The contraceptive pill, long suspected of causing cancer, actually protects against it, researchers say.
Almost 40 years after fears were first raised about the safety of the Pill, taken by three million women a year in the UK, a study has found the benefits almost certainly outweigh the harm. More than 300 million women worldwide are thought to have used oral contraception in the past four decades.
Researchers who analysed data from one of the longest studies of the Pill, spanning 39 years and run by the Royal College of General Practitioners, have concluded that it cuts the risk of cancer for most women who use it for up to eight years.
The reduction in risk is up to 12 per cent, equivalent to one fewer case of cancer for every 2,200 women taking the Pill for a year. The researchers say the reduction could be lower – 3 per cent – depending on how it is measured, but is still significant. However, women who have taken the Pill for longer than eight years, a quarter of those studied, had a slightly increased risk.
Professor Philip Hannaford of Aberdeen University, who conducted the study published in BMJ Online, said the results showed a small increase in cervical cancer but this was outweighed by reductions in ovarian, womb and bowel cancers. "They are not huge reductions but there are 100 million women taking oral contraceptives in the world and that adds up to an important public health benefit," he said.
Oral contraceptives carry a small risk of triggering blood clots and of causing heart disease and stroke in women who smoke or have high blood pressure. But these risks could be largely controlled if women did not smoke and monitored their blood pressure, Professor Hannaford said.
The study was started in 1968 by Dr Clifford Kay, a Manchester GP, who said there had been a "lurking fear [that] something would pop out of the woodwork. This has shown that it hasn't."