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Des/Stilboestrol

Volume 173: debated on Thursday 24 May 1990

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To ask the Secretary of State for Health (1) what evidence he has on a connection between the use of the drug DES/stilboestrol to treat pregnant women and the incidence of cancer in their daughters in early womanhood;(2) if he has any evidence of effects on the sons of women who have been treated with the drug DES/ stilboestrol during pregnancy;

(3) if there is any evidence that treatment of pregnant women with the drug DES/stilboestrol gives rise to congenital abnormality in future generations.

In 1971 a study was published reporting the occurrence in the United States of America of delayed onset genital tract cancer in the daughters of women treated with stilboestrol in pregnancy. In May 1973 the Committee on Safety of Medicines (CSM) sent a letter to all doctors describing these findings, at which time no cases had been reported in the United Kingdom. A retrospective study by CSM in 1973 did not identify any case of genital tract cancer associated with maternal stilboestrol treatment. It was not until 1978 that the first United Kingdom case was reported in a publication. Further communications in 1981 between the authors and CSM described another patient. It has been estimated in the United States of America that the incidence of genital tract cancer is 1ยท4 per 1,000 women whose mothers received stilboestrol. It has been estimated that in the United Kingdom approximately 7,500 women received stilboestrol during pregnancy; on the basis of the incidence figures in the United States of America, we would expect no more than 11 United Kingdom cases of cancer in the second generation. It is possible that the incidence in the United Kingdom is less, since dosage and pattern of usage have been reported to differ from those of the United States of America.A paper published in 1975 reported cases of congenital structural abnormalities of the male and female genital tract in patients whose mothers were treated with stilboestrol during pregnancy. Since then there have been further published papers.CSM has received no reports of congenital abnormality of the reproductive tract associated with stilboestrol treatment.At present in the United Kingdom, stilboestrol is indicated for the treatment of prostatic cancer, and of breast cancer in postmenopausal women. It is contraindicated in pregnancy.