How often does endometriosis lead to cancer?

Not Very Often: Although there is an association between endometriosis and cancer it is not common. Ovarian cancer occurs in about 1-1.5% of all women and seems to be slightly more common in women with endometriosis. The exact reason is unknown. But in general it cannot be assumed that every cyst which is seen is endometriosis.

Rare: There have been reports of endometrial cancer arising for endometriosis, but it is quite rare.

Not really : But patients with endometriosis have a higher risk of a specific type of cancer called endometrioid ovarian carcinoma.