Long-term use of Pill 'increases cancer risk'

Long-term use of the contraceptive pill may increase the risk of cervical cancer up to fourfold in women already infected with the virus known to be the main cause of the cancer, researchers say.

Long-term use of the contraceptive pill may increase the risk of cervical cancer up to fourfold in women already infected with the virus known to be the main cause of the cancer, researchers say.

The finding suggests that the hormones in the pill interact with the human papillomavirus (HPV), to cause the cancer. HPV has been known for more than three decades to be linked with cervical cancer but researchers have been trying to identify the other factors that must be present to trigger the malignant disease.

HPV is extremely common in women but most infections of the cervix are transient – they clear up without treatment. Other factors such as smoking, multiple pregnancies and infections such as Chlamydia have been suggested as causing HPV to persist and convert to cancer.

Now researchers from the International Agency for Research on Cancer (IARC) in Lyon, France, have produced the most definitive evidence yet that the contraceptive pill is implicated too.

Their study of 1,900 women showed that they were at up to three times greater risk of developing cervical cancer if they had used the Pill for five years or longer, and at up to four times the risk if they had used it for more than 10 years.

Women who used the Pill for less than five years had no increased risk. There was also no evidence that long-term use increased the risk of cervical cancer in the absence of HPV. The findings, which are to be published in The Lancet this weekend, were released early after they were leaked to another medical journal.

Family planning experts yesterday reassured women that the Pill was still safe provided users attended for regular cervical screening. They pointed out that the study was carried out in the Far East, South America, Spain and Morocco, where access to cervical screening is lower and rates of cervical cancer higher.

The Family Planning Association said: "The overall likelihood of getting cervical cancer in the UK is low whether you use the Pill for a long time or not. This country has a highly effective screening programme for cervical cancer which has proved successful in reducing both the occurrence of the disease and deaths from it. It is vital that women take up the offer of regular cervical screening."

In addition to preventing pregnancy, the Pill also protects against cancer of the ovaries and of the lining of the womb, so the task for women was to weigh up the benefits against the risks, the researchers said.

In a commentary on the findings, to be published in The Lancet, David Skegg, from the University of Otago in New Zealand, said the findings were most important for the developing world. "From a public health point of view, a key question is the extent to which effects persist after women stop taking oral contraceptives. There is now a need to bring together all the relevant data to quantify the effects," he said.

A second study by IARC researchers found that women who had multiple pregnancies were at higher risk of cervical cancer. The researchers suggest that falling birth rates in the developed world could account for the decline in cervical cancer.

* The effects of the Pill on fish in British rivers is to be investigated by government scientists. The hormone oestrogen present in sewage is believed to be a factor in the feminisation of male fish.