How many days do you bleed if you have ovarian cancer?

Probably not much: Your question is challenging. Many patients with ovarian cancer don't have vaginal bleeding, which makes screening difficult. Perhaps you are talking about menstrual bleeding--an ovarian cancer should not impact the length of menstrual bleeding in a regular cycle. If you suspect ovarian cancer or have excessive menstrual bleeding, you should check with your doctor asap.

Ovarian cancer: Ovarian cancer does not commonly cause bleeding. If you are having abnormal uterine bleeding or postmenopausal uterine bleeding you need to see a gynecologist to get a biopsy (and probably an ultrasound) done.