Breast cancer and abortion: collaborative reanalysis of data from 53 epidemiological studies, including 83?000 women with breast cancer from 16 countries.
Valerie Beral, Diana Bull, Richard Doll, Richard Peto, Gillian Reeves, undefined Collaborative Group on Hormonal Factors in Breast Cancer
The Lancet | Elsevier BV | Published : 2004
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 wh..View full abstract