Overall oral contraceptives are not associated with an increased risk of cancer. Since they prevent pregnancy and thus the risk of maternal mortality, it is far safer for a woman to take OCs than not take them.
But within these broad statements are detailed changes of risk of various conditions which have been studied to confirm or refute the role of combined estrogen and progesterone medication in their aetiology. One such condition is cervical cancer and OCs have long been linked to its increased risk, with some suggesting their carcinogenic role (Sasieni Lancet 2007;370:1591-2).
Despite the causative nature of HPV in cervical cancer, by no means all such infections lead to malignancy, so the quest is now to find what causes some HPV infections to end up as precancerous or invasive cancer while others regress harmlessly.
Given that recurrent HPV infections are part of the process, contraceptive use has been scrutinised to see if barrier methods reduce risk or hormonal methods increase the risk of recurrent infection. Data have now been published for combined OC use which give consistent results from all around the world by the International Collaboration of Epidemiological Studies of Cervical Cancer - Lancet 2007;370:1609-21. They have shown that using OCs for 5 to 10 years doubles the risk, but this diminishes soon after stopping their use and is negligible after a decade.
The authors point out the absolute risks remain very small and the other factors such as screening, smoking and other infections - especially those associated with altered immunity - are more important in the long-term. So, for women taking OCs in their twenties and thirties in developed countries, the additional risk from OCs of eventually developing cervical cancer is very small - something of the order of 0.002% and, for a woman in sub-Saharan Africa, this rises to 0.4%.
In perspective, OCs and other hormones do fit into the complex pathology of cervical cancer but their aetiological role is minor - in the extreme.
