@article{3151049,
    title = "Oral contraceptive use and reproductive factors and risk of ovarian
cancer in the European Prospective Investigation into Cancer and
Nutrition",
    author = "Tsilidis, K. K. and Allen, N. E. and Key, T. J. and Dossus, L. and and Lukanova, A. and Bakken, K. and Lund, E. and Fournier, A. and Overvad, and K. and Hansen, L. and Tjonneland, A. and Fedirko, V. and Rinaldi, S. and and Romieu, I. and Clavel-Chapelon, F. and Engel, P. and Kaaks, R. and and Schuetze, M. and Steffen, A. and Bamia, C. and Trichopoulou, A. and and Zylis, D. and Masala, G. and Pala, V. and Galasso, R. and Tumino, R. and and Sacerdote, C. and Bueno-de-Mesquita, H. B. and van Duijnhoven, F. J. B. and and Braem, M. G. M. and Onland-Moret, N. C. and Gram, I. T. and and Rodriguez, L. and Travier, N. and Sanchez, M-J and Huerta, J. M. and and Ardanaz, E. and Larranaga, N. and Jirstrom, K. and Manjer, J. and Idahl, and A. and Ohlson, N. and Khaw, K-T and Wareham, N. and Mouw, T. and Norat, and T. and Riboli, E.",
    journal = "British Journal of Cancer",
    year = "2011",
    volume = "105",
    number = "9",
    pages = "1436-1442",
    publisher = "Nature Publishing Group",
    issn = "0007-0920, 1532-1827",
    doi = "10.1038/bjc.2011.371",
    keywords = "reproductive history; oral contraceptive use; ovarian cancer; cohort
study",
    abstract = "BACKGROUND: It is well established that parity and use of oral
contraceptives reduce the risk of ovarian cancer, but the associations
with other reproductive variables are less clear.
METHODS: We examined the associations of oral contraceptive use and
reproductive factors with ovarian cancer risk in the European
Prospective Investigation into Cancer and Nutrition. Among 327 396
eligible women, 878 developed ovarian cancer over an average of 9 years.
Hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated
using Cox proportional hazard models stratified by centre and age, and
adjusted for smoking status, body mass index, unilateral ovariectomy,
simple hysterectomy, menopausal hormone therapy, and mutually adjusted
for age at menarche, age at menopause, number of full-term pregnancies
and duration of oral contraceptive use.
RESULTS: Women who used oral contraceptives for 10 or more years had a
significant 45% (HR, 0.55; 95% CI, 0.41-0.75) lower risk compared with
users of 1 year or less (P-trend, <0.01). Compared with nulliparous
women, parous women had a 29% (HR, 0.71; 95% CI, 0.59-0.87) lower
risk, with an 8% reduction in risk for each additional pregnancy. A
high age at menopause was associated with a higher risk of ovarian
cancer (>52 vs <= 45 years: HR, 1.46; 95% CI, 1.06-1.99; P-trend,
0.02). Age at menarche, age at first full-term pregnancy, incomplete
pregnancies and breastfeeding were not associated with risk.
CONCLUSION: This study shows a strong protective association of oral
contraceptives and parity with ovarian cancer risk, a higher risk with a
late age at menopause, and no association with other reproductive
factors. British Journal of Cancer (2011) 105, 1436-1442.
doi:10.1038/bjc.2011.371 www.bjcancer.com Published online 13 September
2011 (C) 2011 Cancer Research UK"
}