The risk of cervical cancer may linger for many years despite preventive treatment in high-risk women, according to a new study.

Researchers found that women who had potentially precancerous cells removed from their cervix remain at increased risk for developing cervical cancer for up to 20 years after treatment.

Cervical cancer is one of the leading causes of cancer deaths among women. But the risk of being diagnosed with cervical cancer or dying from it is dramatically lower in countries that have cervical cancer screening programs in place.

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Removing Precancerous Cells

When potentially precancerous cells are found in the cervix through cervical cancer screening, a condition known as cervical intraepithelial neoplasia (CIN), removal of the cells is recommended to reduce the risk of the cells turning into cancer.

If untreated, researchers estimate that about a third of the cases would result in cervical cancer. But it’s unclear what risk of cervical cancer women who have had the treatment face over the long run.

In the study, published in the British Medical Journal, researchers followed more than 7,500 women treated with CIN from 1974 and 2001 in Finland. The women’s cancer status was tracked through the Finnish cancer registry until 2003.

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Lingering Risk

The results showed that 448 new cases of cervical cancer occurred among the women. That's 96 more cases than researchers anticipated using estimates of cervical cancer rates among the general population.

Researchers found that women were at higher than average risk of developing cervical cancer for up to 20 years after their CIN treatment.

They say their findings conflict with previous studies that suggest the risk of cervical cancer did not increase up to eight years after CIN treatment.

The study also showed that the risk of cervical cancer was higher for women treated for mild or moderate types of CIN. Researchers say this may be because women with less serious forms of the condition may be less vigilant about checkups and additional cervical cancer screening than women treated for more severe forms.

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By Jennifer Warner, reviewed by Louise Chang, MD

SOURCES: Kalliala, I. British Medical Journal, Nov. 19, 2005; vol 331: pp 1183-1185. News release, British Medical Journal.