The Pill reduces ovarian cancer risk

26th October 2011 - Two new studies have been published on risks and benefits of the contraceptive pill. One confirms that taking the Pill for 10 years or more can help protect against ovarian cancer, and the other confirms a small increased risk of blood clots from newer types of the Pill.

Ovarian cancer and the Pill

Cancer Research UK figures show ovarian cancer is the fifth most common cancer in women in the UK. There are more than 6,500 cases diagnosed every year. Previous studies have also found a protective effect against ovarian cancer from the Pill, and this new research adds to that evidence.

Women who take the Pill for 10 years reduce their risk of developing ovarian cancer by 45%, according to University of Oxford researchers reporting in the British Journal of Cancer. They found the pill was more likely to reduce ovarian cancer risk than getting pregnant or having more than one child.

Overall, women who took the Pill for any length of time lowered their risk by around 15% compared to those who'd never used the Pill. The longer the Pill was taken, the more the risk reduced.

Women who'd had a full-term pregnancy had a 29% lower ovarian cancer risk than those women who had never been pregnant. Having more children further reduced the risk, by 8% for each additional child. There was higher risk of ovarian cancer in women with a late age at menopause, but no association with other reproductive factors. The woman’s age when she started menstruating, age at first full-term pregnancy, incomplete pregnancies, and breastfeeding were not associated with increased risk.

How does the Pill protect against ovarian cancer?

The researchers have only identified that the Pill reduces the risk of getting ovarian cancer, not why. Some experts believe that there's a protective effect from hormones in pregnancy or by taking the Pill.

The same protective effect is not seen in all cancers. The Pill increases a woman's risk of breast cancer, but this risk stops after they stop using contraceptive pills.

In a statement, Dr Richard Edmondson from the University of Newcastle, who is  Cancer Research UK women's cancer expert, says: "Women may be reassured to know that the oral contraceptive is not only an effective contraceptive but can have the added benefit of reducing their risk of ovarian cancer.

"This is however balanced against a slightly increased risk of developing breast cancer. To put this in context, it is estimated that if 100,000 women use the Pill for ten years or more there will be 50 more breast cancers than would have otherwise occurred, but 12 fewer ovarian cancers."

Cancer Research UK also points out there are other important things women can do to reduce their cancer risk, besides having babies and taking the Pill. These include stopping smoking and maintaining a healthy weight.  

The new research is part of a bigger European study called EPIC - European Prospective Investigation of Cancer - which is investigating links between diet, lifestyle and cancer, and is part funded by the charity.