The contraceptive pill 'can protect you from cancer for 20 years'

The largest study of its kind has found that the longer a woman uses the contraceptive, the less likely she is to develop the disease.

Taking the Pill for five to ten years gives her the best protection when she stops using it, the scientists said.

Even after a 20-year gap, women's chances of developing ovarian cancer are cut by almost half when compared to those who had never used oral contraceptives.

Scroll down for more...

The cancer is diagnosed in 7,000 women in the UK each year, but a lack symptoms in the early stages mean it is often not discovered until it has spread.

It is known as the 'silent killer' because the symptoms are often diagnosed too late - and it kills about 4,600 women each year.

Previous research has recognised that the Pill gives protection against ovarian cancer.

However, experts say this 28-year study into contraceptive methods and the disease, which involved more than 100,000 women, allowed them to examine the long-term effects of different contraceptive methods.

Alarmingly, the U.S. researchers found that the old coil, an intrauterine device, or IUD, fitted in the 1970s and 1980s, increased the risk of the disease by 76 per cent.

It also found that women who were infertile had a 36 per cent increased risk when compared to those who were fertile.

Sterilisation protected women from the cancer, the researchers from the Harvard Medical School in Boston, said.

Those who were sterilised were 34 per cent less likely to develop it than those women who had not been sterilised.

But the most striking finding, published in the American Journal of Epidemiology, was the long-term protective effect of oral contraceptives. It showed that the longer a woman used the Pill, the more protectionshe gained when she finally stopped.

For it to be of benefit, the protection needs to last for a long time, as most cases of ovarian cancer occur in the over-50s.

The protecting effect may come about because women on the Pill do not produce eggs. The normal process of egg release triggers cell damage and repair that raises the risk of tumour development.

Dr Shelley Tworoger, who led the research, said oral contraceptives appear to protect against ovarian cancer for up to 20 years after a women has stopped using them.

But she warned: 'Oral contraceptives are usually taken in young adulthood, but ovarian cancer incidence peaks after menopause.'

Therefore, 'women may not maintain the protective effect of oral contraceptive use to the time of highest incidence'.

Dr Tworoger's team were unsure why the old coil method should pose such a risk to women. They said: 'It is possible that IUD use increases inflammation in the peritoneal cavity, thereby increasing ovarian cancer risk.

'However, most IUD use in our study was in the 1970s-1980s; our risk estimate may not reflect that for newer IUDs.'

Dr Tworoger believes doctors should continue to monitor the disease. She said: 'Future studprotectiveies should continue to examine the potential waning effect of oral contraceptives with longer time since last use.'

They should also 'continue to explore potential associations with other contraceptive methods and infertility', she added.

A spokesman for fpa, formerly the Family Planning Association, said the study confirmed the effect of oral contraception-against ovarian cancer. She said: 'The Pill has many health benefits other than contraception.

'It protects against cancer of the ovaries, of the womb and against colon cancer.

'It can also protect against pelvic inflammatory disease. So if women are at risk from it, they may wish to use the Pill in addition to their normal contraceptive methods.'

The Pill is linked with an increased risk of breast cancer - but only in women taking it before they are 25.

Many studies have provided evidence that the contraceptive gives no increased risk of breast cancer after that age - when many use it on a regular basis.

Some research suggesting the Pill could raise the breast cancer risk involved women taking highdose oestrogen pills in the 1960s and 1970s, which are no longer in use.