The contents of this section were published in 2003 as part of SEER's 30th Anniversary celebration.
The Cancer and Steroid Hormone (CASH) Study was a population-based, case-control study conducted by eight SEER registries during the 1980s to investigate the relationship between oral contraceptive (OC) use and breast, endometrial, and ovarian cancers among U.S. women. The CASH Study found that current or former OC use did not appear to be associated with a significantly increased risk of breast cancer. Such use did appear to decrease the risk of developing ovarian cancer, and the risk of ovarian cancer also appeared to decrease with longer duration of OC use and remained low long after use was stopped. Exclusive use of combination OCs (in which the daily dose contains estrogen plus progestin) appeared to have a protective effect against the development of endometrial cancer. Users of sequential OCs (in which each monthly cycle consists of several days of estrogen followed by fewer days of estrogen-plus-progestin) and of all other OCs (unknown, progestin only, or two or more other OC types) were at greater risk of developing endometrial cancer than were women who had never used OCs.
Among naturally menopausal women, the risk of breast cancer appeared to increase with increasing body mass index. Severely overweight women had nearly a threefold higher risk of breast cancer compared with the leanest women. This trend appeared stronger with increasing years since menopause. A positive association between body mass and breast cancer risk also was observed for premenopausal women, although risk estimates were lower. Substantial weight gain from adolescence to adulthood was a more important risk factor than was lifelong obesity.
A more recent study, the Women's Contraceptive and Reproductive Experiences (Women's CARE) study, corroborated the earlier findings that OC use does not appear to increase the risk of breast cancer in women. This study included women, 35 to 64 years old, who had invasive breast cancer initially diagnosed between 1994 and 1998. The SEER registries in Atlanta, Detroit, Los Angeles, and Seattle provided support for this study.
Centers for Disease Control Cancer and Steroid Hormone Study:
- Long-term oral contraceptive use and the risk of breast cancer. JAMA 1983;249:1591-1595.
- Long-term oral contraceptive use and the risk of ovarian cancer. JAMA 1983;249:1596-1599.
- Oral contraceptive use and the risk of endometrial cancer. JAMA 1983;249:1600-1604.
The Cancer and Steroid Hormone Study of the Centers for Disease Control and the National Institute of Child Health and Human Development. Oral contraceptive use and risk of breast cancer. New Engl J Med 1986;315:405-411.
Chu SY, Lee NC, Wingo PA, Senie RT, Greenberg RS, Peterson HB. The relationship between body mass and breast cancer among women enrolled in the Cancer and Steroid Hormone Study. J Clin Epidemiol 1991;44:1197-1206.
Marchbanks PA, McDonald JA, Wilson HG, Folger SG, Mandel MG, Daling JR, Bernstein L, Malone KE, Ursin G, Strom BL, Norman SA, Wingo PA, Burkman RT, Berlin JA, Simon MS, Spirtas R, Weiss LK. Oral contraceptives and the risk of breast cancer. New Engl J Med 2002;346(26):2025-2032.
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