Mads Melbye, M.D., Jan Wohlfahrt, M.Sc., Jørgen H. Olsen, M.D., Morten Frisch, M.D., Tine Westergaard, M.D., Karin Helweg-Larsen, M.D., and Per Kragh Andersen, Ph.D.
Background It has been hypothesized that an interrupted pregnancymight increase a woman's risk of breast cancer because breastcells could proliferate without the later protective effectof differentiation.
Methods We established a population-based cohort with informationon parity and vital status consisting of all Danish women bornfrom April 1, 1935, through March 31, 1978. Through linkagewith the National Registry of Induced Abortions, informationon the number and dates of induced abortions among those womenwas combined with information on the gestational age of eachaborted fetus. All new cases of breast cancer were identifiedthrough linkage with the Danish Cancer Registry.
Results In the cohort of 1.5 million women (28.5 million person-years),we identified 370,715 induced abortions among 280,965 women(2.7 million person-years) and 10,246 women with breast cancer.After adjustment for known risk factors, induced abortion wasnot associated with an increased risk of breast cancer (relativerisk, 1.00; 95 percent confidence interval, 0.94 to 1.06). Noincreases in risk were found in subgroups defined accordingto age at abortion, parity, time since abortion, or age at diagnosisof breast cancer. The relative risk of breast cancer increasedwith increasing gestational age of the fetus at the time ofthe most recent induced abortion: <7 weeks, 0.81 (95 percentconfidence interval, 0.58 to 1.13); >12 weeks, 1.38 (1.00to 1.90) (reference category, 9 to 10 weeks).
Conclusions Induced abortions have no overall effect on therisk of breast cancer.
Source Information
From the Department of Epidemiology Research, Danish Epidemiology Science Center, Statens Serum Institut (M.M., J.W., M.F., T.W., P.K.A.), the Danish Cancer Registry (J.H.O.), and the National Board of Health (K.H.-L.) — all in Copenhagen, Denmark. The views expressed in this paper do not necessarily reflect the position or the policy of the U.S. government.
Address reprint requests to Dr. Melbye at the Department of Epidemiology Research, Danish Epidemiology Science Center, Statens Serum Institut, 5 Artillerivej, DK-2300 Copenhagen S, Denmark.
Britt, K., Ashworth, A., Smalley, M.
(2007). Pregnancy and the risk of breast cancer. Endocr Relat Cancer
14: 907-933
[Abstract][Full Text]
Michels, K. B., Xue, F., Colditz, G. A., Willett, W. C.
(2007). Induced and Spontaneous Abortion and Incidence of Breast Cancer Among Young Women: A Prospective Cohort Study. Arch Intern Med
167: 814-820
[Abstract][Full Text]
Medina, D.
(2005). Mammary developmental fate and breast cancer risk. Endocr Relat Cancer
12: 483-495
[Abstract][Full Text]
Brewster, D. H, Stockton, D. L, Dobbie, R., Bull, D., Beral, V.
(2005). Risk of breast cancer after miscarriage or induced abortion: a Scottish record linkage case-control study. J. Epidemiol. Community Health
59: 283-287
[Abstract][Full Text]
Gierach, G. L., Modugno, F., Ness, R. B.
(2005). Relations of Gestational Length and Timing and Type of Incomplete Pregnancy to Ovarian Cancer Risk. Am J Epidemiol
161: 452-461
[Abstract][Full Text]
Arun, B.
(2004). Ductal Lavage and Risk Assessment of Breast Cancer. The Oncologist
9: 599-605
[Abstract][Full Text]
Steinbrook, R.
(2004). Peer Review and Federal Regulations. NEJM
350: 103-104
[Full Text]
Mahue-Giangreco, M., Ursin, G., Sullivan-Halley, J., Bernstein, L.
(2003). Induced Abortion, Miscarriage, and Breast Cancer Risk of Young Women. Cancer Epidemiol. Biomarkers Prev.
12: 209-214
[Abstract][Full Text]
Moynihan, R., Heath, I., Henry, D., Gotzsche, P. C
(2002). Selling sickness: the pharmaceutical industry and disease mongering * Commentary: Medicalisation of risk factors. BMJ
324: 886-891
[Full Text]
Wohlfahrt, J., Andersen, P. K., Mouridsen, H. T., Melbye, M.
(2001). Risk of Late-stage Breast Cancer after a Childbirth. Am J Epidemiol
153: 1079-1084
[Abstract][Full Text]
Goldacre, M J, Kurina, L M, Seagroatt, V, Yeates, D
(2001). Abortion and breast cancer: a case-control record linkage study. J. Epidemiol. Community Health
55: 336-337
[Full Text]
Gardner, H. P., Ha, S. I., Reynolds, C., Chodosh, L. A.
(2000). The CaM Kinase, Pnck, Is Spatially and Temporally Regulated during Murine Mammary Gland Development and May Identify an Epithelial Cell Subtype Involved in Breast Cancer. Cancer Res.
60: 5571-5577
[Abstract][Full Text]
Melbye, M., Wohlfahrt, J., Lei, U., Pedersen, B. N., Mouridsen, H. T., Lambe, M., Michels, K. B.
(2000). {alpha}-Fetoprotein Levels in Maternal Serum During Pregnancy and Maternal Breast Cancer Incidence. JNCI J Natl Cancer Inst
92: 1001-1005
[Abstract][Full Text]
VAN DE VATHORST, S., ALVAREZ-DARDET, C.
(2000). Doctors as judges: the verdict on responsibility for health. J. Epidemiol. Community Health
54: 162-164
[Full Text]
Kroman, N., Jensen, M.-B., Wohlfahrt, J., Mouridsen, H. T, Andersen, P. K., Melbye, M., Tutt, A., Ross, G.
(2000). Factors influencing the effect of age on prognosis in breast cancer: population based study • Commentary: much still to learn about relations between tumour biology, prognosis, and treatment outcome in early breast cancer. BMJ
320: 474-479
[Abstract][Full Text]
Jordan, V. C., Morrow, M.
(1999). Tamoxifen, Raloxifene, and the Prevention of Breast Cancer. Endocr. Rev.
20: 253-278
[Abstract][Full Text]
Valeur-Jensen, A. K., Pedersen, C. B., Westergaard, T., Jensen, I. P., Lebech, M., Andersen, P. K., Aaby, P., Pedersen, B. N., Melbye, M.
(1999). Risk Factors for Parvovirus B19 Infection in Pregnancy. JAMA
281: 1099-1105
[Abstract][Full Text]
Mehigan, S.
(1998). Induced abortion did not increase the risk of breast cancer. Evid. Based Nurs.
1: 21-21
[Full Text]
(1998). Bibliography. Current Sociology
46: 128-144
Brind, J., Chinchilli, V. M., Senghas, R. E., Dolan, M. F., Melbye, M., Wohlfahrt, J., Andersen, P. K.
(1997). Induced Abortion and the Risk of Breast Cancer. NEJM
336: 1834-1835
[Full Text]
Hartge, P.
(1997). Abortion, Breast Cancer, and Epidemiology. NEJM
336: 127-128
[Full Text]
