In:
Cancer Research, American Association for Cancer Research (AACR), Vol. 73, No. 8_Supplement ( 2013-04-15), p. 134-134
Abstract:
Purpose - Recent studies suggest that the period before the first childbirth is important in the relation between smoking and risk of breast cancer. We wanted to examine this association with focus on smoking duration before the first childbirth. Methods - We followed 302,865 Norwegian women born between 1899 -1975 and identified 7,490 cases of primary invasive breast cancer cases during & gt; 4.1 million person years of observation (mean 14 person years). We used Cox proportional hazard models to find hazard ratios (HR) with 95 % confidence intervals (CIs) adjusting for age, education, parity, age at first childbirth, BMI and physical activity. Information came from a questionnaire and a physical examination at enrolment, and from linkages to national registries. Results - Compared with women who had never smoked, current smokers had a 14% [HR= 1.14 (95% CI 1.08-1.20)] and former smokers a 17% [HR=1.17 (95% CI 1.10-1.24)] increased risk of breast cancer. Ever smokers who started to smoke after their first childbirth did not have an increased risk [HR=0.93 (95% CI 0.86-1.02)], compared with never smokers. Those who had smoked for more than 20 years, and who had smoked 11 or more of those years before the first childbirth, showed a doubling in risk [HR=1.97 (95% CI 1.33-2.93)] compared with those starting to smoke after the first childbirth. Conclusions - Our study suggests that duration of smoking before the first childbirth is a key factor in the relationship between smoking and breast cancer. Citation Format: Eivind Bjerkaas, Ranjan Parajuli, Anders Engeland, Gertraud Mascarinec, Randi Selmer, Elisabete Weiderpass, Inger Torhild Gram. Smoking duration before first childbirth: An emerging risk factor for breast cancer? Results from the Norwegian National Health Service Cohort (NHHS). [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 134. doi:10.1158/1538-7445.AM2013-134
Type of Medium:
Online Resource
ISSN:
0008-5472
,
1538-7445
DOI:
10.1158/1538-7445.AM2013-134
Language:
English
Publisher:
American Association for Cancer Research (AACR)
Publication Date:
2013
detail.hit.zdb_id:
2036785-5
detail.hit.zdb_id:
1432-1
detail.hit.zdb_id:
410466-3
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