Case-control study of tobacco smoke exposure and breast cancer risk in Delaware

Health effects associated with exposure to secondhand smoke: a Burden of Proof study

Despite a gradual decline in smoking rates over time, exposure to secondhand smoke (SHS) continues to cause harm to nonsmokers, who are disproportionately children and women living in low- and middle-income countries. We comprehensively reviewed the literature published by July 2022 concerning the adverse impacts of SHS exposure on nine health outcomes. Following, we quantified each exposure-response association accounting for various sources of uncertainty and evaluated the strength of the evidence supporting our analyses using the Burden of Proof Risk Function methodology. We found all nine health outcomes to be associated with SHS exposure. We conservatively estimated that SHS increases the risk of ischemic heart disease, stroke, type 2 diabetes and lung cancer by at least around 8%, 5%, 1% and 1%, respectively, with the evidence supporting these harmful associations rated as weak (two stars). The evidence supporting the harmful associations between SHS and otitis media, asthma, lower respiratory infections, breast cancer and chronic obstructive pulmonary disease was weaker (one star). Despite the weak underlying evidence for these associations, our results reinforce the harmful effects of SHS on health and the need to prioritize advancing efforts to reduce active and passive smoking through a combination of public health policies and education initiatives.

The relationship between tobacco and breast cancer incidence: A systematic review and meta-analysis of observational studies

Background

The effect of tobacco on breast cancer (BC) is controversial. The purpose of this study was to investigate the relationship between tobacco and BC.

Methods

A search was conducted in PubMed, EBSCO, Web of Science and Cochrane Library databases before February 2022. The adjusted odd ratio (OR) and corresponding 95% confidence interval (CI) were used to examine the relationship between active or passive smoking and BC risk.

Results

A total of 77 articles composed of 2,326,987 participants were included for this meta-analysis. Active (OR=1.15, 95% CI=1.11-1.20, p<0.001) and passive (OR=1.17, 95% CI=1.09-1.24, p<0.001) smoking increased the risk of BC in the female population, especially premenopausal BC (active smoking: OR=1.24, p<0.001; passive smoking: OR=1.29, p<0.001), but had no effect on postmenopausal BC (active smoking: OR=1.03, p=0.314; passive smoking: OR=1.13, p=0.218). Active smoking increased the risk of estrogen receptor-positive (ER+) BC risk (OR=1.13, p<0.001), but had no effect on estrogen receptor-negative (ER-) BC (OR=1.08, p=0.155). The risk of BC was positively associated with the duration and intensity of smoking, negatively associated with the duration of smoking cessation. Active smoking increased the risk of BC in the multiparous population (OR=1.13, p<0.001), but had no effect on the nulliparous population (OR=1.05, p=0.432), and smoking before the first birth (OR=1.22, 95% CI=1.17-1.27) had a greater impact on the risk of BC than smoking after the first birth (OR=1.08, 95% CI=1.04-1.12).

Conclusion

Smoking (active and passive) increased the risk of BC in women. The effect of smoking on BC was influenced by smoking-related factors (duration, intensity, years of quitting), population-related factors (fertility status), and BC subtypes.

Systematic Review Registration

identifier CRD42022322699.

Breast cancer awareness package on knowledge, attitude and practice towards breast self examination to prevent breast cancer among women in adopted communities – a pilot analysis

Breast health is extremely important for all women. However, the breast is another region of the human body that is susceptible to cancer. Breast cancer is becoming increasingly common these days, and it is now one of the leading causes of mortality globally. According to the World Health Organization, breast cancer is the most common disease among women worldwide, claiming the lives of hundreds of thousands of women each year and impacting nations at all stages of development. In fact, it is the most common cancer in women, with a significant incidence observed among those aged 30 to 50. The goal of the World Health Organization’s Worldwide Breast Cancer Initiative (GBCI) is to reduce global breast cancer mortality by 2.5 percent each year; As a result, 2.5 million breast cancer deaths will be avoided globally between 2020 and 2040. To achieve these goals, three pillars must be in place: health endorsement for early detection, suitable identification at the right time, and comprehensive breast cancer management. Because of advances in early detection and care, the incidence of women dying of breast cancer has decreased by 41% from 1989 to 2018. During that time, more than 403,000 breast cancer deaths were prevented.

Hair Coloring, Stress, and Smoking Increase the Risk of Breast Cancer: A Case-Control Study

PURPOSE

Epidemiologic characteristics of breast cancer in Iran are significantly different from those in the West and even other regional countries, but little is known about the related factors.

PATIENTS AND METHODS

A hospital-based case-control study was conducted on 1052 women (526 new cases and 526 controls). Logistic regression was performed to investigate associations of study factors with breast cancer risk.

RESULTS

This study introduced occupation (odds ratio [OR]_{employed/household}, 1.77; 95% confidence interval [CI], 1.15-2.69), marital age (OR_{24-30 y/< 18 y}, 2.13; 95% CI, 1.03-4.40), age at first delivery (OR_{≥ 30 y/< 18 y}, 3.53; 95% CI, 1.73-7.18), parity (OR_{1-2/Nulliparous or never married}, 2.61; 95% CI, 1.13-6.02), birth interval (OR_{30-50 mos/< 18 mos}, 2.38; 95% CI, 1.45-3.89), lifetime breastfeeding (OR_{≥ 42 mos/< 6 mos}, 0.37; 95% CI, 0.18-0.77), and menarche age (year) (OR, 0.87; 95% CI, 0.79-0.96) as significant associates of breast cancer. In addition, body mass index (OR, 1.07; 95% CI, 1.02-1.11) and some health-related behaviors including hair coloring on a regular basis (OR_yes/no, 1.93; 95% CI, 1.41-2.62), smoking (OR_yes/no, 2.02; 95% CI, 1.22-3.34), oral contraceptive usage (OR_ever/never. 1.46; 95% CI, 1.05-2.04), physical inactivity (OR_{inactive/regular activity}, 1.54; 95% CI, 1.39-1.75), past life stress (OR_{often stressful/often calm}, 2.40; 95% CI, 1.62-3.56), and regular bedtime (OR_{often regular/no}, 0.32; 95% CI, 0.19-0.54) were related to a higher risk of breast cancer.

CONCLUSION

This study revealed a significant number of factors that seem to contribute to the risk of breast cancer even more than the other previously introduced factors.

Environmental tobacco smoke exposure and risk of breast cancer in nonsmoking women. An updated review and meta-analysis

CONTEXT

In 2006, we reviewed the evidence on environmental tobacco smoke (ETS) and breast cancer in nonsmoking women. Since then various studies and reviews have been published but opinion remains divided.

OBJECTIVE

To provide an updated review.

METHODS

We extracted study details, derived relative risk (RR) estimates with confidence intervals (CIs) for various ETS exposure indices, and conducted meta-analyses.

RESULTS

The update increased the number of studies from 22 to 47. Using an index for each study most closely equivalent to "spouse ever smoked", a weak but significant association was seen (random-effects RR = 1.15, 95% CI = 1.07-1.23). However, the estimates were heterogeneous: higher for Asian studies than for North American or European studies, higher for studies adjusting for fewer potential confounding variables, and close to 1.0 for prospective studies, regardless of whether or not they asked detailed questions on ETS exposure. The RR for eight prospective studies asking detailed questions was 1.003, 95% CI = 0.96-1.05. Risk was increased in premenopausal women (RR = 1.36, 95% CI = 1.15-1.60), but not postmenopausal women. Dose-response findings were similarly heterogeneous. No significant increase was seen for childhood or workplace exposure, but an increase was seen for total exposure (RR = 1.22, 95% CI = 1.09-1.37).

CONCLUSIONS

Increases mainly derived from case-control studies are prone to recall bias. Study weaknesses and possible publication bias limit interpretation. Considering also the weak association of smoking with breast cancer, and the much lower exposures from ETS than from smoking, our analyses do not clearly demonstrate that ETS exposure increases risk of breast cancer in nonsmokers. More research is needed.

Passive Smoking and Breast Cancer Risk among Non-Smoking Women: A Case-Control Study in China

BACKGROUND

The role of passive smoking on breast cancer risk was unclear. This study aimed to evaluate the association between passive smoking and breast cancer risk among Chinese women.

METHODS/PRINCIPAL FINDINGS

A hospital-based case-control study, including 877 breast cancer cases and 890 controls, frequency-matched by age and residence, was conducted. A structured questionnaire was used to collect information on passive smoking history through face-to-face interview by trained interviewers. Unconditional logistic regression models were used to estimate the association between passive smoking and breast cancer risk. A positive association between any passive smoking exposure and breast cancer risk was observed. Compared with women who were never exposed to passive smoking, women who were ever exposed had a higher breast cancer risk, with the adjusted odds ratio (OR) and 95% confidence interval (CI) of 1.35 (1.11-1.65). Similar result was found on home passive smoking exposure and breast cancer risk, but not on workplace passive smoking exposure. Women who were ever exposed to tobacco smoke at home had a higher risk of breast cancer compared with never exposed women, with the adjusted OR (95% CI) of 1.30 (1.05-1.61). Home passive smoking exposure showed significant dose-response relationships with breast cancer risk in smoker-years, cigarettes/day and total pack-years (Ptrend=0.003, 0.006 and 0.009, respectively). An increased total smoker-years of any passive exposure significantly elevated the risk of breast cancer (Ptrend<0.001). Positive associations and dose-response relationships were found among postmenopausal women and all subtypes of estrogen receptor (ER) and progesterone receptor (PR) status of breast cancer.

CONCLUSIONS

Passive smoking was associated with an increased risk of breast cancer among non-smoking Chinese women. A stronger positive association with breast cancer risk was seen mainly among postmenopausal women.

Effect of passive smoking on female breast cancer in China: a meta-analysis

The objective is to explore the relationship between passive smoking and female breast cancer using meta-analysis. Literature on risk factors for female breast cancer published from January 2001 to December 2011 was collected from CBM, CAJD, VIP, WanFangData, and MEDLINE databases. The meta-analysis was performed using Review Manager 5.0.24. A total of 8 studies were included according to inclusion and exclusion standards. The results of the meta-analysis indicated that the combined odds ratio (OR) estimate for those who had been exposed to passive smoke from tobacco was 1.67 (95% confidence interval [CI] = 1.27-2.21). Results of the subgroup analysis were consistent with an OR = 1.98 (95% CI = 1.63-2.42) for 1:1 paired design research and 1.60 (95% CI = 1.08-2.37) for the group design research. Results suggest a possible association between passive tobacco smoke and female breast cancer in China.

Cigarette smoking and breast cancer: a case-control study in Serbia

BACKGROUND

Despite the fact that breast cancer is the most common female cancer worldwide, more than half of the breast cancer risk factors remained unexplained. The aim of this study was to investigate the association of cigarette smoking with risk of breast cancer.

MATERIALS AND METHODS

A case-control study was conducted in the Clinical Centre of Kragujevac, Serbia, covering 382 participants (191 cases and 191 controls). In the analysis of data logistic regression was used.

RESULTS

Breast cancer risk was significantly increased in those who quit smoking at ≤ 50 years of age (OR=2.72; 95% confidence interval - 95%CI=1.02-7.27) and in those who quit smoking less than 5 years before diagnosis of the disease (OR=4.36; 95%CI=1.12-16.88). When smokers were compared with nonsmokers without passive exposure to smoking, former smoking significantly increased breast cancer risk (OR=2.37; 95%CI=1.07-5.24). Risk for breast cancer was significantly increased in those who quit smoking at ≤ 50 years of age (OR=3.29; 95%CI=1.17-9.27) and in those who quit smoking less than 5 years before diagnosis of the disease (OR=5.46; 95%CI=1.34-22.28).

CONCLUSIONS

These data suggest that cigarette smoking is associated with an elevated risk of breast cancer among former smokers in Serbia.

Risk factors for breast cancer in Iranian women: a hospital-based case-control study in tabriz, iran

Purpose

Breast cancer is the most common cancer in women worldwide and the leading cause of cancer death among women. In Asian countries such as Iran, the incidence of breast cancer is increasing. The present study aimed to assess the risk factors for breast cancer of women in Tabriz, Iran.

Methods

A hospital-based case-control study was undertaken to identify breast cancer risk factors. The study consisted of 140 cases confirmed via histopathological analysis and 280 group-matched controls without any malignancy. Data were analyzed using descriptive and inferential statistical methods via the SPSS software version 18.

Results

In a multivariate analysis, educational level (odds ratio [OR], 4.7; 95% confidence interval [CI], 2.11-10.83), menopausal status (OR, 2.54; 95% CI, 1.41-4.59), a high-fat diet (OR, 2.76; 95% CI, 1.51-5.04), abortion (OR, 2.13; 95% CI, 1.20-3.79), passive smoking (OR, 2.76; 95% CI, 1.51-5.04), oral contraceptive use (OR, 3.18; 95% CI, 1.80-5.59), stress (OR, 3.05; 95% CI, 1.74-5.36), and migration (OR, 3.09; 95% CI, 1.39-6.90) were factors associated with a significantly increased risk of breast cancer. Breastfeeding (OR, 0.39; 95% CI, 0.16-0.97) and a diet containing sufficient fruit and vegetables (OR, 0.22; 95% CI, 0.12-0.39) had protective roles against breast cancer.

Conclusion

The study revealed that the risk factors for breast cancer among women in the Tabriz area of Iran are related to the lifestyle. Therefore, the provision of education to change unhealthy lifestyle choices and periodic check-ups for early breast cancer detection are recommended.

Smoking before the first pregnancy and the risk of breast cancer: a meta-analysis

The authors conducted a meta-analysis of the association between smoking before a first pregnancy, when undifferentiated breast tissue may be vulnerable to tobacco carcinogens, and the risk of breast cancer. A search of the published literature through August 2010 identified 23 papers reporting on associations between smoking before a first pregnancy and breast cancer. Odds ratios or hazard ratios and 95% confidence intervals, adjusted for known or suspected breast cancer risk factors, were abstracted from each study. Data were pooled using both fixed- and random-effects models. The fixed-effect summary risk ratio for breast cancer among the women who smoked before their first pregnancy versus women who had never smoked was 1.10 (95% confidence interval: 1.07, 1.14); the random-effects estimate was similar. The separate fixed-effect risk ratios for smoking only before the first pregnancy (5 studies) or only after the first pregnancy (16 studies) were both 1.07, providing no evidence that breast tissue is more susceptible to malignant transformation from smoking before the first pregnancy. While these small summary risk ratios may represent causal effects, residual confounding could readily produce estimates of this size in the absence of any causal effect.

Passive smoking and risk of breast cancer in the California teachers study

BACKGROUND

Although recent reviews have suggested active smoking to be a risk factor for breast cancer, the association with passive smoke exposure remains controversial. This risk association was explored in a large prospective study of women, the California Teachers Study.

METHODS

Detailed lifetime information on passive smoke exposure by setting (home, work, or social) and by age of exposure was collected in 1997 from 57,523 women who were lifetime nonsmokers and had no history of breast cancer. In the ensuing decade, a total of 1,754 women were diagnosed with invasive breast cancer. Cox proportional hazards models were fit to estimate hazard ratios (HR) and 95% confidence intervals (95% CI) associated with several lifetime passive smoke exposure metrics.

RESULTS

For all breast cancer, measures of higher lifetime passive smoking intensity and duration were associated with nonstatistically significant HRs of 1.11 to 1.14. For postmenopausal women, HRs for lifetime low, medium, and high cumulative exposure were 1.17 (95% CI, 0.91-1.49), 1.19 (95% CI, 0.93-1.53), and 1.26 (95% CI, 0.99-1.60). For women exposed in adulthood (age > or =20 years), risk was elevated at the highest level of cumulative exposure (HR, 1.18; 95% CI, 1.00-1.40), primarily among postmenopausal women (HR, 1.25; 95% CI, 1.01-1.56). A statistically significant dose response was detected when analysis was restricted to women with moderate to high levels of passive smoke exposure.

CONCLUSION

These results suggest that cumulative exposures to high levels of sidestream smoke may increase breast cancer risk among postmenopausal women who themselves have never smoked tobacco products.