Long term use of the contraceptive pill could contribute to a woman's risk of developing cervical cancer, researchers suggest.

Human papillomavirus (HPV) is known to be the cause of most cases of the cancer.

But researchers from Cancer Research UK found the longer a woman took the Pill for, the greater her risk of developing cervical cancer.

They said the pattern remained the same even when other factors, such as HPV infection, smoking and number of sexual partners were taken into account.

They said the use of hormonal contraceptives could be a factor in women developing the disease.

But they stressed more research was needed to show if women remain at an increased risk of cervical cancer after they have stopped taking the Pill.

And they say it is vitally important women continue to be screened for cervical cancer, whether or not they take the Pill.

Around 3,200 women are diagnosed with cervical cancer each year in the UK.

Implications

Researchers from Cancer Research UK's epidemiology unit in Oxford and the international agency for research on cancer reviewed 28 studies, covering around 12,500 women, which had looked at Pill use and cervical cancer.

They found that compared with women who had never used the Pill, women had a 10% increased risk of cervical cancer if they had taken the Pill for less than five years, 60% for five to nine years' use and double the risk if they had taken it for 10 years or more.

Dr Amy Berrington, from the Cancer Research UK epidemiology unit at the Radcliffe Infirmary in Oxford, says: "This study shows that use of hormonal contraceptives for long periods of time may increase the risk of cervical cancer.

"However, the public health implications of these findings largely depend on whether this risk remains long after use of hormonal contraceptives has stopped and this cannot be properly evaluated from published data.

"There is some evidence to suggest that the risk may drop after women stop using the pill but further research is needed to confirm this."

Dr Lesley Walker, director of information at Cancer Research UK said: "Previous studies have shown that the pill may increase the risk of breast cancer and lower the risk of ovarian cancer.

"Now the new data suggests that it could raise the risk of cervical cancer. It's vitally important that we continue to gather all the information we can on cancer risk and the pill so women can make fully informed choices about contraception."

'Low risk'

But Anne Weyman, chief executive of the Family Planning Association, said the benefits of taking the Pill outweighed the risks for most women.

She said: "The Pill is highly effective in preventing pregnancy and reduces the risk of both cancer of the ovaries and womb.

"These findings suggest that the longer a woman uses the pill, the greater her risk of developing cervical cancer, but the UK's national cervical screening programme means the absolute risk of developing cervical cancer remains very low."