Induced and spontaneous abortion and incidence of breast cancer among young women - A prospective cohort study
ABSTRACT Induced abortion has been inconsistently associated with breast cancer risk in case-control studies. Retrospective cohort studies using registry information in Scandinavia have not suggested an increase in the incidence of breast cancer, although data on individual reproductive factors were not accounted for.
We examined the association between induced and spontaneous abortion and the incidence of breast cancer in a prospective cohort of young women, the Nurses' Health Study II. The study included 105 716 women 29 to 46 years old at the start of follow-up in 1993. Information on induced or spontaneous abortions was collected in 1993 and updated biennially. During 973 437 person-years of follow-up between 1993 and 2003, 1458 newly diagnosed cases of invasive breast cancer were ascertained.
A total of 16 118 participants (15%) reported a history of induced abortion, and 21 753 (21%) reported a history of spontaneous abortions. The hazard ratio for breast cancer among women who had 1 or more induced abortions was 1.01 (95% confidence interval, 0.88-1.17) after adjustment for established breast cancer risk factors; among women with 1 or more spontaneous abortions, the covariate-adjusted hazard ratio was 0.89 (95% confidence interval, 0.78-1.01). The relation between induced abortion and the incidence of breast cancer did not differ materially by number of abortions (P for trend = .98), age at abortion (P for trend = .68), parity (P for interaction = .54), or timing of abortion with respect to a full-term pregnancy (P for interaction = .10).
Among this predominantly premenopausal population, neither induced nor spontaneous abortion was associated with the incidence of breast cancer.
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ABSTRACT: The purpose was to investigate the prevalence rate, characteristics and related factors of breast cancer among women in Eastern China. A total of 122,058 female subjects completed the study, with 320 confirmed cases of breast cancer (crude prevalence: 262.5/100,000; standardized prevalence: 207.7/100,000). Among all of the identified breast cancer cases, 91.6% were diagnosed after the age of 35 and 60.0% were diagnosed before menopause. The odds ratios (95% confidence interval) of those breast cancer risk factors as selected through multivariate logistic regression were as follows: 5.438 (1.553-19.004) for family history of breast cancer, 3.556 (1.880-6.728) for high behavior intervention score, 3.556 (0.904-13.994) for history of diabetes, 3.357 (1.131-9.969) for history of benign breast tumors, 2.196 (1.355-3.556) for poor overall life satisfaction, 1.826 (0.995-3.350) for premenopause of breast cancer, 1.528 (1.083-2.155) for high BMI index, 1.500 (0.920-2.446) for poor financial status, 1.497 (1.014-2.211) for multiple miscarriages/abortions, and 1.231 (0.972-1.559) for infrequent consumption of garlic (frequent garlic consumption is a protective factor). There were significantly more cases of breast cancer diagnosed prior to menopause than after menopause, and most of the patients were diagnosed after the age of 35. These findings suggest that attention should be focused on the incidence of breast cancer among premenopausal women older than 35.PLoS ONE 06/2012; 7(6):e37784. DOI:10.1371/journal.pone.0037784 · 3.53 Impact Factor
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ABSTRACT: Breast cancer is the most prevalent type of cancer among Iranian females; it is noteworthy that the condition of this type of cancer among Iranian women does not significantly differ from what has been reported from other countries. Considering the importance of this issue, identification of the backgrounds factors and risk factors of the breast cancer risk are highly needed. Therefore, the present study is aimed to compare the risk factors of resident patients of Isfahan province, Iran, with accredited risk factors by other countries and also identify the importance of each factor in the incidence of cancer.International Journal of Health Promotion and Education 06/2014; 3:69. DOI:10.4103/2277-9531.134818