A woman who currently takes oral contraceptives runs a higher risk of developing cancer of the cervix, compared to a woman who has never taken oral contraceptives. However, this raised risk goes back to normal levels ten years after the woman stops using them, according to an article published in The Lancet, this weeks edition.

Dr. Jane Green, Cancer Epidemiology Unit, University of Oxford, UK and team from the International Collaboration of Epidemiological Studies of Cervical collected and re-examined data from 24 studies from around the globe, involving 16,000 women with cervical cancer and 35,000 healthy women.

The study found, as had previous ones, that the longer a woman has been taking oral contraceptives the higher is her risk of developing invasive cervical cancer. A woman who has been taking oral contraceptives for 5 consecutive years (and is still taking them) runs approximately twice the risk compared to a woman who has never used them. This new study, unlike the previous ones, shows how long the higher risk persists after the woman stops using oral contraceptives. The researchers explain that a similar pattern of risk was observed both for invasive and in-situ cancer, and also in women who tested positive for the high-risk type of HPV (human papillomavirus) which causes cancer of the cervix.

“The incidence of cervical cancer increases with age and so the contribution of hormonal contraceptives to the lifetime incidence of cervical cancer will depend largely on the effects at older ages, when most women are past users,” the researchers point out.

The researchers also estimate that 10 years’ use of oral contraceptives from about age 20-30 years raises the cumulative incidence of invasive cervical cancer by age 50 from 2.8 to 4.5 per 1,000 women in industrialized countries, and from 7.3 to 8.3 per 1,000 women in developing countries.

“However, these results need to be seen in context – in the long term the extra risk of cervical cancer in oral contraceptive users is more than outweighed by a reduction in risk of ovarian and endometrial cancers,” the researchers say (this quote is not in the paper).

Accompanying Comment

Dr Peter Sasieni, Wolfson Institute of Preventive Medicine, Queen Mary University of London, UK, writes that this study will lead to a better understanding of the cofactors that impact cervical cancer. The results, which show a small increase in absolute risk, should reassure women that fear of cervical cancer should not be a reason not to use oral contraceptives.

“Cervical cancer and hormonal contraceptives”
International Collaboration of Epidemiological Studies of Cervical Cancer

“Cervical cancer prevention and hormonal contraception”
P Sasieni

The Lancet Volume 370 • Number 9599 • November 10 – 16, 2007

Written by׃ Christian Nordqvist