Cancer of the Cervix and Oral Contraceptives

There is some evidence that long-term use of OCs may increase the risk of cancer of the cervix (the narrow, lower portion of the uterus). The results of a study conducted by scientists at NCI and other cancer centers support a relationship between extended use of the pill (5 or more years) and a slightly increased risk of cervical cancer. However, the exact nature of the association between OC use and risk of cervical cancer remains unclear.

One reason that the association is unclear is that many studies on OCs and cervical cancer have not accounted for the influence of Human Papillomaviruses (HPVs) on cervical cancer risk. HPVs are a group of more than 70 types of viruses, some of which are known risk factors for cervical cancer. Compared to non-OC users, women who use OCs may be less likely to use barrier methods of contraception (such as condoms). Since condoms can prevent the transmission of HPVs, OC users who do not use them may be at increased risk of becoming infected with HPVs. Therefore, the increased risk of cervical cancer that some studies found to be caused by prolonged OC use may actually be the result of undetected HPV infection.

There is evidence that pill users who never use a barrier method of contraception or who have a history of genital infections are at a higher risk for developing cervical cancer. This association suggests the possibility that OCs may act together with sexually transmitted agents (such as HPVs) in the development of cervical cancer. Researchers continue to investigate the exact nature of the relationship between OC use and cancer of the cervix.

OC product labels have been revised to warn of the possible risk of cervical cancer; OC users are advised to have a yearly Pap test to monitor for possible cellular changes in the cervix. 

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