GP study finds no overall risk of cancer in oral contraception users

Women taking the contraceptive pill can be reassured that it does not increase their chances of developing cancer and may even reduce the risk, say UK researchers.

A 36-year study at the University of Aberdeen found an absolute risk reduction of 10 to 45 per 100 000 woman years for those who use oral contraceptives at some point in their lives.

However, despite this overall net benefit the study did identify a increased risk in any cancer in women who had taken the pill for more than eight years – in particular cervical and central nervous system cancer – although the same women had a reduced risk of ovarian cancer.

In women who had remained registered with their recruiting GP, the RCGP Oral Contraception Study reported a 3% reduced risk of developing any cancer.

In a larger dataset of women who had moved GP but had been flagged up on NHS cancer registries they found a 12% overall reduced risk of cancer.

Evidence suggests that the protective effect of taking the pill lasts for at least 15 years after stopping.

Professor Philip Hannaford said the research, published online in the BMJ covered more than a million women years of observation.

"Many women, especially those who used the first generation of oral contraceptives many years ago, are likely to be reassured.

"These results suggest that, at least in this relatively healthy UK cohort, the cancer benefits associated with oral contraception outweigh the risks."