Risk of Cancer and the Oral Contraceptive Pill

Full assessment of the risk of cancer needs a long follow-up as effects of the pill may persist many years after its use has been stopped. Between 1968 and 1969, 45 950 women in the United Kingdom were enrolled in the study, and they were followed for a mean of 24 years. Incidence rates of cancer in women who ever used the pill were compared with rates in women who never used the pill. On balance, no higher risk of cancer was found in pill users. Risks were significantly lower for cancer of the colon or rectum, uterine body, or ovaries; the main gynaecological cancers combined (uterine body, ovaries, cervix); and for any diagnosis of cancer. The incidence of breast cancer was similar in pill users and never users. The results show that—in a developed country with an effective cervical cancer screening programme such as the UK—the pill is a safe contraceptive method with respect to cancer. In some developing countries—with inadequate cervical cancer screening and healthcare services, and high cervical cancer rates—the balance of cancer risk is probably less favourable.However, in such settings, contraceptive benefits must be weighed against the risk of cervical cancer, and the balance would tilt in favour of the pill because of the high morbidity and mortality associated with unplanned pregnancies.
Hannaford et. al., BMJ 2007 335: 651.