Tobacco.org

• A review of human carcinogens—Part E: tobacco, areca nut, alcohol, coal smoke, and salted fish 

New evidence continues to add to the extensive list of tobacco-related cancers (table); there is now sufficient evidence that tobacco smoking causes cancer of the colon3 and of the ovary.4 More than 150 epidemiological studies of tobacco smoking and breast cancer were reviewed. Large cohort studies5, 6 published since 20022 consistently show a small positive association (relative risks 1·1—1·3). Many chemicals in tobacco smoke cause mammary-gland tumours in animals, and these carcinogens are stored in breast adipose tissue in women; therefore, the Working Group concluded that there is limited evidence that tobacco smoking causes breast cancer. A causal link between parental smoking and childhood cancers has been established. Four recent studies showed that children born of parents who smoke (father, mother, or both, including the preconception period and pregnancy) are at significantly higher risk of hepatoblastoma, a rare embryonic cancer. The UK Childhood Cancer Study7 reported a relative risk of 1·86 for paternal smoking only and 2·02 for maternal smoking only, increasing to 4·74 (95% CI 1·68—13·35) when both parents smoke. For childhood leukaemia, a meta-analysis reported an association with paternal smoking before pregnancy (summary relative risk 1·12, 1·04—1·21).8 Second-hand smoke causes lung cancer.2 There is now limited evidence for an association with cancers of the larynx and the pharynx,9 whereas evidence for female breast cancer remains inconclusive. Since second-hand smoke contains most of the constituents of mainstream smoke, it might also be associated with other cancer sites. Many types of smokeless tobacco are marketed and all contain nicotine and nitrosamines. Hundreds of millions of people use smokeless tobacco, mainly in India and southeast Asia, but also in Sweden and the USA. Earlier findings showed a causal association between use of smokeless tobacco and cancers of the oral cavity and pancreas, and there is now sufficient evidence for cancer of the oesophagus.10 All of the forms of tobacco discussed above induce malignant tumours in laboratory animals.

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• Smoking May Increase Risk of Breast Cancer 

Researchers from the Mayo Clinic have reported that women who have smoked 100 or more cigarettes in their life have a significantly increased risk of developing breast cancer. The details of this study were published in the September-October 2009 issue of The Breast Journal.[1]

Although both active and passive smoking are known to increase the risk of lung cancer, findings for breast cancer have been mixed. A recent review of published studies suggests that both active and passive smoking may increase the risk of breast cancer—particularly premenopausal breast cancer. The following observations were made from this review of 19 studies:

* Passive smoking increased the risk of breast cancer by 27%.

* Among premenopausal women, passive smoking increased risk of breast cancer by 68%. . . .

[1] Croghan IT, Pruthi S, Hays JT, et al. The role of smoking in breast cancer development: An analysis of a Mayo Clinic cohort. The Breast Journal. 2009; 15: 489-495.

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• Nearly any lifetime smoking ups breast cancer risk  

Women taking the next puff of a cigarette might consider this: smoking 100 or more cigarettes may substantially increase their odds of developing breast cancer, researchers report.

Previous studies linked regular exercise, limiting alcohol intake, and avoiding postmenopausal obesity as lifestyle changes that can reduce women's odds of developing breast cancer, notes Dr. Ivana T. Croghan and colleagues in The Breast Journal.

The current study provides new evidence that "a woman smoker can reduce her risk of breast cancer by stopping smoking as soon as possible," Croghan commented to Reuters Health via email.

Croghan's group compared smoking history and other breast cancer risk factors among 1,225 women who developed breast cancer and 6,872 who did not during the first year after their initial visit to the Mayo Clinic Breast Clinic. . . .

SOURCE: The Breast Journal, September/October 2009

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• Second Breast Cancer: 3 Lifestyle Risks 

The study, published in the advance online edition of the Journal of Clinical Oncology, focused on women with estrogen receptor-positive (ER-positive) breast cancer. Most breast cancers are ER-positive, which means the tumors grow when exposed to the hormone estrogen.

Data came from more than 1,000 Seattle-area breast cancer patients, including 365 women who developed a second breast cancer in their opposite breast.

The women were interviewed about their smoking and drinking; their BMI (body mass index) was noted in their medical records.

The odds of developing a second breast cancer in the opposite breast were greater for obese women, for women who drank at least seven alcoholic beverages per week, and current smokers.

"We found that obese women had a 50% increased risk, women who consumed at least one alcoholic drink per day had a 90% increased risk, and women who were current smokers had a 120% increased risk of developing a second breast cancer," researcher Christopher Li, MD, PhD, says in a news release.

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• Wyeth’s Menopause Hormones Increase Risk of Lung Cancer Deaths 

Wyeth’s hormone replacement therapy, a menopause treatment whose use has declined after being linked to heart attack, stroke and breast cancer, increases the risk of death from lung tumors, a study found.

After five years on Wyeth’s Prempro, a combination of the hormones estrogen and progestin, 67 women died from non-small cell lung cancer, compared with 39 on placebo, the research showed. Results of the trial, which examined women age 50 to 79 and included current and former smokers, were presented today at the American Society of Clinical Oncology meeting in Orlando.

Sales of the pills plunged in 2002 after a U.S. study linked the therapy to breast cancer and cardiovascular risks. As many as 6 million women took the menopause treatments before the study curbed use. The products generated $1.1 billion last year, down from more than $2 billion in 2001.

“This is a new finding that tells us women who smoke shouldn’t take estrogen and progestin for menopause symptoms,” said Rowan Chlebowski, the study author and a researcher at Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, in an interview.

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• ACTIVE SMOKING AND SECOND-HAND SMOKE LINKED TO BREAST CANCER 

There is now enough scientific evidence to link both active smoking and second-hand smoke to breast cancer, according to an international panel convened by the Ontario Tobacco Research Unit, an affiliate of the Dalla Lana School of Public Health, University of Toronto, with support from the Public Health Agency of Canada.

“Until recently, evidence about the link between breast cancer and tobacco smoke, although voluminous, was inconclusive. But the Panel’s careful analysis of all available evidence, particularly recent evidence, led us to conclude that there is persuasive evidence of risk,” said Neil Collishaw, Chair of the Panel. “An estimated 80 to 90 per cent of women have been exposed to tobacco smoke in adolescence and adulthood. Those women face an increased risk of breast cancer because of that exposure.”

There have been many studies over the years on the relationship between cigarette smoke and breast cancer in women. The Panel comprehensively reviewed all available evidence, including important recent evidence, and concluded there was a risk even non-smoking young women face through passive exposure to cigarette smoke. The Panel also concluded that the relationship of active smoking to both pre- and post-menopausal breast cancer is consistent with causality, but there is not yet enough evidence to draw a conclusion about the nature of the relationship between exposure to second-hand smoke and breast cancer for older, post-menopausal women.

“It is important from a public health perspective to get the message out to the public

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• Smoking plus gene variant raises breast cancer risk  

Women with a particular gene mutation linked to breast cancer may further raise their risk of the disease if they smoke, a study has found.

The gene in question is known as the ataxia-telangiectasia, or A-T, gene. At least 1 percent of the population carries a mutation in the gene, and women who carry mutated A-T have a higher-than-average risk of developing breast cancer.

But until now it had not been known whether smoking increases this risk even more. Studies on smoking and breast cancer in the population as a whole have generally found little or no evidence that the habit contributes to the disease.

These latest findings, however, should give women yet another reason not to smoke, according to lead researcher Dr. Michael Swift, of the Disease Insight Research Foundation in Ardsley, New York.

While the study focused only on women with an A-T mutation, most women who carry such a mutation do not know it, Swift told Reuters Health.

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• Study Links Nicotine With Breast Cancer Growth And Spread 

A study published in Cancer Research, a journal of the American Association for Cancer Research, suggests a possible role for nicotine in breast tumor development and metastases.

The study, conducted by researchers at the Beth Israel Deaconess Medical Center, is among the first to explore the effects of nicotine on mammary cells.

"Although numerous studies indicate the role of nicotine exposure in tumor promotion, little is known about the effect of nicotine on breast tumor development, especially on the metastatic process of breast cancer," said lead author Chang Yan Chen, Ph.D., M.D., at Beth Israel Deaconess Medical Center.

Through a series of in vitro tests Chen and her team of researchers determined that breast epithelial-like MCF10A cells and cancerous MCF7 cells both express several subunits of nAChR (nicotine receptor), that when bound, initiate a signaling process, potentially increasing cell growth and migration.

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• Tobacco smoke exposure does not increase breast cancer risk 

Exposure to tobacco smoke during childhood or as an adult does not increase the risk for developing breast cancer among women who have never smoked, a large prospective study has shown.

The researchers claim that previous positive findings from retrospective studies suggesting such a link have been distorted by the fact that women were more likely to report past exposures because they knew that they had breast cancer. . . .

As reported in the International Journal of Epidemiology, women who were exposed to passive smoke as children were at no greater risk for developing breast cancer than those who were not exposed (adjusted relative risk [RR]=0.98), nor were women who were exposed as adults (RR=1.02).

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• Active and passive smoking, IL6 , ESR1 , and breast cancer risk 

We evaluated the association between smoking and risk of breast cancer in non-Hispanic white (NHW) and Hispanic or American Indian (HAI) women living in the Southwestern United States. . . .

Passive smoke increased risk of pre-menopausal breast cancer for HAI women (OR 1.9, 95% CI 1.1–3.1 everyone; OR 2.3, 95% CI 1.2–4.5 nonsmokers). HAI pre-menopausal women who were exposed to 10+ h of passive smoke per week and had the rs2069832 IL6 GG genotype had over a fourfold increased risk of breast cancer (OR 4.4, 95% CI 1.5–12.8; P for interaction 0.01). Those with the ESR1 Xba1 AA genotype had a threefold increased risk of breast cancer if they smoked ≥15 pack-years relative to non-smokers (P interaction 0.01). These data suggest that breast cancer risk is associated with active and passive smoking.

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• Common gene boosts breast cancer risk in smokers  

Researchers have confirmed yet another ill effect of smoking cigarettes: it increases the risk of breast cancer in women with a common genetic variation.

The gene involved, N-acetyltransferase 2 (NAT2), is believed to help clear the body of aromatic amines, a major carcinogen in tobacco smoke. The researchers found that women with the slower-acting form of this gene -- who represent 50 percent to 60 percent of the white population and 35 percent to 40 percent of African-Americans -- are more likely to get breast cancer if they smoke.

But the study's lead author said the finding shouldn't motivate people to undergo; instead, she said, it should spur them to quit smoking. "We still know very little about what these genes do and how they might affect risk-we think the most important thing for people to do is to live a healthy lifestyle," Dr. Christine B. Ambrosone of the Roswell Park Cancer Institute in Buffalo, New York, told Reuters Health.

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• Smoking Increases Breast Cancer Risk Based On Genes, Study Shows 

Women who smoke and have a specific genetic makeup are at significant risk for the development of breast cancer, according to a recent study published by the journal Cancer Epidemiology, Biomarkers and Prevention.

A research group led by Christine Ambrosone, PhD, Cancer Prevention and Population Sciences Program, Roswell Park Cancer Institute (RPCI) and Jenny Chang-Claude, PhD, Professor in Epidemiology at University of Heidelberg analyzed data from 10 of the 13 studies published in the last 10 years in which they evaluated genetic information, smoking habits and breast cancer risk in 4,889 premenopausal and 7,033 postmenopausal women.

Analysis demonstrated a significant interaction between breast cancer risk, smoking, and a specific gene called the NAT2 that produces the enzyme, N-acetyltransferase 2 (NAT2).

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• Smoking ups risk with radiation for breast cancer  

Cigarette smoking dramatically increases the risk that a woman who has undergone radiation treatment for breast cancer will develop lung cancer later on, a new study shows.

Radiation after mastectomy may be considered for some high-risk breast cancer patients, Dr. Elizabeth L. Kaufman and colleagues from Columbia University in New York City point out in their report. However, radiation can cause many complications, including increasing the likelihood that a patient will develop lung cancer 10 or more years after treatment, they add.

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• Cigarette link to breast cancer 

SMOKING more than doubles the risk of developing breast cancer among women with a strong family history of the disease, a study of Australians has revealed.

The major international review is the first to show a connection between the disease and tobacco in women with the highest risk breast cancer genes, BRCA1 or BRCA2.

About half of women with faulty versions of these genes will develop cancer by the age of 70. . . .

The review, published in the journal Breast Cancer Research and Treatment, analysed data collected from 780 women involved in large breast cancer trials, including more than 300 from the Melbourne-based Australian Breast Cancer Family study.

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• Smoking doubles danger of developing breast cancer for high risk women, says new international study 

Women who carry a faulty BRCA1 or BRCA2 gene - which puts them at high risk of developing breast cancer - will further double their risk if they smoke, says a new international study.

University of Melbourne researchers were key collaborators on the study, currently published online in the journal Breast Cancer Research and Treatment.

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