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Does Smoking Cause Breast Cancer

Assessment Of Smoking Status

Breast Cancer Environmental Risk Factors

Underreporting of smoking

The questionnaires used in the different studies have not been published and therefore we cannot conclude on how uniform they were in content. Bjerkaas et al. included data from three different cohorts resulting in three different questionnaires . This is also the case in the large cohort study by Ordóñez-Mena et al. . When investigating smoking habits by questionnaire there is a substantial risk of underreporting. A large review by Gorber et al. investigated 54 published studies on the accuracy of self-reported smoking and found that in most cases patients underestimated their smoking. In 41 out of 54 studies underreporting was observed ranging from a few per cent to forty-six per cent . In most of the studies included in our analysis, the questionnaire was filled out by the patientâs themselves. The effect of possible underreporting should, however, be equally present in most of the included articles. Seibold et al. conducted interviews to fill out these forms and their patientâs answers might be more uniform, and possibly more accurate, than the self-reported ones .

Classification of exposure variable: time of assessment of smoking status

Classification of exposure variable: definition of smoking status

Passive smoking as a confounder

Classification of the outcome: mortality

Duplicate cases

Statistical heterogeneity

Risk of bias between studies

The importance of smoking cessation

How Many Cigarettes A Day Is A Heavy Smoker

Smoking five or fewer cigarettes a day can cause almost as much damage to your lungs as smoking two packs a day. Thats according to a recent study from Columbia University that examined the lung function of 25,000 people, including smokers, ex-smokers, and those who have never smoked.

Secondhand Smoke And Breast Cancer

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A growing body of recent scientific evidence shows that secondhand smoke exposure is a cause of breast cancer.1 Breast cancer is the most common cancer among women in Western countries and is the leading cancer killer in nonsmoking women.2 Secondhand smoke is a cause of breast cancer, primarily in young, pre menopausal women who have never smoked, and it contributes to preventable and premature death among women.

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Myth: Secondhand Smoke Isnt That Bad

Secondhand smoke is a risk factor for lung cancer because the smoke exposes the nonsmoker to the same cancer-causing chemicals as the smoker. Nonsmokers exposed to secondhand smoke at home or work have a 20 percent to 30 percent increased risk of lung cancer compared to those who have not been exposed to secondhand smoke.

The more youre exposed to secondhand smoke, the greater your lung cancer risk becomes. Even brief secondhand smoke exposure may damage cells in ways that set the cancer process in motion, the U.S. Centers for Disease Control and Prevention says on its website.

A 2018 study published in the International Journal of Environmental Research and Public Healthconfirmed that exposure to secondhand smoking significantly increases the risk of overall cancer for never smokers. In particular, secondhand smoking significantly increases the risk of breast and lung cancer and cancers in women. The researchers estimated that secondhand smoking increased the risk of breast cancer by 24 percent and lung cancer by 25 percent in the patients studied.

What Are The Risk Factors For Breast Cancer

Fresh look at cancer shows smoking, obesity top causes ...

Being a woman and getting older are the main risk factors for breast cancer.

Studies have shown that your risk for breast cancer is due to a combination of factors. The main factors that influence your risk include being a woman and getting older. Most breast cancers are found in women who are 50 years old or older.

Some women will get breast cancer even without any other risk factors that they know of. Having a risk factor does not mean you will get the disease, and not all risk factors have the same effect. Most women have some risk factors, but most women do not get breast cancer. If you have breast cancer risk factors, talk with your doctor about ways you can lower your risk and about screening for breast cancer.

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Results Of The Individual Studies

Characteristics and results of the individual studies can be seen in Table S1.

All-cause death

Ten articles reported HRs for all-cause deaths in former smokers . Four found a statistically significant increase in mortality with HRs ranging from 1.11â1.47 .

Ten articles reported HRs for all-cause deaths in current smokers . Eight found a significant increase in mortality with HRs ranging from 1.16â2.45 .

Breast cancer-associated death

Nine articles reported HRs for breast cancer associated deaths in former smokers . Ordóñez-Mena et al. was the only one finding a statistically significant increase in mortality, HR 1.15 . Pierce et al., who stratified their group of former smokers into subgroups depending on pack-years smoked found a statistically significant increase among those who had smoked > 35 py .

Ten articles reported HRs for breast cancer associated deaths in current smokers . Five detected a statistically significant increase in mortality with HRs ranging from 1.15â1.73 .

What Is Secondhand Smoke

Secondhand smoke is also called environmental tobacco smoke . Its a mixture of 2 forms of smoke that come from burning tobacco:

  • Mainstream smoke: The smoke exhaled by a person who smokes.
  • Sidestream smoke: Smoke from the lighted end of a cigarette, pipe, or cigar, or tobacco burning in a hookah. This type of smoke has higher concentrations of nicotine and cancer-causing agents than mainstream smoke.

When people who don’t smoke are exposed to SHS its called involuntary smoking or passive smoking. When you breathe in SHS, you take in nicotine and toxic chemicals the same way people who smoke do. The more SHS you breathe, the higher the levels of these harmful chemicals in your body.

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Smoking And Breast Cancer Risk

This summary table contains detailed information about research studies. Summary tables are a useful way to look at the science behind many breast cancer guidelines and recommendations. However, to get the most out of the tables, its important to understand some key concepts. Learn how to read a research table.

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.

Risk Factors You Can Change

Dr. Hamilton Discusses Risks of Smoking for Breast Cancer Patients on TODAY Show Sarah Cannon
  • Not being physically active. Women who are not physically active have a higher risk of getting breast cancer.
  • Being overweight or obese after menopause. Older women who are overweight or obese have a higher risk of getting breast cancer than those at a normal weight.
  • Taking hormones. Some forms of hormone replacement therapy taken during menopause can raise risk for breast cancer when taken for more than five years. Certain oral contraceptives also have been found to raise breast cancer risk.
  • Reproductive history. Having the first pregnancy after age 30, not breastfeeding, and never having a full-term pregnancy can raise breast cancer risk.
  • Drinking alcohol. Studies show that a womans risk for breast cancer increases with the more alcohol she drinks.

Research suggests that other factors such as smoking, being exposed to chemicals that can cause cancer, and changes in other hormones due to night shift working also may increase breast cancer risk.

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What Can Be Done About Secondhand Smoke

Many US local and state governments, and even federal governments in some other countries, have decided that protecting the health of employees and others in public places is of the utmost importance and have passed clean indoor air laws. Although the laws vary from place to place, they are becoming more common. Detailed information on smoking restrictions in each state is available from the American Lung Association.

You dont have to wait for the government to act. Even if you smoke, you can decide to make your home and car smoke-free. This is the safest thing to do for your children, other family members, pets, and guests.

Busted: 7 Myths About Smoking And Cancer

Kicking the tobacco habit is never a bad idea, and its never a bad time to quit. Maybe you have a baby on the way. Your new partner doesnt like the smell. Perhaps you realize the money youd save by quitting. Or maybe youve been diagnosed with a serious health condition or disease, like cancer.

Of course, if quitting was easy, 40 million Americans may not still be smoking, despite the known health risks. Studies, in fact, show that up to 90 percent of smokers who try to quit relapse in the first year. The good news is that the relapse rate drops up to 4 percent for each year a smoker abstains from cigarettes.

So, if youre looking for reasons to quit, here are some busted myths about smoking that may inspire you to kick the habit.

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Smoking And Breast Cancer

Although smoking cigarettes has been linked to a variety of chronic health problems including heart disease, stroke and several types of cancer health experts have found no relationship between a woman’s status as a smoker and her breast cancer risk. Over the past 40 years, dozens of studies, large and small, have found no indication that smoking cigarettes either increases or decreases the likelihood of a woman developing breast cancer.

Why this is the case is not clear. When researchers look at the relationship between smoking and other cancers, the results are dramatic: Smoking has been highly correlated to lung cancer risk, for example. Cigarettes contain many known carcinogens, and the chemical byproducts of smoking have been found in breast tissue and breast milk. So why is there no apparent connection with breast cancer?

Researchers theorize that smoking might equally increase and decrease risk because smoking acts against the production of estrogen, a hormone that plays a leading role in breast cancer. Women who smoke also are less likely to have endometrial cancer, which is related to estrogen, and tend to start menopause earlier. In theory, the anti-estrogenic effects of smoking could counter the cancer-causing effects of some of the chemicals in cigarettes.

Are Lingering Smoking Odors Harmful

Why Don

Theres very little research so far on whether lingering tobacco smoke odors or residuals from it on surfaces can cause cancer in people. Research does show that particles from secondhand tobacco smoke can settle in dust and on surfaces and remain there long after the smoke is gone. Some studies suggest the particles can last for months. Even though its no longer in the form of smoke, researchers often call this thirdhand smoke or residual tobacco smoke.

Particles that settle out from tobacco smoke have been shown to combine with gases in the air to form cancer-causing compounds that settle onto surfaces. For instance, some of the carcinogens that are known to cause lung cancer have been found in dust samples taken from the homes of people who smoke. Research has also shown that thirdhand smoke can damage human DNA in cell cultures and might increase lung cancer risk in lab animals.

Though its not yet clear if such smoke residue can cause cancer, any effects would probably be small compared with direct exposure to SHS. Still, the compounds may be stirred up and inhaled with other house dust, and may also be accidentally taken in through the mouth. Because of this, any risk the compounds pose is probably greater for babies and children who play on the floor and often put things in their mouths.

The health risks of THS are an active area of research.

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In Vivo Adoptive Transfer Of Cd11b+ly6g+ N2

For adoptive transfer of N2-neutrophils, tumor-free Balb/c mice pre-exposed to nicotine were used to isolate neutrophils from bone marrow . In brief, femur and tibia of sham and nicotine-treated naive, non-tumor-bearing euthanized mice were removed and flushed using a 25-gauge needle filled with PBS. The resulting cell suspension was gently disaggregated and passed through a 40µm cell strainer to produce a single-cell suspension. All red blood cells were hypotonically lysed by adding 20mL of 0.2% NaCl for 20s, followed by neutralization with 20mL of 1.6% NaCl. Neutrophils were then isolated using MACS-based neutrophil isolation kit as per manufacturers recommendation and characterized for N2 phenotype as described in Flow cytometry section. Recipient mice were injected i.v. with single injection of N2 neutrophils resuspended in ice-cold HBSS in a volume of 200µl at the indicated time point.

Smoking Linked To Higher Risk Of Breast Cancer

Doctors have long suspected some type of link between cigarette smoking and breast cancer risk, but research results have been mixed. A large study has found that smoking increases breast cancer risk in women, especially women who start smoking before they have their first child.

The research was published online on Feb. 28, 2013 by the Journal of the National Cancer Institute. Read the abstract of Active Smoking and Breast Cancer Risk: Original Cohort Data and Meta-Analysis.

While many earlier studies found a slight increase in overall breast cancer risk for women who smoke, they didnt find that smoking more cigarettes per day or smoking for more years increased risk even more. Also, the effects of drinking alcohol affected many of these studies. Alcohol is a risk factor for breast cancer and women who smoke are more likely to drink alcohol. So it was difficult for the researchers to tease out how much only smoking or only drinking alcohol was affecting breast cancer risk.

In this study, researchers looked at information from nearly 74,000 women in the American Cancer Societys Cancer Prevention Study II Nutrition Cohort, a large long-term study looking at lifestyle factors and cancer prevention. When the study started in 1992, the women were ages 50 to 74. They reported how much they smoked currently, as well as their smoking history. At the beginning of the study:

  • 8% of the women smoked
  • 36% of the women had quit smoking
  • 56% of the women had never smoked

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Vapor Smoke Vs Cigarette Smoke

So the question is, does vapor smoke have the same cancer-causing properties as cigarette smoke?

Smoke from e-cigarettes is different from cigarette smoke. While cigarette smoke results from the burning of tobacco and other cigarette additives, e-cigs create smoke by heating a liquid, creating a chemical-filled aerosol which is then inhaled. Since they dont contain combustion byproducts , e-cigarettes do offer an improvement over traditional cigarettes in this area. According to a FDA-sponsored report, there is substantial evidence that except for nicotine, under typical conditions of use, exposure to potentially toxic substances from e-cigarettes is significantly lower compared with combustible tobacco cigarettes.

But whats in vapor smoke exactly? Heres the thing, we dont know. Because e-cigarettes only recently came under FDA regulation in 2016, many e-cig manufacturers havent registered and submitted product data and only preliminary regulations have been created. We know at a minimum that most e-cigs contain tobacco-extracted nicotine, a base , and most contain colors, flavorings, and other additives.

And in 2015, the New England Journal of Medicine reported that multiple samples of e-cigarette vapor contained formaldehyde-releasing agents, thought to be a byproduct of the vaporization of the propylene glycol e-liquid base. Researchers stated,

Toxins In Secondhand Smoke Target Breast Tissue

Is There a Link Between Smoking and Breast Cancer?
  • Tobacco smoke contains multiple fatsoluble compounds known to induce mammary tumors.1,3
  • Of the 50 known cancercausing agents in cigarettes, 20 specifically target breast tissue and mammary glands.1
  • Chemicals from tobacco smoke reach breast tissue and have been found in breast fluid and breast milk.4

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Studies Of Cigarette Smoking And Breast Density

Mammographic density refers to the relative amount and configuration of breast tissue as it appears on a mammogram, with fat appearing dark , and epithelial and stromal tissues appearing light . Mammographic density can be classified according to Wolfe patterns , the percentage of dense area in the breast, or the degree of density in dense areas of the breast . Studies have consistently shown that women with a large proportion of dense tissue in the breast are at severalfold greater risk of breast cancer than women with a relatively small proportion of dense breast tissue . Two studies of cigarette smoking and mammographically defined breast density have been conducted, including a case-control study of high risk parenchymal patterns nested within the European Prospective Investigation of Cancer cohort study and a cross-sectional analysis of percentage of breast density in a cohort of family members of women with breast cancer . Both of these studies showed lower measures of breast density in current smokers than in nonsmokers. Because exposure to estrogen has been associated positively with breast density, the results of these studies are consistent with an antiestrogenic effect of cigarette smoking.


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