Active and passive cigarette smoke and breast cancer survival

The Association between Smoking and Mortality in Women with Breast Cancer: A Real-World Database Analysis

Smoking increases the cancer-specific and overall mortality risk in women with breast cancer (BC). However, the effect of smoking cessation remains controversial, and detailed research is lacking in Asia. We aimed to investigate the association between smoking status and mortality in women with BC using the population-based cancer registry. The Taiwan Cancer Registry was used to identify women with BC from 2011 to 2017. A total of 54,614 women with BC were enrolled, including 1687 smokers and 52,927 non-smokers. The outcome, mortality, was identified using Taiwan’s cause-of-death database. The association between smoking status and mortality was estimated using Cox proportional regression. Women with BC who smoked had a 1.25-fold higher (95% C.I.: 1.08–1.45; p = 0.0022) risk of overall mortality and a 1.22-fold higher (95% C.I.: 1.04–1.44; p = 0.0168) risk of cancer-specific mortality compared with non-smokers. The stratified analysis also indicated that women with BC who smoked showed a significantly higher overall mortality risk (HR: 1.20; 95% CI: 1.01–1.43; p = 0.0408) than women with BC who did not smoke among women without comorbidities. Additionally, current smokers had a 1.57-fold higher risk (95% CI: 1.02–2.42; p = 0.0407) of overall mortality compared with ever smokers among women with BC who smoked. It was shown that a current smoking status is significantly associated with an increase in overall and cancer-specific mortality risk in women with BC. Quitting smoking could reduce one’s mortality risk. Our results underscore the importance of smoking cessation for women with BC.

Relationship between Cigarette Smoking and Cancer Characteristics and Survival among Breast Cancer Patients

Carcinogenic effects of tobacco smoke may affect breast tumorigenesis. To assess whether cigarette smoking is associated with breast cancer characteristics, we investigated the relationships between smoking, pathological characteristics, and outcomes in 2153 women diagnosed with breast cancer 2001-2016. Patients were classified as never, former, or current smokers at the time of diagnosis. Logistic regression and multivariable Cox proportional hazards analysis were performed to determine whether smoking was associated with tumor characteristics. Multivariable Cox proportional hazards analysis was conducted to compare former or current smokers to never smokers in survival with adjustment for the potential confounders. The majority of women (61.8%) never smoked, followed by former smokers (26.2%) and current smokers (12.0%). After adjustment for demographic variables, body mass index, and comorbidities, tumor characteristics were not significantly associated with smoking status or pack-years smoked. Ten-year overall survival was significantly lower for former and current smokers compared to never smokers (p = 0.0105). However, breast cancer specific survival did not differ significantly between groups (p = 0.1606). Although cigarette smoking did not alter the underlying biology of breast tumors or breast cancer-specific survival, overall survival was significantly worse in smokers, highlighting the importance of smoking cessation in the recently diagnosed breast cancer patient.

The Impact of Treatment for Smoking on Breast Cancer Patients' Survival

BACKGROUND

Smoking negatively affects overall survival after successful breast cancer (BC) treatment. We hypothesized that smoking cessation would improve survival outcomes of BC patients who were smokers at the time of diagnosis.

METHODS

This was a retrospective analysis of self-identified smokers with BC treated at The University of Texas MD Anderson Cancer Center. Patient demographics, date of diagnosis, tumor stage, tobacco treatment program (TP) participation, and time to death were extracted from our departmental databases and institutional electronic health records. We examined associations between tobacco abstinence status and survival using survival models, with and without interactions, adjusted for personal characteristics and biomarkers of disease.

RESULTS

Among all 31,069 BC patients treated at MD Anderson between 2006 and 2017, we identified 2126 smokers (6.8%). From those 2126 self-identified smokers, 665 participated in the TP, reporting a conservative estimate of 31% abstinence (intent-to-treat) 9 months into the program. Patients without reported follow-up abstinence status (including TP and non-TP participants) were handled in the analyses as smokers. Survival analysis controlled for multiple factors, including disease characteristics and participation in the TP, indicated that abstainers were more likely to be alive with no evidence of disease compared to non-abstainers (HR, 0.593; 95% CI, 0.386-0.911; p = 0.017).

CONCLUSION

Our results suggest that quitting smoking is associated with improved survival among BC patients who were smokers at time of diagnosis across all tumor stages. Comprehensive approaches for smoking cessation in patients diagnosed with BC may prolong survival when started as early as the time of diagnosis.

The impact of smoking on adjuvant breast cancer radiation treatment: A systematic review

BACKGROUND

The influence of cigarette smoking on cancer risk has been well-studied. Similarly, exposure to ionizing radiation from radiotherapy (RT) can produce detrimental effects on an individual's health. In patients administered RT, there has been an observed relationship in other primary carcinomas. The purpose of this systematic review was to summarize the influence of cigarette smoking on outcomes post adjuvant RT in breast cancer patients.

METHODS

OVID Medline, Cochrane and Embase were searched and 1893 articles were identified. A total of 71 articles were included in the review. Study type, published year and sample size, age, systemic therapies, RT techniques and treatment side effects were collected if available.

RESULTS

The review found 198 different outcomes which fell into 7 categories and similar outcomes were recorded. 40% of skin reaction outcomes, 50% of cardiovascular outcomes, 71% of reconstruction outcomes, 29% of pulmonary function outcomes, 33% of mortality outcomes and 42% of secondary recurrence outcomes reported significant differences between smokers and non-smokers. None of the articles reported non-smokers to have a higher risk than smokers.

CONCLUSION

Cigarette smoking can pose a higher risk of post-treatment complications that can influence an individual's quality of life, survival rate and/or recurrence risk. This review further assessed the impact of smoking on various patient outcomes and side-effects in the adjuvant breast RT setting. The information provided in this review suggest that smoking cessation programs would help educate patients to understand their risks of being a current or former smoker when undergoing RT.

Influence of Preexisting Diabetes on Survival After a Breast Cancer Diagnosis in First Nations Women in Ontario, Canada

PURPOSE

Survival after a breast cancer diagnosis is poorer in First Nations women with a preexisting comorbidity compared with comorbidity-free First Nations women in Ontario, Canada. Given the high prevalence of diabetes in this population, it is important to determine whether preexisting diabetes is related to poorer survival after a breast cancer diagnosis.

METHODS

All First Nations women were identified from a cohort of First Nations people diagnosed with breast cancer in diagnostic periods-1995 to 1999 and 2000 to 2004-and seen at a regional cancer program (RCP) in Ontario. Preexisting diabetes status and other factors, such as age at diagnosis, body mass index, and stage at diagnosis, were collected from medical charts at the regional cancer programs. The association between preexisting diabetes and First Nations status was examined by each of the demographic, personal, tumor, and treatment factors using logistic regression models. Survival was compared between First Nations women with (n = 67) and without (n = 215) preexisting diabetes, adjusted by significant study factors using a Cox proportional hazards regression model.

RESULTS

The 5-year survival rate among First Nations women with diabetes was 59.8% versus 78.7% among those without diabetes (P < .01). Preexisting diabetes significantly increased the risk of death among First Nations women with breast cancer (hazard ratio, 1.87; 95% CI, 1.12 to 3.13) after adjustment for age group, period of diagnosis, body mass index, other comorbidities at diagnosis, and stage.

CONCLUSION

This study recommends awareness of this survival discrepancy among the treatment team for First Nations patients with breast cancer with preexisting diabetes.

Smoking increases risks of all-cause and breast cancer specific mortality in breast cancer individuals: a dose-response meta-analysis of prospective cohort studies involving 39725 breast cancer cases

Smoking is associated with the risks of mortality from breast cancer (BC) or all causes in BC survivors. Two-stage dose-response meta-analysis was conducted. A search of PubMed and Embase was performed, and a random-effect model was used to yield summary hazard ratios (HRs). Eleven prospective cohort studies were included. The summary HR per 10 cigarettes/day, 10 pack-years, 10 years increase were 1.10 (95% confidence interval (CI) = 1.04–1.16), 1.09 (95% CI = 1.06–1.12), 1.10 (95% CI = 1.06–1.14) for BC specific mortality, and 1.15 (95% CI = 1.10–1.19), 1.15 (95% CI = 1.10–1.20), 1.17 (95% CI = 1.11–1.23) for all-cause mortality, respectively. The linear or non-linear associations between smoking and risks of mortality from BC or all causes were revealed. Subgroup analyses suggested a positive association between ever or former smoking and the risk of all-cause mortality in BC patients, especially in high doses consumption. In conclusion, higher smoking intensity, more cumulative amount of cigarettes consumption and longer time for smoking is associated with elevated risk of mortality from BC and all causes in BC individuals. The results regarding smoking cessation and “ever or former” smokers should be treated with caution due to limited studies.

The association between smoking and breast cancer characteristics and outcome

Background

Smoking is associated with an increased incidence of hormone receptor positive breast cancer. Data regarding worse breast cancer outcome in smokers are accumulating. Current literature regarding the impact of smoking on breast cancer characteristics is limited. We evaluated the impact of smoking on breast cancer characteristics and outcome.

Methods

This was a retrospective single center study. All women diagnosed from 4/2005 through 3/2012 and treated in our institute for early, estrogen receptor positive, human epidermal growth factor receptor 2 (HER2) negative breast cancer, whose tumors were sent for Oncotype DX analysis were included. Medical records were reviewed for demographics, clinico-pathological parameters, treatment and outcome. Data regarding smoking were retrieved according to patients’ history at the first visit in the oncology clinic. Patients were grouped and compared according to smoking history (ever smokers vs. never smokers), smoking status (current vs. former and never smokers) and smoking intensity (pack years ≥30 vs. the rest of the cohort). Outcomes were adjusted in multivariate analyses and included age, menopausal status, ethnicity, tumor size, nodal status and grade.

Results

A total of 662 women were included. 28.2% had a history of smoking, 16.6% were current smokers and 11.3% were heavy smokers. Smoking had no impact on tumor size, nodal involvement and Oncotype DX recurrence score. Angiolymphatic and perineural invasion rates were higher in current smokers than in the rest of the cohort (10.4% vs. 5.1%, p = 0.045, 8.3% vs. 3.5%, p = 0.031, respectively). Smoking had no other impact on histological characteristics. Five-year disease free survival and overall survival rates were 95.7% and 98.5%, respectively. Smoking had no impact on outcomes. Adjusted disease free survival and overall survival did not influence the results.

Conclusions

Smoking had no clinically significant influence on tumor characteristics and outcome among women with estrogen receptor positive, HER2 negative, early breast cancer. As the study was limited to a specific subgroup of the breast cancer population in this heterogeneous disease and since smoking is a modifiable risk factor for the disease, further research is required to clarify the possible impact of smoking on breast cancer.

Active smoking and survival following breast cancer among African American and non-African American women in the Carolina Breast Cancer Study

PURPOSE

To examine racial differences in smoking rates at the time of breast cancer diagnosis and subsequent survival among African American and non-African American women in the Carolina Breast Cancer Study (Phases I/II), a large population-based North Carolina study.

METHODS

We interviewed 788 African American and 1,020 Caucasian/non-African American women diagnosed with invasive breast cancer from 1993 to 2000, to assess smoking history. After a median follow-up of 13.56 years, we identified 717 deaths using the National Death Index; 427 were breast cancer-related. We used Cox regression to examine associations between self-reported measures of smoking and breast cancer-specific survival within 5 years and up to 18 years after diagnosis conditional on 5-year survival. We examined race and estrogen receptor status as potential modifiers.

RESULTS

Current (vs never) smoking was not associated with 5-year survival; however, risk of 13 year conditional breast cancer-specific mortality was elevated among women who were current smokers at diagnosis (HR 1.54, 95% CI 1.06-2.25), compared to never smokers. Although smoking rates were similar among African American (22.0%) and non-African American (22.1%) women, risk of breast cancer-specific mortality was elevated among African American (HR 1.69, 95% CI 1.00-2.85), but only weakly elevated among non-African American (HR 1.22, 95% CI 0.70-2.14) current (vs. never) smokers (P Interaction = 0.30). Risk of breast cancer-specific mortality was also elevated among current (vs never) smokers diagnosed with ER- (HR 2.58, 95% CI 1.35-4.93), but not ER+ (HR 1.11, 95% CI 0.69-1.78) tumors (P Interaction = 0.17).

CONCLUSIONS

Smoking may negatively impact long-term survival following breast cancer. Racial differences in long-term survival, as related to smoking, may be driven by ER status, rather than by differences in smoking patterns.

Do Breast Cancer Risk Factors Affect the Survival of Breast Cancer Patients in Southern Sri Lanka?

Background:

Breast cancer continues to be a major cause of morbidity among women in Sri Lanka. Possible effects of etiological risk factors on breast cancer specific survival (BCSS) of the disease is not clear. This study was designed to explore the impact of breast cancer risk factors on the BCSS of patients in Southern Sri Lanka.

Method:

This retro-prospective study included all breast cancer patients who had sought immunohistochemistry services at our unit from May 2006 to December 2012. A pre-tested, interviewer-administered questionnaire was used to gather information on risk factors. BCSS was estimated using the Kaplan-Meier model. Univariate Cox-regression analysis was performed with 95% confidence intervals using the SPSS statistical package.

Results:

A total of 944 breast cancer patients were included. Five year BCSS was 78.8%. There was a statistically significant difference between the patients who had a family history of breast cancer and no family history of any cancer in terms of the presence/absence of lymph node metastasis (p=0.011) and pathological stage (p=0.042). The majority of the premenopausal patients had associated DCIS (p<0.001) and large tumours (p=0.015) with positive lymph nodes (p=0.016). There was no statistically significant association between hormone receptor subtypes and hormone related risk factors. Univariate analysis revealed that breast cancer risk factors had no significant effect on the BCSS.

Conclusion:

Even though family history of breast cancer and premenopausal status are associated with poor prognostic features, they, in line with the other breast cancer risk factors, appear to have no significant effect on the BCSS of patients in Southern Sri Lanka.

Environmental Tobacco Smoke Exposure and Survival Following Breast Cancer

BACKGROUND

Environmental tobacco smoke (ETS) exposure is hypothesized to influence survival after breast cancer, but few studies have examined this association.

METHODS

A population-based cohort of women (N = 1,508) diagnosed with first primary invasive or in situ breast cancer in 1996 to 1997 was interviewed shortly after diagnosis and again approximately 5 years later to assess ETS exposure, and women were followed for more than 18 years using the National Death Index; 597 deaths (237 associated with breast cancer) were identified. Multivariable Cox regression was used to estimate adjusted HRs and 95% confidence intervals (CI) for mortality among women with breast cancer as related to at-diagnosis and at-/postdiagnosis changes in ETS exposure.

RESULTS

There was little or no association between at-diagnosis ETS exposure and all-cause (HR = 1.04; 95% CI, 0.78-1.40) or breast cancer-specific (HR = 0.98; 95% CI, 0.63-1.52) mortality. Mortality was elevated among women who reported cessation in postdiagnosis ETS exposure up to 1 year before the follow-up assessment, for all-cause (HR = 1.81; 95% CI, 0.87-3.74) and breast cancer mortality (HR = 1.89; 95% CI, 0.68-5.24); however, estimates were imprecise.

CONCLUSIONS

We found little evidence of an association between at-diagnosis ETS exposure and mortality after breast cancer. Postdiagnosis cessation of ETS exposure was positively associated with mortality, although we could not rule out chance and reverse causation as possible explanations.

IMPACT

Exposure to ETS does not appear to influence mortality after breast cancer. Cancer Epidemiol Biomarkers Prev; 26(2); 278-80. ©2016 AACR.

Modifiable Lifestyle Factors and Triple-negative Breast Cancer Survival: A Population-based Prospective Study

BACKGROUND

Very little is known about the effect of modifiable lifestyle factors on outcomes of triple-negative breast cancer. We examined this association in a population-based prospective cohort study of patients with triple-negative breast cancer.

METHODS

A total of 518 women with confirmed triple-negative breast cancer, recruited by the Shanghai Breast Cancer Survival Study, completed 6-, 18-, 36-, and 60-month postdiagnosis surveys. We applied Cox proportional hazard models to evaluate the associations.

RESULTS

The mean age at diagnosis was 53.4 (standard deviation = 10.6) years old. After a median follow-up of 9.1 years (range: 0.6-11.8), 128 deaths and 112 recurrences were documented. Exercise during the first 60 months postdiagnosis was inversely associated with total mortality and recurrence/disease-specific mortality with adjusted hazard ratios (HRs) of 0.67 (95% confidence interval [CI] = 0.46, 0.96) and 0.58 (95% CI = 0.39, 0.86), respectively. Women with higher exercise-metabolic equivalent scores (≥7.6 metabolic equivalent-hours/week) and longer duration of exercise (≥2.5 hours/week) had lower risk of total and recurrence/disease-specific mortality than did nonexercisers. Compared with nontea drinkers, survival was better among women who were regular tea drinkers during the first 60 months for all cause (HR = 0.57, 95% CI = 0.34, 0.93) and recurrence/disease-specific mortality (HR = 0.54, 95% CI = 0.31, 0.96). There was no dose-response pattern for tea consumption. No interactions were observed for body mass index, menopausal status, and comorbidity.

CONCLUSIONS

These findings show that postdiagnosis exercise and tea intake were associated with improved survival among women with triple-negative breast cancer.

[Systematizing support in cessation smoking to improve care for cancer patients]

Approximately 20% of cancer patients smoke at diagnosis (all localizations included), and over two thirds continue despite the therapeutic management of their cancer, especially when cancer is not associated with tobacco. The impact of smoking on quality of care for patients is actually not enough considered. A literature review conducted by the French National Cancer Institute emphasizes the importance of tobacco cessation to improve the prognosis (decreased mortality from all causes and specific); to reduce the risk of second primary cancers; to reduce per- and post-surgical risks as long as some toxicities related to treatments and to improve the quality of physical and mental life of patients. It is important that a communication with the patient takes place at the beginning of the treatment to impact the smoking behavior. All oncology health professionals should deliver a clearly and personalized cessation advice in the light of scientific data and ensure that smoking cessation help will be offered to the patient.

Cigarette Smoking Before and After Breast Cancer Diagnosis: Mortality From Breast Cancer and Smoking-Related Diseases

PURPOSE

Cigarette smoking increases overall mortality, but it is not established whether smoking is associated with breast cancer prognosis.

METHODS

We evaluated the association between smoking status before and after breast cancer diagnosis and mortality in the Collaborative Breast Cancer and Women's Longevity Study, a population-based prospective observational study conducted in Wisconsin, New Hampshire, and Massachusetts. Participants included 20,691 women, ages 20 to 79 years, diagnosed with incident localized or regional invasive breast cancer between 1988 and 2008; a subset of 4,562 of these women were recontacted a median of 6 years after diagnosis. Hazard ratios (HRs) with 95% CIs were calculated according to smoking status for death as a result of breast cancer; cancers of the lung, pharynx, or intrathoracic organs; other cancer; respiratory disease; and cardiovascular disease.

RESULTS

During a median of 12 years, 6,778 women died, including 2,894 who died as a result of breast cancer. Active smokers 1 year before breast cancer diagnosis were more likely than never smokers to die of breast cancer (HR, 1.25; 95% CI, 1.13 to 1.37), respiratory cancer (HR, 14.48; 95% CI, 9.89 to 21.21), other respiratory disease (HR, 6.02; 95% CI, 4.55 to 7.97), and cardiovascular disease (HR, 2.08; 95% CI, 1.80 to 2.41). The 10% of women who continued to smoke after diagnosis were more likely than never smokers to die of breast cancer (HR, 1.72; 95% CI, 1.13 to 2.60). When compared with women who continued to smoke after diagnosis, those who quit smoking after diagnosis had lower mortality from breast cancer (HR, 0.67; 95% CI, 0.38 to 1.19) and respiratory cancer (HR, 0.39; 95% CI, 0.16 to 0.95).

CONCLUSION

Smoking before or after diagnosis was associated with a higher mortality from breast cancer and several other causes.

Active and passive cigarette smoking and mortality among Hispanic and non-Hispanic white women diagnosed with invasive breast cancer

PURPOSE

Women who smoke at breast cancer diagnosis have higher risk of breast cancer-specific and all-cause mortality than nonsmokers; however, differences by ethnicity or prognostic factors and risk for noncancer mortality have not been evaluated.

METHODS

We examined associations of active and passive smoke exposure with mortality among Hispanic (n = 1020) and non-Hispanic white (n = 1198) women with invasive breast cancer in the Breast Cancer Health Disparities Study (median follow-up of 10.6 years).

RESULTS

Risk of breast cancer-specific (HR = 1.55, 95% CI = 1.11-2.16) and all-cause (HR = 1.68, 95% CI = 1.30-2.17) mortality was increased for current smokers, with similar results stratified by ethnicity. Ever smokers had an increased risk of noncancer mortality (HR = 1.68, 95% CI = 1.12-2.51). Associations were strongest for current smokers who smoked for 20 years or more were postmenopausal, overweight and/or obese, or reported moderate and/or high alcohol consumption; however, interactions were not significant. Breast cancer-specific mortality was increased two fold for moderate and/or high recent passive smoke exposure among never smokers (HR = 2.12, 95% CI = 1.24-3.63).

CONCLUSIONS

Findings support associations of active-smoking and passive-smoking diagnosis with risk of breast cancer-specific and all-cause mortality and ever smoking with noncancer mortality, regardless of ethnicity, and other factors. Smoking is a modifiable lifestyle factor and effective smoking cessation, and maintenance programs should be routinely recommended for women with breast cancer.

Smoking and survival after breast cancer diagnosis in Japanese women: A prospective cohort study

The results of previous studies investigating whether there is an association between active smoking and risk of death among breast cancer patients have been inconsistent. We investigated the association between active and passive smoking and risk of all-cause and breast cancer-specific death among female breast cancer patients in relation to menopausal and tumor estrogen/progesterone receptor (ER/PR) status. The present study included 848 patients admitted to a single hospital in Japan from 1997 to 2007. Active or passive smoking status was assessed using a self-administered questionnaire. The patients were followed until 31 December 2010. We used a Cox proportional-hazard model to estimate hazard ratios (HR). During a median follow-up period of 6.7 years, 170 all-cause and 132 breast cancer-specific deaths were observed. Among premenopausal patients, current smokers showed a non-significant higher risk of all-cause and breast cancer-specific death. A duration of smoking >21.5 years was positively associated with all-cause (HR = 3.09, 95% confidence interval [CI], 1.17–8.20) and breast cancer-specific death (HR = 3.35, 95% CI: 1.22–9.23, P_trend = 0.035) among premenopausal patients. In premenopausal patients with ER+ or PR+ tumors, there was some suggestion that a longer duration of smoking was associated with higher risk of all-cause and breast cancer-specific death. Passive smoking demonstrated no significant risk. Our results suggest that a longer duration of active smoking is associated with an increased risk of all-cause and breast cancer-specific death among premenopausal patients, possibly with hormonal receptor-positive tumors. Breast cancer patients should be informed about the importance of smoking cessation.

Smoking and mortality after breast cancer diagnosis: the health and functioning in women study

We examined the effect of smoking on long-term mortality from breast cancer and other causes among a cohort of women with breast cancer. A total of 975 women diagnosed with breast cancer and aged 40-84 years were followed for a median follow-up of 11 years in the U.S. Health and Functioning in Women (HFW) study. The impact of the individual smoking status and smoking intensity reported in the first few months following breast cancer diagnosis on the risk of mortality from breast cancer and other causes was examined using Cox proportional hazards models. In this study, former smoking was associated with increased risk of other-cause mortality (hazard ratio [HR] = 1.47, 95% confidence interval [CI]: 1.13-1.90), and the risk doubled with increased intensity (HR for <50 pack-years [py]: 1.36, 95% CI: 1.03-1.79; HR for ≥50 py: 2.45, 95% CI: 1.41-4.23). Current smoking (HR = 2.45, 95% CI: 1.81-3.32) and each additional 10 py smoked (HR = 1.16, 95% CI: 1.11-1.22) were associated with statistically significant increases in the risk of other-cause mortality. The effect of current smoking on other-cause mortality decreased with advancing stage and increasing body mass index (BMI). Breast cancer-specific mortality was associated with current smoking of ≥50 py (HR = 2.36, 95% CI: 1.26-4.44), and each additional 10 py smoked (HR = 1.07, 95% CI: 1.01-1. 14). Current smoking, but not former smoking, was associated with increased risk of breast cancer-specific mortality in women with local disease (HR = 2.32, 95% CI: 1.32-4.09), but not in those with regional and distant disease (HR = 1.10, 95% CI: 0.73-1.68). Our findings suggest that current smoking at the time of breast cancer diagnosis may be associated with increased risk of breast-cancer specific and other-cause mortality, whereas former smoking is associated with increased risk of other-cause mortality. Smoking cessation at the time of diagnosis may lead to better prognosis among women with breast cancer.

Tobacco use in the oncology setting: advancing clinical practice and research

Although tobacco is a well-established causal agent for many human cancers, less emphasis has been placed on translating this evidence by evaluating the effects of continued tobacco use after a cancer diagnosis. A broad assessment of the effects of continued tobacco use demonstrates that tobacco increases cancer treatment toxicity, recurrence, second primary tumors, and mortality in patients with cancer. Few studies report the potential benefits of cessation after a cancer diagnosis, but data suggest improved treatment outcomes in patients with cancer who quit smoking. Improving tobacco cessation treatment efficacy and access to cessation support has been sparsely researched in the oncology setting compared with the general population; however, patients with cancer are receptive to standard evidence-based tobacco cessation guidelines. Several studies demonstrate moderate tobacco cessation success in patients with cancer using the general principles of evidence-based tobacco cessation support. Several systems-level issues and research efforts are needed to standardize tobacco use definitions, increase access to tobacco cessation support, improve tobacco cessation efficacy, understand the time-dependent effects of tobacco and cessation on cancer biology, and realize the potential benefits of tobacco cessation for patients with cancer.

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.

Smoking at time of diagnosis and breast cancer-specific survival: new findings and systematic review with meta-analysis

INTRODUCTION

In women with breast cancer who smoke, it is unclear whether smoking could impair their survival from the disease.

METHODS

We examined the relation of smoking at diagnosis to breast cancer-specific and overall survival among 5,892 women with invasive breast cancer treated in one Canadian center (1987 to 2008). Women were classified as never, former or current smokers. Current smokers were further classified according to total, intensity and duration of smoking. Deaths were identified through linkage to population mortality data. Cox proportional-hazards multivariate models were used. A systematic review with meta-analysis combines new findings with published results.

RESULTS

Compared with never smokers, current smokers at diagnosis had a slightly, but not statistically significant, higher breast cancer-specific mortality (hazard ratio = 1.15, 95% confidence interval (CI): 0.97 to 1.37). Among current smokers, breast cancer-specific mortality increased with total exposure to, intensity and duration of smoking (all Ptrend <0.05). Compared to never smokers, breast cancer-specific mortality was 32 to 56% higher among heavy smokers (more than 30 pack years of smoking, more than 20 cigarettes per day or more than 30 years of smoking). Smoking at diagnosis was associated with an increased all-cause mortality rate. A meta-analysis of all studies showed a statistically significant, 33% increased mortality from breast cancer in women with breast cancer who are smokers at diagnosis compared to never smokers (hazard ratio = 1.33, 95% CI: 1.12 to 1.58).

CONCLUSIONS

Available evidence to date indicates that smoking at diagnosis is associated with a reduction of both overall and breast cancer-specific survival. Studies of the effect of smoking cessation after diagnosis on breast cancer-specific outcomes are needed.

Lifetime cigarette smoking and breast cancer prognosis in the After Breast Cancer Pooling Project

BACKGROUND

There is controversy on whether former smokers have increased risk for breast cancer recurrence or all-cause mortality, regardless of how much they smoked.

METHODS

Data were from three US cohorts in the After Breast Cancer Pooling Project, with detailed information on smoking among 9975 breast cancer survivors. Smoking was assessed an average of 2 years after diagnosis. Delayed entry Cox proportional hazards models were used to examine the relationships of smoking status, cigarettes per day, years of smoking, and pack years with breast cancer prognosis. Endpoints included breast cancer recurrence (n = 1727), breast cancer mortality (n = 1059), and overall mortality (n = 1803).

RESULTS

Compared with never smokers, former smokers with less than 20 pack-years of exposure had no increased risk of any outcome. However, former smokers with 20 to less than 34.9 pack-years of exposure had a 22% increased risk of breast cancer recurrence (hazard ratio [HR] = 1.22; 95% confidence interval [CI] = 1.01 to 1.48) and a 26% increased risk of all-cause mortality (HR = 1.26; 95% CI = 1.07 to 1.48). For former smokers with 35 or more pack-years of exposure, the probability of recurrence increased by 37% (HR = 1.37; 95% CI = 1.13 to 1.66), breast cancer mortality increased by 54% (HR = 1.54; 95% CI = 1.24 to 1.91), and all-cause mortality increased by 68% (HR = 1.68; 95% CI = 1.44 to 1.96). Current smoking increased the probability of recurrence by 41% (HR = 1.41; 95% CI = 1.16 to 1.71), increased breast cancer mortality by 60% (HR = 1.61; 95% CI = 1.28 to 2.03), and doubled the risk of all-cause mortality (HR = 2.17; 95% CI = 1.85 to 2.54).

CONCLUSIONS

Lifetime cigarette smoking was statistically significantly associated with a poor prognosis among women diagnosed with breast cancer, dose-dependent increased risks of recurrence, and breast cancer and all-cause mortality.

Mortality risk in former smokers with breast cancer: pack-years vs. smoking status

It is unclear why successful quitting at time of breast cancer diagnosis should remove risk from a significant lifetime of smoking. Studies concluding this may be biased by how smoking is measured in many epidemiological cohorts. In the late 1990s, a randomized trial of diet and breast cancer outcomes enrolled early-stage female breast cancer survivors diagnosed within the previous 4 years. Smoking history and key covariate measures were available at study entry for 2,953 participants. Participants were followed for an average of 7.3 years (96% response rate). There were 10.1% deaths (83% from breast cancer). At enrollment, 55.2% were never smokers, 41.2% former smokers and 4.6% current smokers. Using current smoking status in a Cox regression, there was no increased risk for former smokers for either all-cause mortality [hazard ratio (HR) = 1.11; 95% confidence interval (CI) = 0.87-1.41; p-value = 0.42) or breast cancer mortality. However, when we categorized on extensive lifetime exposure, former smokers with 20+ pack-years of smoking (25.8%) had a significantly higher risk of both all-cause (HR = 1.77; 95% CI = 1.17-2.48; p-value = 0.0007) and breast cancer-specific mortality (HR = 1.62; 95% CI = 1.11-2.37; p-value = 0.01). Lifetime smoking exposure, not current status, should be used to assess mortality risk among former smokers.

Serum cotinine and prognosis in breast cancer

Various studies have suggested that women who smoke have a worse prognosis if they develop breast cancer. Cotinine levels have been measured in sera from 511 patients with stage I and II breast cancer diagnosed between 1975 and 1980, all of whom had complete follow-up. Although the known prognostic factors, axillary nodal status, tumour size and grade were found to be significant, there was no relationship between serum cotinine and metastasis-free survival. A point estimate of serum cotinine was not found to be a determinant of survival in women with early breast cancer.

Sensitization of epithelial growth factor receptors by nicotine exposure to promote breast cancer cell growth

Introduction

Tobacco smoke is known to be the main cause of lung, head and neck tumors. Recently, evidence for an increasing breast cancer risk associated with tobacco smoke exposure has been emerging. We and other groups have shown that nicotine, as a non-conventional carcinogen, has the potential to facilitate cancer genesis and progression. However, the underlying mechanisms by which the smoke affects the breast, rather than the lung, remain unclear. Here, we examine possible downstream signaling pathways of the nicotinic acetylcholine receptor (nAChR) and their role in breast cancer promotion.

Methods

Using human benign MCF10A and malignant MDA-MB-231 breast cells and specific inhibitors of possible downstream kinases, we identified nAChR effectors that were activated by treatment with nicotine. We further tested the effects of these effector pathways on the regulation of E2F1 activation, cell cycle progression and on Bcl-2 expression and long-term cell survival.

Results

In this study, we demonstrated a novel signaling mechanism by which nicotine exposure activated Src to sensitize epidermal growth factor receptor (EGFR)-mediated pathways for breast cancer cell growth promotion. After the ligation of nAChR with nicotine, EGFR was shown to be activated and then internalized in both MCF10A and MDA-MB-231 breast cancer cells. Subsequently, Src, Akt and ERK1/2 were phosphorylated at different time points following nicotine treatment. We further demonstrated that through Src, the ligation of nicotine with nAChR stimulated the EGFR/ERK1/2 pathway for the activation of E2F1 and further cell progression. Our data also showed that Akt functioned directly downstream of Src and was responsible for the increase of Bcl-2 expression and long-term cell survival.

Conclusions

Our study reveals the existence of a potential, regulatory network governed by the interaction of nicotine and nAChR that integrates the conventional, mitogenic Src and EGFR signals for breast cancer development.

Stage at diagnosis and comorbidity influence breast cancer survival in First Nations women in Ontario, Canada

BACKGROUND

Indigenous populations in Canada and abroad have poorer survival after a breast cancer diagnosis compared with their geographic counterparts; however, the influence of many demographic, personal, tumor, and treatment factors has not been examined to describe this disparity according to stage at diagnosis.

METHODS

A case-case design was employed to compare First Nations (FN) women (n = 287) to a frequency-matched random sample of non-FN women (n = 671) diagnosed with breast cancer within the Ontario Cancer Registry. Women were matched on period of diagnosis (1995-1999 and 2000-2004), age at diagnosis (<50 vs. ≥50), and Regional Cancer Centre (RCC). Stage and other factors were collected from medical charts at the RCCs. Survival was compared using an adjusted Cox proportional hazards model and stratified by stage at diagnosis (I, II, and III-IV). Determinants of survival in FN women stratified by stage at diagnosis were also modeled.

RESULTS

Survival was more than three times poorer for FN women diagnosed at stage I than for non-FN women (HR = 3.10, 95% CI = 1.39-6.88). The risk of death after a stage I breast cancer diagnosis was about five times higher among FN women with a comorbidity other than diabetes (HR = 4.65, 95% CI = 1.39-15.53) and was more than five times greater for women with diabetes (HR = 5.49, 95% CI = 1.69-17.90) than for those without a comorbidity.

CONCLUSIONS

Having a preexisting comorbidity was the most important factor in explaining the observed survival disparity among FN women.

IMPACT

Improving the general health status of FN women could increase their survival after an early-stage breast cancer diagnosis.

Detection of later stage breast cancer in First Nations women in Ontario, Canada

OBJECTIVE

To compare the distribution of stage at breast cancer diagnosis between First Nations (FN) and non-FN women, and to investigate factors associated with later diagnosis in FN women.

METHODS

A case-case design was employed to compare FN women (N = 287) to a frequency-matched random sample of women (N = 671) from the general population diagnosed with breast cancer in the Ontario Cancer Registry. Women were matched (2:1) on period of diagnosis (1995-1999, 2000-2004), age at diagnosis (< 50 vs. > or = 50), and Regional Cancer Centre (RCC). Stage and data relevant to the determinants of stage were collected from medical charts at the RCCs. The association between stage (stage II + vs. I) and FN status was modeled using logistic regression analyses; for FN women, the association between risk factors and stage was examined.

RESULTS

FN women (66%) were diagnosed with a later stage significantly more often than non-FN women (56%). FN women with a non-screened cancer (OR 5.03, 95% CI 2.48-10.21) and those who were overweight or obese (OR 2.98, 95% CI 1.27-6.98 and OR 4.46, 95% CI 1.95-10.21, respectively) were significantly more likely to be diagnosed at a later stage. Having a comorbidity reduced the odds of a later stage (OR 0.51, 95% CI 0.27-0.96) in FN women.

CONCLUSION

This study demonstrates the need for FN women, in particular those who are not accessing the health care system, to participate in breast screening programs aimed at detecting breast cancers earlier with a better prognosis. These findings suggest that the cancer care system in Ontario should better target this population through increasing awareness and access to screening.

Modifiable risk factors and survival in women diagnosed with primary breast cancer: results from a prospective cohort study

This study examines the impact of smoking, body mass index, alcohol consumption, hormone replacement therapy, and physical activity on all-cause mortality among 528 Danish women diagnosed with primary breast cancer. Participants were women enrolled in the Copenhagen City Heart Study. Prospective self-reported exposure information was collected from four points of follow-up in 1976-1978, 1981-1983, 1991-1994, and 2001-2003. Kaplan-Meier survival curves and multivariate Cox regression analyses were performed adjusting for age, disease stage, adjuvant treatment, menopausal status, parity, alcohol intake, smoking, physical activity, body mass index, and hormone replacement therapy. The study shows that smoking for total mortality [hazard ratio, 1.16; 95% confidence interval, 1.05-1.29] and obesity for both total mortality (1.61; 1.12-2.33) and breast cancer-specific mortality (1.82; 1.11-2.99) were significantly associated with decreased survival after breast cancer diagnosis. A moderate alcohol intake of 1-6 units/week (0.85; 0.64-1.12), 7-14 units/week (0.77; 0.56-1.08), and treatment with hormone replacement therapy (0.79; 0.59-1.05) were less than 1, but not statistically significantly associated with prolonged survival. A moderate physical activity of 2-4 h/week (1.07; 0.77-1.49) and a high physical activity of more than 4 h/week (1.00; 0.69-1.45) showed no association with survival after breast cancer diagnosis.

Combination treatment with luteolin and quercetin enhances antiproliferative effects in nicotine-treated MDA-MB-231 cells by down-regulating nicotinic acetylcholine receptors

Large-scale epidemiological cohort studies performed in the United States indicate that breast cancer risk is associated with active and passive smoking. As of yet, however, there is no direct evidence of antitumor effects by agents that block the effect of tobacco compound nicotine (Nic) on relevant nicotinic receptors (nAChR) involved in breast tumorigenesis. In the present study, the expression profiles of different nAChR subunits in the human breast cancer cell line (MDA-MB-231) were characterized by RT-PCR. Nic (>0.1 microM, 6 h) significantly increased alpha9-nAChR mRNA and protein expression levels in human breast cancer cells (MDA-MB-231 cells). On the other hand, combined treatment with luteolin (Lut, 0.5 microM) and quercetin (Que, 0.5 microM) profoundly decreased MDA-MB-231 proliferation by down-regulating alpha9-nAChR expression. MDA-MB-231 cells were cultured in soft agar to evaluate anchorage-independent colony formation; combined treatment of Lut+Que inhibited Nic-induced MDA-MB-231 colony formation. Interestingly, the number of colonies formed was profoundly reduced in alpha9-nAChR knockdown (Si alpha9) cells in the combined (Lut+Que)-treated group as compared to the relevant control groups. Such results show that Lut- or Que-induced antitransforming activities were not limited to specific inhibition of the alpha9-nAChR receptor. Both alpha5- and alpha9-nAChR appear to be important molecular targets for Lut- and Que-induced antitumor effects in human breast cancer cells.

Do lifestyle or social factors explain ethnic/racial inequalities in breast cancer survival?

Despite numerous studies documenting ethnic inequalities in breast cancer survival between minority and majority ethnic groups worldwide, reasons for these inequalities remain unclear. The authors performed a systematic review of published literature to identify studies that investigated the explanatory power of smoking, alcohol consumption, body mass index (BMI), and socioeconomic position (SEP) on ethnic inequalities in breast cancer survival. Sixteen studies were included in the review. From 5 studies, the authors found that differences in breast cancer survival between ethnic groups may be in part explained by BMI, but there was little evidence to implicate smoking or alcohol consumption as explanatory factors of this inequality. From 12 studies, the authors found that SEP explains part of the ethnic inequality in all-cause survival but that it was not evident for breast-cancer-specific survival. SEP explains more of the disparities among African-American versus white women in the United States compared with other ethnic comparisons. Furthermore, given social patterning of BMI and other lifestyle habits, it is possible that results for SEP and BMI are measuring the same effect. In this review, the authors make suggestions regarding the role of epidemiology in facilitating further research to better inform the development of effective policies to address ethnic differences in survival.

Polycyclic aromatic hydrocarbon-DNA adducts and survival among women with breast cancer

Polycyclic aromatic hydrocarbons (PAH) are mammary carcinogens in animal studies, and a few epidemiologic studies have suggested a link between elevated levels of PAH-DNA adducts and breast cancer incidence. An association between PAH-DNA adducts and survival among breast cancer cases has not been previously reported. We conducted a survival analysis among women with newly diagnosed invasive breast cancer between 1996 and 1997, enrolled in the Long Island Breast Cancer Study Project. DNA was isolated from blood samples that were obtained from cases shortly after diagnosis and assayed for PAH-DNA adducts using ELISA. Among the 722 cases with PAH-DNA adduct measurements, 97 deaths (13.4%) from all causes and 54 deaths (7.5%) due to breast cancer were reported to the National Death Index (NDI) by December 31, 2002. Using Cox proportional hazards models and controlling for age at diagnosis, we did not find evidence that all-cause mortality (hazard ratio (HR)=0.88; 95% confidence interval (CI): 0.57-1.37), or breast cancer mortality (HR=1.20; 95% CI: 0.63-2.28) was strongly associated with detectable PAH-DNA adduct levels compared with non-detectable adducts; additionally, no dose-response association was observed. Among a subgroup with treatment data (n=520), adducts were associated with over a two-fold higher mortality among those receiving radiation, but mortality for adducts was reduced among hormone therapy users. Results from this large population-based study do not provide strong support for an association between detectable PAH-DNA adducts and survival among women with breast cancer, except perhaps among those receiving radiation treatment.

Socioeconomic inequalities in cancer survival in New Zealand: the role of extent of disease at diagnosis

We examined socioeconomic inequalities in cancer survival in New Zealand among 132,006 people ages 15 to 99 years who had a cancer registered (1994-2003) and were followed up to 2004. Relative survival rates (RSR) were calculated using deprivation-specific life tables. A census-based measure of socioeconomic position (New Zealand deprivation based on the 1996 census) based on residence at the time of cancer registration was used. All RSRs were age-standardized, and further standardization was used to investigate the effect of extent of disease at diagnosis on survival. Weighted linear regression was used to estimate the deprivation gap (slope index of inequality) between the most and least deprived cases. Socioeconomic inequalities in cancer survival were evident for all of the major cancer sites, with the deprivation gap being particularly high for prostate (-0.15), kidney and uterus (both -0.14), bladder (-0.12), colorectum (-0.10), and brain (+0.10). Accounting for extent of disease explained some of the inequalities in survival from breast and colorectal cancer and melanoma and all of the deprivation gaps in survival of cervical cancer; however, it did not affect RSRs for cancers of the kidney, uterus, and brain. No substantial differences between the total compared with the non-Māori population were found, indicating that the findings were not due to confounding by ethnicity. In summary, socioeconomic disparities in survival were consistent for nearly all cancer sites, persisted in ethnic-specific analyses, and were only partially explained by differential extent of disease at diagnosis. Further investigation of reasons for persisting inequalities is required.

Effect of obesity and other lifestyle factors on mortality in women with breast cancer

A few lifestyle characteristics before cancer diagnosis have been suggested to modify the prognosis of breast cancer. Follow-up information from 1,453 women with incident invasive breast cancer, diagnosed between 1991 and 1994 and interviewed within the framework of an Italian multicenter case-control study, was used to assess the effect of obesity and of a large spectrum of other factors on breast cancer mortality. Five hundred and three deaths, including 398 breast cancer deaths, were identified. Hazard ratios (HR) for all-cause and breast cancer mortality and corresponding 95% confidence intervals (CI), were calculated using Cox proportional hazards models and adjusted for age and breast cancer characteristics (stage and receptor status). Increased risk of death for breast cancer emerged for body mass index (BMI) >/= 30 kg/m(2) (HR = 1.38; 95% CI: 1.02-1.86), compared to <25, or waist-to-hip ratio (WHR) >/= 0.85 (HR = 1.27; 95% CI: 0.98-1.64), compared to <0.80, and the strongest association was observed for women with BMI >/=30 and high WHR (>/=0.85), compared to women with BMI <25 and WHR < 0.85 (HR = 1.57, 95% CI: 1.08-2.27). The unfavorable effect of high BMI was similar in women <55 and >/=55 years of age, whereas it was stronger in women with I-II stage than III-IV stage breast cancer. Low vegetable and fruit consumption and current or past smoking were also associated to marginally worse breast cancer survival. No significant relationship with survival after breast cancer emerged for several other major lifestyle factors, including physical activity, alcohol drinking, exogenous hormones use and fat intake. High BMI was the lifestyle risk factor that most consistently modified breast cancer prognosis in our study.

Passive smoking and breast cancer in never smokers: prospective study and meta-analysis

BACKGROUND

Active smoking has little or no effect on women's risk of developing breast cancer, but it has been suggested that passive exposure to tobacco smoke may increase this risk among women who have never smoked.

OBJECTIVE

To evaluate the possible relationship between passive smoking and breast cancer risk within the Million Women Study, a large UK prospective study, and to report a meta-analysis of published results.

METHODS

In the large prospective study, 224 917 never smokers who completed a questionnaire that asked women whether their parents had smoked and if their current partner smoked were followed up for an average of 3.5 years for incident breast cancer. In the meta-analysis, studies that had recorded exposure information prospectively and retrospectively were considered separately. Main outcome measures Adjusted relative risk of breast cancer in never smokers who were passively exposed to tobacco smoke at various ages compared with never smokers with no such exposure.

RESULTS

In the prospective study, 2518 incident invasive breast cancers occurred during follow-up and the adjusted relative risk of breast cancer for passive exposure either as a child or as an adult vs neither exposure was 0.98 (95% CI 0.88-1.09); results were similarly null for childhood exposure (0.98, 0.88-1.08) and adult exposure (1.02, 0.89-1.16) separately. We identified seven other studies with prospectively recorded exposure data; when results of all eight studies were combined (including 5743 never smokers with breast cancer), the aggregate relative risk was 0.99 (0.93-1.05) for any passive exposure. The aggregate findings differed substantially (P = 0.0002) between these 8 studies and 17 other studies with retrospectively recorded information (including 5696 never smokers with breast cancer).

CONCLUSIONS

Aggregate results from studies with prospectively reported information show that the incidence of breast cancer is similar in women who did and did not report passive exposure to tobacco smoke either as a child or as an adult. The aggregate findings from the retrospective studies may have been distorted by some women becoming more likely to report past exposures because they knew that they had breast cancer.