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Oral Contraceptive Use and the Risk of Breast Cancer
in Young Women
In March 1983, preliminary results were published by CDC and
the
National Institute of Child Health and Human Development from the
Cancer and Steroid Hormone Study. This is a case-control study of
breast, endometrial, and ovarian cancer in relation to oral
contraceptive (OC) use. The preliminary findings suggested that
there
is no association between OC use and breast cancer (1). Since
then,
two studies of breast cancer have been published, one suggesting
that
women who use so-called "high-progestogen"* combination-type OCs
before 25 years of age have an increased risk of developing breast
cancer before age 37 (2); the other, that women who use OCs before
their first term birth have an increased risk of developing breast
cancer before age 45 (3). CDC has further analyzed the Cancer and
Steroid Hormone Study data to look at these two specific issues.
Table 1 reports the relative risk of breast cancer by duration
of
use of high-progestogen, combination-type OCs before age 25. No
significant association was found between the use of
high-progestogen
OCs before age 25 and the development of breast cancer before age
37.
Similar results were obtained by using as the reference group women
who had never used OCs and by restricting the analysis to those
women
still nulliparous at age 25. Adjustment for known risk factors for
breast cancer did not appreciably alter the results.
Table 2 shows the relative risk of breast cancer before age 45
in
women who used any OCs before their first full-term pregnancy; only
parous women are included. Women who did not use OCs before their
first full-term pregnancy constituted the reference group. No
significant association was found between use of OCs before first
term
birth and subsequent development of breast cancer by age 45.
Inclusion of nulliparous women and their OC use in this table did
not
substantially alter the risk estimates.
Reported by Epidemiologic Studies Br, Research and Statistics Br,
Div
of Reproductive Health, Center for Health Promotion and Education,
CDC. Editorial Note
Editorial Note: Different studies have reported conflicting results
concerning the risk of breast cancer for young women using OCs
(1-11). It is possible that methodologic differences between the
studies account for the differences. The Cancer and Steroid
Hormone
Study data show that (1) use of "high-progestogen" OCs before age
25
does not increase a woman's risk of developing breast cancer before
age 37, and (2) use of OCs before first full-term pregnancy does
not
increase a woman's risk of developing breast cancer before age 45.
The Cancer and Steroid Hormone Study is a population-based
case-control study. Results were presented in 1983 (1) from the
first
6 months of data collected. The data presented here are from the
complete 29-month data file.
References
The Centers for Disease Control Cancer and Steroid Hormone
Study.
Long-term oral contraceptive use and the risk of breast cancer.
JAMA 1983;249:1591-5.
Pike MC, Henderson BE, Krailo MD, Duke A, Roy S. Breast cancer
in
young women and use of oral contraceptives: possible modifying
effect of formulation and age at use. Lancet 1983;II:926-30.
McPherson K, Neil A, Vessey MP, Doll R. Oral contraceptives
and
breast cancer (Letter). Lancet 1983;II:1414-5.
Paffenbarger RS Jr, Fasal E, Simmons ME, et al. Cancer risk as
related to use of oral contraceptives during fertile years.
Cancer 1977;39:1887-91.
Brinton LA, Williams RR, Hoover RN, Stegens NL, Feinleib M,
Fraumeni JF Jr. Breast cancer risk factors among screening
program participants. J Natl Cancer Inst 1979;62:37-44.
Vessey MP, Doll R, Jones K, McPherson K, Yeates D. An
epidemiological study of oral contraceptives and breast cancer.
Br Med J 1979;1:1757-60.
Royal College of General Practitioners. Breast cancer and oral
contraceptives: findings in Royal College of General
Practitioners' study. Br Med J 1981;282:2089-93.
Pike MC, Henderson BE, Casagrande JT, Rosario I, Gray GE. Oral
contraceptive use and early abortion as risk factors for breast
cancer in young women. Br J Cancer 1981;43:72-6.
Vessey MP, McPherson K, Yeates D, Doll R. Oral contraceptive
use
and abortion before first term pregnancy in relation to breast
cancer risk. Br J Cancer 1982;45:327-31.
Harris NV, Weiss NS, Francis AM, Polissar L. Breast cancer in
relation to patterns of oral contraceptive use. Am J Epidemiol
1982;116:643-51.
Rosenberg L, Miller DR, Kaufman DW, et al. Breast cancer and
oral
contraceptive use. Am J Epidemiol 1984;119:167-76.
*See footnote to Table 1.
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