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Risk of breast cancer among young women: relationship to induced abortion.
J Natl Cancer Inst 1994; 86(21):1584-92JNCI

Abstract

BACKGROUND

Certain events of reproductive life, especially completed pregnancies, have been found to influence a woman's risk of breast cancer. Prior studies of the relationship between breast cancer and a history of incomplete pregnancies have provided inconsistent results. Most of these studies included women beyond the early part of their reproductive years at the time induced abortion became legal in the United States.

PURPOSE

We conducted a case-control study of breast cancer in young women born recently enough so that some or most of their reproductive years were after the legalization of induced abortion to determine if certain aspects of a woman's experience with abortion might be associated with risk of breast cancer.

METHODS

Female residents of three counties in western Washington State, who were diagnosed with breast cancer (n = 845) from January 1983 through April 1990, and who were born after 1944, were interviewed in detail about their reproductive histories, including the occurrence of induced abortion. Case patients were obtained through our population-based tumor registry (part of the Surveillance, Epidemiology, and End Results Program of the National Cancer Institute). Similar information was obtained from 961 control women identified through random digit dialing within these same counties. Logistic regression analysis was used to estimate odds ratios and confidence intervals (CIs).

RESULTS

Among women who had been pregnant at least once, the risk of breast cancer in those who had experienced an induced abortion was 50% higher than among other women (95% CI = 1.2-1.9). While this increased risk did not vary by the number of induced abortions or by the history of a completed pregnancy, it did vary according to the age at which the abortion occurred and the duration of that pregnancy. Highest risks were observed when the abortion was done at ages younger than 18 years--particularly if it took place after 8 weeks' gestation--or at 30 years of age or older. No increased risk of breast cancer was associated with a spontaneous abortion (RR = 0.9; 95% CI = 0.7-1.2).

CONCLUSION

Our data support the hypothesis that an induced abortion can adversely influence a woman's subsequent risk of breast cancer. However, the results across all epidemiologic studies of this premise are inconsistent--both overall and within specific subgroups. The risk of breast cancer should be reexamined in future studies of women who have had legal abortion available to them throughout the majority of their reproductive years, with particular attention to the potential influence of induced abortion early in life.

Authors+Show Affiliations

Division of Public Health Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA 98104.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

7932822

Citation

Daling, J R., et al. "Risk of Breast Cancer Among Young Women: Relationship to Induced Abortion." Journal of the National Cancer Institute, vol. 86, no. 21, 1994, pp. 1584-92.
Daling JR, Malone KE, Voigt LF, et al. Risk of breast cancer among young women: relationship to induced abortion. J Natl Cancer Inst. 1994;86(21):1584-92.
Daling, J. R., Malone, K. E., Voigt, L. F., White, E., & Weiss, N. S. (1994). Risk of breast cancer among young women: relationship to induced abortion. Journal of the National Cancer Institute, 86(21), pp. 1584-92.
Daling JR, et al. Risk of Breast Cancer Among Young Women: Relationship to Induced Abortion. J Natl Cancer Inst. 1994 Nov 2;86(21):1584-92. PubMed PMID: 7932822.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Risk of breast cancer among young women: relationship to induced abortion. AU - Daling,J R, AU - Malone,K E, AU - Voigt,L F, AU - White,E, AU - Weiss,N S, PY - 1994/11/2/pubmed PY - 1994/11/2/medline PY - 1994/11/2/entrez KW - Abortion, Induced KW - Age Factors--women KW - Americas KW - Biology KW - Breast Cancer KW - Cancer KW - Case Control Studies KW - Demographic Factors KW - Developed Countries KW - Diseases KW - Family Planning KW - Fertility Control, Postconception KW - Fetus KW - Gestational Age KW - Maternal Age KW - Neoplasms KW - North America KW - Northern America KW - Parental Age KW - Population KW - Population Characteristics KW - Pregnancy KW - Reproduction KW - Research Report KW - Risk Factors KW - Studies KW - United States KW - Washington SP - 1584 EP - 92 JF - Journal of the National Cancer Institute JO - J. Natl. Cancer Inst. VL - 86 IS - 21 N2 - BACKGROUND: Certain events of reproductive life, especially completed pregnancies, have been found to influence a woman's risk of breast cancer. Prior studies of the relationship between breast cancer and a history of incomplete pregnancies have provided inconsistent results. Most of these studies included women beyond the early part of their reproductive years at the time induced abortion became legal in the United States. PURPOSE: We conducted a case-control study of breast cancer in young women born recently enough so that some or most of their reproductive years were after the legalization of induced abortion to determine if certain aspects of a woman's experience with abortion might be associated with risk of breast cancer. METHODS: Female residents of three counties in western Washington State, who were diagnosed with breast cancer (n = 845) from January 1983 through April 1990, and who were born after 1944, were interviewed in detail about their reproductive histories, including the occurrence of induced abortion. Case patients were obtained through our population-based tumor registry (part of the Surveillance, Epidemiology, and End Results Program of the National Cancer Institute). Similar information was obtained from 961 control women identified through random digit dialing within these same counties. Logistic regression analysis was used to estimate odds ratios and confidence intervals (CIs). RESULTS: Among women who had been pregnant at least once, the risk of breast cancer in those who had experienced an induced abortion was 50% higher than among other women (95% CI = 1.2-1.9). While this increased risk did not vary by the number of induced abortions or by the history of a completed pregnancy, it did vary according to the age at which the abortion occurred and the duration of that pregnancy. Highest risks were observed when the abortion was done at ages younger than 18 years--particularly if it took place after 8 weeks' gestation--or at 30 years of age or older. No increased risk of breast cancer was associated with a spontaneous abortion (RR = 0.9; 95% CI = 0.7-1.2). CONCLUSION: Our data support the hypothesis that an induced abortion can adversely influence a woman's subsequent risk of breast cancer. However, the results across all epidemiologic studies of this premise are inconsistent--both overall and within specific subgroups. The risk of breast cancer should be reexamined in future studies of women who have had legal abortion available to them throughout the majority of their reproductive years, with particular attention to the potential influence of induced abortion early in life. SN - 0027-8874 UR - https://www.unboundmedicine.com/medline/citation/7932822/Risk_of_breast_cancer_among_young_women:_relationship_to_induced_abortion_ L2 - https://academic.oup.com/jnci/article-lookup/doi/10.1093/jnci/86.21.1584 DB - PRIME DP - Unbound Medicine ER -