Active and passive cigarette smoking and breast cancer risk: Results from the EPIC cohort

• Published in: International journal of cancer Vol. 134; no. 8; pp. 1871 - 1888
• Main Authors: Dossus, Laure, Boutron‐Ruault, Marie‐Christine, Kaaks, Rudolf, Gram, Inger T., Vilier, Alice, Fervers, Béatrice, Manjer, Jonas, Tjonneland, Anne, Olsen, Anja, Overvad, Kim, Chang‐Claude, Jenny, Boeing, Heiner, Steffen, Annika, Trichopoulou, Antonia, Lagiou, Pagona, Sarantopoulou, Maria, Palli, Domenico, Berrino, Franco, Tumino, Rosario, Vineis, Paolo, Mattiello, Amalia, Bueno‐de‐Mesquita, H. Bas, Duijnhoven, Franzel J.B., Bakker, Marieke F., Peeters, Petra HM, Weiderpass, Elisabete, Bjerkaas, Eivind, Braaten, Tonje, Menéndez, Virginia, Agudo, Antonio, Sanchez, Maria‐Jose, Amiano, Pilar, Tormo, Maria‐Jose, Barricarte, Aurelio, Butt, Salma, Khaw, Kay‐Tee, Wareham, Nicholas, Key, Tim J., Travis, Ruth C., Rinaldi, Sabina, McCormack, Valerie, Romieu, Isabelle, Cox, David G., Norat, Teresa, Riboli, Elio, Clavel‐Chapelon, Françoise
• Format: Journal Article
• Language: English
• Published: Hoboken, NJ Wiley-Blackwell 15.04.2014; Wiley Subscription Services, Inc
• Subjects: 1st childbirth; association; Biological and medical sciences; Breast cancer; Breast Neoplasms - chemically induced; Breast Neoplasms - epidemiology; Breast Neoplasms - etiology; california teachers; Cancer; carcinogens; Cohort Studies; Confidence intervals; Dose-Response Relationship, Drug; environmental tobacco-smoke; exposure; Female; Gynecology. Andrology. Obstetrics; Health risk assessment; Humans; Incidence; Mammary gland diseases; Medical research; Medical sciences; metaanalysis; Multiple tumors. Solid tumors. Tumors in childhood (general aspects); never smokers; postmenopausal women; prospective; Prospective Studies; reanalysis; Risk; Risk Factors; second‐hand smoke; Smoking; Smoking - epidemiology; Surveys and Questionnaires; tobacco smoke; Tobacco Smoke Pollution - adverse effects; Tumors; Womens health; Tobacco smoke; Breast disease; Risk; Breast cancer; Malignant tumor; second-hand smoke; Hand; Cigarette; Prospective; Mammary gland diseases; Cancerology; Cohort study; Risk factor; Passive smoking; Cancer; breast cancer; tobacco smoke; prospective
• ISSN: 0020-7136; 1097-0215; 1097-0215
• DOI: 10.1002/ijc.28508

Recent cohort studies suggest that increased breast cancer risks were associated with longer smoking duration, higher pack‐years and a dose‐response relationship with increasing pack‐years of smoking between menarche and first full‐term pregnancy (FFTP). Studies with comprehensive quantitative life‐time measures of passive smoking suggest an association between passive smoking dose and breast cancer risk. We conducted a study within the European Prospective Investigation into Cancer and Nutrition to examine the association between passive and active smoking and risk of invasive breast cancer and possible effect modification by known breast cancer risk factors. Among the 322,988 women eligible for the study, 9,822 developed breast cancer (183,608 women with passive smoking information including 6,264 cases). When compared to women who never smoked and were not being exposed to passive smoking at home or work at the time of study registration, current, former and currently exposed passive smokers were at increased risk of breast cancer (hazard ratios (HR) [95% confidence interval (CI)] 1.16 [1.05–1.28], 1.14 [1.04–1.25] and 1.10 [1.01–1.20], respectively). Analyses exploring associations in different periods of life showed the most important increase in risk with pack‐years from menarche to FFTP (1.73 [1.29–2.32] for every increase of 20 pack‐years) while pack‐years smoked after menopause were associated with a significant decrease in breast cancer risk (HR = 0.53, 95% CI: 0.34–0.82 for every increase of 20 pack‐years). Our results provide an important replication, in the largest cohort to date, that smoking (passively or actively) increases breast cancer risk and that smoking between menarche and FFTP is particularly deleterious. What's new? The EPIC study is the largest cohort analysis on smoking and breast cancer to date. In this analysis of data from that study, the authors have confirmed that both active and passive exposure to cigarette smoke increases breast cancer risk. These results emphasize that it's important to distinguish between passive exposure and no exposure when analyzing the relationship between smoking and breast cancer. The authors also confirm that the most potent window of exposure for smoking and breast cancer risk is between menarche and first full term pregnancy.