Do oral contraceptives increase the risk of cancer? The answer is no, but it has taken 40 years to prove it. In 1968 GPs recruited a large group of women who had, or had not, taken oral contraceptives and followed them to see if the pill had carcinogenic effects.
The UK Royal College of GPs has now published the results of over a million women-years and the outcomes are reassuring (Hannaford et al BMJ 2007;335:651-4).
Most of the 46 000 women are now post-menopausal and moving into the years when cancers are more common but pill use is more distant, so the detection of protection or enhancement of risk is now measurable.
Overall, pill-users had a lower risk of cancers of the colon, rectum, uterus, ovaries and tumours of unknown site. The differences were statistically significant trends with absolute values of 1 to 5 per 10 000 women years. The authors believe that today's lower doses of estrogen will have similar effects, so we can reassure our patients that there are benefits rather than risks as far as cancer and the pill are concerned.
