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Ovarian cancer and oral contraceptives: collaborative reanalysis of data from 45 epidemiological studies including 23 257 women with ovarian cancer and 87 303 controls

Calle, E E ; Rodriguez, C ; Talamini, R ; Hankinson, S E ; Tworoger, S S ; Chetrit, A ; Hirsh-Yechezkel, G ; Lubin, F ; Sadetzki, S and Appleby, P , et al. (2008) In The Lancet 371(9609). p.303-314
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

... (More)
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 200 000 ovarian cancers and 100 000 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.

Article Outline (Less)
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author collaboration
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
The Lancet
volume
371
issue
9609
pages
303 - 314
publisher
Elsevier
external identifiers
  • scopus:39749180158
ISSN
1474-547X
DOI
10.1016/S0140-6736(08)60167-1
language
English
LU publication?
yes
id
19780d29-cfb6-4a1f-8037-1f60d5d0f450 (old id 1144004)
date added to LUP
2016-04-04 11:48:05
date last changed
2022-04-24 00:56:53
@article{19780d29-cfb6-4a1f-8037-1f60d5d0f450,
  abstract     = {{Background<br/><br>
<br/><br>
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.<br/><br>
Methods<br/><br>
<br/><br>
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.<br/><br>
Findings<br/><br>
<br/><br>
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&lt;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.<br/><br>
Interpretation<br/><br>
<br/><br>
Use of oral contraceptives confers long-term protection against ovarian cancer. These findings suggest that oral contraceptives have already prevented some 200 000 ovarian cancers and 100 000 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.<br/><br>
Article Outline}},
  author       = {{Calle, E E and Rodriguez, C and Talamini, R and Hankinson, S E and Tworoger, S S and Chetrit, A and Hirsh-Yechezkel, G and Lubin, F and Sadetzki, S and Appleby, P and Banks, E and Beral, V and Berrington de Gonzalez, A and Bull, D and Crossley, B and Goodill, A and Green, I and Green, J and Hermon, C and Key, T and Reeves, G and Collins, R and Doll, R and Peto, R and Gonzalez, C A and Lee, N and Marchbanks, P and Ory, H W and Peterson, H B and Wingo, P A and Martin, N and Pardthaisong, T and Silpisornkosol, S and Theetranont, C and Boosiri, B and Chutivongse, S and Jimakorn, P and Virutamasen, P and Wongsrichanalai, C and Titus-Ernstoff, L and Mosgaard, B J and Vessey, M and Yeates, D and Chang-Claude, J and Rossing, M A and Thomas, D and Weiss, N and Franceschi, S and Bladström, Anna and Olsson, Håkan}},
  issn         = {{1474-547X}},
  language     = {{eng}},
  number       = {{9609}},
  pages        = {{303--314}},
  publisher    = {{Elsevier}},
  series       = {{The Lancet}},
  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}},
  url          = {{http://dx.doi.org/10.1016/S0140-6736(08)60167-1}},
  doi          = {{10.1016/S0140-6736(08)60167-1}},
  volume       = {{371}},
  year         = {{2008}},
}