@article{3137859,
    title = "Ovarian cancer and oral contraceptives: collaborative reanalysis of data
from 45 epidemiological studies including 23 257 women with ovarian
cancer and 87 303 controls",
    author = "Beral, V. and Doll, R. and Hermon, C. and Peto, R. and Reeves, G. and and Brinton, L. and Green, A. C. and Marchbanks, P. and Negri, E. and Ness, and R. and Peeters, P. and Vessey, M. and Calle, E. E. and Rodriguez, C. and and Dal Maso, L. and Talamini, R. and Cramer, D. and Hankinson, S. E. and and Tworoger, S. S. and Chetrit, A. and Hirsh-Yechezkel, G. and Lubin, F. and and Sadetzki, S. and Appleby, P. and Banks, E. and de Gonzalez, A. and Berrington and Bull, D. and Crossley, B. and Goodil, A. and Green, I. and and Green, J. and Key, T. and Collins, R. and Gonzalez, C. A. and Lee, and N. and Ory, H. W. and Peterson, H. B. and Wingo, P. A. and Martin, N. and and Pardthaisong, T. and Silpisornkosol, S. and Theetranont, C. and and Boosiri, B. and Chutivongse, S. and Jimakorn, P. and Virutamasen, P. and and Wongsrichanalai, C. and Titus-Ernstoff, L. and Mosgaard, M. J. and and Yeates, D. and Chang-Claude, J. and Rossing, M. A. and Thomas, D. and and Weiss, N. and Franceschi, S. and La Vecchia, C. and Adami, H. O. and and Magnusson, C. and Riman, T. and Weiderpass, E. and Wolk, A. and Brinton, and L. A. and Freedman, D. M. and Hartge, P. and Lacey, J. M. and Hoover, R. and and Schouten, L. J. and van den Brandt, P. A. and Chantarakul, N. and and Koetsawang, S. and Rachawat, D. and Graff-Iversen, S. and Selmer, R. and and Bain, C. J. and Green, A. C. and Purdie, D. M. and Siskind, V. and Webb, and P. M. and McCann, S. E. and Hannaford, P. and Kay, C. and Binns, C. W. and and Lee, A. H. and Zhang, M. and Nasca, P. and Coogan, P. F. and Kelsey, and J. and Paffenbarger, R. and Whittemore, A. and Katsouyanni, K. and and Trichopoulou, A. and Trichopoulos, D. and Tzonou, A. and Dabancens, A. and and Martinez, L. and Molina, R. and Salas, O. and Goodman, M. T. and and Laurie, G. and Carney, M. E. and Wilkens, L. R. and Bladstrom, A. and and Olsson, H. and Ness, R. B. and Grisso, J. A. and Morgan, M. and Wheeler, and J. E. and Peeters, P. and Casagrande, J. and Pike, M. C. and Ross, R. K. and and Wu, A. H. and Kumle, M. and Lund, E. and McGowan, L. and Shu, X. O. and and Zheng, W. and Farley, T. M. M. and Holck, S. and Meirik, O. and and Risch, H. A. and Collaborative Grp Epidemiological",
    journal = "The Lancet Neurology",
    year = "2008",
    volume = "371",
    number = "9609",
    pages = "303-314",
    publisher = "EXCERPTA MEDICA INC-ELSEVIER SCIENCE INC",
    doi = "10.1016/s0140-6736(08)60167-1",
    abstract = "Background Oral contraceptives were introduced almost 50 years ago, and
over 100 million women currently use them. Oral contraceptives can
reduce the risk of ovarian cancer, but the eventual public-health
effects of this reduction will depend on how long the protection lasts
after use ceases. We aimed to assess these effects.
Methods Individual data for 23 257 women with ovarian cancer (cases) and
87 303 without ovarian cancer (controls) from 45 epidemiological studies
in 21 countries were checked and analysed centrally. The relative risk
of ovarian cancer in relation to oral contraceptive use was estimated,
stratifying by study, age, parity, and hysterectomy.
Findings Overall 7308 (31%) cases and 32 717 (37%) controls had ever
used oral contraceptives, for average durations among users of 4 . 4 and
5 . 0 years, respectively. The median year of cancer diagnosis was 1993,
when cases were aged an average of 56 years. The longer that women had
used oral contraceptives, the greater the reduction in ovarian cancer
risk (p<0. 0001). This reduction in risk persisted for more than 30
years after oral contraceptive use had ceased but became somewhat
attenuated over time the proportional risk reductions per 5 years of use
were 29% (95% CI 23-34%) for use that had ceased less than 10 years
previously, 19% (14-24%) for use that had ceased 10-19 years
previously, and 15% (9-21%) for use that had ceased 20-29 years
previously. Use during the 1960s, 1970s, and 1980s was associated with
similar proportional risk reductions, although typical oestrogen doses
in the 1960s were more than double those in the 1980s. The incidence of
mucinous tumours (12% of the total) seemed little affected by oral
contraceptives, but otherwise the proportional risk reduction did not
vary much between different histological types. In high-income
countries, 10 years use of oral contraceptives was estimated to reduce
ovarian cancer incidence before age 75 from 1 . 2 to 0 . 8 per 100 users
and mortality from 0 . 7 to 0 . 5 per 100; for every 5000 woman-years of
use, about two ovarian cancers and one death from the disease before age
75 are prevented.
Interpretation Use of oral contraceptives confers long-term protection
against ovarian cancer. These findings suggest that oral contraceptives
have already prevented some 200000 ovarian cancers and 100000 deaths
from the disease, and that over the next few decades the number of
cancers prevented will rise to at least 30 000 per year."
}