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Long‐term effects of oral contraceptives on ovarian cancer risk
Author(s) -
Bosetti Cristina,
Negri Eva,
Trichopoulos Dimitrios,
Franceschi Silvia,
Beral Valerie,
Tzonou Anastasia,
Parazzini Fabio,
Greggi Stefano,
La Vecchia Carlo
Publication year - 2002
Publication title -
international journal of cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.475
H-Index - 234
eISSN - 1097-0215
pISSN - 0020-7136
DOI - 10.1002/ijc.10696
Subject(s) - medicine , ovarian cancer , odds ratio , gynecology , confidence interval , cancer , risk factor , case control study , breast cancer , obstetrics
Several epidemiologic studies have reported a protective effect of oral contraceptives (OCs) on ovarian cancer. However, there remain open issues, including better quantification of time‐related factors such as time since last use, age at first use and time since first use. We performed a collaborative reanalysis of 6 case‐control studies conducted between 1978 and 1999 in the United Kingdom, Greece and Italy, including a total of 2,768 incident, histologically confirmed cases of epithelial ovarian cancer and 6,274 hospital controls under age 70 years. A reduced risk of ovarian cancer was found for ever‐ compared to never‐users [odds ratio (OR) = 0.66, 95% confidence interval (CI) 0.56–0.79], and a stronger reduction was observed for women who had used OCs for ≥5 years (OR = 0.50, 95% CI 0.33–0.76) compared to those who had used them for <5 years. The protective effect of OCs on ovarian cancer was consistent across strata of age, parity, menopausal status and family history of breast or ovarian cancer. After allowance for duration of use, no other time factor was related to ovarian cancer risk: the reduced risk was similar for women who stopped OC use ≥20 years before compared to <10 years; likewise, no significant modification of risk reduction was observed for age at first OC use and time since first OC use. The present analysis indicates that, after taking into account duration of OC use, the OC protection from ovarian cancer persists for a long time after stopping use. © 2002 Wiley‐Liss, Inc.