The relationship between use of oral contraceptives (OCs) and other contraceptive methods and the risk of ovarian cancer was examined in a combined analysis of 3 hospital-based case-control studies conducted in Italy, the United Kingdom, and Greece, for a total of 971 ovarian cancer cases and 2,258 controls under age 65. Compared with never-users, the combined multivariate relative risk (RR) for ever-users was 0.6 (95% confidence interval, CI = 0.4-0.8) and the estimates were consistent in the 3 datasets. The protection was also similar across strata of age and parity. Considering various measures of OC use, available in the Italian and British datasets only, the protection conveyed on ovarian cancer risk increased with the duration of use and persisted in the medium-long period: the RR in women reporting their last OC use greater than or equal to 15 years prior to diagnosis was 0.5 (95% CI = 0.2-1.0). The risks in ever-users were appreciably lower in those women who reported their first OC use before 25 years of age (RR = 0.3 for first use before age 25, 0.8 for first use at age 25-34 and 0.7 at 35 years or after). Such findings emerged similarly from Italian and British data. This combined analysis, besides offering further quantitative estimates of the protective effects of OCs on ovarian cancer risk in European populations, provides useful insights into the time pattern of the relationship between OC use and ovarian carcinogenesis, suggesting that the protection persists for 15 years or more after cessation of use and may be larger for use at younger age.

Type

Journal article

Journal

Int J Cancer

Publication Date

19/08/1991

Volume

49

Pages

61 - 65

Keywords

Age Factors, Biology, Cancer, Case Control Studies, Contraception, Contraceptive Methods--beneficial effects, Contraceptive Usage, Data Analysis, Demographic Factors, Demographic Impact, Diseases, Economic Factors, Family Planning, Fertility, Fertility Measurements, Neoplasms, Oral Contraceptives--beneficial effects, Ovarian Cancer, Parity, Population, Population Characteristics, Population Dynamics, Research Methodology, Risk Factors, Socioeconomic Factors, Studies, Time Factors, Adult, Age Factors, Aged, Case-Control Studies, Contraceptives, Oral, Epithelium, Europe, Female, Humans, Middle Aged, Ovarian Neoplasms, Parity, Risk Factors, Time Factors