Skin patches which deliver oestrogen into the blood may be a cheaper and safer treatment for prostate cancer than current therapies, a study says.

The main treatment is injections of a chemical to cut levels of testosterone - the driving force of many prostate cancers - but it causes side effects. The Imperial College London study in the Lancet Oncology compared patches and injections in 254 patients.

It found patches were safe and should avoid menopause-like side effects.

Using oestrogen to treat prostate cancer is an old treatment.

Both oestrogen and testosterone are very similar chemically, so ramping up the levels of oestrogen in the body can reduce the amount of testosterone produced - and slow prostate cancer growth.

However, taking oral oestrogen pills caused significant health problems by overdosing the liver. The organ then produced chemicals which caused blood clots, heart attacks and strokes.

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