Breast Cancer Risk Among Women Who Start Smoking as Teenagers

There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

Abstract

Objective: To examine the effect of smoking on breast cancer risk in a large population-based cohort of women, many of whom started smoking as teenagers.

Methods: We followed 102,098 women, ages 30 to 50 years, completing a mailed questionnaire at recruitment to the Norwegian-Swedish Cohort Study in 1991/1992, through December 2000. We used Cox proportional hazard regression models to estimate relative risk (RR) of breast cancer associated with different measures of smoking initiation, duration, and intensity adjusting for confounding variables. We conducted analyses on the entire study population, among women who had smoked for at least 20 years, among nondrinkers, and separately for each country.

Results: Altogether, 1,240 women were diagnosed with incident, invasive breast cancer. Compared with never smokers, women who smoked for at least 20 years and who smoked 10 cigarettes or more daily had a RR of 1.34 (95% CI, 1.06-1.70). Likewise, those who initiated smoking prior to their first birth (1.27, 1.00-1.62), before menarche (1.39, 1.03-1.87), or before age 15 (1.48, 1.03-2.13) had an increased risk. In contrast, women who had smoked for at least 20 years, but started after their first birth, did not experience an increased breast cancer risk. The increased RR associated with smoking was observed among nondrinkers of alcohol, women with and without a family history of breast cancer, premenopausal and postmenopausal women, and in both countries.

Conclusion: Our results support the notion that women who start smoking as teenagers and continue to smoke for at least 20 years may increase their breast cancer risk.

Related collections

Most cited references 29

Record: found
Abstract: not found
Article: not found

Regression Models and Life-Tables

D R Cox (1972)

0 comments Cited 1524 times – based on 0 reviews      Review now

Bookmark

Record: found
Abstract: found
Article: not found

Alcohol, tobacco and breast cancer – collaborative reanalysis of individual data from 53 epidemiological studies, including 58 515 women with breast cancer and 95 067 women without the disease

Jonas Ranstam (2002)

Alcohol and tobacco consumption are closely correlated and published results on their association with breast cancer have not always allowed adequately for confounding between these exposures. Over 80% of the relevant information worldwide on alcohol and tobacco consumption and breast cancer were collated, checked and analysed centrally. Analyses included 58 515 women with invasive breast cancer and 95 067 controls from 53 studies. Relative risks of breast cancer were estimated, after stratifying by study, age, parity and, where appropriate, women's age when their first child was born and consumption of alcohol and tobacco. The average consumption of alcohol reported by controls from developed countries was 6.0 g per day, i.e. about half a unit/drink of alcohol per day, and was greater in ever-smokers than never-smokers, (8.4 g per day and 5.0 g per day, respectively). Compared with women who reported drinking no alcohol, the relative risk of breast cancer was 1.32 (1.19–1.45, P<0.00001) for an intake of 35–44 g per day alcohol, and 1.46 (1.33–1.61, P<0.00001) for ⩾45 g per day alcohol. The relative risk of breast cancer increased by 7.1% (95% CI 5.5–8.7%; P<0.00001) for each additional 10 g per day intake of alcohol, i.e. for each extra unit or drink of alcohol consumed on a daily basis. This increase was the same in ever-smokers and never-smokers (7.1% per 10 g per day, P<0.00001, in each group). By contrast, the relationship between smoking and breast cancer was substantially confounded by the effect of alcohol. When analyses were restricted to 22 255 women with breast cancer and 40 832 controls who reported drinking no alcohol, smoking was not associated with breast cancer (compared to never-smokers, relative risk for ever-smokers=1.03, 95% CI 0.98–1.07, and for current smokers=0.99, 0.92–1.05). The results for alcohol and for tobacco did not vary substantially across studies, study designs, or according to 15 personal characteristics of the women; nor were the findings materially confounded by any of these factors. If the observed relationship for alcohol is causal, these results suggest that about 4% of the breast cancers in developed countries are attributable to alcohol. In developing countries, where alcohol consumption among controls averaged only 0.4 g per day, alcohol would have a negligible effect on the incidence of breast cancer. In conclusion, smoking has little or no independent effect on the risk of developing breast cancer; the effect of alcohol on breast cancer needs to be interpreted in the context of its beneficial effects, in moderation, on cardiovascular disease and its harmful effects on cirrhosis and cancers of the mouth, larynx, oesophagus and liver. British Journal of Cancer (2002) 87, 1234–1245. doi:10.1038/sj.bjc.6600596 www.bjcancer.com © 2002 Cancer Research UK

0 comments Cited 72 times – based on 0 reviews      Review now

Bookmark

Record: found
Abstract: found
Article: not found

Tobacco use and cancer causation: association by tumour type.

Hillechiena Kuper, P Boffetta, H O Adami (2002)

In the second part of our review we describe the association between tobacco use and risk of specific cancer types. There is evidence for an established association of tobacco use with cancer of the lung and larynx, head and neck, bladder, oesophagus, pancreas, stomach and kidney. In contrast, endometrial cancer is less common in women who smoke cigarettes. There are some data suggesting that tobacco use increases the risk for myeloid leukaemia, squamous cell sinonasal cancer, liver cancer, cervical cancer, colorectal cancer after an extended latency, childhood cancers and cancer of the gall bladder, adrenal gland and small intestine. Other forms of cancer, including breast, ovarian and prostate cancer, are unlikely to be linked to tobacco use.