wrans/answers2025-08-18 conversation_3
Source: hansard.parliament.uk (2025-08-18)

UK Parliament Hansard data: wrans/answers2025-08-18 conversation_3

Lisa Smart:To ask the Secretary of State for Health and Social Care, if his Department will take steps to support people who have reported (a) long-term health and (b) personal impacts due to being prescribed Diethylstilbestrol (DES) between 1950 and 1980. \p Karin Smyth: The Medicines and Healthcare products Regulatory Agency (MHRA) regulates medicines supplied in the United Kingdom. Our activity spans the whole of a medicine’s lifecycle. Diethylstilboestrol (DES) is an oestrogenic hormone formerly used in the treatment of threatened miscarriage.  In 1971, it was identified in a US study that DES could cause a distinct type of cancer in the daughters of women who took DES in early pregnancy. It was subsequently contraindicated in pregnancy, pre-menopausal women, children and young adults. The issue of DES and vaginal carcinoma in the daughters of women who took DES in pregnancy was reviewed by the predecessor to the Commission on Human Medicines, the Committee on Safety of Medicines (CSM) in the early 1970s. In 1973, the CSM wrote to all doctors to inform them of the results of the US study and the absence of identified cases in the UK.

DES may still be prescribed in the UK for certain types of cancer, including cancer of the prostate and metastatic post-menopausal cancer of the breast. The product information for DES clearly describes the risk of harms related to its use in pregnancy and for this reason its use is contra-indicated in pregnant women; it is not suitable for pre-menopausal women, and should not be prescribed to children or young people due to its carcinogenic potential. The use of DES is now only justified in the management of malignant disease.

The MHRA continuously assesses the benefit risk balance of all medicines at the time of initial licensing and throughout their use in clinical practice, carefully evaluating any emerging evidence on their benefits and risks.

A small increased risk of breast cancer in women who received DES whilst pregnant was first identified in the 1980s and confirmed in further studies in the 1990s, when longer follow up of women who had taken DES was available. No increased risk of other cancers has been established, including endometrial cancer or ovarian cancer.

Since 1992 the National Cancer Institute at the US National Institutes of Health has been conducting the DES Follow-up Study of more than 21,000 mothers, daughters, and sons, exposed in the womb during the mother’s pregnancy, to better understand the long-term health effects of exposure to DES. The findings of this follow up have been published in the scientific literature.

Daughters of individuals exposed to DES are at increased risk of clear cell cancer of the cervix and vagina. The current advice from the UK Health Security Agency is that routine cervical screening is appropriate for those who believed they were exposed to DES in utero; the advice is available at the following link:

https://www.gov.uk/government/publications/cervical-screening-programme-and-colposcopy-management/5-screening-and-management-of-immunosuppressed-individuals

Participation in the National Breast Screening Programme is also recommended. Pregnant women who know that they were exposed in utero to DES should inform their obstetrician and be aware of the increased risks of ectopic pregnancy and preterm labour.