Risk of cancer and the oral contraceptive pill

In the preface to the first comprehensive publication from the Royal College of General Practitioners' oral contraception study Sir Richard Doll wrote, “Final judgement [on the safety of the pill] must still await the passage of time, when observations can be made of women who have used the pill for 10 or 20 years.”1 Thirty years later, in this week's BMJ, Hannaford and colleagues2 report incidence rates of cancer in relation to use of the pill among women in the study cohort.

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. 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. 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; …