Arch Intern Med. 2007 Apr 23;167(8):814-20.
Induced and spontaneous abortion and incidence of breast cancer among young women: a prospective cohort study.
Michels KB, Xue F, Colditz GA, Willett WC.
Obstetrics and Gynecology Epidemiology Center, Department of Obstetrics and Gynecology, Brigham and Women's Hospital, Harvard Medical School, Boston, Mass 02115, USA.
Background:
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.
Methods:
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.
Results:
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).
Conclusion:
Among this predominantly premenopausal population, neither induced nor spontaneous abortion was associated with the incidence of breast cancer.
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- 1 What is cancer (malignancy)
- 2 What is meant by cancer staging?
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- 4 How prevalent are womens' cancers?
- 5 What causes cancer?
- 6 Is cancer a hereditary condition?
- 7 How can gynaecological cancer present?
- 8 How can we reduce the risks of the womens' cancers?
Reducing the Risks of Womens' Cancers.
- 9 What are screening tests?
- 10 What are the reactions to a diagnosis of cancer?
- 11 Is there a place for counselling when cancer is diagnosed?
- 12 Can personality alter the prognosis?
- 13 Is the incidence of deaths from the female cancers changing?
- 14 Is there a place for a holistic approach to cancer?
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- 17 How long an interval should there be between cervical screening (smear) (PAP) tests?
- 18 Is there any evidence that cervical screening can reduce the incidence of cervical cancer?
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- 21 Are there screening tests for endometrial cancer?
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- 22a How can endometrial cancer be prevented?
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Cancer of the Ovary.
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- 25 What are tumour markers?
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- 33 What treatment options are available for gynaecological cancer?
- Q32.33c What treatment options are available for ovarian cancer?
Cancer of the Vulva, Vagina and Fallopian Tube
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Breast Cancer
- 35 What is the incidence of breast cancer?
- 35 ?What is the cause of breast cancer?
- 35a What are the advantages of breast cancer screening - mammography - mammograms?
- 14 Is there a place for a holistic approach to cancer?
- 36 How often should breast screening be carried out?
- 37 Are there any problems having a mammogram?
- 38 Should I check myself for breast lumps?
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- 41 What happens if a mammogram shows an abnormality?
- 42 What are the advantages and disadvantages of tamoxifen in the management of breast cancer?
- 42a Breast Cancer Treatment - What is available?
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Web sites and Support Groups
- 44 Are there any support groups?
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- 45 Support Groups.
- 46 Breast Cancer Support Groups
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