Taking the contraceptive pill does not increase a woman’s chances of developing cancer and may even reduce the risk for most women, according to a study published on British Medical Journal website today.

However, there was an increased risk for women who used it for more than 8 years.

Since its introduction in the early 1960s, more than 300 million women are thought to have used oral contraception. Although several studies have looked at the overall balance of cancer deaths associated with oral contraceptives, none have so far examined the absolute risks or benefits.

Researchers from the University of Aberdeen analysed data spanning a 36 year period from the Royal College of General Practitioners (RCGP) Oral Contraception Study which began in 1968.

The study recruited 46,000 women, with an average age of 29. Approximately half were using oral contraceptives; the other half had never taken it. Every six months their GP provided the study with information on the women’s health.

In addition, three quarters of the women were ‘flagged’ at the NHS central registries so that deaths and cancers were notified to the study even if women had left their recruitment GP.

Professor Philip Hannaford and colleagues used the data to calculate the risk of developing any type of cancer and the main gynaecological cancers combined. They also considered the effects of variables such as age, smoking and social class.

There was no overall increased risk of cancer among pill users, the study revealed. But the researchers did sound a note of caution. When the women were examined by how long they had used the pill, women who used it for more than 8 years – less than a quarter of pill users in the study - had a statistically significant increased risk of developing any cancer, in particular cervical and central nervous system cancer.

However the same women were at reduced risk of developing ovarian cancer.

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

The authors say that many women, especially those who used the first generation of oral contraceptives many years ago, are likely to find the results reassuring:

“In this UK cohort oral contraception was not associated with an overall increased risk of any cancer, indeed it may even produce a net public health gain." 

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