Risk of Ovarian Cancer in Relation to Estrogen and Progestin Dose and Use Characteristics of Oral Contraceptives

Abstract

Although past studies have shown that oral contraceptives with 50 microg or more of estrogen reduce the risk of ovarian cancer, it is not clear whether newer, lower-dose formulations do as well. We conducted a population-based, case-control study in the Delaware Valley to assess the impact of dose of oral contraception on risk of ovarian cancer. Cases aged 20-69 years with a diagnosis of epithelial ovarian cancer ascertained between May 1994 and July 1999 (n = 767) were compared with community controls (n = 1,367). Compared with never users, the adjusted risk of ovarian cancer was reduced by 40% for oral contraceptive users overall, with longer duration of use affording greater protection. The ovarian cancer risk reduction was similar for women who initiated oral contraception before 1972, when high-dose pills dominated the market; between 1972 and 1980; and after 1980, when newer, lower-dose pills dominated. Oral contraceptive estrogen and progestin content were compared for cases and controls after adjustment for current age, number of pregnancies, race, and family history of ovarian cancer. Use of low-estrogen/low-progestin pills afforded an estimated risk reduction (odds ratio = 0.5, 95% confidence interval: 0.3, 0.6) that was identical to that for high-estrogen/high-progestin pills (odds ratio = 0.5, 95% confidence interval: 0.3, 0.7).

Low-dose oral contraceptives: Protective effect on ovarian cancer risk

“…The results were predominantly based on earlier monophasic formulations containing higher doses of ethinyl estradiol rather than formulations which were introduced later. Substantial evidence of a protective effect of lower dose oral contraceptives on ovarian cancer risk was first provided recently by a study conducted in the U.S. 11 Our data from Germany also indicate that the well established protective effect of OC use is not restricted to high-dose formulations only.…”

“…9 These studies, however, included only a relatively small number of users of low dose OC. A recently completed study in the U.S. was first able to show a strong protective effect of both high dose and low dose OC formulations independent of the absolute ethinyl estradiol and progestin content, whereby ethinyl estradiol was dichotomized by 50 g. 11 We have conducted a population-based case-control study designed to determine the effects of different OC formulations on ovarian cancer risk. Our study thus provides the first European data on the relationship between ovarian cancer risk and low-dose oral contraceptives with 35g or less ethinyl estradiol content.…”

Physical activity, body size and composition, and risk of ovarian cancer

“…Established risk factors for ovarian cancer include age, family history, mutations in the BRCA1 and BRCA2 genes, and hereditary non-polyposis colorectal cancer (HNPCC) syndrome [3][4][5][6][7]. Established protective factors include increased parity, use of the oral contraceptive pill, hysterectomy, and tubal ligation [8][9][10][11][12][13][14][15][16][17][18][19][20][21]. Physical activity has been proposed to reduce ovarian cancer risk through a reduction in endogenous oestrogen exposure [22][23][24] and chronic inflammation [25][26][27], anovulation [28,29] and alterations in the function of the immune system [25,30].…”

Contraception for the older woman: an update

“…A more recent case-control study does not confirm the small increased risk in COC users (relative risk 1.0) 26 . During counselling, the risk of breast cancer should be weighed against the protective effects of COCs against endometrial, ovarian, epithelial, and probably colorectal cancers 11,[23][24][25][27][28][29] . Older women should be offered a low-estrogen dose formulation.…”