Footnotes for "The Politics of Breast Cancer Research," by Rachel Mary MacNair
"An epidemiological study
of cancer in Japan" Segi, M., I. Fukushima, and M. Kurihara
GANN 48(Supp): 1(1957) Reported a higher rate of both spontaneous
and induced abortions among breast cancer patients; increased
risk ranged from 100% to 400% among the different subgroups in
"Epidemiology of cancer
of the uterine cervix and corpus, breast and ovary in Israel and
New York City" Stewart, H.L. and L.J. Dunham J. Natl.
Cancer Inst. 37:1-95(1966) More Israeli breast cancer patients
had pregnancies which terminated in the first trimester than did
the control group.
"Lactation and reproductive
histories of breast-cancer patients in Tokyo, Japan" Yuasa,
S. and B. MacMahon Bull. WHO 42:195-204(1970) "There
was a significant excess of [cancer] cases reporting one or more
of cancer of the breast in Taiwan" Lin, T.M., K.P. Chen,
and B. MacMahon Cancer 27:1497-1504(1970) Women with one
or more abortions had a cancer risk 50% higher than that of women
who did not; with two or more abortions, the risk rose to 100%
"Breast cancer in an area
of high parity" Mirra, P. P. Cole, and B. MacMahon Cancer
Res. 31:77-83(1971) In a Brazilian study, more breast cancer
patients reported having had abortions than did the control group.
"Breast Cancer in pre-menopausal
and post-menopausal women"
Stavraky, K. and S. Emmons J Natl. Cancer Inst. 53:647-654(1974) Thirty-seven percent of patients who developed breast cancer after menopause had had at least one abortion, while only 27% of women with other cancers reported having had an abortion.
"Risk factors of breast
cancer in Finland" Soini, I.
Intl. J. Epidemiol. 6:365-373(1977) Rate of breast cancer among women in Finland increased with number of abortions.
"An epidemiologic study
of breast cancer" Choi, N.W., G.R. Howe, A.B. Miller, V.
Matthews, R.W. Morgan, L. Munan, J.D. Burch, J. Feather, M. Jain,
and A. Kelly Amer J. Epidemiol. 107:510-521(1978) Women
whose pregnancies lasted four months or less showed a statistically
significant increase in breast cancer.
"The role of reproductive
history in breast cancer causation" Dvoirin, V.V. and A.B.
Medvedev Methods and results of studies of breast cancer epidemiology,
53-56. Tallinn, Estonia (in Russian)(1978) Case-control study
in the North Caucasus, Soviet Union, found an increased risk in
women with three or more induced abortions of 240%. With one or
two induced abortions, the increase in risk was 100%.
"A review of the epidemiology
of human breast cancer" Kelsey, J.L. Epidemiol. Rev.
1:74-109(1979) "Pregnancies of less than four to five months
duration may be associated with an increased risk."
"Susceptibility of mammary
gland to carcinogenesis: Pregnancy interruption as a risk factor."
Russo, J., Russo, I.H. American Journal of Pathology
100:497-512(1980). The breast tissue of rats is similar to that
of humans, and this study in rats found that animals who had an
induced abortion were at the same risk of breast cancer as animals
treated with a chemical typically used to induce cancer in rats.
Whether the developmental mechanisms are the same in women requires
further study, of course, but this study was cited by the National
Women's Health Network as giving a plausible explanation for why
there should be a connection.
"Oral contraceptive use
and early abortion as risk factors for breast cancer in young
women" Pike, M.C., B.E. Henderson, J.T. Casagrande, I. Rosario,
and G.E. Gray Brit. J. Cancer 43:72-76(1981) First trimester
abortion of first pregnancies led to increased risk of 140% (2.4
times) among women under 32.
in the aetiology of breast cancer" Brinton, L.A., R. Hoover,
and J.F. Fraumeni, Jr. Brit. J. Cancer 47:757-782(1983)
Raw numbers in this study nearly duplicate Pike's findings two
as one indicator of poor prognosis in T1, T2, No, Mo primary breast
cancer" Ownby, H.E., S. Martino, L. D. Roi, L. Howard, J.
Russo, S. Brooks, and M.J. Brennan
Breast Cancer Res. Treat. 3:339-344(1983) Women with one abortion had twice as many recurrences of cancer as those with none; women with two or more abortions had three times as many cases of cancer.
"Occurrence of breast
cancer in relation to diet and reproductive history: a case-control
study in Fukuoka, Japan" Hirohata, T., T. Shigematsu, A.M.Y.
Nomura Natl. Cancer Inst. Mono. 69:187(1985) After multiple
logistic regression analysis, risk among women with any induced
abortion was 52% higher than from women who had no abortions.
"Abortion before first
live birth and risk of breast cancer" Hadjimichael, O.C.,
C.A. Boyle, and J.W. Meigs Brit. J. Cancer 53:281-284(1986)
Abortion before first live birth, after adjusting for other known
risk factors, increased risk by 250% (3.5 times).
of breast cancer in Norther Italy" La Vecchia, C., A. Decarli,
F. Parazzini, A. Gentile, E. Negi, G. Cecchetti and S. Franceschi
Intl. J. Epidemiol. 16:347-355(1987) Risk among Italian women
with one or more legal abortions before first live birth was increased
by 42%. Researchers reported "little relation of breast cancer
risk with abortions or miscarriages", and this study is cited
as one to make the connection inconclusive. Yet it did show a
positive increase when only the abortion of a first pregnancy
"Risk of breast cancer
in relation to reproductive factors in Denmark" Ewertz, M.
and S.W. Duffy Brit. J. Cancer 58:99-104(1988) Termination
of first pregnancy before 28 weeks increased risk by 43% ; two
or more abortions before the first full pregnancy increased the
risk by 73%; one induced abortion with no live births increased
risk by 285%.
"Risk factors for breast
cancer in Chinese women in Shanghai" Yuan, J.M., M.C. Yu,
and R.K. Ross Cancer Res. 48:1949(1988)
Among Chinese women who developed breast cancer before the age of 40, abortion before first full-term pregnancy led to increased risk of 140%.
"Breast cancer and pregnancy:
the ultimate challenge" Clark, R.M. and T. Chua Clin.
Oncol. Royal Coll. Radiol. 1:11-18(1989) Among women who developed
cancer while pregnant: those who carried pregnancy to term had
a 20% survival rate; women who miscarried received more aggressive
treatment and had a 42% survival rate, but every woman who chose
"Early abortion and breast-cancer
risk among women under 40" Howe, Holly, R.T. Senie, H. Bzduch,
and P. Herzfeld Int. J. Epidemiol. 18:300-304(1989) Abortion
of first pregnancy led to increased risk of 90% (1.9 times). Repeated
abortions heightened risk by 300%.
"Risk of cancer of the
breast after legal abortion during first trimester: A Swedish
register study" Lindefors-Harris, B.M., G. Edlund, O. Meirik,
L.E. Rutqvist, and K. Wiklund Brit. Med. J. 299:1430-1432(1989)
Women who had an abortion before a live birth had an 88% greater
risk of breast cancer than did women who had a live birth before
"Proliferation and DNA
ploidy in malignant breast tumors in relation to early oral contraceptive
use and early abortions"
Olsson, H., J. Ranstam, B. Baldetop, S.-B. Ewers, M. Ferno, D. Killander, H. Sigurdsson Cancer 67:1285-1290(1991) Abortion of first pregnancy led to more aggressive tumors.
"Her-2/neu and INT2 proto-oncogene
amplification in malignant breast tumors in relation to reproductive
factors and exposure to exogenous hormones" Olsson, H., A.
Borg, M. Ferno, J. Ranstam, and H. Sidgurdsson J Natl. Cancer
Breast cancers of women who aborted their first pregnancy showed many times the normal rate of INT2, a specific gene associated with breast cancer.
"Spontaneous and induced
abortions and risk of breast cancer"
Parazzini, F., C. La Vecchia, and E. Negri Int. J. Cancer 48:816-820(1991) Legal abortions in Italy before first birth led to increased risk of 30%. Again, a report cited as showing no relation between abortion and live birth, but actually containing data showing one with abortion of the first pregnancy is considered..
"Variations in the risk
of breast cancer associated with a family history of breast cancer
according to age at onset and reproductive factors" Andrieu,
Nadine, et. al.J. Clin. Epidemiol. 46:973-980(1993)Researchers
found no statistically significant abortion-related increase in
breast cancer risk for women in general, but made the statistically
significant finding that women with a family history of breast
cancer were 280% more likely to get cancer if they had had two
or more abortions.
"Breast cancer risk factors
in African-American women: the Howard University Tumor Registry
experience," Laing, Amelia, et. al.
J. Natl. Med. Assoc. 85:931-939(1993) Shows a 50% increase in risk at or near the age of 40, a 180% increase in risk between 40-49, and a 370% increase for women 50 and older.
"Role of genetic and reproductive
factors in breast cancer" Genetic Epidemiol. 11:285(1994).
Did show an increase in risk, though not one that could eliminate
the possibility of chance.
"Reproductive and lifestyle
risk factors for breast cancer in African-American women"
Genetic Epidemiol. 11:285(1994) Done under a National Cancer
Institute grant, this was a follow-up to the exploratory research
at Howard University of the previous year. The study shows a significantly
significant 144% increase in breast cancer risk for women who
have had abortions.
"Does abortion increase
breast cancer risk?" J. Natl. Cancer Inst. 85:1987-88(1993)
Dr. Janet Daling is quoted as saying, "There is a 50% to
90% increase in risk for women who had an abortion before the
age of 18." This large-scale study was done at the Fred Hutchinson
Cancer Research Center in Seattle, and more extensive findings
from this study will be out in the Fall of 1994.
"Risk of breast cancer
among young women: relationship to induced abortion," Daling,
Jnet. J. Natl. Cancer Inst. 86:1584(1994). This study found
a 50% increased chance of breast cancer for women under 45, and
a higher risk when the first abortion was prior to 18 years of
Information on the studies
cited was supplied by Scott Somerville, Esq.--Ed.