The Birth control pills actually DECREASE your chance of endometrial and ovarian cancer. and are the only way to decrease you chance of ovarian cancer (that we know of) other than taking out your ovaries.

If you personally have breast cancer or liver cancer, the pills can make it worse.

There is an association of birth control pills and breast cancer – but that is not certain if that is causation. i.e. Women who delay having kids until they are older increase their chance of breast cancer. Women who are the pill delay having kids. We do know that delaying having kids causes breast cancer, so we think that is most likely what is going with birth control pills and breast cancer.