Stilbestrol

Indications

Diethylstilbestrol (DES) is a synthetic, non-steroidal oestrogen (female hormone). Today it is used only rarely and under specialist care, mainly in the hormonal treatment of advanced prostate cancer, and occasionally for some advanced breast cancers in women well past the menopause. It was once used in pregnancy, but this stopped decades ago after it was found to harm children exposed before birth.

How It Works

Diethylstilbestrol acts like natural oestrogen in the body. In men with prostate cancer, it signals the brain to reduce the hormones that tell the testes to make testosterone, and so lowers testosterone levels; many prostate cancers need testosterone to grow, so this slows the cancer. It may also have a direct effect on prostate cancer cells.

Dosage and Administration

Used only as prescribed by a cancer specialist. The dose is set individually and treatment is closely monitored. It is often given together with low-dose Aspirin or another blood thinner to reduce the risk of blood clots. Take the tablets at the same time each day and do not stop or change the dose without your doctor's advice.

Interactions

• Medicines that speed up liver enzymes, such as Rifampicin, Carbamazepine, Phenytoin and St John's Wort, may reduce its effect.
• It may change the effect of Warfarin and other anticoagulants, diabetes medicines and blood pressure medicines.
• It may raise levels of some medicines, such as Cyclosporine and certain corticosteroids.
• Smoking increases the risk of blood clots and heart problems with oestrogen treatment.

Contraindications

• Pregnancy, or possible pregnancy.
• Known or suspected oestrogen-dependent cancers (other than when used under specialist care for the cancers above), or undiagnosed vaginal bleeding.
• Current or past blood clots (deep vein thrombosis, pulmonary embolism), stroke or heart attack.
• Severe liver disease.
• Allergy to Diethylstilbestrol.

Side Effects

Common effects include breast tenderness and enlargement (in men), nausea, fluid retention and swelling of the ankles, weight gain, reduced sex drive and erectile problems, and headache.

Serious risks include blood clots in the legs or lungs, heart attack, stroke, heart failure, raised blood pressure, liver problems and high calcium in people with cancer that has spread to the bones.

Get urgent medical help if you have chest pain, sudden breathlessness or coughing blood, pain or swelling in one leg, sudden severe headache, weakness or numbness on one side, trouble speaking or seeing, yellowing of the skin or eyes, or severe stomach pain.

Pregnancy and Lactation

Diethylstilbestrol must not be used in pregnancy. Exposure before birth is known to cause abnormalities of the reproductive organs and a rare vaginal cancer in daughters, and other problems in sons. It must not be used while breastfeeding.

Precautions and Warnings

• Regular check-ups, including blood pressure, heart, liver tests and blood calcium, are needed.
• Tell your doctor if you have heart disease, high blood pressure, diabetes, migraine, epilepsy, kidney or liver disease, or a history of depression.
• Stop smoking; stay active and avoid long periods without moving.
• Your doctor may stop treatment before surgery or long periods of bed rest because of the clot risk.
• People born to mothers who took DES in pregnancy should tell their doctor, as they may need extra health checks.

Overdose

Overdose may cause nausea, vomiting and, in women, vaginal bleeding. Seek medical advice promptly. Treatment is supportive.

Therapeutic Class

Synthetic non-steroidal oestrogen; hormonal antineoplastic agent.

Storage

Store below 30°C in a dry place, away from light and out of the reach of children. Pregnant women should avoid handling broken tablets.