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- Beral, Valerie, et al.
(författare)
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Breast cancer and abortion: collaborative reanalysis of data from 53 epidemiological studies, including 83?000 women with breast cancer from 16 countries
- 2004
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Ingår i: The Lancet. - 1474-547X. ; 363:9414, s. 1007-1016
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The Collaborative Group on Hormonal Factors in Breast Cancer has brought together the worldwide epidemiological evidence on the possible relation between breast cancer and previous spontaneous and induced abortions. METHODS: Data on individual women from 53 studies undertaken in 16 countries with liberal abortion laws were checked and analysed centrally. Relative risks of breast cancer--comparing the effects of having had a pregnancy that ended as an abortion with those of never having had that pregnancy--were calculated, stratified by study, age at diagnosis, parity, and age at first birth. Because the extent of under-reporting of past induced abortions might be influenced by whether or not women had been diagnosed with breast cancer, results of the studies--including a total of 44000 women with breast cancer--that used prospective information on abortion (ie, information that had been recorded before the diagnosis of breast cancer) were considered separately from results of the studies--including 39000 women with the disease--that used retrospective information (recorded after the diagnosis of breast cancer). FINDINGS: The overall relative risk of breast cancer, comparing women with a prospective record of having had one or more pregnancies that ended as a spontaneous abortion versus women with no such record, was 0.98 (95% CI 0.92-1.04, p=0.5). The corresponding relative risk for induced abortion was 0.93 (0.89-0.96, p=0.0002). Among women with a prospective record of having had a spontaneous or an induced abortion, the risk of breast cancer did not differ significantly according to the number or timing of either type of abortion. Published results on induced abortion from the few studies with prospectively recorded information that were not available for inclusion here are consistent with these findings. Overall results for induced abortion differed substantially between studies with prospective and those with retrospective information on abortion (test for heterogeneity between relative risks: chi2(1) =33.1, p<0.0001). INTERPRETATION: Pregnancies that end as a spontaneous or induced abortion do not increase a woman's risk of developing breast cancer. Collectively, the studies of breast cancer with retrospective recording of induced abortion yielded misleading results, possibly because women who had developed breast cancer were, on average, more likely than other women to disclose previous induced abortions.
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| 2. |
- Beral, Valerie, et al.
(författare)
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The number of women who would need to be screened regularly by mammography to prevent one death from breast cancer
- 2011
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Ingår i: Journal of medical screening. - : SAGE Publications. - 1475-5793 .- 0969-1413. ; 18:4, s. 210-212
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Tidskriftsartikel (refereegranskat)abstract
- The number of women who would need to be screened regularly by mammography to prevent one death from breast cancer depends strongly on several factors, including the age at which regular screening starts, the period over which it continues, and the duration of follow-up after screening. Furthermore, more women would need to be INVITED for screening than would need to be SCREENED to prevent one death, since not all women invited attend for screening or are screened regularly. Failure to consider these important factors accounts for many of the major discrepancies between different published estimates. The randomised evidence indicates that, in high income countries, around one breast cancer death would be prevented in the long term for every 400 women aged 50-70 years regularly screened over a ten-year period.
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| 3. |
- of Epidemiological Studies of Cervical Cancer, International Collaboration, et al.
(författare)
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Cervical cancer and hormonal contraceptives: Collaborative reanalysis of individual data for 16 573 women with cervical cancer and 35 509 women without cervical cancer from 24 epidemiological studies
- 2007
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Ingår i: The Lancet. - 1474-547X. ; 370:9599, s. 1609-1621
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Tidskriftsartikel (refereegranskat)abstract
- Background Combined oral contraceptives are classified by the International Agency for Research on Cancer as a cause of cervical cancer. As the incidence of cervical cancer increases with age, the public-health implications of this association depend largely on the persistence of effects long after use of oral contraceptives has ceased. Information from 24 studies worldwide is pooled here to investigate the association between cervical carcinoma and pattern of oral contraceptive use. Methods Individual data for 16 573 women with cervical cancer and 35 509 without cervical cancer were reanalysed centrally. Relative risks of cervical cancer were estimated by conditional logistic regression, stratifying by study, age, number of sexual partners, age at first intercourse, parity, smoking, and screening. Findings Among current users of oral contraceptives the risk of invasive cervical cancer increased with increasing duration of use (relative risk for 5 or more years' use versus never use, 1-90 [95% Cl 1-69-2-13]). The risk declined after use ceased, and by 10 or more years had returned to that of never users. A similar pattern of risk was seen both for invasive and in-situ cancer, and in women who tested positive for high-risk human papillornavirus. Relative risk did not vary substantially between women with different characteristics. Interpretation The relative risk of cervical cancer is increased in current users of oral contraceptives and declines after use ceases. 10 years' use of oral contraceptives from around age 20 to 30 years is estimated to increase the cumulative incidence of invasive cervical cancer by age 50 from 7.3 to 8.3 per 1000 in less developed countries and from 3.8 to 4.5 per 1000 in more developed countries.
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