The Surgeon General Report on Smoking and Health 50 Years Later: Breast Cancer and the Cost of Increasing Caution

Smoking Cessation after Cancer Diagnosis and Enhanced Therapy Response: Mechanisms and Significance

The adverse effects of smoking on human health have been recognized for several decades, especially in the context of cancer. The ability of tobacco smoke components, including tobacco-specific carcinogens and additive compounds such as nicotine, to initiate or promote tumor growth have been described in hundreds of studies. These investigations have revealed the tumor-promoting activities of nicotine and other tobacco smoke components and have also recognized the ability of these agents to suppress the efficacy of cancer therapy; it is now clear that smoking can reduce the efficacy of most of the widely used therapeutic modalities, including immunotherapy, radiation therapy, and chemotherapy. Several studies examined if continued smoking after cancer diagnosis affected therapy response; it was found that while never smokers or non-smokers had the best response to therapy, those who quit smoking at the time of diagnosis had higher overall survival and reduced side-effects than those who continued to smoke. These studies also revealed the multiple mechanisms via which smoking enhances the growth and survival of tumors while suppressing therapy-induced cell death. In conclusion, smoking cessation during the course of cancer therapy markedly increases the chances of survival and the quality of life.

Never-smokers and the fraction of breast cancer attributable to second-hand smoke from parents during childhood: the Norwegian Women and Cancer Study 1991-2018

BACKGROUND

Second-hand smoke (SHS) is not an established risk factor for breast cancer. We examined exposure to SHS from parents during childhood and breast-cancer risk overall and by oestrogen- and progesterone-receptor status in the Norwegian Women and Cancer Study. Furthermore, we utilized our nationally representative prospective cohort study to estimate the fraction of breast cancer attributable to parental SHS during childhood.

METHODS

We followed 45 923 never-smoking women, aged 34-70 years, who completed a baseline questionnaire between 1991 and 2007 through linkages to national registries through December 2018. We used Cox proportional-hazards models to estimate age-adjusted hazard ratios (HRs) and 95% confidence intervals (CIs). We estimated the attributable and the population attributable fraction of breast cancer with 95% CIs.

RESULTS

During a mean follow-up of 19.8 (6.8) years, 2185 women developed invasive breast cancer, confirmed by histology. Women exposed to SHS from parents during childhood had an 11% higher (95% CI: 1.02-1.22) risk of breast cancer compared with those who were not. No difference was found for oestrogen (Pheterogeneity = 0.31) and progesterone (Pheterogeneity = 0.95) receptor status. For women exposed, the attributable fraction was 10.3% (95% CI: 1.8-18.0), whereas the population attributable fraction of breast cancer was 7.0% (95% CI: 1.0-13.0).

CONCLUSIONS

Our results suggest that 1 in 14 breast-cancer cases could have been avoided in the absence of SHS exposure from parents during childhood in a population of never-smoking women. The cancer burden attributable to SHS may be underestimated.

Causes of death among women with breast cancer: A follow-up study of 50 481 women with breast cancer in Finland

Our study aims to assess mortality from causes other than breast cancer among women with breast cancer with focus on indications of joint aetiology. Data on female breast cancer patients were obtained from the Finnish Cancer Registry and their underlying causes of death in 54 categories from the Statistics Finland. Standardised mortality ratios (SMR) and their 95% confidence intervals (CIs) were calculated for 50 481 patients diagnosed between 1971 and 2000 and followed until December 2012, stratified by histology, age at diagnosis and time since diagnosis. The expected numbers of deaths were based on respective mortality rates among the Finnish general population. Hazard ratio (HR) was estimated from Poisson regression model to compare risks of cause of death by histology. 41% of 30 841 deaths were due to causes other than breast cancer. Significant excess mortality was observed for stomach cancer (SMR 1.43, 95% CI 1.26-1.62), circulatory system diseases (SMR 1.17, 95% CI 1.14-1.20) and suicide (SMR 1.51, 95% CI 1.28-1.78). In an age-adjusted analysis, significantly higher relative risk of stomach cancer mortality was observed for lobular vs ductal subtype (HR 2.00, 95% CI 1.32-3.02). Significantly increased SMRs were observed for cancers of respiratory organs among premenopausal women, and for other respiratory system diseases, dementia and Alzheimer disease among postmenopausal women. We conclude that female breast cancer patients are at increased risk of death from causes other than the breast cancer diagnosis including circulatory and respiratory system diseases and cancer of stomach, ovary and respiratory systems. The excess mortality because of different causes varies based on menopausal status and histology. There might be shared aetiological factors between the diagnosis of breast cancer and the causes of death among these patients.

Association of Cigarette Type and Nicotine Dependence in Patients Presenting for Lung Cancer Screening

BACKGROUND

Over decades, there have been several alterations to cigarettes, including the addition of filters and flavoring. However, lung cancer remains the leading cause of cancer-related death in the United States.

RESEARCH QUESTION

The aim of this study was to examine the association of type of cigarette on nicotine dependence in the setting of lung cancer screening.

STUDY DESIGN AND METHODS

This study is a secondary analysis of the American College of Radiology Imaging Network arm of the National Lung Screening Trial. Tobacco dependence was evaluated by using the Fagerstrӧm Test for Nicotine Dependence, the Heaviness of Smoking Index, and time to first cigarette. Clinical outcomes, including nicotine dependence and tobacco abstinence, were assessed with descriptive statistics and χ2 tests, stratified according to cigarette tar level, flavor, and filter. Logistic regression was used to study the influence of variables on smoking abstinence.

RESULTS

More than one-third of individuals presenting for lung cancer screening are highly addicted to nicotine and smoke within 5 min of waking up. Smokers of unfiltered cigarettes were more nicotine dependent compared with filtered cigarette smokers (OR, 1.32; P < .01). Although smokers of light/ultralight cigarettes had lower dependence (OR, 0.76, P < .0001), there was no difference in smoking abstinence compared with regular cigarette smokers. There was no difference in outcomes when comparing smokers of menthol vs unflavored cigarettes.

INTERPRETATION

In a screening population, the type of cigarette smoked is associated with different levels of dependence. Eliciting type of cigarette and time to first cigarette has the potential to allow for tailored tobacco treatment interventions within this context.

Smoking and breast cancer risk by race/ethnicity and oestrogen and progesterone receptor status: the Multiethnic Cohort (MEC) study

BACKGROUND

The purpose of this study was to examine if the smoking-related higher breast cancer risk was similar for the five race/ethnicity groups in the Multiethnic Cohort (MEC) study and by oestrogen (ER) and progesterone (PR) receptor status.

METHODS

From 1993 to 2013, we followed 67 313 women who were enrolled in the MEC study at 45-75 years of age. We identified breast cancer cases and tumour receptor status via linkage to the Hawaii and California Surveillance, Epidemiology and End Results Program cancer registries through December 2013. We used Cox proportional hazards regression to estimate multivariable-adjusted hazard ratios with 95% confidence intervals (CI).

RESULTS

During a mean follow-up of 16.7 years, we identified 4230 incident, invasive breast cancer cases. Compared with parous never smokers, parous ever smokers who had smoked more than 5 years before their first live childbirth had a higher risk of breast cancer overall of 31% (95% CI: 1.14-1.51). This higher risk was 51% (95% CI: 1.05-2.16) for African Americans, 66% (95% CI: 1.10-2.50) for Native Hawaiians, 42% (95% CI: 1.13-1.78) for Whites, 37% (95% CI: 1.17-1.61) for ER-positive (ER+) tumours and 33% (95% CI: 1.11-1.59) for PR+ tumours. No difference was suggested by racial/ethnic groups (Pheterogeneity = 0.15) or tumour receptor status (Pheterogeneity = 0.60 by ER status and 0.95 by PR status).

CONCLUSIONS

We find that the higher breast cancer risk related to smoking is similar across racial/ethnic groups and by ER and PR status, indicating that breast cancer should be considered as a smoking-related cancer.

Electronic cigarettes: where to from here?

Although the usage of electronic (e)-cigarettes (EC) and similar devices has gained in popularity as an apparent smoking cessation strategy, serious concerns are emerging in relation to both the efficacy of this strategy, as well as the inappropriate use of these devices. While the comparative safety of e-cigarettes is based on the reasonable contention that the levels of inhaled toxicants present in the aerosols generated by these devices are considerably lower than those present in tobacco smoke, the perception that they are indeed relatively risk-free is being challenged on several fronts. Notwithstanding lack of convincing evidence of efficacy as a superior smoking cessation strategy, foremost among emerging concerns is the increasing use of electronic nicotine-delivery devices by young never-smokers. Other concerns include increasing levels of sophistication in the design and capacity of these devices in relation to nicotine content and delivery, the potential threat of manipulation of the contents of e-liquids, as well as other additives such as illicit drugs and other potentially toxic agents that can be vaporised. These issues, together with the potential risks to respiratory health, specifically "e-cigarette or vaping product use-associated lung injury" represent the major thrusts of this review.

Are sociodemographic, lifestyle, and psychosocial characteristics associated with sexual orientation group differences in mental health disparities? Results from a national population-based study

PURPOSE

Sexual minority mental health disparities are well documented. However, distinct sexual minority subgroups are often collapsed into a single "lesbian, gay, or bisexual" (LGB) analytic group. While limited research has shown sexual minority subgroup differences in mental health, little is known about the factors underlying these differences. This study examines whether sociodemographic, lifestyle, and psychosocial characteristics are associated with sexual orientation subgroup differences in mental health.

METHODS

Using the National Epidemiologic Survey on Alcohol and Related Conditions, Wave III, differences in various mental health measures, and sociodemographic, lifestyle, and psychosocial characteristics were assessed across three sexual minority subgroups [lesbians/gay men, bisexuals, and heterosexuals reporting same-sex attractions or behaviors ("heterosexual-identified sexual minorities, HSM")] and heterosexuals reporting only opposite-sex attractions and behaviors ("heterosexuals"). Sequential linear regressions evaluated the degrees to which different factors attenuated mental health (SF-12) disparities between heterosexuals and sexual minority subgroups. Analyses were sex-stratified.

RESULTS

Several sociodemographic, lifestyle, and psychosocial characteristic differences existed between sexual orientation groups. Further, all sexual minority subgroups had lower SF-12 scores than heterosexuals, except lesbian women. Sociodemographic factors attenuated the disparity for bisexual men. Sociodemographic, lifestyle, plus psychosocial factors attenuated the disparity for HSM men. However, sociodemographic, lifestyle, and psychosocial factors partially, but did not fully, attenuate the disparity for gay men, bisexual women, or HSM women.

CONCLUSIONS

Different factors are associated with mental health disparities for sexual minority subgroups. To maximize health intervention efforts, additional research is needed to uncover the specific mechanisms contributing to health disparities across diverse sexual minority populations.

Exposure to household tobacco smoke and risk of cancer morbidity and mortality: Analysis of data from the Afghanistan Demographic and Health Survey 2015

Active and secondhand tobacco exposures are major causes of cancer. Cancer prevention efforts are particularly relevant in resource-constrained settings in which significant barriers to early detection and cancer treatments contribute to poor outcomes. We assess the associations between exposure to household tobacco smoke and cancer morbidity and mortality. We used household data from Afghanistan Demographic and Health Survey, which was a national cross-sectional survey that applied a two-stage stratified random sampling technique in 2015 and 2016. We performed regression analysis to estimate associations between exposure to household tobacco smoke and cancer morbidity and mortality at the household level. Exposure to household tobacco smoke was significantly associated with household reports of a history of any cancer (Adjusted Odds Ratio (AOR): 1.90; 95% Confidence Interval (CI): 1.44, 2.51), breast cancer (1.59; 1.00, 2.55), lung cancer (2.88; 1.58, 5.27), and liver cancer (2.56; 1.10, 5.96), compared to households with no tobacco smoke exposure. These associations persisted after controlling for household location, wealth index, type of cooking fuel used in house, and location of food preparation. Households in a rural location experienced significantly higher mortality of any cancer (4.40; 95% CI: 1.57, 12.38), breast cancer (2.91; 1.02, 8.25), and liver cancer (3.91; 1.29, 11.89) vs. those in an urban location. Exposure to household tobacco smoke is a risk factor for cancer morbidity in Afghanistan. Strategies to implement comprehensive smoking cessation and smoke free housing policies are urgently needed as primary cancer prevention strategy in Afghanistan and comparable resource-constrained settings.

Long-term exposure to extremely low-dose of nicotine and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) induce non-malignant breast epithelial cell transformation through activation of the a9-nicotinic acetylcholine receptor-mediated signaling pathway

Breast cancer (BC) is the most common cancer affecting women worldwide and has been associated with active tobacco smoking. Low levels of nicotine (Nic) and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), have been detected in cases of second-hand smoke (SHS). However, the correlation between SHS and BC risk remains controversial. In this study, we investigated whether the physiological SHS achievable dose of Nic and tobacco specific nitrosamine, NNK act together to induce breast carcinogenesis using an in vitro breast cell carcinogenesis model. Immortalized non-tumorigenic breast epithelial cell line, HBL-100 used for a time-course assay, was exposed to very low levels of either Nic or NNK, or both. The time-course assay consisted of 23 cycles of nitrosamines treatment. In each cycle, HBL-100 cells were exposed to 1pM of Nic and/or 100 femtM of NNK for 48 hours. Cells were passaged every 3 days and harvested after 10, 15, and 23 cycles. Our results demonstrated that the tumorigenicity of HBL-100, defined by soft agar colony forming, proliferation, migration and invasion abilities, was enhanced by co-exposure to physiologically SHS achievable doses of Nic and NNK. In addition, α9-nAChR signaling activation, which plays an important role in cellular proliferation and cell survival, was also observed. Importantly, an increase in stemness properties including the prevalence of CD44+/CD24- cells, increase Nanog expression and mammosphere-forming ability were also observed. Our results indicate that chronic and long term exposure to environmental tobacco smoke, may induce breast cell carcinogenesis even at extremely low doses.

Modifiable Lifestyle Factors: Opportunities for (Hereditary) Breast Cancer Prevention - a Narrative Review

Increasing rates of obesity, lack of physical activity, sedentary behavior, and frequent alcohol consumption are major lifestyle-related risk factors for breast cancer. In fact, it has been estimated that about one-third of breast cancer cases are attributable to factors women can change. Most research has focused on examining the impact of one single exposure on breast cancer risk while adjusting for other risk modifiers. Capitalizing on big data, major efforts have been made to evaluate the combined impact of well-established lifestyle factors on overall breast cancer risk. At the individual level, data indicate that even simple behavior modifications could have a considerable impact on breast cancer prevention. Moreover, there is emerging new evidence that adopting a healthy lifestyle may be particularly relevant for women with hereditary susceptibility to breast cancer. On the absolute risk scale, studies suggest that the presence of certain risk factors, such as excessive body weight, had a substantially higher impact on breast cancer risk if women had a hereditary predisposition to cancer. The existing body of knowledge gives the medical professionals guidance as to which factors to focus on when counseling patients. However, well-designed randomized controlled trials utilizing objective methods are crucial to providing concrete recommendations.

Pooled analysis of active cigarette smoking and invasive breast cancer risk in 14 cohort studies

Background

The 2014 US Surgeon General's report noted research gaps necessary to determine a causal relationship between active cigarette smoking and invasive breast cancer risk, including the role of alcohol consumption, timing of exposure, modification by menopausal status and heterogeneity by oestrogen receptor (ER) status.

Methods

To address these issues, we pooled data from 14 cohort studies contributing 934 681 participants (36 060 invasive breast cancer cases). Cox proportional hazard regression models were used to calculate multivariable-adjusted hazard ratios (HRs) and 95% confidence intervals (CIs).

Results

Smoking duration before first birth was positively associated with risk ( P -value for trend = 2 × 10 -7 ) with the highest HR for initiation >10 years before first birth (HR = 1.18, CI 1.12-1.24). Effect modification by current alcohol consumption was evident for the association with smoking duration before first birth ( P -value=2×10 -4 ); compared with never-smoking non-drinkers, initiation >10 years before first birth was associated with risk in every category of alcohol intake, including non-drinkers (HR = 1.15, CI 1.04-1.28) and those who consumed at least three drinks per day (1.85, 1.55-2.21). Associations with smoking before first birth were limited to risk of ER+ breast cancer ( P -value for homogeneity=3×10 -3 ). Other smoking timing and duration characteristics were associated with risk even after controlling for alcohol, but were not associated with risk in non-drinkers. Effect modification by menopause was not evident.

Conclusions

Smoking, particularly if initiated before first birth, was modestly associated with ER+ breast cancer risk that was not confounded by amount of adult alcohol intake. Possible links with breast cancer provide additional motivation for young women to not initiate smoking.

Persistent alterations of gene expression profiling of human peripheral blood mononuclear cells from smokers

The number of validated biomarkers of tobacco smoke exposure is limited, and none exist for tobacco-related cancer. Additional biomarkers for smoke, effects on cellular systems in vivo are needed to improve early detection of lung cancer, and to assist the Food and Drug Administration in regulating exposures to tobacco products. We assessed the effects of smoking on the gene expression using human cell cultures and blood from a cross-sectional study. We profiled global transcriptional changes in cultured smokers' peripheral blood mononuclear cells (PBMCs) treated with cigarette smoke condensate (CSC) in vitro (n = 7) and from well-characterized smokers' blood (n = 36). ANOVA with adjustment for covariates and Pearson correlation were used for statistical analysis in this study. CSC in vitro altered the expression of 1 178 genes (177 genes with > 1.5-fold-change) at P < 0.05. In vivo, PBMCs of heavy and light smokers differed for 614 genes (29 with > 1.5-fold-change) at P < 0.05 (309 remaining significant after adjustment for age, race, and gender). Forty-one genes were persistently altered both in vitro and in vivo, 22 having the same expression pattern reported for non-small cell lung cancer. Our data provides evidence that persistent alterations of gene expression in vitro and in vivo may relate to carcinogenic effects of cigarette smoke, and the identified genes may serve as potential biomarkers for cancer. The use of an in vitro model to corroborate results from human studies provides a novel way to understand human exposure and effect. © 2015 Wiley Periodicals, Inc.

The fraction of breast cancer attributable to smoking: The Norwegian women and cancer study 1991-2012

Background:

Results from several recent cohort studies on smoking and breast cancer incidence and mortality suggest that the burden of smoking on society is underestimated. We estimated the fraction of breast cancer attributable to smoking in the Norwegian Women and Cancer Study, a nationally representative prospective cohort study.

Methods:

We followed 130 053 women, aged 34–70 years, who completed a baseline questionnaire between 1991 and 2007, through linkages to national registries through December 2012. We used Cox proportional hazards models to estimate hazard ratios (HRs) with 95% confidence intervals (CIs), while adjusting for confounders. Never smokers, excluding passive smokers, were used as the reference group in all main analyses. We estimated attributable fractions (AFs) % in smokers and in the population (PAFs) % with 95% CIs.

Results:

Altogether, 4293 women developed invasive breast cancer, confirmed by histology. Compared with never active, never passive smokers, ever (former and current) smokers had an overall risk of breast cancer that was 21% higher (HR=1.21; 95% CI=1.08–1.34). For ever smokers, the AF was 17.3% (95% CI =7.4–25.4) and for the population the PAF of breast cancer was 11.9% (95% CI=5.3–18.1). For passive smokers, the PAF of breast cancer was 3.2% (95% CI=1.0–5.4). When we applied PAF estimates for ever smoking on the 2907 new breast cancer cases among Norwegian women aged 35+ at diagnosis in 2012, this yielded 345 (95% CI=154–526) breast cancer cases that could have been avoided in the absence of active smoking that year.

Conclusions:

In smokers, one in six and in the population, one in nine breast cancer cases could have been avoided in the absence of active smoking. Our findings support the notion that the global cancer burden due to smoking is substantially underestimated.

Can diet and lifestyle prevent breast cancer: what is the evidence?

Breast cancer is the most common cancer among women in both developed and less-developed countries. Rates of breast cancer are increasing worldwide, with a particular increase in postmenopausal and estrogen receptor-positive cases. The World Cancer Research Fund (WCRF) and American Cancer Society (ACS) cancer prevention guidelines recommend maintaining a healthy weight, undertaking at least 150 minutes of moderate intensity exercise per week, limiting alcohol consumption, and eating a plant-based diet. Observational data link adherence to physical activity and alcohol guidelines throughout life to a reduced risk of developing pre- and postmenopausal breast cancer. Weight control throughout life appears to prevent cases after menopause. Adherence to a healthy dietary pattern does not have specific effects on breast cancer risk but remains important as it reduces the risk for other common diseases, such as cardiovascular disease (CVD), diabetes, and dementia. Emerging data suggest that smoking during adolescence or early adulthood increases later risk of breast cancer. Lifestyle factors appear to modify risk among high-risk women with a family history and those with typical risk of the general population, although their effects among carriers of BRCA mutations are not well defined. Recent expert reports estimate that successful lifestyle changes could prevent 25% to 30% of cases of breast cancer. These reductions will only be achieved if we can implement targeted prevention programs for high-risk women and women in population-based breast screening programs during childhood, adolescence, and early adulthood when the rapidly developing breast is particularly susceptible to carcinogenesis.

The association between lifetime smoking exposure and breast cancer mortality--results from a Norwegian cohort

Several recent cohort studies have found an association between smoking and breast cancer, but the association between lifetime smoking exposure and breast cancer mortality is less well described. We examined whether smoking before breast cancer diagnosis is a predictor of breast cancer mortality in a large cohort with more than 4.1 million years of follow-up, with a special focus on women who initiated smoking before first childbirth. Information on smoking status was collected before breast cancer diagnosis and used to estimate hazard ratios (HRs) and corresponding 95% confidence intervals (CIs) of breast cancer mortality in a cohort of 302,865 Norwegian women with 1106 breast cancer deaths. Women were enrolled between 1974 and 2003 and followed up through linkages to national registries until 31 December 2007. We found that breast cancer mortality was slightly but significantly increased for current (HR = 1.15, 95% CI 1.01-1.32) and ever (HR = 1.15, 95% CI 1.02-1.30) smokers as compared to never smokers. No statistically significantly increased mortality was found for women who initiated smoking before first childbirth, and no dose-response association was revealed for any of the different measures of smoking exposure. A large proportion of heavy smokers may have died from other causes than breast cancer during follow-up, possibly diluting our results. This study found that lifetime smoking exposure had a significantly increased risk of breast cancer mortality compared with never smokers.

A social media approach to inform youth about breast cancer and smoking: an exploratory descriptive study

Tobacco exposure during periods of breast development has been shown to increase risk of premenopausal breast cancer. An urgent need exists, therefore, to raise awareness among adolescent girls about this new evidence, and for adolescent girls and boys who smoke to understand how their smoking puts their female peers at risk for breast cancer. The purpose of this study was to develop two youth-informed, gender specific YouTube-style videos designed to raise awareness among adolescent girls and boys about tobacco exposure as a modifiable risk factor for breast cancer and to assess youths' responses to the videos and their potential for inclusion on social media platforms. Both videos consisted of a combination of moving text, novel images, animations, and youth-friendly music. A brief questionnaire was used to gather feedback on two videos using a convenience sample of 135 youth in British Columbia, Canada. The overall positive responses by girls and boys to their respective videos and their reported interest in sharing these videos via social networking suggests that this approach holds potential for other types of health promotion messaging targeting youth. The videos offer a promising messaging strategy for raising awareness about tobacco exposure as a modifiable risk factor for breast cancer. Tailored, gender-specific messages for use on social media hold the potential for cost-effective, health promotion and cancer prevention initiatives targeting youth.

Impact of smoking on estrogenic efficacy

Depending on the type, duration and intensity of cigarette smoking, the efficacy of endogenous and exogenous estrogen can be reduced or completely cancelled. Not only does smoking diminish the beneficial effects of estrogen on hot flushes and urogenital symptoms and its positive effects on lipid metabolism, but smoking also can reduce estrogen's ability to prevent osteoporosis and perhaps also cardiovascular diseases. This is mainly caused by dose-dependent elevated hepatic clearance, partially in conjunction with lower estrogen levels, and has been demonstrated so far only with oral estrogen applications. Compensation for the failure of therapeutic action should not be made by increasing the dose in smokers since this might result in the production of potentially mutagenic estrogen metabolites associated with a higher risk of breast cancer. Since the favorable effects of estrogens seem to be not lost in smokers when estrogens are applied transdermally, this route should be preferred in smokers. The most important conclusion from the data presented is that the effects of smoking are very complex and dependent on a multiplicity of factors, so that different types of clinically relevant negative effects must be expected. Women who continue to smoke despite all warnings should be informed that smoking, in addition to all its other negative effects, can also jeopardize the success of hormone replacement therapy.