Oral contraceptive pill

Convincing: There is compelling and consistent evidence that the factor increases or decreases the risk of endometrial cancer. Decreases risk

Using an oral contraceptive* is associated with a decreased risk of endometrial cancer. The longer a woman uses an oral contraceptive, the lower her risk of endometrial cancer becomes. This protective effect continues for several decades after a woman stops using an oral contraceptive.

The risk of endometrial cancer has been shown to be around 30% lower in women who use or have previously used an oral contraceptive compared with women who have never used one. An Australian study estimates that use of combined oral contraceptives prevented about 1038 cases of endometrial cancers in 2013.

However, taking combined oral contraceptives is associated with a small increased risk of breast cancer while a woman is currently using it.

The protective effect of oral contraceptives is likely to be due to their effects on female hormones. Increased activity of the hormone oestrogen is associated with an increased risk of endometrial cancer. By reducing the activity of oestrogen, oral contraceptives may reduce the risk of endometrial cancer. 

*Oral contraceptives are also known as birth control pills or ‘the Pill’. Most women use a ‘combined’ oral contraceptive that contains oestrogen and progestogen. Some women (for example women who are breast feeding) use a progestogen-only oral contraceptive.