinoma . The bronchial epithelium in current and former smokers also demonstrates multiple foci of genetic changes, as seen in patients with lung cancers. Importantly, these changes may persist for many years after smoking cessation . These persistent abnormalities serve as a driving force for increased risk in a growing population there are more than 45 million former smokers in the United States, and the majority of new lung cancer diagnoses now occurs in former smokers.

How Many People Develop Lung Cancer Because Of Exposure To Radon

Cigarette smoking is the most common cause of lung cancer. Radon represents a far smaller risk for this disease, but it is the second leading cause of lung cancer in the United States. Scientists estimate that 15,000 to 22,000 lung cancer deaths in the United States each year are related to radon.

Exposure to the combination of radon gas and cigarette smoke creates a greater risk of lung cancer than exposure to either factor alone. The majority of radon-related cancer deaths occur among smokers. However, it is estimated that more than 10 percent of radon-related cancer deaths occur among nonsmokers.

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What Happens To Cancer Risk After A Person Stops Drinking Alcohol

Most of the studies that have examined whether cancer risk declines after a person stops drinking alcohol have focused on head and neck cancers and on esophageal cancer. In general, these studies have found that stopping alcohol consumption is not associated with immediate reductions in cancer risk. The cancer risks eventually decline, although it may take years for the risks of cancer to return to those of never drinkers.

For example, ex-drinkers still had higher risks of oral cavity and pharyngeal cancers than never drinkers even 16 years after they stopped drinking alcohol, although it was lower than before they stopped drinking . One study estimated that it would take more than 35 years for the higher risks of laryngeal and pharyngeal cancers associated with alcohol consumption to decrease to the level of never drinkers .

What Other Organizations Offer Information Related To Asbestos Exposure

The organizations listed below can provide more information about asbestos exposure.

The Agency for Toxic Substances and Disease Registry is the principal Federal agency responsible for evaluating the human health effects of exposure to hazardous substances. This agency works in close collaboration with local, state, and other Federal agencies, with tribal governments, and with communities and local health care providers to help prevent or reduce harmful human health effects from exposure to hazardous substances. The ATSDR provides information about asbestos and where to find occupational and environmental health clinics. The ATSDR can be contacted at:

Agency for Toxic Substances and Disease Registry18002324636 18882326348

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What Is Tobacco Smoke

Tobacco smoke is a mixture of gases and chemicals that is sent into the air during the burning of tobacco products or from the smoke that is exhaled by a smoker. The smoke that is present in the environment contains multiple chemicals linked to breast cancer, such as benzene and vinyl chloride, both designated as known carcinogens by the International Agency for Research on Cancer or the National Toxicology Program,,, as well as 1, 3-butadiene, toluene, and nicotine-derived nitrosamine ketone that may cause mammary tumors in animals. NNK is a tobacco-specific carcinogen that studies have shown to increase tumor cell proliferation and the transformation of healthy breast epithelial cells into cancer cells.,,

Passive smoke is the involuntary exposure to somebody elses tobacco smoke. Passive smokers inhale secondhand smoke from the exhaled smoke of active smokers, and also from the smoke that emerges from smoldering tobacco. Of increasing concern are exposures to third hand smoke, that is, contamination from active smoking that remains in indoor environments long after first and second hand smoke has been released into the air. Third hand smoke is found in in many places, including carpets, furniture, blankets, toys, and even on walls. Over time, as the chemicals from second hand smoke break down, the concentrations of NNK rise and surpass levels found in both active and second-hand smoke residues.

Is It Important For Someone Diagnosed With Cancer To Quit Smoking

Quitting smoking improves the prognosis of cancer patients. For patients with some cancers, quitting smoking at the time of diagnosis may reduce the risk of dying by 30% to 40% . For those having surgery, chemotherapy, or other treatments, quitting smoking helps improve the bodys ability to heal and respond to therapy . It also lowers the risk of pneumonia and respiratory failure . In addition, quitting smoking may lower the risk that the cancer will recur, that a second cancer will develop, or that the person will die from the cancer or other causes .

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Why Dont Patients Quit

But quitting is difficult, especially when patients have to face a host of invasive surgeries and side effect-ridden treatments.

Melissa Graham, a breast cancer patient from California, said she was an âon again, off againâ smoker from age 11 or 12 until she was diagnosed at 33. She struggled but was finally able to quit three months after she learned of her cancer.

âI smoked right up until the very last day that my plastic surgeon gave me to quit,â she said. âAnd I still struggle when Iâm stressed out to not buy a pack, even though the smell makes me nauseous now. Itâs crazy how strong the draw is even four years later.â

Manders, who counsels patients through SCCAâs Living Tobacco-Free Services, said quitting is extremely hard in the best of circumstances but even more so post-diagnosis.

âFor many people, smoking is the ultimate coping mechanism that they have,â she said. âThe vast majority of people start before the age of 21. They start at a very young age using it as a coping skill. And their brains produce a huge amount of dopamine quickly when they smoke. Thatâs why itâs so addictive.â

Patients there talk about using cigarettes as a crutch to deal with the stress of cancer and call themselves âstupidâ or âungratefulâ for potentially destroying a âsecond chance at life.â Many talk about being ashamed and embarrassed, especially when loved ones discover theyâre still smoking.

The Development And Causes Of Cancer

The fundamental abnormality resulting in the development of is the continual unregulated proliferation of cancer cells. Rather than responding appropriately to the signals that control normal cell behavior, cancer cells grow and divide in an uncontrolled manner, invading normal tissues and organs and eventually spreading throughout the body. The generalized loss of growth control exhibited by cancer cells is the net result of accumulated abnormalities in multiple cell regulatory systems and is reflected in several aspects of cell behavior that distinguish cancer cells from their normal counterparts.

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Generation Of Conditioned Medium

Condition medium were prepared by seeding 0.51×106 THP1, MRC-5, and HL-60 cells with or without 1M Nicotine in regular culture medium supplemented with 10% FBS. After 24h, cells were washed by PBS and incubated further for 24h in serum-free culture condition. The harvested CM was then centrifuged at 300×g for 10min to remove cells and debris and store at 80°C. To prepare primary neutrophil CM, 12×106 freshly procured neutrophils were washed with HBSS and cultured overnight in serum-free RPMI or AIM-V medium in the presence or absence of 1M nicotine. After overnight incubation, the harvested neutrophil conditioned medium was then centrifuged to remove cells and debris at 300×g for 10min and stored at 80°C.

How Your Diet May Affect Your Risk Of Breast Cancer

Eating right is one important way you may be able to lower your risk of breast cancer. The American Cancer Society recommends eating mostly vegetables, fruits, and whole grains, and less red meat , less processed meat , and fewer sweets. A healthy diet can help reduce the risk of heart disease, diabetes, stroke, and certain cancer types.

A healthy diet can also help you get to and stay at a healthy weight. Overweight and obesity increase the risk for getting breast cancer. Whats less clear is the link between breast cancer risk and any one food type. Many studies about foods and breast cancer risk have had different results, but no clear-cut answers. Here is what the evidence tells us about fat, vitamin supplements, soy, dairy, and sugar.

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Can People’s Genes Affect Their Risk Of Alcohol

A personâs risk of alcohol-related cancers is influenced by their genes, specifically the genes that encode enzymes involved in metabolizing alcohol .

For example, one way the body metabolizes alcohol is through the activity of an enzyme called alcohol dehydrogenase, or ADH, which converts ethanol into the carcinogenic metabolite acetaldehyde, mainly in the liver. Recent evidence suggests that acetaldehyde production also occurs in the oral cavity and may be influenced by factors such as the oral microbiome .

Many individuals of East Asian descent carry a version of the gene for ADH that codes for a “superactive” form of the enzyme. This superactive ADH enzyme speeds the conversion of alcohol to toxic acetaldehyde. Among people of Japanese descent, those who have this form of ADH have a higher risk of pancreatic cancer than those with the more common form of ADH .

Another enzyme, called aldehyde dehydrogenase 2 , metabolizes toxic acetaldehyde to non-toxic substances. Some people, particularly those of East Asian descent, carry a variant of the gene for ALDH2 that encodes a defective form of the enzyme. In people who produce the defective enzyme, acetaldehyde builds up when they drink alcohol. The accumulation of acetaldehyde has such unpleasant effects that most people who have inherited the ALDH2 variant are unable to consume large amounts of alcohol and therefore have a low risk of developing alcohol-related cancers.

What Does The Current Evidence Show

There are some things that research has told us about smoking and breast cancer. Lets examine what we know.

It appears that breast cancer risk is linked to a smoking habit thats lasted for many years. For example, people with a history of smoking have about a breast cancer risk than people whove never smoked.

A found that the risk of breast cancer increased in women who:

• currently smoke or previously smoked a large number of cigarettes
• started smoking at a younger age
• smoked for many years
• smoke a higher number of pack-years, with risk increasing with every 20 pack-years
• smoked before the birth of their first child

A more recent looked at data pooled from 14 different cohort studies and found that:

• The overall association of smoking with breast cancer was modest.
• Smoking for more than 10 years before the birth of a first child carried a high risk of breast cancer.
• Smoking 40 or more cigarettes per day was associated with the highest risk of breast cancer.
• Drinking alcohol can have a compounding effect on breast cancer risk, particularly when heavy drinking is combined with smoking a large number of cigarettes or smoking for many years.

Exposure to secondhand smoke may also increase a womans risk of breast cancer. A found that women who were frequently around secondhand smoke had similar breast cancer risk to active smokers.

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A History Of Breast Cancer Or Breast Lumps

Women who have previously had breast cancer are more likely to have it again than those who have no history of the disease.

Having some types of noncancerous breast lump increases the chance of developing cancer later on. Examples include atypical ductal hyperplasia or lobular carcinoma in situ.

Individuals with a history of breast, ovarian, fallopian tube, or peritoneal cancer

How Do We Know Obesity Causes Cancer

There is lots of high-quality research showing the link between excess weight and cancer.

There are consistent results from decades of research involving millions of people. We see more cancer cases in groups that are overweight compared to groups that are a healthy weight.

The risk increases the more weight is gained, so we can be more sure the link is real . And there are good explanations for how extra fat cells in the body could cause cancer. We can confidently rule out other explanations .

International organisations like the International Agency for Research on Cancer and the World Cancer Research Fund agree.

A person’s risk of cancer depends on lots of different factors. This includes things you can’t change like your age and genes. Factors like smoking, obesity and UV rays also affect our cancer risk.

This doesn’t mean that everybody who is overweight, smokes or spends too much time in the sun will develop cancer. But, they are more likely to get cancer.

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Being Overweight Or Obese

Being overweight or obese after menopause increases breast cancer risk. Before menopause your ovaries make most of your estrogen, and fat tissue makes only a small part of the total amount. After menopause , most of a womans estrogen comes from fat tissue. Having more fat tissue after menopause can raise estrogen levels and increase your chance of getting breast cancer. Also, women who are overweight tend to have higher blood insulin levels. Higher insulin levels have been linked to some cancers, including breast cancer.

Still, the link between weight and breast cancer risk is complex.

For instance, the risk of breast cancer after menopause is higher for women who gained weight as an adult, but the risk before menopause is actually lower in women who are obese. The reasons for this arent exactly clear.

Weight might also have different effects on different types of breast cancer. For example, being overweight after menopause is more strongly linked with an increased risk of hormone receptor-positive breast cancer, whereas some research suggests that being overweight before menopause might increase your risk of the less common triple-negative breast cancer.

The American Cancer Society recommends you stay at a healthy weight throughout your life and avoid excess weight gain by balancing your food intake with physical activity.

How Does Smoking Cause Breast Cancer

Medical studies from the last twenty years agree that smoking is bad news when it comes to breast cancer. Smoking increases breast cancer recurrenceThe reappearance of the disease after it has been treated. In breast cancer, recurrence following primary breast cancer can be local , regional or metastatic ., increases breast cancer mortality and is linked to poor prognosisThe expected or likely outcome of a disease, usually based on a statistical analysis of large groups of patients. . In addition, smoking between a womans first period and first pregnancy is particularly risky.

We know that smoking is a substantial risk factor for breast cancer. According to the National Cancer Institute at least 250 chemicals found in tobacco smoke are known to be harmful and at least 69 of those have been shown to cause cancer in general, not just breast cancer. We know chemicals from cigarette smoke reach the breast because those chemicals have been found in the breast fluid of female smokers and lactating women. Numerous carcinogenic chemicals found in cigarette smoke are known to induce mammary tumors in rats.

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