Based on many clinical studies that involve thousands of women, women who used talcum powder on their genitals have an approximately 30% higher chance of getting ovarian cancer than women who have not. This means over your life, your risk of ovarian cancer increases from 1.3% to 1.7%. That is still a very low risk, but think of it this way: If one million women regularly use talcum powder, 4,000 more of that group will get ovarian cancer at some point.
If you use talcum powder on your genitals, it is advised to dust only the outside of the vagina and not directly on it. There is a chance the powder can work its way through the female reproductive system and lodge in the ovaries, which may cause cancer.