Pill's cancer risk 'reversible'

Oral contraceptives increase the risk of developing cervical cancer, but the risk falls once women stop using them, an Oxford-led international study says.

The Lancet study of 52,000 women found the risk increased with the length of time oral contraceptives were used.

But after a 10-year break from the pill, a woman's risk was the same as if she had never taken it, it found.

Experts said the additional risks were small but advised women to have regular cervical screening.

Past work has linked the pill with a higher breast-cancer risk but a lower risk of ovarian and womb cancer.

The international team of researchers looked at more than 52,000 women who had taken part in 24 studies around the world.


The take-home message should be that all women must come for screening when invited
Professor Ciaran Woodman, University of Birmingham

They found that for those who had taken the pill for at least five years, the cervical cancer risk increased to twice that of women who had never taken it.

But the risk fell again once women stopped using oral contraceptives and returned to normal by 10 years.

It is not the first time research has shown a link between the pill and cervical cancer but it had been unclear how long any risk lasted for.

Small risk

Millions of women take the pill in the UK every year.

Overall, the additional risk of cervical cancer associated with the pill is small, the researchers said.

In developed countries, such as the UK, the chance of developing cervical cancer in women who have never used the pill is UK 3.8 in 1,000, rising to 4 per 1000 in those who have taken it for five years, and to 4.5 per 1000 in those who take the pill for 10 years.

In the future, many cases of cervical cancer will be prevented as a result of the government's decision to vaccinate schoolgirls against the virus that causes most cases of the disease.

Study leader Dr Jane Green, a researcher based at Cancer Research UK's epidemiology unit at the University of Oxford, said: "The pill remains one of the most effective forms of contraception, and in the long term the small increases in risk for cervical and breast cancers are outweighed by reduced risks for ovarian and womb cancer."

Professor Peter Sasieni, an expert in cancer epidemiology at the Wolfson Institute of Preventive Medicine in London, said women should be reassured by the results.

"For the individual women regularly going for screening the lifetime risk is more like two in 10,000.

"One in three women will get cancer in their lifetime anyway so the risk is fairly small.

"The important thing in this study is it shows what happens when you stop the pill."

Professor Ciaran Woodman, from the Division of Cancer Studies at the University of Birmingham, said: "In the UK we are fortunate that we have a well organised screening programme and that deaths from cervical cancer are still falling.

"The take-home message should be that all women must come for screening when invited."